| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| B-basis | B-基础 |
Mechanical property value above which at least 90% of the population of values is expected to fall, with a confidence of 95%. 机械性能值超过该值时，至少90%的值预计会下降，置信度为95%。 |
| Bainitic hardening | 贝氏体硬化 |
Quench-hardening treatment resulting principally in the formation of bainite. 淬火硬化处理主要导致贝氏体的形成。 |
| Balance piston | 平衡活塞 |
(balance drum, dummy piston) A disc attached to the shaft of a turbine or compressor, to one side of which high or low pressure is applied to counteract the axial thrust produced by the pressure change across the machine. A form of thrust bearing. （平衡鼓，假活塞）连接在涡轮机或压缩机轴上的圆盘，在其一侧施加高压或低压，以抵消机器压力变化产生的轴向推力。推力轴承的一种形式。 |
| Balance weight | 平衡器 |
A corrective mass used in the static or dynamic balancing of a rotating object. 用于旋转物体的静态或动态平衡的校正质量。 |
| Balancing machine | 平衡机 |
A device that assesses the state of static and dynamic balance of a rotating part, and indicates the magnitude and location of weights to be added to give balance. 一种装置，用于评估旋转部件的静态和动态平衡状态，并指示为获得平衡而添加的砝码的大小和位置。 |
| Ball mill | 球磨机 |
A mill for grinding and pulverizing materials, consisting of a horizontal rotating drum containing loose steel or ceramic balls. 一种用于研磨和粉碎物料的磨机，由装有松散钢球或陶瓷球的水平旋转滚筒组成。 |
| Ball screw and nut | 滚珠丝杠和螺母 |
A nut and bolt assembly having semi-circular helical grooves, as opposed to threads, in which run ball bearings. On rotation of the nut, the balls move along the helix and carry the axial load. Balls reaching the end of the groove are recirculated back to the beginning. Such devices have low friction and very little backlash, and are used in some steering mechanisms. 一种螺母和螺栓组件，具有半圆形螺旋槽，与螺纹相反，在其中运行滚珠轴承。在螺母旋转时，滚珠沿螺旋线移动并承受轴向载荷。到达凹槽末端的滚珠被循环回起点。这种装置具有低摩擦和非常小的背隙，并且用于一些转向机构。 |
| Ballonet | 气囊 |
An airbag used in a hybrid airship. Helium gas expels air from the ballonet during ascent. Fans draw air in during descent. 混合动力飞艇中使用的安全气囊。氦气在上升过程中将空气从气囊中排出。风扇在下降过程中吸入空气。 |
| Band clutch | 带式离合器 |
A friction clutch in which drive is achieved by a band contracting on to the rim of the clutch. 一种摩擦离合器，其驱动是通过一条带在离合器边缘上收缩来实现的。 |
| Bánki turbine | 班基涡轮机 |
A cross-flow, impulse-type water turbine for very low heads in which a jet of water in the form of a flat sheet passes transversely through the turbine, so going through the runner twice. The thin runner blades which run horizontally across the turbine parallel to the axis of rotation are profiled in cross section. 一种用于非常低水头的横流脉冲式水轮机，其中平板形式的水射流横向穿过涡轮机，因此穿过转轮两次。平行于旋转轴水平穿过涡轮机的薄转轮叶片在横截面上具有轮廓。 |
| Bar | 巴（气压单位） |
A widely used (non-SI) unit of pressure approximately equal to normal atmospheric pressure at sea level. The conversion to SI is 1 bar = 105 Pa. Unit of pressure – the pressure created by a column of€mercury 75.006 cm high at 0ºC, or about 33.45 feet of water at 4ºC. It is equal to 105 pascal. Standard atmospheric pressure (at sea level) is 1.01325 bar, or 1013.25 mb. 一种广泛使用的（非SI）压力单位，大约等于海平面上的正常大气压。转换为SI为1bar=105Pa。压力单位——0ºC时75.006厘米高的水银柱或4ºC时约33.45英尺水柱产生的压力。它等于105帕斯卡。标准大气压（海平面）为1.01325bar或1013.25mb。 |
| Barcol hardness test | 巴氏硬度测试 |
An indentation test, similar to the Shore hardness test but using a pointed indentor with a flat tip, used to determine the hardness of such materials as rigid plastics and composites. 一种压痕测试，类似于肖氏硬度测试，但使用带有扁平尖端的尖头压头，用于确定硬质塑料和复合材料等材料的硬度。 |
