| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| Safe working load (Unit N) | 安全工作负荷（单位：N） |
The steady or unsteady load against which a component or structure is designed for normal operation. It is lower than that which would cause failure by buckling, fracture, or yielding, so as to accommodate uncertainty, possible fault or accident conditions. 部件或结构设计用于正常运行的稳定或不稳定荷载。该值低于因屈曲、断裂或屈服而导致失效的值，以适应不确定性、可能的故障或事故条件。 |
| Safety valve (safety-relief valve) | 安全阀（安全泄压阀） |
A mechanical valve, fitted by law to all pressure vessels (e.g. steam boilers), which opens to prevent the internal pressure exceeding the maximum design value for that vessel. The valve closes again once the pressure reduces to a safe level. 根据法律安装在所有压力容器（如蒸汽锅炉）上的机械阀，其打开以防止内部压力超过该容器的最大设计值。一旦压力降至安全水平，阀门将再次关闭。 |
| Salt bath heat treatment | 盐浴热处理 |
Heat treatment carried out in a bath of molten salt. 在熔融盐浴中进行的热处理。 |
| Salt-velocity meter | 盐速计 |
A volume flow meter based on detecting the transit time for a small quantity of salt or radioactive isotope in a flow by measuring electrical conductivity or radiation level. 一种体积流量计，通过测量电导率或辐射水平来检测流量中少量盐或放射性同位素的渡越时间。 |
| Sample average | 样本平均值 |
The sum of all the observed values in a sample divided by the sample size. It is a point estimate of the population mean. Also known as arithmetic mean. 样本中所有观察值的总和除以样本大小。它是总体平均值的点估计。也称为算术平均值。 |
| Sample median | 样本中间值 |
The middle value when all observed values in a sample are arranged in order of magnitude. If an even number of samples are tested, the average of the two middlemost values is used. It is a point estimate of the population median, or 50% point. 当样本中的所有观测值按数量级排列时的中间值。如果测试的样本数为偶数，则使用两个中间值的平均值。这是人口中位数的一个点估计值，或50%的点。 |
| Sample percentage | 样本百分比 |
The percentage of observed values between two stated values of the variable under consideration. It is a point estimate of the percentage of the population between the same two stated values. 所考虑变量的两个规定值之间的观测值百分比。它是对相同两个规定值之间的总体百分比的点估计。 |
| Sample standard deviation (s) | 样本标准偏差（s） |
The square root of the sample variance. It is a point estimate of the population standard deviation, a measure of the “spread”of the frequency distribution of a population. This value of sprovides a statistic that is used in computing interval estimates and several test statistics. For small sample sizes, s underestimates the population standard deviation. 样本方差的平方根。它是总体标准偏差的点估计，是总体频率分布“扩散”的度量。SPR的这个值提供了一个用于计算区间估计和若干测试统计量的统计量。对于小样本，s低估了总体标准偏差。 |
| Sample variance (s²) | 样本方差（s²） |
The sum of the squares of the differences between each observed value and the sample average divided by the sample size minus one. It is a point estimate of the population variance. 每个观测值与样本平均值之差的平方和除以样本大小减1。它是总体方差的点估计。 |
| Sampling | 抽样 |
The process of measuring a series of values of a time-varying quantity. 测量一系列时变量值的过程。 |
| Sampling frequency (Unit Hz) | 采样频率（单位Hz） |
(sampling rate) The number of measurement samples per unit time taken from a continuous analogue signal to produce a discrete signal. It is the inverse of the time between successive measurements (sampling interval, sampling period, or sampling time). （采样率）从连续模拟信号中提取以产生离散信号的每单位时间的测量样本数。它是连续测量之间时间的倒数（采样间隔、采样周期或采样时间）。 |
| Sawing | 锯切 |
Sawing is the process of cutting a workpiece with power band saws, hacksaws, and circular saws. Each of these methods is used in cutoff operations (cutting pieces to a required length), although band sawing also provides a method of cutting contours. 锯切是用带锯、钢锯和圆锯切割工件的过程。这些方法中的每一种都用于切割操作（将工件切割到所需长度），尽管带锯也提供了一种切割轮廓的方法。 |
| Scale effect | 规模效应 |
The change in behaviour with size of a material, component, or structure. For example, cube-square scaling where one element changes with volume and another with area, as in the range of a projectile or ship, droplet formation, and fracture mechanics. 性能随材料、部件或结构尺寸的变化。例如，立方体平方比例，其中一个元素随体积变化，另一个元素因面积变化，如在射弹或飞船的射程、液滴形成和断裂力学中。 |
| Scale height (Unit m) | 刻度高度（单位：m） |
The altitude H at which the atmospheric pressure has decreased to a certain fraction of its value at sea level B. It depends on the model adopted for the atmosphere: for an isothermal atmosphere, the pressure decreases exponentially with altitude. If H is taken as the altitude at which the pressure has fallen to B/e, then H = RT/g where R is the gas constant for air, T is the absolute temperature T, and g is the acceleration due to gravity. 大气压力降低到其在海平面B处数值的某一部分的高度H。它取决于大气采用的模型：对于等温大气，压力随高度呈指数下降。如果取H作为压力下降到B/e的高度，则H=RT/g，其中R是空气的气体常数，T是绝对温度T，g是重力引起的加速度。 |
| Scatter | 分散 |
Data points or calculations are said to be scattered when they are not all the same. A ‘‘lot of scatter in preload’’ means wide variation in the preloads found in individual bolts. 当数据点或计算不尽相同时，它们被称为分散的。“预载的大量分散”意味着单个螺栓中的预载差异很大。 |
| Scleroscope hardness number (HSc or HSd) | 硬化镜硬度值（HSc或HSd） |
A number related to the height of rebound of a diamond-tipped hammer dropped on the material being tested. It is measured on a scale determined by dividing into 100 units the average rebound of the hammer from a quenched(to maximum hardness) and untempered AISI W5 tool steel test block. 与落在被测材料上的菱形锤的回弹高度相关的数字。通过将锤子从淬火（达到最大硬度）和未淬火的AISI W5工具钢试块上的平均回弹分为100个单位来测量。 |
| Scleroscope hardness test | 反跃式硬度试验 |
A dynamic indentation-hardness test using a calibrated instrument that drops a diamond-tipped hammer from a fixed height onto the surface of the material being tested. The height of rebound of the hammer is a measure of the hardness of the material. Also known as Shore hardness test. 使用校准仪器的动态压痕硬度测试，该仪器将金刚石锤从固定高度落在被测材料表面上。锤的回弹高度是材料硬度的一种度量。也称为肖氏硬度测试。 |
| Scoring | 划痕 |
In tribology, a severe form of wear characterized by the formation of extensive grooves and scratches in the direction of sliding. 在摩擦学中，一种严重的磨损形式，其特征是在滑动方向上形成大面积的凹槽和划痕。 |
| Scragging machine | 刮擦机 |
1. A machine to test springs by impulsive loading 2. A machine to increase the service life of coil springs by compressing them to their minimum solid length before use, thereby inducing favourable residual stresses. 1.一种通过冲击载荷测试弹簧的机器2.一种在使用前将螺旋弹簧压缩至其最小实心长度以提高其使用寿命的机器，从而产生有利的残余应力。 |
| Scratch hardness | 划痕硬度 |
The resistance of a material, such as a metal, alloy, plastic, or mineral, to scratching by a much harder indenter, such as a diamond stylus, moved slowly across the surface. The scratch hardness number is computed from the loads and the dimensions of the residual scratch. 一种材料（如金属、合金、塑料或矿物）对更硬的压头（如金刚石触针）划伤的抵抗力，在表面上缓慢移动。根据载荷和残余划痕的尺寸计算划痕硬度值。 |
| Scratch hardness test | 划痕硬度测试 |
A form of hardness test in which a sharp-pointed stylus or corner of a mineral specimen is traversed along a surface so as to determine the resistance of that surface to cutting or abrasion. 硬度测试的一种形式，用尖头笔或矿物样品的一角沿一个表面移动，以确定该表面的抗切割或耐磨性。 |
| Scratching | 刮擦 |
In tribology, the mechanical removal or displacement, or both, of material from a surface by the action of abrasive particles or protuberances sliding across the surfaces. 在摩擦学中，通过在表面上滑动的磨粒或突起的作用，材料从表面上的机械移除或移位，或两者兼而有之。 |
| Screw | 螺钉 |
Threaded fastener designed to be used in a tapped or untapped (e.g., wood screw) hole, but not with a nut. A fastener with a screw thread cut or rolled into its cylindrical or conical shank, intended either to cut its own thread (as in a wood screw) or engage in a threaded hole. A self-tapping screw (sheet-metal screw, tapping screw) has a sufficiently hard thread that it cuts an internal thread in thin sheet or a component made of soft material when driven into a hole in the sheet or component. The screw head is the part of a screw used to apply torque to the screw. Common screw-head designs are circular in cross section with a diametral slot or cross, or hexagonal and recessed with a cross or hexagon. A screw thread is one or more continuous helical grooves of uniform section along either the exterior surface (male thread) or the interior surface (female thread) of a cylindrical or conical body. The three-dimensional shape that results when the thread cross section is rotated and axially advanced along an axis is called a helicoid, the angle that the thread makes when projected on to the axis being called the angle of inclination. Threads are employed in fasteners such as bolts, nuts, and screws; location and measuring instruments; in power drives; in some electrical fittings (Edison thread); and on the ends of crankshafts to suppress oil leakage (thrower thread). Parallel threads are formed on cylinders; tapered threads on cones, typically with a taper rate of 1:16. A screw with a righthanded thread appears to move away from the observer when turned clockwise. All standard screws, bolts and