| Barometer | 气压计 |
An instrument used to measure atmospheric pressure. An instrument for measuring atmospheric pressure. There are two main types – the mercury barometer, and the aneroid barometer. 用于测量大气压力的仪器。有两种主要类型——水银气压计和无液气压计。 |
| Barrier protection | 屏障保护 |
The coating on a fastener is said to provide barrier protection if it merely isolates the fastener from the environment. Paint, for example, provides barrier protection. 如果仅将紧固件与环境隔离，则据说紧固件上的涂层可提供屏障保护。例如，油漆提供屏障保护。 |
| Base metal hardness | 母材硬度 |
Hardness closest to the surface (when traversing from core to outside diameter) just before an increase or decrease occurs, denoting, respectively, carburization or decarburization. 在发生增加或减少之前最接近表面的硬度（从芯部到外径时），分别表示渗碳或脱碳。 |
| Batch | 一批 |
A definite quantity of some product or material produced under conditions that are considered uniform. A batch is usually smaller than a lot. 在被认为是均匀的条件下生产的一定数量的某些产品或材料。批次通常小于很多。 |
| Batch furnace | 间歇式炉 |
A furnace used to heat treat a single load at a time. Batch-type furnaces are necessary for large parts such as heavy forgings and are preferred for complex alloy grades requiring long cycles. 用于一次热处理单个负载的炉子。对于重型锻件等大型零件，间歇式炉是必需的，对于需要长周期的复杂合金牌号来说是首选。 |
| Bearing area | 承载面积 |
The product of the pin (or hole) diameter and specimen thickness in a bearing test. (bearing surface) (Unit m²) The projected area of a hole, such as a rivet hole, that carries a transverse load. 轴承测试中销（或孔）直径和试样厚度的乘积。（承载面）（单位m²）承载横向载荷的孔（例如铆钉孔）的投影面积。 |
| Bearing failure | 轴承故障 |
A failure that occurs in a riveted or bolted joint when the transverse load divided by the bearing area results in a stress that leads to permanent plastic deformation. 当横向载荷除以承载面积产生导致永久塑性变形的应力时，铆接或螺栓连接中发生的失效。 |
| Bearing strain | 轴承应变 |
The ratio of the deformation of the bearing hole, in the direction of the applied force, to the pin diameter in a bearing test. 轴承孔在作用力方向上的变形与轴承测试中销直径的比值。 |
| Bearing strength | 承载强度 |
The maximum bearing stress that a material is capable of sustaining. 材料能够承受的最大承载应力。 |
| Bearing stress | 承受应力 |
The force per unit of bearing area. 每单位承载面积的力。 |
| Bearing test | 轴承测试 |
A method of determining the response to stress (load) of metal products that are subjected to riveting, bolting, or a similar fastening procedure. The purpose of the test is to determine the bearing strength of the material and to measure the bearing stress versus the deformation of the hole created by a pin or rod of circular cross section that pierces the sheet perpendicular to the surface. 一种确定经受铆接、螺栓连接或类似紧固程序的金属产品对应力（载荷）的响应的方法。测试的目的是确定材料的承载强度，并测量承载应力与由垂直于表面刺穿板材的圆形横截面的销或杆产生的孔的变形。 |
| Bearing yield strength | 轴承屈服强度 |
The bearing stress at which a material exhibits a specified limiting deviation from the proportionality of bearing stress to bearing strain in a bearing test. 在轴承测试中，材料在轴承应力与轴承应变的比例之间表现出特定的极限偏差时的轴承应力。 |
| Belt drive | 带传动 |
Transmission of motion from one shaft to another by means of a continuous plain, or toothed, flexible band (belt) passing over pulleys. In contrast to chain drives, belt drives tend to be employed in low-torque applications. Reduction in transmissible power may occur due to stretch of a plain transmission belt which results in slack in the drive (belt creep) or slip of a belt on a driving or driven pulley (belt slip). 通过穿过滑轮的连续平带或带齿柔性带（带）将运动从一根轴传递到另一根轴。与链条传动相比，皮带传动往往用于低扭矩应用。由于普通传动带的拉伸可能会导致传动松弛（皮带蠕变）或主动或从动皮带轮上的皮带打滑（皮带打滑），从而导致传动功率降低。 |
| Belt furnace | 带式炉 |
A continuous-type furnace which uses a mesh-type or cast-link belt to carry parts through the furnace. 一种连续式炉，它使用网状或铸造链带将零件运送通过炉子。 |
| Bend test | 弯曲试验 |
A test for determining the relative ductility of metal that is to be formed (usually sheet, strip, plate, or wire) or for determining soundness and toughness of metal (after welding, for example). The specimen is usually repeatedly bent over a specified diameter through a specified angle and then unbent for a specified number of cycles. There are four general types of bend tests, named according to the manner in which the forces are applied to the specimen to make the bend: free bend, guided bend, semiguided bend, and wrap-around bend. 确定待成形金属（通常为薄板、带材、板材或线材）的相对延展性或确定金属的坚固性和韧性（例如，焊接后）的试验。试样通常在规定的直径上重复弯曲一个规定的角度，然后在规定的循环次数内弯曲。弯曲试验有四种一般类型，根据施加在试样上的力进行弯曲的方式命名：自由弯曲、引导弯曲、半引导弯曲和环绕弯曲。 |
| Bernoulli’s law | 伯努利定律 |
For a steadily flowing fluid (liquid or gas), the sum of the pressure, kinetic energy per unit volume and potential energy per unit volume is constant at any point in the fluid. Using this relationship, it is possible to measure the velocity of a fluid by measuring its pressure at two points, as with a manometer or Pitot tube. 对于稳定流动的流体（液体或气体），压力、每单位体积的动能和每单位体积的势能之和在流体中的任何点都是恒定的。使用这种关系，可以通过在两个点测量流体的压力来测量流体的速度，就像使用压力计或皮托管一样。 |
| Beta annealing | β退火 |
Producing a beta phase by heating certain titanium alloys in the temperature range of which this phase forms followed by cooling at an appropriate rate to prevent its decomposition. 通过在形成β相的温度范围内加热某些钛合金，然后以适当的速率冷却以防止其分解，从而产生β相。 |
| Bias pressure (Unit Pa) | 偏压（单位Pa） |
In a fluidic device controlled by pressure difference, the magnitude of that difference. 在由压力差控制的流体装置中，该差值的大小。 |
| Biaxial stress | 双轴应力 |
Generalized loading of a body in a single plane with no loading normal to it. 物体在一个平面内的广义载荷，没有垂直于它的载荷。 |
| Bimetallic strip | 双金属片 |
A strip formed by welding, riveting or brazing together two metals having different coefficients of expansion, which causes the strip to curl when its temperature changes. Typical combinations are steel and copper or steel and brass. 将两种膨胀系数不同的金属焊接、铆接或钎焊在一起形成的带材，当温度变化时，带材会卷曲。典型的组合是钢和铜或钢和黄铜。 |
| Binary vapour cycle | 二元蒸气循环 |
A power cycle which combines a steam cycle at relatively low temperature (the bottoming cycle) with a higher temperature cycle (the topping cycle) in which a working fluid such as mercury, sodium or potassium is used. 一种动力循环，它将相对低温的蒸汽循环（底部循环）与高温循环（顶部循环）相结合，其中使用了诸如汞、钠或钾之类的工作流体。 |
| Biodiesel | 生物柴油 |
A substitute for diesel fuel derived from the oily seeds of sunflowers, oilseed rape, soya beans, etc. 从向日葵、油菜、大豆等的油性种子中提取的柴油的替代品。 |
| Bioenergy | 生物能源 |
1. Energy derived from materials such as purpose-grown energy crops, including sugar cane, maize, wheat, and rice, as well as wood, straw, and animal waste, including sewage, manure, and animal litter. 2. A term sometimes used to cover biomass and biofuels together. 1.来自特定种植的能源作物（包括甘蔗、玉米、小麦和大米）以及木材、稻草和动物粪便（包括污水、粪便和动物垃圾）等材料的能源。2.有时用于同时涵盖生物质和生物燃料的术语。 |