nuts have right-hand threads, but left-handed threads are sometimes employed. The axial distance between corresponding points on adjacent threads is called the screw pitch or screw rate and, for a single continuous helical groove (a single-start thread), is the same as the change in axial distance (the lead) between a nut and the head of a bolt during one revolution, the number of thread forms per mm then being the reciprocal of the pitch. For the same screw diameter, coarse threads have fewer threads per mm than fine threads. A multiple-start screw thread (usually coarse, see later) consists of two or more identical threads running simultaneously along its axis so as to provide greater bearing area and greater velocity ratio. The starts are separated by 180° (double start), 120° (triple start), 90° (quadruple start) etc., depending upon the number of threads. Thus, in double-start threads, the lead is twice the pitch; and so on. The axial distance between corresponding points on two adjacent threads in a multiple start thread is called the divided pitch. The position on a screw thread where there is equal distance between the flanks on the solid part of the thread and in the space between the threads is the pitch point, the associated diameter of which is termed the pitch diameter. The basic nomenclature for threads, some of which is common with that for toothed gearing, is shown in the diagrams. A helix formed or cut on a cylindrical surface which may advance along the axis to the right or left. The helix may be single or multiple. 一种螺纹紧固件，设计用于攻丝或未攻丝（如木螺钉）孔，但不与螺母配合使用。其螺纹被切割或卷成圆柱形或锥形柄，用于切割自身螺纹（如木螺钉）或嵌入螺纹孔。自攻螺钉（钣金螺钉、自攻螺钉）具有足够硬的螺纹，当打入薄板或部件中的孔时，它会在薄板或软材料部件中切割内螺纹。螺钉头是螺钉的一部分，用于向螺钉施加扭矩。常见的螺钉头设计为横截面为圆形，带有直径槽或十字，或为六边形，并带有十字或六边形凹槽。螺纹是沿圆柱形或锥形体的外表面（外螺纹）或内表面（内螺纹）具有均匀截面的一个或多个连续螺旋槽。当螺纹横截面旋转并沿轴轴向前进时产生的三维形状称为螺旋面，螺纹投影到轴上时形成的角度称为倾角。螺纹用于紧固件，如螺栓、螺母和螺钉；定位和测量仪器；在动力驱动中；在一些电气配件中（爱迪生螺纹）；并安装在曲轴端部，以抑制漏油（抛掷器螺纹）。在圆柱体上形成平行螺纹；圆锥上的锥形螺纹，通常具有1:16的锥形率。当顺时针旋转时，具有右手螺纹的螺钉似乎会远离观察者。所有标准螺钉、螺栓和螺母都有右手螺纹，但有时使用左手螺纹。相邻螺纹上对应点之间的轴向距离称为螺距或螺纹率，对于单个连续螺旋槽（单个起始螺纹），与螺母和螺栓头之间的轴向间距（导程）在一周内的变化相同，每mm的螺纹形式数为螺距的倒数。对于相同的螺钉直径，粗螺纹的每毫米螺纹数少于细螺纹。多头螺纹（通常为粗螺纹，见下文）由两个或多个沿其轴线同时延伸的相同螺纹组成，以提供更大的承载面积和更大的速比。根据螺纹的数量，起点之间的间隔为180°（双起点）、120°（三起点）、90°（四起点）等。因此，在双起始螺纹中，导程是螺距的两倍；多起点螺纹中两个相邻螺纹上对应点之间的轴向距离称为分割螺距。螺纹上的位置，即螺纹实体部分的侧面和螺纹之间的空间之间的距离相等，即节点，其相关直径称为节径。图中显示了螺纹的基本术语，其中一些与齿轮传动的基本术语相同。在圆柱面上形成或切割的螺旋线，可沿轴线向右或向左前进。螺旋可以是单个或多个。 |
| Screw area (Unit m²) | 螺丝面积（单位m²） |
The area of a circle described by the tips of a propeller. 螺旋桨尖端所描述的圆的面积。 |
| Screw compressor | 螺杆压缩机 |
A positive-displacement rotary compressor in which gas is progressively compressed by two intermeshing, counter-rotating, helical screws. 一种容积式旋转压缩机，其中气体由两个相互啮合、反向旋转的螺旋螺杆逐渐压缩。 |
| Screw conveyor | 螺旋输送机 |
(auger, spiral conveyor, worm conveyor) A machine for bulk handling of semi-solid materials, consisting of a helical screw which rotates in a trough or casing. （螺旋输送机、螺旋输送机、蜗杆输送机）一种用于散装搬运半固态材料的机器，由在槽或外壳中旋转的螺旋螺杆组成。 |
| Screw displacement | 螺杆位移 |
A rotation of a rigid body about an axis accompanied by a translation of the body along the same axis. 刚体绕轴旋转，同时刚体沿同一轴平移。 |
| Screw extractor | 螺钉拔 |
A device for removing broken-off screws from threaded holes. It resembles a drill with, for broken right-hand threads, a fast (long-pitch) left-hand thread that is driven into a hole drilled in the broken screw, thus untwisting it. 从螺纹孔中去除断裂螺钉的装置。它类似于一个钻头，对于断裂的右螺纹，一个快速（长螺距）的左螺纹被打入在断裂螺钉上钻的孔中，从而将其松开。 |
| Screw feeder | 螺旋给料机 |
A mechanism for handling bulk materials in which a rotating helicoidal screw moves the material axially forward. Similar to a screw conveyor, but required to discharge material at a controlled rate very accurately. It operates with the screw completely full. 一种用于处理散装物料的机构，其中旋转的螺旋螺杆使物料轴向向前移动。类似于螺旋输送机，但需要以受控速率非常精确地排出物料。它在螺杆完全充满的情况下运行。 |
| Screw jack | 螺旋千斤顶 |
A lifting device (jack) consisting of a nut and square-threaded shaft at the top of which is a load-bearing pad. Rotation of the nut raises or lowers the pad. 一种起重装置（千斤顶），由螺母和方形螺纹轴组成，其顶部为承重垫。螺母的旋转可升高或降低衬垫。 |
| Screw machine | 螺丝机 |
A machine tool for high-volume manufacture of small turned components from rod or bar. 一种用棒或棒大批量制造小零件的机床。 |
| Screw pair | 螺旋副 |
Two links connected together to form a kinematic pair, in which the contacting surfaces are screw threads, so that their relative motion consists of rotation and sliding. 两个连杆连接在一起形成运动副，其中接触面为螺纹，因此它们的相对运动包括旋转和滑动。 |
| Screw pump | 螺杆泵 |
A positive-displacement pump that uses one or more helical rotors rotating within a casing to transfer liquids or slurries. 一种容积式泵，使用一个或多个在外壳内旋转的螺旋转子输送液体或泥浆。 |
| Screw thread | 螺纹 |
A ridge of uniform section or shape in the form of a helix on the external or internal surface of a cylinder, or in the form of a conical spiral on the external or internal surface of a cone. 在圆柱体的外表面或内表面上呈螺旋形或在圆锥体的外表面和内表面上以锥形螺旋形的均匀截面或形状的脊。 |
| Scuffing | 擦伤 |
A form of adhesive wear that produces superficial scratches or a high polish on the rubbing surfaces. It is observed most often on inadequately lubricated parts. 粘着磨损的一种形式，在摩擦表面上产生表面划痕或高度抛光。通常在润滑不足的零件上观察到。 |
| Seal | 密封件 |
A component which controls or prevents leakage of fluids into or out of parts of a machine. 控制或防止流体流入或流出机器部件的部件。 |
| Secant modulus | 割线模量 |
The slope of the secant drawn from the origin to any specified point on a stress-strain curve. Compare with chord modulus. 从原点到应力应变曲线上任何指定点的割线斜率。与弦模量进行比较。 |
| Second (s) | 秒（s） |
The SI base unit of time equal to 9 192 631 770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. SI基时间单位等于9192631770倍的辐射周期，对应于铯-133原子基态的两个超精细能级之间的跃迁。 |
| Secondary hardening | 二次硬化 |
The process whereby some low-alloy steels, quenched to produce martensite, produce fine precipitates when tempered above 550°C, which inhibit dislocation motion and reverse the trend towards lower strength at higher tempering temperatures. 某些低合金钢经淬火产生马氏体，在550°C以上回火时产生细小沉淀的过程，这抑制了位错运动，扭转了在较高回火温度下强度降低的趋势。 |
| Secondary stresses (Unit Pa) | 二次应力（单位Pa） |
Stresses different from those induced by the major loading but nevertheless resulting from the major loads; for example, the hoop stresses that occur around the circumference of barrelled compression testpieces and forgings. 与主要荷载引起的应力不同，但主要荷载产生的应力；例如，桶装压缩试件和锻件周围产生的环向应力。 |
| Selective heating | 局部加热 |
Intentionally heating only certain portions of a workpiece. 有意仅加热工件的某些部分。 |
| Selective quenching | 局部淬火 |
Quenching only certain portions of an object. 仅淬火工件的某些部分。 |
| Self-locking nut | 自锁螺母 |
A nut with an inherent locking action which minimizes loosening due to vibration. A self-locking screw locks itself in place without the need for a separate selflocking nut or lock washer. 一种具有固有锁定作用的螺母，可将振动引起的松动降至最低。自锁螺钉将自身锁定到位，无需单独的自锁工件或锁紧垫圈。 |
| Self-loosening | 自松动 |
The process by which a supposedly tightened fastener becomes loose, as a result of vibration, thermal cycles, shock, or anything else which cause transverse slip between joint members and between male and female threads. Vibration loosening is a common, but special, case of self-loosening. 由于振动、热循环、冲击或任何其他导致接头构件之间以及阳螺纹和阴螺纹之间横向滑动的原因，紧固件松动的过程。振动松动是自松动的一种常见但特殊的情况。 |
| Semi-rotary pump | 半回转泵 |
A form of self-priming pump, often hand-operated, suitable for pumping water and light oils such as diesel oil and petrol. As shown in the diagram, liquid is sucked into one side of the pump through flap valves and simultaneously ejected from the other side on one stroke. The sequence is reversed on each successive stroke. 一种自吸泵，通常是手动的，适用于泵送水和轻油，如柴油和汽油。液体通过翻板阀吸入泵的一侧，同时在一个冲程中从另一侧排出。在每个连续冲程上，顺序颠倒。 |
| Semiguided bend | 半导弯曲 |
The bend obtained by applying a force directly to the specimen in the portion that is to be bent. The specimen is either held at one end and forced around a pin or rounded edge, or is supported near the ends and bent by a force applied on the side of the specimen opposite the supports and midway between them. In some instances, the bend is started in this manner and finished in the manner of a free bend. 通过将力直接施加于待弯曲部分中的试样而获得的弯曲。将试样固定在一端，并围绕销或圆边施力，或者在靠近端部的位置支撑试样，并通过施加在试样与支撑件相对的一侧以及两者中间的力进行弯曲。在某些情况下，折弯以此方式开始，然后以自由折弯的方式结束。 |
| Serrations | 锯齿 |
A row of notches or tooth-like projections on an edge or surface. On an engineering drawing, serrations on the surface of a circular component are shown over about 60° of arc. 边缘或表面上的一排凹口或齿状突起。在工程图纸上，圆形部件表面的锯齿超过约60°的圆弧。 |
| Set pressure (Unit Pa) | 设定压力（单位Pa） |
The pressure at which a relief valve or safety valve is set to open, corresponding to the relevant code or standard which applies to the pressure vessel being protected. 安全阀或安全阀开启时的压力，对应于适用于受保护压力容器的相关规范或标准。 |
| Set screw | 紧定螺钉（平头螺钉、紧定螺栓） |