| Bioengineering | 生物工程 |
(biological engineering) The application of engineering principles to biology, medicine, agriculture, etc. （生物工程）工程原理在生物学、医学、农业等方面的应用。 |
| Biomechanics | 生物力学 |
The application of mechanical-engineering principles, including thermodynamics, fluid mechanics, and solid mechanics together with materials engineering, to biological systems. 机械工程原理（包括热力学、流体力学和固体力学以及材料工程）在生物系统中的应用。 |
| Biomedical engineering | 生物医学工程 |
The application of engineering principles and methodology to the medical field. Examples involving mechanical engineering include the design and construction of artificial limbs and hearts, heart-lung machines, prosthetic eyes, and orthopaedic implants such as hip joints and pins to stabilize fractured bones. 工程原理和方法在医学领域的应用。涉及机械工程的例子包括假肢和心脏、心肺机、假眼和骨科植入物（如髋关节和用于稳定骨折骨骼的销钉）的设计和建造。 |
| Black annealing | 黑退火 |
Box annealing or pot annealing ferrous alloy sheet, strip, wire to impart a black color to the oxidized surface. 对铁合金板、带、线进行箱式退火或罐式退火，使氧化表面呈黑色。 |
| Black oxide | 黑色氧化物 |
A black finish on a metal produced by immersing it in hot oxidizing salts or salt solutions. 通过将金属浸入热氧化盐或盐溶液中产生的黑色饰面。 |
| Blade compressor | 叶片式压缩机 |
An oil-free, double-acting rotary compressor in which an angled blade attached to the inner surface of a rotating housing passes through a slot in a disk rotating about an axis perpendicular to that of the housing but offset from it. Air enters through apertures in the housing and leaves through a port in the housing. 一种无油双作用旋转式压缩机，其中连接到旋转外壳内表面的倾斜叶片穿过圆盘上的槽，该槽绕垂直于外壳的轴旋转，但偏离外壳。空气通过壳体中的孔进入，并通过壳体的端口离开。 |
| Blank carburizing | 毛坯渗碳 |
Simulating the carburizing operation without introducing carbon. This is usually accomplished by using an inert material in place of the carburizing agent, or by applying a suitable protective coating to the ferrous alloy. 在不引入碳的情况下模拟渗碳操作。这通常通过使用惰性材料代替渗碳剂或通过在铁合金上施加合适的保护涂层来实现。 |
| Blank nitriding | 空白渗氮 |
Simulating the nitriding operation without introducing nitrogen. This is usually accomplished by using an inert material in place of the nitriding agent or by applying a suitable protective coating to the ferrous alloy. 在不引入氮气的情况下模拟氮化操作。这通常通过使用惰性材料代替氮化剂或通过在铁合金上施加合适的保护涂层来实现。 |
| Blanking shear test | 落料剪力试验 |
A method used to determine the through-thickness shear strength of sheet material that involves blanking a disk out of flat strip using a simple punch-and-die method. Alson known as punching shear test. 一种用于确定板材全厚度剪切强度的方法，包括使用简单的冲模方法从扁平带材中冲裁出圆盘。也称为冲切试验。 |
| Blind rivet | 盲孔铆钉 |
A rivet that enables a connexion to be made from one side only of an assembly. 一种铆钉，可以仅从组件的一侧进行连接。 |
| Blow moulding | 吹塑 |
The manufacture of hollow polymer objects (e.g. bottles) by expanding, with internal air pressure, a tube sealed at one end (parison) against the walls of a cavity mould. 通过使用内部气压使一端密封的管子（型坯）靠在型腔模具的壁上膨胀来制造中空聚合物物体（例如瓶子）。 |
| Blowing | 吹气 |
The process by which a gas is transferred through a porous surface over which there is a gas flow. The effect is used to decrease skin friction and increase heat transfer, for example in turbine-blade cooling. 气体通过有气流的多孔表面转移的过程。该效应用于减少表面摩擦和增加传热，例如在涡轮叶片冷却的过程中。 |
| Blue annealing | 蓝色退火 |