Usually a hardened steel screw having either no head or a square head and with various degrees of points or ends to lock or tighten adjustable machine parts in position on a shaft. A short, headless screw with a recess at one end to receive a screwdriver or key, the other end being pointed, square, or otherwise shaped. Typically used to secure a pulley, gear, or other component on a shaft. 通常是一种硬化钢螺钉，无头或方头，具有不同程度的点或端部，用于将可调机械部件锁定或拧紧在轴上的适当位置。一端有凹槽，用来装螺丝刀或钥匙，另一端是尖的、方形的或其他形状的。通常用于将皮带轮、齿轮或其他部件固定在轴上。 |
| Shank | 螺杆 |
Portion of a bolt which lies under the head. 1. The stem of a tool, such as a broach, drill bit, reamer, or tap, which fits into a holder such as a chuck. 2. The stem of a rivet or the unthreaded part of a screw or bolt. 3. The shaft of a tool connecting the tip and the handle. 螺栓头部下方的部分。1.一种工具的柄部，如拉刀、钻头、铰刀或丝锥，可装入夹具（如卡盘）中。铆钉的杆或螺钉或螺栓的无螺纹部分。3.连接尖端和手柄的工具的轴。 |
| Sharp-notch strength | 锐缺口强度 |
The notch tensile strength measured using specimens with very small notch root radii (approaching the limit for machining capability); values of sharp-notch strength usually depend on notch root radius. 使用缺口根部半径非常小（接近加工能力极限）的试样测量的缺口抗拉强度；锐缺口强度值通常取决于缺口根部半径。 |
| Shear | 扭剪 |
The type of force that causes or tends to cause two contiguous parts of the same body to slide relative to each other in a direction parallel to their plane of contact. 导致或倾向于导致同一物体的两个相邻部分在平行于其接触面的方向上相对滑动的力的类型。 |
| Shear fracture | 剪切断裂 |
A ductile fracture in which a crystal (or a polycrystalline mass)has separated by sliding or tearing under the action of shear stresses. Contrast with cleavage fracture. 在剪切应力作用下，晶体（或多晶块）通过滑动或撕裂而分离的韧性断裂。与解理断裂形成对比。 |
| Shear joint | 剪切接头 |
A joint which is subjected primarily to loads acting more or less perpendicular to the axes of the bolts. 主要承受或多或少垂直于螺栓轴线的载荷的接头。 |
| Shear lip | 剪切唇 |
A narrow, slanting ridge along the edge of a fracture surface. The term sometimes also denotes a narrow, often crescent-shaped, fibrous region at the edge of a fracture that is otherwise of the cleavage type, even though this fibrous region is in the same plane as the rest of the fracture surface. 沿断裂面边缘的狭窄倾斜脊。该术语有时还表示断裂边缘处的狭窄、通常为新月形的纤维区域，否则为解理型，即使该纤维区域与断裂表面的其余部分位于同一平面内。 |
| Shear modulus (G) | 剪切模量（G） |
The ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material. Values of shear modulus are usually determined by torsion testing. Also known as modulus of rigidity. 对于低于材料比例极限的剪切应力，剪切应力与相应剪切应变之比。剪切模量值通常通过扭转试验确定。也称为刚度模量。 |
| Shear strain | 剪切应变 |
The tangent of the angular change, as a response to force, between two lines originally perpendicular to each other through a point in a body. Also known as shearing strain. 角变化的切线，作为对力的响应，在两条原本通过物体中的一个点相互垂直的线之间。也称为剪切应变。 |
| Shear strain rate(Unit 1/s) | 剪切应变率（单位1/s） |
In the deformation of solids, the rate at which shear strain is applied in a test or changes with time in a loaded component or structure. 在固体变形中，在试验中施加剪切应变的速率，或在加载部件或结构中随时间变化的速率。 |
| Shear strength | 抗剪强度 |
The maximum shear stress that a material is capable of sustaining. Shear strength is calculated from the maximum load during a shear or torsion test and is based on the original dimensions of the cross section of the specimen. 材料能够承受的最大剪切应力。抗剪强度根据剪切或扭转试验期间的最大载荷计算，并基于试样横截面的原始尺寸。 |
| Shear strength (Unit Pa) | 抗剪强度（单位Pa） |
The maximum shear stress that can be withstood by a material either (a) before plasticity occurs or (b) before rupture. 材料在（a）塑性发生之前或（b）断裂之前能够承受的最大剪切应力。 |
| Shear stress (Unit Pa) | 剪应力（单位Pa） |
(1) A stress that exists when parallel planes in metal crystals slide across each other. (2) The stress component tangential to the plane on which the forces act. Also known as tangential stress. (shearing stress, tangential stress, τ) 1. The stress which acts parallel to any plane within a solid material. It can arise due to a bending moment, a shear force, or torque applied to the body. 2. The stress corresponding to velocity gradients within a flowing viscous fluid. （剪应力，切向应力，τ）（1）当金属晶体中的平行平面彼此滑动时存在的应力。（2）与力作用平面相切的应力分量。也称为切向应力。1.平行于固体材料内任何平面的应力。它可能是由于施加在身体上的弯矩、剪力或扭矩引起的。2.对应于流动粘性流体内的速度梯度的应力。 |
| Shear test | 剪切试验 |
Any of several tests to obtain shear strength of a metal. Common tests used on mill products include the double-shear test, single-shear test, the blanking shear test (also known as the punching shear test) and the torsion test. 获得金属剪切强度的几种测试中的任何一种。轧机产品上常用的试验包括双剪试验、单剪试验、落料剪切试验（也称为冲切试验）和扭转试验。 |
| Shell hardening | 壳型硬化 |
A surface-hardening process in which a suitable steel workpiece, when heated through and quench hardened, develops a martensitic layer or shell that closely follows the contour of the piece and surrounds a core of essentially pearlitic transformation product. This result is accomplished by a proper balance among section size, steel hardenability, and severity of quench. 一种表面硬化工艺，在该工艺中，合适的钢工件在加热和淬火硬化后，会形成一层马氏体层或壳，该层或壳紧随工件的轮廓，并包围一个基本上为珠光体相变产物的核心。这一结果通过截面尺寸、钢淬透性和淬火强度之间的适当平衡来实现。 |
| Shim | 垫片 |
A thin piece of material, such as metal of accurately-known thickness, placed between two surfaces to ensure they are the correct distance apart. A thin piece of material placed between two surfaces to obtain a proper fit, adjustment, or alignment. The piece can also be analyzed to measure furnace carbon potential (that is, because while in the furnace it will quickly carburize to a level equal to the furnace carbon potential). 一块薄的材料，如厚度精确已知的金属，放置在两个表面之间，以确保它们之间的距离正确。放置在两个表面之间以获得适当配合、调整或对齐的一块薄材料。还可以对工件进行分析，以测量熔炉碳势（也就是说，在熔炉中，工件将快速渗碳至与熔炉碳势能相等的水平）。 |
| Shock load | 冲击载荷 |
The sudden application of an external force that results in a very rapid build-up of stress. 突然施加外力，导致应力迅速增加。 |
| Shore hardness | 肖氏硬度 |
A measure of the hardness of materials such as elastomers, plastics, and rubbers determined using a Shore durometer which measures the penetration depth of a hardened steel rod (the indenter) 1.1–1.4 mm in diameter into the test material for a given force applied rapidly with a calibrated spring. There are two main indenter designs: type A (for softer materials) for which the end of the rod is a truncated 35° cone tapering to a diameter of 0.79 mm, and type D (harder materials) for which the end is a 30° cone with a 0.1 mm radius tip. The spring force is 8.05 N for type A and 44.45 N for type D. The hardness value is related to the penetration depth (limited to a maximum of 2.5 mm) such that for zero penetration the hardness is 100 and for maximum penetration the hardness is zero. The relevant standards are ISO 48-1, 48-4, and 48-7. Shore hardness values of selected materials are as follows: ABS 100, cellulose acetate 50–95, high-density polyethylene 60–70, low density polyethylene 40–50, polymethylmethacrylate 90–99, PTFE 50–65, and plasticized PVC 15–70. 使用肖氏硬度计测量弹性体、塑料和橡胶等材料的硬度，肖氏硬度仪测量直径为1.1–1.4mm的硬化钢棒（压头）在用校准弹簧快速施加的给定力下渗入试验材料的深度。有两种主要的压头设计：A型（适用于较软的材料），其杆端为截头35°锥形，逐渐变细至直径0.79 mm；D型（较硬的材料），端部为30°锥形，尖端半径为0.1mm。A型的弹簧力为8.05N，D型为44.45N。硬度值与渗透深度相关（最大限制为2.5mm），因此，对于零渗透，硬度为100，对于最大渗透，硬度是零。相关标准为ISO 48-1、48-4和48-7。所选材料的肖氏硬度值如下：ABS100、醋酸纤维素50-95、高密度聚乙烯60-70、低密度聚乙烯40-50、聚甲基丙烯酸甲酯90-99、PTFE50-65和塑化PVC15-70。 |
| Shoulder | 轴肩 |
The portion of a shaft, stepped component, or flanged component, where a change in diameter or other dimension occurs. Even for a nominal step change, in practice there will be a radius where shoulder and shaft meet in order to avoid too severe a stress concentration. 轴、阶梯部件或法兰部件的直径或其他尺寸发生变化的部分。即使是名义阶跃变化，在实践中，肩部和轴相交处也会有一个半径，以避免出现过严重的应力集中。 |
| Shoulder bolt | 轴肩螺栓 |
A bolt for which the unthreaded cylindrical section between the thread and the head is of larger diameter than the threaded section, precisely machined to length and diameter and hardened 一种螺栓，其螺纹和头部之间的无螺纹圆柱段的直径大于螺纹段的直径，精确加工至长度和直径并硬化 |
| Shoulder joint | 轴肩关节 |
The second joint on an articulated robot, which has a horizontal axis and is analogous to the human shoulder. 关节机器人上的第二个关节，具有水平轴，类似于人的肩膀。 |
| Shoulder screw | 轴肩螺钉 |
A screw having two or more diameters or shoulders and commonly used for supporting levers and other machine parts that have to operate freely. 一种具有两个或两个以上直径或轴肩的螺钉，通常用于支撑杠杆和其他必须自由操作的机器部件。 |
| Shrink fit | 过盈配合 |
A tight interference fit between two components resulting from heating an outer part and/or cooling an inner part to allow easy assembly. The outer component contracts on cooling, while the inner part expands on warming to ambient temperature, thus gripping the two parts together. 由于加热外部部件和/或冷却内部部件而导致的两个部件之间的紧密过盈配合，以便于组装。外部部件在冷却时收缩，而内部部件在加热到环境温度时膨胀，从而将两个部件夹在一起。 |
| Shrink ring | 预紧环 |
A ring, which is expanded by heating, is placed around an assembly of parts, and then contracts upon cooling to hold the assembly in place. 通过加热膨胀的环被放置在零件组件周围，然后在冷却时收缩以将组件固定到位。 |