Heating hot-rolled ferrous sheet in an open furnace to a temperature within the transformation range and then cooling in air, in order to soften the metal. The formation of a bluish oxide on the surface is incidental. 在开放式炉中将热轧铁板加热到转变范围内的温度，然后在空气中冷却，以软化金属。在表面上形成蓝色氧化物是偶然的。 |
| Blue brittleness | 蓝色脆性 |
Anomalous loss of ductility when quenched steels are tempered in the range 250–350°C (temperatures that produce blue tints on the surface of components). Brittleness exhibited by some steels after being heated to some temperature within the range of about 205 to 370 °C (400 to 700 °F), particularly if the steel is worked at the elevated temperature. Killed steels are virtually free of this kind of brittleness. 当淬火钢在250–350°C范围内回火（在部件表面产生蓝色色调的温度）时，延展性异常损失。某些钢在加热到约205至370°C（400至700°F）范围内的某个温度后表现出脆性，特别是在高温下加工钢时。镇静钢几乎没有这种脆性。 |
| Blueing | 发蓝 |
Application of blue dye (‘engineers’ blue’) to identify high spots on surfaces in contact, or for marking out. 应用蓝色染料（“工程师蓝”）来识别接触表面上的高点，或用于标记。 |
| Boiler and Pressure Vessel Code | 锅炉和压力容器规范 |
A large and complex document, maintained and published by the American Society of Mechanical Engineers. The code 一份庞大而复杂的文件，由美国机械工程师协会出版和维护。 |
| Bolt | 螺栓 |
(machine bolt) A fastener in the form of an externally-threaded cylinder with a head on one end that is inserted through holes in assembled parts that are then held together by a nut tightened on to the thread. A bolt has an unthreaded region below the head so that when located in a hole, transverse loads are borne by two plain cylindrical surfaces in contact. In contrast, use of a machine screw, that has threads all along its length, results in threads bearing against the plain surface of a hole. Officially, a threaded fastener designed to be used with a nut. （机械螺栓）外螺纹圆柱状紧固件：一端有头的紧固件，通过装配零件上的孔插入，然后通过拧紧到螺纹上的螺母固定在一起。螺栓头部下方有一个无螺纹区域，因此当位于孔中时，横向载荷由两个接触的平面圆柱面承担。相反，使用沿其长度具有螺纹的机器螺钉，会导致螺纹支撑在孔的平面上。正式情况下，螺纹紧固件设计用于与螺母一起使用。 |
| Bolt blank | 螺栓毛坯 |
A rod on which a head has been formed, but on which no thread has been cut, from which bolts or screws may be made as required. 一种已形成头部但未切割螺纹的杆，可根据需要从中制造螺栓或螺钉。 |
| Bolt gage | 螺栓量规 |
An ultrasonic instrument used to measure the stress or strain in bolts. 用于测量螺栓应力或应变的超声波仪器。 |
| Bolt length | 螺栓长度 |
The bolt length shall be the distance measured parallel to the axis of the product from the bearing surface of the head to the extreme end of the bolt including point. 螺栓长度应为平行于产品轴线测量的从头部的支承面到包括点在内的螺栓末端的距离。 |
| Bolt stress (Unit Pa) | 螺栓应力（单位Pa） |
The axial tensile stress induced in a bolt by tightening. 通过拧紧在螺栓中产生的轴向拉应力。 |
| Bond strength (Unit Pa) | 结合强度（单位Pa） |
The tensile, compressive or shear stress at which joints fail, e.g. by fracture or excessive deformation. 接头失效的拉伸、压缩或剪切应力，例如断裂或过度变形。 |
| Box annealing | 箱式退火 |
Annealing a metal or alloy in a sealed container under conditions that minimize oxidation. In box annealing a ferrous alloy, the charge is usually heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly; this process is also called close annealing or pot annealing. 在使氧化最小化的条件下，在密封容器中对金属或合金进行退火。在对铁合金进行箱式退火时，通常将装料缓慢加热至低于转变范围的温度，但有时会高于或低于转变范围，然后缓慢冷却；这个过程也称为紧密退火或罐式退火。 |
| Boyle’s law | 波义耳定律 |