| SI system | SI国际单位制 |
SI is an abbreviation of Système International d’Unités, i.e., the international unit measurement system – an internationally established system of measurement units built on older metric systems. SI是Système International d‘Unités的缩写，即国际单位计量系统——一种基于旧公制的国际公认计量单位系统。 |
| Sigma phase | σ相 |
A hard, brittle, nonmagnetic intermediate phase with a tetragonal crystal structure, containing 30 atoms per unit cell, space group P42/mnm, occurring in many binary and ternary alloys of the transition elements. The composition of this phase in the various systems is not the same, and the phase usually exhibits a wide range in homogeneity. Alloying with a third transition element usually enlarges the field of homogeneity and extends it deep into the ternary section. 一种硬、脆、非磁性中间相，具有四方晶体结构，每单位晶胞含有30个原子，空间群P42/mnm，存在于许多过渡元素的二元和三元合金中。该相在各种系统中的组成不尽相同，并且该相通常表现出宽范围的均匀性。与第三过渡元素的合金化通常会扩大均匀性范围，并将其延伸到三元区。 |
| Sigma-phase embrittlement | σ相脆化 |
Embrittlement of iron-chromium alloys (most notably austenitic stainless steels) caused by precipitation at grain boundaries of the hard, brittle intermetallic sigma phase during long periods of exposure to temperatures between approximately 565 and 980 °C (1050 and 1800 °F). Sigmaphase embrittlement results in severe loss in toughness and ductility and can make the embrittled material structure susceptible to intergranular corrosion. 铁铬合金（最显著的是奥氏体不锈钢）的脆化是由于在长时间暴露于约565至980°C（1050至1800°F）的温度下，硬脆金属间化合物σ相的晶界处沉淀造成的。σ相脆化导致韧性和延展性的严重损失，可使脆化的材料结构易于发生晶间腐蚀。 |
| Significance level | 显着性水平 |
The stated probability (risk) that a given test of significance will reject the hypothesis that a specified effect is absent when the hypothesis is true. 当假设为真时，给定的显著性检验将拒绝特定效应不存在的假设的所述概率（风险）。 |
| Silky fracture | 丝状断口 |
A metal fracture in which the broken metal surface has a fine texture, usually dull in appearance. Characteristic of tough and strong metals. 一种金属断裂，断裂的金属表面具有精细的纹理，通常外观暗淡。具有坚韧和坚固金属的特征。 |
| Single thread | 单头螺纹 |
A screw thread cut around a cylinder having a single start in which the lead is equal to the pitch. 一种螺纹，在一个圆柱体上切割而成，具有一个单一的起点，在这个起点上，导程等于螺距。 |
| Single-shear test | 单剪试验 |
(1) A shear test similar to the double-shear test used for round-bar specimens, but that uses only one stationary shear blade. (2) A shear test that uses a sheet or thin-plate specimen. （1）一种剪切试验，类似于用于圆棒试样的双剪切试验，但仅使用一个固定剪切刀片。（2）使用薄板或薄板试样的剪切试验。 |
| Sinter (sintering) | 烧结 |
A solid-state diffusion densification process for the production of objects, particularly porous objects, from raw material in powder, granular, mesh, perforatedsheet, or fibre form by heating to a temperature below the melting point until the constituents bond together. It is used for ceramic materials and metals. Applications of sintered materials include filtration, separation, flow control, fluidization, and noise reduction. The bonding of adjacent surfaces in a mass of particles by molecular or atomic attraction on heating at high temperatures below the melting temperature of any constituent in the material. Sintering strengthens a powder mass and normally produces densification and, in powdered metals, recrystallization. 一种固态扩散致密化工艺，用于从粉末、粒状、网状、穿孔片或纤维形式的原材料中生产物体，尤其是多孔物体，方法是加热至低于熔点的温度，直到成分结合在一起。它用于陶瓷材料和金属。烧结材料的应用包括过滤、分离、流量控制、流化和降噪。在低于材料中任何成分熔化温度的高温下加热时，通过分子或原子引力将大量颗粒的相邻表面结合起来。烧结增强了粉末质量，通常会产生致密化，在粉末金属中还会产生再结晶。 |
| Size dimension (Unit m) | 尺寸范围（单位：米） |
The specified value of a diameter, length, width, etc. of a feature required to specify the finished form of a component or assembly. 指定部件或组件的成品形状所需的特征的直径、长度、宽度等的指定值。 |
| Size effect | 尺寸效应 |
Effect of the dimensions of a piece of metal on its mechanical and other properties and on manufacturing variables such as forging reduction and heat treatment. In general, the mechanical properties are lower for a larger size. 金属件的尺寸对其机械和其他性能以及对制造变量（如锻造、压下和热处理）的影响。一般来说，尺寸越大，机械性能越低。 |
| Sizing | 颗粒化 |
1. A finishing operation to ensure the specified dimensions and tolerances for a component are met. 2. (size classification) Separating an aggregate of mixed particles into groups according to size using a series of screens. 1.精加工操作，以确保满足部件的规定尺寸和公差。2.（粒度分类）使用一系列筛网根据粒度将混合颗粒的聚集体分成组。 |
| Slack quenching | 欠速淬火 |
The incomplete hardening of steel due to quenching from the austenitizing temperature at a rate slower than the critical cooling rate for the particular steel, resulting in the formation of one or more transformation products in addition to martensite. 由于从奥氏体化温度以低于特定钢临界冷却速度的速度淬火而导致钢的不完全硬化，导致除马氏体外还形成一种或多种相变产物。 |
| Slant fracture | 倾斜裂缝 |
A type of fracture appearance, typical of plane-stress fractures, in which the plane of metal separation is inclined at an angle (usually about 45°) to the axis of the applied stress. 一种断裂现象，典型的平面应力断裂，其中金属分离面与施加应力的轴成一定角度（通常约45°）倾斜。 |
| Slenderness ratio | 长细比 |
The effective unsupported length of a uniform column divided by the least radius of gyration of the cross-sectional area. 均匀柱的有效无支撑长度除以横截面积的最小回转半径。 |
| Sliding-vane compressor | 滑片压缩机 |
(rotary-vane compressor, vane compressor) A rotary compressor in which gas is compressed as the spaces between spring-loaded sliding vanes held in an offset rotor reduce as the rotor revolves within a cylindrical housing. （旋转叶片压缩机，叶片压缩机）一种旋转式压缩机，当转子在圆柱形外壳内旋转时，偏置转子中的弹簧加载滑动叶片之间的空间减小，从而压缩气体。 |
| Slip | 滑落 |
Plastic deformation by the irreversible shear displacement (translation)of one part of a crystal relative to another in a definite crystallographic direction and usually on a specific crystallographic plane. Sometimes called glide. 晶体的一部分在一定的晶体学方向上相对于另一部分的不可逆剪切位移（平移）引起的塑性变形，通常在特定的晶体主义平面上。有时被称为滑翔。 |
| Slip band | 滑带 |
A group of parallel slip lines so closely spaced as to appear as a single line when observed under an optical microscope. 一组平行滑移线，间距如此之近，以至于在光学显微镜下观察时显示为一条直线。 |
| Slip joint | 滑动接头 |
A mechanical connection which allows limited endwise relative movement of two components such as pipes, rods, and ducts. 一种机械连接，允许两个部件（如管道、杆和管道）进行有限的轴向相对运动。 |
| Slip line | 滑移线 |
The trace of the slip plane on a viewing surface; the trace is usually observable only if the surface has been polished before deformation. The usual observation on metal crystals (under the light microscope) is of a cluster of slip lines known as a slip band. 滑动平面在观察表面上的轨迹；只有在变形前对表面进行抛光，才能观察到痕迹。通常对金属晶体的观察（在光学显微镜下）是一组称为滑移带的滑移线。 |
| Slot | 狭槽 |
A groove machined into a component, e.g. to allow for thermal expansion, or in which the tongue or tip of another component can fit or slide. 在部件上加工的凹槽，例如，允许热膨胀，或另一部件的榫舌或尖端可在其中安装或滑动。 |
| Slug | 猛击 |
1. A starting workpiece for forging and similar operations, such as a length of wire or rod to make a bolt blank on which a thread can be rolled or cut. 2. (geepound) An obsolete imperial (non-SI) unit of mass, being the mass which under an acceleration of one foot per second squared gives a force of one pound-force. The conversion to SI is 1 slug = 14.593 902 94 kg. 3. A large-scale flow structure which occurs in the transition from laminar to turbulent flow in a pipe. 1.一种用于锻造和类似操作的起始工件，如用于制造螺栓毛坯的一段线材或棒材，在该毛坯上可以轧制或切割螺纹。2.（吉磅）一种已被淘汰的英制（非国际单位制）质量单位，在一英尺/秒平方加速度下产生一磅力的质量。转化为SI国际单位制的转化率为1slug=14.59390294kg。3.一种大规模流动结构，其发生在管道中从层流到湍流的过渡中。 |
| Slug wrench | 缓动扳手 |
A box wrench with an anvil on the end of the handle. Torque is produced by striking the anvil with a sledge hammer. 柄端有铁砧的套筒扳手。扭矩是通过用大锤敲击铁砧产生的。 |
| Snap temper | 快速回火 |
A precautionary interim stress-relieving treatment applied to high-hardenability steels immediately after quenching to prevent cracking because of delay in tempering them at the prescribed higher temperature. 在淬火后立即对高淬透性钢进行预防性临时应力消除处理，以防止因在规定的更高温度下回火延迟而开裂。 |
| Socket head | 凹头 |
Screw head having a hexagonal or other form of recessed socket in the head so that the screw can be turned with a wrench or key, as a hexagon key. 螺钉头上有六角或其他形式的凹座，可以用扳手或钥匙（如六角钥匙）转动螺钉。 |
| Socket wrench | 套筒扳手 |
A form of spanner with an internally ridged steel socket to fit a nut or the head of a bolt or screw. 扳手的一种形式，带有内脊钢套筒，用于安装螺母或螺栓或螺钉的头部。 |
| Solenoid | 螺线管 |
A coil of electrically-conducting wire wrapped around a metal core, typically iron, to produce a magnetic field and hence a force on the core when an electric current passes through the coil. Solenoids are widely used to produce linear movement to actuate valves (solenoid valves) and other devices. 绕在金属芯（通常为铁）上的导线线圈，当电流通过线圈时产生磁场，从而在芯上产生力。电磁阀广泛用于产生线性运动以驱动阀（电磁阀）和其他装置。 |
| Solution heat treatment | 固溶热处理 |
Heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more constituents to enter into solid solution, and then cooling rapidly enough to hold these constituents in solution. 将合金加热到合适的温度，在该温度下保持足够长的时间以使一种或多种成分进入固溶体，然后快速冷却以将这些成分保持在溶液中。 |