The product of the pressure of a gas p and its volume is constant at a given absolute temperature T. Together with Charles law, it yields the ideal gas equation p = Mrt where m is the mass of gas and R is the specific gas constant. The volume of a gas at constant temperature is inversely proportional to the pressure. This means that as pressure increases, the volume of a gas decreases. 在给定的绝对温度T下，气体的压力p与其体积的乘积是恒定的。与查尔斯定律一起，它产生了理想的气体方程p=Mrt，其中m是气体的质量，R是特定的气体常数。恒温下气体的体积与压力成反比。这意味着随着压力的增加，气体的体积会减少。 |
| Brake fluid | 制动液 |
The hydraulic fluid used to transmit force to the pistons in disc brakes or the wheel cylinders in drum brakes. Requirements include a high boiling point and low hygroscopy. 用于将力传递到盘式制动器中的活塞或鼓式制动器中的轮缸的液压油。要求包括高沸点和低吸湿性。 |
| Brake lining | 制动衬片 |
The replaceable friction material that covers a brake shoe in an internally expanding brake. 在内膨胀制动器中覆盖制动的可更换摩擦材料。 |
| Brayton cycle | 布雷顿循环 |
(Joule cycle) An air standard cycle that is the ideal cycle for a gasturbine engine. As shown on the diagram of pressure (p) ʋs specific volume (ʋ), it consists of four internally reversible processes: isentropic compression in a compressor (1–2), isobaric heat addition in a combustor (2–3), isentropic expansion in a turbine (3–4) and isobaric heat rejection. The cycle can be extended to include regeneration, reheating, and intercooling. （焦耳循环）一种空气标准循环，是燃气轮机发动机的理想循环。循环可以扩展到包括再生、再热和中冷。 |
| Breaking load | 断裂载荷 |
The maximum load (or force) applied to a test specimen or structural member loaded to rupture. 施加到加载到破裂的试样或结构构件上的最大载荷（或力）。 |
| Breaking load (Unit N) | 断裂负荷（单位N） |
The load applied at some point to a component or structure which leads to fracture. The breaking stress (breaking strength) is the average stress at which a member breaks, given by the breaking load divided by the area over which it acts. 在某个点施加到导致断裂的部件或结构的载荷。断裂应力（断裂强度）是构件断裂时的平均应力，由断裂载荷除以其作用的面积给出。 |
| Breaking stress | 断裂应力 |
The stress at failure. Also known as rupture stress. 失效时的应力。也称为破裂应力。 |
| Breaks | 断裂 |
Creases or ridges usually in “untempered” or in aged material where the yield point has been exceeded. Depending on the origin of the break, it may be termed a cross break, a coil break, an edge break, or a sticker break. 通常在“未回火”或超过屈服点的老化材料中出现折痕或隆起。根据断裂的起源，它可能被称为交叉断裂、线圈断裂、边缘断裂或贴纸断裂。 |
| Bright annealing | 光亮退火 |
Annealing in a protective medium to prevent discoloration of the bright surface. 在保护介质中退火以防止光亮表面变色。 |
| Bright nitriding | 光亮氮化 |
Nitriding in a protective medium to prevent discoloration of the bright surface. 在保护介质中氮化，以防止光亮表面变色。 |
| Brine quenching | 盐水淬火 |
A quench in which brine (salt water-chlorides, carbonates, and cyanides) is the quenching medium. The salt addition improves the efficiency of water at the vapor phase or hot stage of the quenching process. 一种淬火，其中盐水（盐水-氯化物、碳酸盐和氰化物）是淬火介质。添加盐提高了水在淬火过程的气相或热阶段的效率。 |
| British Standards Institution (BSI) | 英国标准协会（BSI） |
The Institution in the UK responsible for the preparation and publication of standard specifications (British standards) for manufactured goods, their design, manufacture and testing. 负责为制成品及其设计、制造和测试制定和发布标准规范（英国标准）的英国机构。 |
| British thermal unit (BTU, Btu) | 英热单位（BTU，Btu） |
An obsolete (non-SI) imperial unit of energy defined as the energy required to raise the temperature of one pound of pure water at 68°F by 1°F. The conversion to SI is 1 Btu = 1.055 056 × 103 J. 一种已被淘汰的（非SI）英制能量单位，定义为将68°F的一磅纯水的温度升高1°F所需的能量。转换为SI为1Btu=1.055056×103J。 |
| Brittle | 脆性材料 |