| Sound pressure (Unit μPa) | 声压（单位：μPa） |
The instantaneous deviation of pressure from the ambient pressure caused by the passage of a sound wave, which can be measured by a microphone in air and a hydrophone in water. 声波传播引起的压力与环境压力的瞬时偏差，可通过空气中的麦克风和水中的水听器测量。 |
| Spalling | 剥落 |
The separation of macroscopic particles from a surface in the form of flakes or chips. 以薄片或碎片形式从表面分离宏观颗粒。 |
| Span (Unit m) | 跨度（单位：m） |
A dimension measured between the extremities of a body or structure, such as between the tips of a wing or the supports of a bridge. 在身体或结构的末端之间测量的尺寸，如机翼尖端或桥梁支架之间。 |
| Spanner (wrench) | 扳手 |
A tool for applying torque to tighten or loosen a nut, bolt, or screw. Grip is applied by a serrated ring or an open U-shape at the end of the tool. On imperial-size spanners, the BSW and BSF marking refers to the diameter of the screw thread; similarly for BA spanners. Spanners for unified and metric threads are marked with the distance across the flats (‘A/F’) of the nut or head of the bolt. 拧紧或松开螺母、螺栓或螺丝的工具。通过工具端部的锯齿环或开口U形应用夹持。在英制扳手上，BSW和BSF标记是指螺纹的直径；类似于BA扳手。用于统一螺纹和公制螺纹的扳手在螺母或螺栓头的平面（'A/F'）上标记距离。 |
| Specific heat capacity | 比热容 |
The heat necessary to raise the temperature of 1 kg of a substance by 1 K. It is measured in J/(kg K). 将1千克物质的温度升高1K所需的热量。单位为J/（kg K）。 |
| Specific weight (γ) (Unit N/m³) | 比重（γ）（单位：N/m³） |
The weight per unit volume of a substance: if W is the weight of a volume of the substance, ρ is its density, and g is the acceleration due to gravity, γ = W/ = ρg. 物质单位体积的重量：W是物质体积的重量，ρ是其密度，g是重力引起的加速度，γ=W/=ρg。 |
| Specimen | 样品 |
A test object, often of standard dimensions or configuration, that is used for destructive or nondestructive testing. One or more specimens may be cut from each unit of a sample. 用于破坏性或无损检测的测试对象，通常具有标准尺寸或配置。可以从样品的每个单位切割一个或多个样品。 |
| Speed of rotation (N) | 转速（N） |
(Unit rps or rpm) For an object rotating about a fixed axis, the speed of rotation is the number of turns (revolutions) of the object per unit time. It is equal to the angular velocity Ω (or ω) (unit rad/s) divided by 2π. （单位rps或rpm）对于绕固定轴旋转的物体，旋转速度是物体每单位时间的转数。它等于角速度Ω（或ω）（单位rad/s）除以2π。 |
| Spherical washer | 球面垫圈 |
A washer whose upper surface is semispherical. Used with a nut whose contact face is also semispherical. Reduces bending stress in a bolt or stud, by allowing some self-alignment and some compensation for nonparallel joint surfaces or Angularity. 上表面为半球形的垫圈。与接触面也是半球形的螺母一起使用。减少螺栓或螺柱中的弯曲应力，允许一些自对准，并对不平行的接头表面或角度进行一些补偿。 |
| Spinner | 旋转器 |
A co-axial streamlined fairing enclosing the hub of a propeller and rotating with it. 一种同轴流线型整流罩，包围螺旋桨毂并随其旋转。 |
| Spray quenching | 喷雾淬火 |
A quenching process using spray nozzles to spray water or other liquids on a part. The quench rate is controlled by the velocity and volume of liquid per unit area per unit of time of impingement. 使用喷嘴将水或其他液体喷射到零件上的淬火过程。淬火速率由每单位撞击时间内每单位面积的液体速度和体积控制。 |
| Spring | 弹簧 |
An elastic component which stores mechanical energy and exerts a force when deformed. The slope of the curve of applied force F to the deflexion of a spring x, dF/dx, is termed the spring rate or spring modulus k with unit N/m. For a linear spring, the F(x) curve is proportional and k is called the spring constant. An elastic device which yields under stress or pressure but returns to its original state or position when the stress or pressure is removed. 储存机械能并在变形时施加力的弹性部件。作用力F与弹簧x偏转的曲线斜率dF/dx称为弹簧率或弹簧模量k，单位为N/m。对于线性弹簧，F（x）曲线成比例，k称为弹簧常数。一种弹性装置，在应力或压力下屈服，但在应力和压力消除后恢复到其原始状态或位置。 |
| Spring clip | 弹簧夹 |
A clip made of a material such as spring steel which grips an inserted part. 由弹簧钢等材料制成的夹子，用于夹住插入的零件。 |
| Spring constant | 弹簧常数 |
The ratio between the forces exerted on a spring (or a bolt) and the deflection thereof. Has the dimensions of force per unit change in length (e.g., lb=in.). Also called Stiffness. 施加在弹簧（或螺栓）上的力与其挠度之间的比率。具有每单位长度变化的力的尺寸（例如lb=in.）。也称为刚度。 |
| Spring load (Unit N) | 弹簧载荷（单位：N） |
A load exerted on a component by bending, compressing, extending, or twisting an attached spring. Mechanical energy stored in the spring can be released if any constraints on the component are removed. 通过弯曲、压缩、延伸或扭转连接的弹簧而施加在部件上的载荷。如果部件上的任何约束被移除，则可以释放弹簧中存储的机械能。 |
| Spring materials | 弹簧材料 |
Mainly metals including plain-carbon and corrosion-resisting steels, phosphor bronze, spring brass, beryllium copper and nickel alloys, all of which in their workhardened states permit large reversible elastic strains without permanent deformation. 主要是金属，包括普通碳钢和耐腐蚀钢、磷青铜、弹簧黄铜、铍铜和镍合金，所有这些金属在其加工硬化状态下都允许大的可逆弹性应变而不会产生永久变形。 |
| Spring temper | 弹簧回火 |
A temper of nonferrous alloys and some ferrous alloys characterized by tensile strength and hardness about two-thirds of the way from full hard to extra spring temper. 非铁合金和一些铁合金的一种回火，其特点是抗拉强度和硬度约为全硬回火到超弹性回火的三分之二。 |
| Springback | 回弹 |
The extent to which metal tends to return to its original shape or contour after undergoing a forming operation. 金属在经历成形操作后趋于恢复其原始形状或轮廓的程度。 |
| Square | 正方 |
1. A regular quadrilateral, i.e. a polygon with four equal sides and four right angles. 2. An instrument to check angles of internal and external surfaces and flatness. 1.正四边形，即具有四条等边和四个直角的多边形。2.一种检查内外表面角度和平面度的仪器。 |
| Square thread | 方螺纹 |
A form of screw thread in which the cross–section of the thread forms a square, making the width of the thread equal to the space between the threads. 螺纹的一种形式，螺纹的横截面形成正方形，使螺纹的宽度等于螺纹之间的间距。 |
| Stability | 稳定性 |
1. A term relating to whether a body, structure, system, or flow is in a state of stable, unstable, or neutral equilibrium. 2. In numerical analysis, whether numerical errors, such as roundoff or input-data errors, are damped, propagate, or cause divergence of the solution as the numerical method proceeds. 3. A control system is often described as stable when a step change in input results in a steady output without continuing oscillation. 1.与物体、结构、系统或流是否处于稳定、不稳定或中性平衡状态有关的术语。2.在数值分析中，随着数值方法的进行，数值误差（如舍入误差或输入数据误差）是否衰减、传播或导致解发散。3.当输入的阶跃变化导致稳定输出而无持续振荡时，控制系统通常被描述为稳定的。 |
| Stabilizing treatment | 稳定化处理 |
(1) Before finishing to final dimensions, repeatedly heating a ferrous or nonferrous part to or slightly above its normal operating temperature and then cooling to room temperature to ensure dimensional stability in service. (2) Transforming retained austenite in quenched hardenable steels, usually by cold treatment. (3) Heating a solution-treated stabilized grade of austenitic stainless steel to 870 to 900 °C (1600 to 1650 °F) to precipitate all carbon as TiC, NbC, or TaC so that sensitization is avoided on subsequent exposure to elevated temperature. （1）在精加工至最终尺寸之前，反复加热含铁或非铁零件至或略高于其正常工作温度，然后冷却至室温，以确保使用中的尺寸稳定性。（2）在淬火可淬硬钢中转变残余奥氏体，通常通过冷处理。（3）将固溶处理的稳定等级奥氏体不锈钢加热至870至900°C（1600至1650°F），使所有碳沉淀为TiC、NbC或TaC，从而避免在随后暴露于高温时敏化。 |
| Stainless steels | 不锈钢 |
Iron-base alloys that are highly resistant to corrosion in many environments. The predominant alloying element is chromium, which, like iron at room temperature, has BCC crystal structure. Corrosion resistance by passivation is achieved by the formation of chromium oxide on the steel surface. Nickel, which has FCC crystal structure, is another important addition for some steels. Other additions used to enhance properties include manganese, molybdenum, niobium, and titanium. There are several classes of stainless steel. 在许多环境中具有高度耐腐蚀性的铁基合金。主要的合金元素是铬，与室温下的铁一样，铬具有BCC晶体结构。钝化抗腐蚀性是通过在钢表面形成氧化铬来实现的。具有FCC晶体结构的镍是某些钢的另一种重要添加剂。其他用于增强性能的添加剂包括锰、钼、铌和钛。不锈钢的种类有好几种。 |
| Standard | 标准 |
(standard specification) A set of specifications for components, machines, materials, or processes intended to achieve uniformity, efficiency, and a specified quality. In the UK, standards issued by the British Standards Institution (BSI) are now generally those of the International Organization for Standardization (ISO). （标准规范）为实现一致性、效率和特定质量而制定的一套组件、机器、材料或工艺规范。在英国，英国标准协会（BSI）发布的标准现在基本上是国际标准化组织（ISO）的标准。 |
| Standard deviation (σ) | 标准偏差（σ） |
A statistical term used to quantify the Scatter in a set of data points. If the standard deviation is small, most of the data points are ‘‘nearly equal.’’ A large deviation means less agreement. The most usual measure of the dispersion of observed values or results expressed as the positive square root of the variance. The square root of variance, a measure of the spread of data about the mean value. 用于量化一组数据点中分散度的统计术语。如果标准偏差很小，则大多数数据点“几乎相等”大的偏差意味着更少的一致性。观测值或结果离散度的最常用度量，表示为方差的正平方根。方差的平方根，衡量平均值的数据分布。 |
| Standard fit | 标准匹配 |
The fit of a component machined or otherwise manufactured to standardized clearances and tolerances. 根据标准间隙和公差加工或以其他方式制造的部件的配合。 |
| Standard gauge | 标准量规 |
A highly-accurate reference gauge against which to check working gauges. 一种高精度的基准量规，用于检查工作量规。 |
| Standard hole | 标准孔 |
A hole in a workpiece bored to a specified tolerance where clearance with a shaft is accomplished by allowance on the shaft. A standard shaft is machined to a specified tolerance where clearance with a hole is accomplished by allowance on the hole. 工件上的孔，钻孔至规定公差，其中与轴的间隙通过轴上的余量来实现。标准轴加工至规定公差，其中与孔的间隙通过孔上的公差实现。 |
| Standardization | 标准化 |
1. National and international agreements for design, manufacture, materials, performance, practices, requirements, strength, etc. which ensure common results wherever an item is made and wherever used. 2. The manufacture of components so that interchangeability of parts during assembly of new, or repair of old, items is possible without ‘fitting’. 1.关于设计、制造、材料、性能、惯例、要求、强度等的国家和国际协议，确保在任何地方制造和使用物品都能产生共同结果。2.部件的制造，以便在装配新部件或维修旧部件时，无需“装配”即可实现部件的互换性。 |
| Starting friction | 起动摩擦 |
(limiting friction, static friction, stiction) (Unit N) The force required to initiate movement between two bodies in contact. （极限摩擦力、静摩擦力、粘滞）（单位N）在两个接触物体之间启动运动所需的力。 |
| Starting taper | 起始锥度 |
The taper on the end of a reamer or tap which aids in starting the cut. 铰刀或丝锥端部的锥度，有助于开始切割。 |
| Starting torque (Unit N.m) | 起动扭矩（单位：N.m） |
The torque developed by a motor at zero rotational speed in order to initiate rotation of the applied load. 电机在零转速下产生的扭矩，以启动所施加负载的旋转。 |
| Starting valve (regulator) | 起动阀（调节器） |
A valve which admits steam from the boiler to the cylinder(s) of a steam engine. 将蒸汽从锅炉送入蒸汽机汽缸的阀门。 |
| Static equilibrium | 静态平衡 |
A solid body, structure, or physical system (or any subdivided part) will be in static equilibrium, either at rest or moving with constant velocity, if the resultants of all external forces and moments acting on it are zero. 如果作用在固体上的所有外力和力矩的合力为零，则固体、结构或物理系统（或任何细分部分）无论是静止还是以恒定速度移动，都是处于静态平衡。 |
| Static fatigue | 静态疲劳 |
A term referring to a time-dependent reduction in strength with a static (noncyclic) load. The term may refer to hydrogen-induced delayed cracking or the effect of creep on the strength of plastics. Delayed fracture caused by environmental effects under dead-weight loading of materials such as glass. The name is unfortunate, as cyclic loads are not involved and glass is not susceptible to fatigue. 指静态（非循环）载荷下强度随时间变化的降低。该术语可指氢致延迟开裂或蠕变对塑料强度的影响。在玻璃等材料的自重荷载下，由环境影响引起的延迟断裂。 |
| Statistic | 统计 |
A summary value calculated from the observed values in a sample. 根据样本中的观察值计算得出的汇总值。 |
| Stator | 定子 |
A ring of non-rotating blades or nozzles in a compressor, turbine, or other turbomachine, which directs fluid flow into an adjacent rotor. 涡轮压缩机、涡轮或其他涡轮机械中的一圈不旋转的叶片或喷嘴，将流体引导到相邻的转子中。 |
| Steady loads | 稳定负载 |
Loads that do not change in intensity or that change so slowly they may be regarded as steady. 强度不变或变化缓慢的荷载可视为稳定荷载。 |
| Steady pin | 定位销 |
A dowel, key, or pin that prevents a pulley from turning on its shaft. 防止滑轮在其轴上转动的销钉、键或销。 |
| Stead’s brittleness | 斯特德脆性 |
A condition of brittleness that causes transcrystalline fracture in the coarse grain structure that results from prolonged annealing of thin sheets of low-carbon steel previously rolled at a temperature below about 705 °C (1300 °F). The fracture usually occurs at about 45° to the direction of rolling. 一种脆性状态，导致粗晶结构中发生穿晶断裂，这是由于之前在低于约705°C（1300°F）的温度下轧制的低碳钢薄板经过长时间退火造成的。断裂通常发生在与轧制方向约45°处。 |
| Steam gauge | 汽压表 |
A pressure gauge used to measure gauge pressure in a line, boiler, cylinder, or other device operating with steam. 一种压力表，用于测量管道、锅炉、汽缸或其他与蒸汽一起工作的装置中的表压。 |
| Steel-wire rope | 钢丝绳 |
A rope or cable made up of many steel strands wrapped helically about an axis, each strand being made of metal wires twisted together like a helix. 一种绳索或缆绳，由许多绕轴螺旋缠绕的钢绞线组成，每根钢绞线由金属丝缠绕在一起形成螺旋。 |
| Stiffness | 刚度 |
(1) The ability of a metal or shape to resist elastic deflection.(2) The rate of stress increase with respect to the rate of increase in strain induced in the metal or shape; the greater the stress required to produce a given strain, the stiffer the material is said to be. （1）金属或形状抵抗弹性变形的能力。（2）所述应力增加速率相对于在所述金属或形状中诱导的应变增加速率；产生给定应变所需的应力越大，材料就越硬。 |
| Stove bolt | 炉用螺栓 |
This bolt has been so named because of its use in stove building. It is made in a number of different forms, either with a round button, or flat countersunk head, the head having a slot for a screwdriver and the threaded end being provided with a square or hexagon nut. 这种螺栓因其在炉灶建筑中的用途而得名。它有多种不同的形式，有圆形按钮或平沉头，头部有螺丝刀槽，螺纹端有方形或六角螺母。 |
| Strain | 拉紧 |
The unit of change in the size or shape of a body due to force. Also known as nominal strain. 物体的大小或形状因力而变化的单位。也称为标称应变。 |
| Strain aging | 应变时效 |
The changes in ductility, hardness, yield point, and tensile strength that occur when a metal or alloy that has been cold worked is stored for some time. In steel, strain aging is characterized by a loss of ductility and a corresponding increase in hardness, yield point, and tensile strength. 已冷加工的金属或合金在储存一段时间后发生的延展性、硬度、屈服点和抗拉强度的变化。在钢中，应变时效的特点是延性损失，硬度、屈服点和抗拉强度相应增加。 |
| Strain energy | 应变能 |
A measure of the energy absorption characteristics of a material determined by measuring the area under the stress-strain diagram. 通过测量应力-应变图下的面积确定的材料能量吸收特性的度量。 |
| Strain gage | 应变计 |
A device for measuring small amounts of strain produced during tensile and similar tests on metal. A coil of fine wire is mounted on a piece of paper, plastic, or similar carrier matrix (backing material), which is rectangular in shape and usually about 25 mm (1.0 in.) long. This is glued to a portion of metal under test. As the coil extends with the specimen, its electrical resistance increases in direct proportion. This is known as bonded resistance-strain gage. Other types of gages measure the actual deformation. Mechanical, optical, or electronic devices are sometimes used to magnify the strain for easier reading. 一种测量金属拉伸和类似试验中产生的少量应变的装置。将一卷细线安装在一张纸、塑料或类似载体基质（背衬材料）上，该载体基质呈矩形，通常约25mm（1.0in.）长，这是粘在测试金属的一部分。随着线圈随试样延伸，其电阻成正比增加，这被称为粘结电阻应变计。其他类型的量规测量实际变形。机械、光学或电子设备有时用于放大应变以便于读取。 |
| Strain hardening | 应变硬化 |
An increase in hardness and strengthcaused by plastic deformation at temperatures below the recrystallization range. Also known as work hardening. (workhardening) The increase in stress above the initial yield stress required to deform a metal to greater strains in the plastic range at temperatures below the recrystallization range (cold working). Unloading after some strain or work input gives a harder and stronger material. 在低于再结晶范围的温度下，塑性变形导致硬度和强度的增加。也称为加工硬化。（加工硬化）在低于再结晶范围（冷加工）的温度下，使金属在塑性范围内变形至更大应变所需的高于初始屈服应力的应力增加。在一定的应变或功输入后卸载，会得到更硬、更强的材料。 |
| Strain rate | 应变率 |
The time rate of straining for the usual tensile test. Strain as measured directly on the specimen gage length is used for determining strain rate. Because strain is dimensionless, the units of strain rate are reciprocal time. 通常拉伸试验的应变时间速率。直接在试样标距上测量的应变用于确定应变率。因为应变是无因次的，所以应变率的单位是倒数时间。 |
| Strain-age embrittlement | 应变时效脆化 |
A loss in ductility accompanied by an increase in hardness and strength that occurs when low-carbon steel (especially rimmed or capped steel) is aged following plastic deformation. The degree of embrittlement is a function of aging time and temperature, occurring in a matter of minutes at about 200°C (400 °F), but requiring a few hours to a year at room temperature. 塑性变形后低碳钢（尤其是边缘钢或封顶钢）时效时发生的延展性损失，伴随着硬度和强度的增加。脆化程度是老化时间和温度的函数，在大约200°C（400°F）的温度下，在几分钟内发生，但在室温下需要几小时到一年。 |
| Strain-hardening exponent (n value) | 应变硬化指数（n值） |
The value n in the relationship σ = Kεn, where σ is the true stress, ε is the true strain, and K, the strength coefficient, is equal to the true stress at a true strain of 1.0. The strain hardening exponent is equal to the slope of the true stress/true strain curve up to maximum load, when plotted on log-log coordinates. The n-value relates to the ability of a sheet of material to be stretched in metalworking operations. The higher the n-value, the better the formability(stretchability). Also known as the strain-hardening coefficient. 关系式σ=Kεn中的值n，其中σ是真应力，ε是真应变，K是强度系数，等于真应变为1.0时的真应力。在对数坐标上绘制时，应变硬化指数等于真应力/真应变曲线的斜率，直到最大载荷。n值与一片材料在金属加工操作中拉伸的能力有关。n值越高，成形性（拉伸性）越好。也称为应变硬化系数。 |
| Strength (Unit Pa) | 强度（单位Pa） |
The maximum stress, in tension, compression, shear, or combinations thereof, that may be monotonically applied to a material, component, or structure before failure (defined as fracture, yielding, buckling, etc. as appropriate). 在破坏前（视情况定义为断裂、屈服、屈曲等），材料、部件或结构在拉伸、压缩、剪切或其组合中可能单调施加的最大应力。 |
| Strength of bolt | 螺栓强度 |