A brittle material is one that breaks, often suddenly, with no permanent deformation. Examples of brittle materials are some cast irons, glass, concrete, and some plastics. A bolt is said to be brittle if it will break when stretched only a small amount past its yield point. 脆性材料通常会突然断裂，不会产生永久变形。脆性材料的例子有一些铸铁、玻璃、混凝土和一些塑料。如果螺栓在拉伸时仅超过其屈服点一小部分就会断裂，则称其为脆性螺栓。 |
| Brittle fracture | 脆性断裂 |
The fracture of a component or structure in the globally-elastic range of loading, so that the broken pieces may be refitted to regain the original article. Separation of a solid accompanied by little or no macroscopic plastic deformation. Typically, brittle fracture occurs by rapid crack propagation with less expenditure of energy than for ductile fracture. 部件或结构在全局弹性载荷范围内的断裂，以便可以将破碎的碎片重新装配以恢复原始物品。固体的分离伴随着很少或没有宏观塑性变形。通常，脆性断裂通过快速裂纹扩展发生，能量消耗比韧性断裂少。 |
| Brittle lacquer coating | 脆性漆涂层 |
A lacquer that, when painted on to an unloaded body, reveals the direction of maximum tension stresses from the pattern of cracking produced in the lacquer when the body is loaded. 一种漆，当涂在未加载的车身上时，从车身加载时在漆中产生的裂纹图案中显示出最大拉应力的方向。 |
| Bucket | 吊桶 |
1. A cup-shaped vane with a central dividing ridge attached to the periphery of the runner of an impulse water turbine such as a Pelton turbine. 2. A rotor blade in a compressor or turbine. 1.一种杯形叶片，所述杯形叶片具有附接到冲击式水轮机（例如冲击式水轮机台）的转轮的外围的中央分隔脊。2.压缩机或涡轮机中的转子叶片。 |
| Bulk density (Unit kg/m³) | 容重（单位kg/m³） |
The average density of a mass of granular or powdered material at ambient conditions. 在环境条件下大量粒状或粉状材料的平均密度。 |
| Bulk velocity | 体积速度 |
(average velocity, V) (Unit m/s) For fluid flow in a pipe or duct, the average flow velocity, given by V = ṁ/ρA where ṁ is the mass flow rate, ρ is the fluid density, and A is the duct cross-sectional area. （平均速度，V）（单位m/s）对于管道或管道中的流体流动，平均流速，由V=ṁ/ρA给出，其中ṁ是质量流量，ρ是流体密度，A是管道截面积。 |
| Burning | 燃烧化 |
(1) Permanently damaging a metal or alloy by heating to cause either incipient melting or intergranular oxidation. See overheating, grain-boundary liquation. (2) In grinding, getting the work hot enough to cause discoloration or to change the microstructure by tempering or hardening. （1）通过加热导致初期熔化或晶间氧化而永久损坏金属或合金。参见过热、晶界液化。（2）在磨削过程中，使工件热到足以引起变色或通过回火或硬化改变微观结构。 |
| Butt joint | 对接接头 |
The end-to-end joining of two plates either by welding or by overlapping plates that are bolted or riveted. 通过焊接或通过螺栓或铆接的重叠板将两块板端对端连接。 |
| Butterfly valve | 蝶阀 |
A valve in which a disc rotates on a shaft at right angles to the axis of a pipe to regulate flow. When open, the disc is edge-on to the flow and offers limited resistance. When closed, the disc is pressed against a seat in the valve body. 阀瓣在与管道轴线成直角的轴上旋转以调节流量的阀门。当打开时，圆盘与水流边缘并提供有限的阻力。关闭时，阀瓣被压在阀体内的阀座上。 |
| Bypass flow meter | 旁通流量计 |
(shunt flow meter) A flow meter installed in a pipework bypass which may itself be part of the flow meter. An orifice plate is used to ensure a fraction of the main flow passes through the bypass. （分流流量计）安装在管道旁路中的流量计，它本身可能是流量计的一部分。孔板用于确保一部分主流通过旁路。 |
| Bypass ratio | 旁路比 |
In a turbofan engine, the ratio of the mass flow rate of the bypass stream to the mass flow rate through the core of the engine. 在涡扇发动机中，旁通流的质量流量与通过发动机核心的质量流量之比。 |
| Bypass valve | 旁通阀 |
A valve that directs flow through a bypass. 引导流过旁路的阀门。 |