An ambiguous term which can mean Ultimate strength or Proof load or Endurance limit or Yield strength. 一个模棱两可的术语，可表示极限强度或验证荷载或耐久极限或屈服强度。 |
| Strength of materials | 材料强度 |
A confusing name for what is really stress analysis, reflecting older engineering design based upon elasticity and ‘theories of strength’ for different materials, without regard to cracks. 对于真正的应力分析，这是一个具有迷惑性的名称，反映了基于弹性和不同材料的“强度理论”的旧工程设计，而不考虑断裂。 |
| Stress | 应力（单位Pa） |
The intensity of the internally distributed forces or components of forces that resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress is expressed in force per unit area and is calculated on the basis of the original dimensions of the cross section of the specimen. Stress can be either direct (tension or compression)or shear. 1. Stress ‘at a point’ (i.e. over a volume of material that is very small compared with that of the component or structure) is the load per unit area for every face of an infinitesimal cube surrounding the point. 2. In fluid flow the stress tensor σij is the sum of an isotropic part −pδij, δij being the Kronecker delta, having the same form as the stress tensor for a fluid at rest, p being the static pressure, and the non-isotropic, deviatoric stress tensor dij which is due entirely to the fluid motion. 内部分布力或力分量的强度，这些力或力的分量抵抗正在或已经受到外力的材料的体积或形状的变化。应力以单位面积的力表示，并根据试样横截面的原始尺寸计算。应力可以是直接（拉伸或压缩）或剪切。1.“在一点”的应力（即在与组件或结构相比非常小的材料体积上）是围绕该点的无限小立方体的每个面的单位面积载荷。2. 在流体流动中，应力张量σij是各向同性部分-pδij的总和，δij是Kroneckerδ，具有与静止流体的应力张量相同的形式，p是静压，非各向同性, 偏应力张量 dij 完全由流体运动引起。 |
| Stress amplitude | 应力幅值 |
One-half the algebraic difference between the maximum and minimum stress in one cycle of a repetitively varying stress. 重复变化应力的一个循环中最大和最小应力之间代数差的一半。 |
| Stress area | 应力面积 |
The effective cross-sectional area of the threaded section of a fastener. Used to compute average stress levels in that section. Based on the mean of pitch and minor diameters. 紧固件螺纹部分的有效横截面积。用于计算该截面中的平均应力水平。基于节距和小直径的平均值。 |
| Stress corrosion | 应力腐蚀 |
(stress-corrosion cracking) Corrosion failure accelerated by local stresses (particularly tensile) which enhance cracking in both monotonic and fatigue loading. （应力腐蚀开裂）局部应力（特别是拉伸应力）加速的腐蚀失效，该局部应力在单调载荷和疲劳载荷下都会增强开裂。 |
| Stress corrosion cracking (SCC) | 应力腐蚀开裂（SCC） |
A common form of Stress cracking in which an Electrolyte encourages the growth of a crack in a highly stressed bolt. Only a tiny quantity of electrolyte need be present, at the tip or face of the crack. A time-dependent process in which a metallurgically susceptible material fractures prematurely under conditions of simultaneous corrosion and sustained loading at lower stress levels than would be required in the absence of a corrosive environment. Tensile stress is required at the metal surface and may be a residual stress resulting from heat treatment or fabrication of the metal or the result of external loading. Cracking may be intergranular or transgranular, depending on the combination of alloy and environment. 一种常见的应力开裂形式，其中电解液促使高应力螺栓中的裂纹扩展。在裂纹尖端或表面，只需存在少量电解质。一种随时间变化的过程，其中冶金敏感材料在同时腐蚀和持续加载的条件下过早断裂，其应力水平低于无腐蚀环境时的要求。在金属表面需要拉应力，拉应力可以是金属的热处理或制造或外部负载产生的残余应力。裂纹可能是沿晶开裂或穿晶开裂，这取决于合金和环境的组合。 |
| Stress cracking | 应力开裂 |
A family of failure modes, each of which involves high stress and chemical action. The family includes Hydrogen embrittlement, Stress corrosion cracking, stress embrittlement, and hydrogen-assisted stress corrosion. 一系列失效模式，每种模式都涉及高应力和化学作用。该系列包括氢脆、应力腐蚀开裂、应力脆化和氢辅助应力腐蚀。 |
| Stress cycle | 应力循环 |
The smallest segment of the stress-time function that is repeated periodically. 周期性重复的应力时间函数的最小段。 |
| Stress cycles endured (N) | 承受的应力循环（N） |
The number of cycles of a specified character (that produce fluctuating stress and strain) that a specimen has endured at any time in its stress history. 试样在其应力历史中任何时间所经受的特定特征（产生波动应力和应变）的循环次数。 |
| Stress difference (Unit Pa) | 应力差（单位Pa） |
The algebraic difference between the largest and least principal stresses in a loaded body, equal to twice the greatest shear stress in the system. For σ1 > σ2 > σ3, it is given by (σ1 − σ3). 载荷体中最大和最小主应力之间的代数差，等于系统中最大剪应力的两倍。由（σ1− σ3).，可得σ1＞σ2＞σ3。 |
| Stress distribution | 应力分布 |
The manner in which tensile, compressive, and shear stresses are distributed within a loaded body, indicated by loci of constant stress. 拉应力、压应力和剪应力在受载物体内的分布方式，由恒定应力轨迹表示。 |
| Stress equalizing | 应力均衡 |
A low-temperature heat treatment used to balance stresses in cold-worked material without an appreciable decrease in the mechanical strength produced by cold working. 一种低温热处理，用于平衡冷加工材料中的应力，而不会明显降低冷加工产生的机械强度。 |
| Stress factor | 应力因子 |
A calibration constant used in ultrasonic measurement of bolt stress or strain. It is the ratio between the change in ultrasonic transit time caused by the change in length of the fastener, under load, to the total change in transit time. 用于螺栓应力或应变超声波测量的校准常数。它是由紧固件长度变化引起的超声波传输时间变化与总传输时间变化之间的比率。 |
| Stress raisers | 局部应力集中 |
Changes in contour or discontinuities in structure that cause local increases in stress. 导致局部应力增加的轮廓变化或结构不连续性变化。 |
| Stress ratio (A or R) | 应力比（A或R） |
The algebraic ratio of two specified stress values in a stress cycle. Two commonly used stress ratios are the ratio of the alternating stress amplitude to the mean stress, A = Sa/Sm, and the ratio of the minimum stress to the maximum stress, R = Smin/Smax. 应力循环中两个指定应力值的代数比。两种常用的应力比是交变应力振幅与平均应力之比，A=Sa/Sm，以及最小应力与最大应力之比R=Smin/Smax。 |
| Stress relaxation | 应力松弛 |
The slow decrease in stress level within a part (e.g., a bolt) which is heavily loaded under constant deflection conditions. A ‘‘cousin’’ to creep, which is a slow change in geometry under constant stress conditions. The time-dependent decrease in stress in a solid under constant strain at constant temperature due to creep. The stress-relaxation behavior of a metal is usually shown in a stress-relaxation curve. 在恒定挠曲条件下，零件（如螺栓）内的应力水平缓慢降低，该零件承受重荷载。蠕变的“表亲”，是在恒定应力条件下几何结构的缓慢变化。在恒定温度下，由于蠕变，固体在恒定应变下的应力随时间变化的减小。金属的应力松弛行为通常显示在应力松弛曲线中。 |
| Stress relieving | 应力消除 |
Heating to a suitable temperature, holding long enough to reduce residual stresses, and then cooling slowly enough to minimize the development of new residual stresses. 加热到合适的温度，保持足够长的时间以减少残余应力，然后缓慢冷却以尽量减少新残余应力的产生。 |
| Stress wave | 应力波 |
An unbalanced force, such as an impact, applied at one location in a body sets the material there into vibration that is transmitted to adjacent elements and ultimately to all parts of the body in the form of stress waves or wave packets. 施加在物体某个位置的不平衡力（如冲击力）会使物体中的材料产生振动，并以应力波或波包的形式传递到相邻元件，最终传递到物体的所有部位。 |
| Stress-concentration factor (Kt) | 应力集中系数（Kt） |
A multiplying factor for applied stress that allows for the presence of a structural discontinuity such as a notch or hole; Kt equals the ratio of the greatest stress in the region of the discontinuity to the nominal stress for the entire section. Also known as theoretical stress-concentration factor. 施加应力的倍增系数，允许存在结构不连续性，如缺口或孔；Kt等于不连续区域的最大应力与整个截面的标称应力之比。也称为理论应力集中系数。 |
| Stress-intensity calibration | 应力强度校准 |
A mathematical expression, based on empirical or analytical results, that relates the stress-intensity factor to load and crack length for a specific specimen planar geometry. Also known as Kcalibration. 基于经验或分析结果的数学表达式，该表达式将特定试样平面几何形状的应力强度因子与载荷和裂纹长度联系起来。也称为K校准。 |
| Stress-intensity factor | 应力强度因子 |
A scaling factor, usually denoted by the symbol K, used in linear-elastic fracture mechanics to describe the intensification of applied stress at the tip of a crack of known size and shape. At the onset of rapid crack propagation in any structure containing a crack, the factor is called the critical stress-intensity factor, or the fracture toughness. 一种标度因子，通常用符号K表示，在线弹性断裂力学中用于描述已知尺寸和形状的裂纹尖端施加应力的增强。在任何含有裂纹的结构中，裂纹快速扩展开始时，该因子称为临界应力强度因子，或断裂韧性。 |
| Stress-relaxation curve | 应力松弛曲线 |
A plot of the remaining, or relaxed, stress in a stress-relaxation test as a function of time. The relaxed stress equals the initial stress minus the remaining stress. Also known as a stress-time curve. 应力松弛试验中剩余应力或松弛应力随时间变化的曲线图。松弛应力等于初始应力减去剩余应力。也称为应力-时间曲线。 |
| Stress-strain diagram | 应力-应变图 |
A graph in which corresponding values of stress and strain are plotted against each other. Values of stress are usually plotted vertically(ordinates or y-axis) and values of strain horizontally (abscissas or xaxis). Also known as deformation curve and stress-strain curve. 对应的应力和应变值相对绘制的图表。应力值通常垂直绘制（纵坐标或y轴），应变值水平绘制（横坐标或X轴）。也称为变形曲线和应力-应变曲线。 |
| Stress–strain curve | 应力-应变曲线 |
(stress–strain diagram) A plot of stress vs strain for a solid material obtained from a test in which a specimen is loaded in tension, compression, shear, or combinations thereof. Diagrams of true stress vs true strain deviate from those of nominal stress vs nominal strain only at large strains where appreciable changes in cross section of testpieces occur. （应力-应变图）从试验中获得的固体材料的应力与应变图，其中试样在拉伸、压缩、剪切或其组合中加载。只有在试件横截面发生明显变化的大应变下，真实应力与真实应变图与标称应力与标称应变图不同。 |
| Stretch forming | 拉伸成型 |
A manufacturing process in which sheet-metal components are physically stretched over a forming die using a press, punch, or edge clamps. Stretching combined with bending reduces springback. 一种制造工艺，其中使用压力机、冲头或边缘夹具在成形模上物理拉伸金属板部件。拉伸与弯曲相结合可减少回弹。 |
| Stretch ratio (extension ratio, λ) | 拉伸比（拉伸比，λ） |
A measure, used for highly-extensible materials such as rubber, of the extensional or normal strain of a component subjected to tension and defined as the ratio of the final length l, for a given load, to the initial or gauge length l0, where the coordinate axes are those of principal strain. It is related to the engineering strain e by λ = 1 + e. 用于高度可延展材料（如橡胶）的一种测量方法，用于测量受拉构件的拉伸或法向应变，定义为给定载荷下的最终长度l与初始或标距长度l0之比，其中坐标轴为主应变轴。它与工程应变e的关系为λ=1+e。 |
| Stretch-bending test | 拉伸弯曲试验 |
A simulative test for sheet metal formability in which a strip of sheet metal is clamped at its ends in lock beads and deformed in the center by a punch. Test conditions are chosen so that fracture occurs in the region of punch contact. 金属板成形性的模拟试验，其中金属板条在其端部夹紧在锁珠中，并通过冲头在中心变形。选择试验条件，以便在冲头接触区域发生断裂。 |
| Striation | 条纹组织 |
A fatigue fracture feature, often observed in electron micrographs, that indicates the position of the crack front after each succeeding cycle of stress. The distance between striations indicates the advance of the crack front across that crystal during one stress cycle, and a line normal to the striation indicates the direction of local crack propagation. 一种疲劳断裂特征，通常在电子显微照片中观察到，表明每次应力循环后裂纹前沿的位置。条纹之间的距离表示在一个应力循环期间裂纹前沿穿过该晶体的前进，垂直于条纹的线表示局部裂纹扩展的方向。 |
| Stroke | 一击 |
1. (stroke length) (Unit m) The linear distance between top dead centre and bottom dead centre of a piston in a reciprocating engine or mechanism. 2. The movement of a piston or plunger in a reciprocating machine to execute a particular function; for example, the exhaust stroke of an engine in which the exhaust gases are expelled from a cylinder. 1.（冲程长度）（单位：m）往复式发动机或机构中活塞上止点和下止点之间的线性距离。2.活塞或柱塞在往复式机器中执行特定功能的运动；例如发动机的排气冲程，其中排气从气缸中排出。 |
| Structural analysis | 结构分析 |
The determination of the forces, displacements, stresses, and strains in a given structure. 确定给定结构中的力、位移、应力和应变。 |
| Structural engineering | 结构工程 |
A branch of civil engineering concerned with the design of buildings, dams, bridges, and other large structures. 土木工程的一个分支，涉及建筑物、水坝、桥梁和其他大型结构的设计。 |
| Structural frame | 结构框架 |
The underlying load-bearing framework of beams, columns, bracing, etc., of steel, concrete, brick, stone, timber etc., required to support the static and dynamic forces a building or component is subjected to, including its weight and that of its contents. 由钢、混凝土、砖、石、木材等制成的梁、柱、支撑等构成的底层承重框架，用于支撑建筑物或构件承受的静态和动态力，包括其重量及其内含物的重量。 |
| Structural-integrity analysis | 结构完整性分析 |
Assessment of components and structures for likelihood of failure by buckling, fracture, yielding, etc. under conditions of normal and accident loading. 在正常和事故荷载条件下，评估部件和结构因屈曲、断裂、屈服等而失效的可能性。 |
| Structure | 结构体 |
An assembly, usually load bearing, of connected (pinned, riveted, screwed, bolted, welded, etc.) components, such as bars, tubes, beams, and plates. 由连接（销接、铆接、螺纹连接、螺栓连接、焊接等）部件组成的组件，通常为承重组件，如杆、管、梁和板。 |
| Stud | 螺柱 |
A rod having thread on both ends. A headless threaded fastener, threaded on both ends, with an unthreaded body in the middle section, or threaded from end to end. Used with two nuts, or with one nut and a tapped hole. A plain cylindrical piece having a threaded portion of suitable length at each end or a continuous thread over the entire length. One end is screwed into a machine or workpiece after which a second part is placed over the stud and held in place by a nut. 两端都有螺纹的杆。无头螺纹紧固件，两端有螺纹，中间部分有无螺纹主体，或从一端到另一端有螺纹。与两个螺母或一个螺母和一个螺纹孔一起使用。一种普通的圆柱形部件，其两端具有适当长度的螺纹部分，或在整个长度上具有连续螺纹。一端拧入机器或工件，然后将第二部分放在螺柱上，并用螺母固定到位。 |
| Subcritical annealing | 不完全退火 |
A process anneal performed on ferrous alloys at a temperature below Ac1. 在低于Ac1的温度下对铁合金进行的工艺退火。 |
| Submerged-electrode furnace | 浸入式电极炉 |
A furnace used for liquid carburizing of parts by heating molten salt baths with the use of electrodes submerged in the ceramic lining. 一种通过使用浸入陶瓷衬里中的电极加热熔融盐浴对零件进行液体渗碳的炉。 |
| Supercharging | 增压 |
The process of increasing the mass flow rate of air (or air/fuel mixture) into the cylinder(s) of a piston engine using a compressor driven from the crankshaft (the supercharger). The power output is increased compared with a naturally-aspirated engine of the same capacity. The process also increases the air pressure and density to greater than ambient. In the past, most superchargers were mechanically driven from the engine’s crankshaft, but these have been largely superseded by turbochargers. 使用由曲轴（增压器）驱动的压缩机增加进入活塞式发动机气缸的空气（或空气/燃料混合物）质量流率的过程。与相同容量的自然吸气发动机相比，功率输出增加。该过程还将空气压力和密度增加到大于环境压力和密度。在过去，大多数增压器都是由发动机曲轴机械驱动的，但这些增压器在很大程度上已被涡轮增压器所取代。 |
| Supercooling | 过冷 |
Cooling below the temperature at which an equilibrium phase transformation can take place, without actually obtaining the transformation. 在没有实际获得相变的情况下，冷却到可以发生平衡相变的温度以下。 |
| Superheating | 过热 |
Heating above the temperature at which an equilibrium phase transformation should occur without actually obtaining the transformation. 在不实际获得相变的情况下，加热到应发生平衡相变的温度以上。 |
| Surface hardening | 表面硬化 |
A generic term covering several processes applicable to a suitable ferrous alloy that produces, by quench hardening only, a surface layer that is harder or more wear resistant than the core. There is no significant alteration of the chemical composition of the surface layer. The processes commonly used are carbonitriding, carburizing, induction hardening, flame hardening, nitriding, and nitrocarburizing. Use of the applicable specific process name is preferred. 一个通用术语，涵盖适用于仅通过淬火硬化产生比型芯更硬或更耐磨的表面层的合适铁合金的几种工艺。表面层的化学成分没有显著改变。常用的工艺有碳氮共渗、渗碳、感应淬火、火焰淬火、氮化和氮碳共渗。最好使用适用的特定工艺名称。 |
| Surface hardness | 表面硬度 |
(superficial hardness) Indentation hardness on, and for some distance below, the surface of a component, as opposed to its bulk hardness. Depending on the resolution required, micro- or nano-hardness testing machines are employed. （表面硬度）与整体硬度相反，部件表面及其下方一定距离的压痕硬度。根据所需的分辨率，可使用微型或纳米硬度测试机。 |
| Surface roughness (roughness) | 表面粗糙度 |
The small-scale, irregular peaks and troughs in a solid surface which are quantified using a surface analyser. Roughness may be a consequence of wear and corrosion, or of the manufacturing process. It leads to increased friction in solid– solid contact or fluid flow over a surface. Errors of form and waviness are excluded, but surface texture includes roughness and waviness. Surface topography incorporates the small-scale, three-dimensional geometry of a surface including surface roughness, machined, and etched features, typically at sub-mm scales. 固体表面中的小尺度不规则峰谷，使用表面分析仪进行量化。粗糙度可能是磨损和腐蚀或制造过程的结果。它会导致表面上的固-固接触或流体流动中的摩擦增加。不包括形状和波纹度误差，但表面纹理包括粗糙度和波纹度。表面形貌包括表面的小尺度三维几何结构，包括表面粗糙度、机加工和蚀刻特征，通常为亚毫米尺度。 |
| Surface tension (σ, γ) (Unit N/m) | 表面张力（σ，γ）（单位：N/m） |
At the interface between a liquid and a gas or two immiscible liquids, unbalanced cohesive forces acting on the liquid molecules at the interface lead to the property surface tension which causes tensile forces to develop as if it were a skin or membrane. 液体和气体或两种不混溶液体之间的界面处，作用在界面处的液体分子上的不平衡内聚力导致表面张力的性质，从而导致张力的发展，就像皮肤或薄膜一样。 |
| Surface treatment | 表面处理 |
Any process, including chemical, electrochemical, mechanical, and thermal, designed to protect a surface against corrosion and wear or to alter its mechanical properties. 任何旨在保护表面免受腐蚀和磨损或改变其机械性能的工艺，包括化学、电化学、机械和热处理。 |
| Swept volume (Unit m³) | 扫描体（单位m³) |
In the cylinder of a piston engine or other device, the volume between top and bottom dead centre positions of a piston; equal to πR2S where R is the piston radius and S is the stroke. 在活塞发动机或其他装置的气缸中，活塞上止点和下止点位置之间的体积；等于πR2S，其中R是活塞半径，S是冲程。 |
| Swift cup test | 斯威夫特杯测试 |
A simulative cupping test in which circular blanks of various diameters are clamped in a die ring and deep drawn into cups by a flat-bottomed cylindrical punch. 一种模拟拔杯试验，将不同直径的圆形坯料夹紧在模环中，并用平底圆柱冲头将其深拉入杯中。 |
| System engineering | 系统工程 |
A methodology which integrates all disciplines and specialty groups into a team effort, forming a structured development process that proceeds from concept to production to operation. 一种将所有学科和专业组整合到团队工作中的方法，形成从概念到生产再到运营的结构化开发过程。 |