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詞或詞組	中文	英文解釋中文解釋
B-basis	B-基礎	Mechanical property value above which at least 90% of the population of values is expected to fall, with a confidence of 95%. 機械性能值超過該值時，至少90%的值預計會下降，置信度為95%。
Bainitic hardening	貝氏體硬化	Quench-hardening treatment resulting principally in the formation of bainite. 淬火硬化處理主要導致貝氏體的形成。
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）連接在渦輪機或壓縮機軸上的圓盤，在其一側施加高壓或低壓，以抵消機器壓力變化產生的軸向推力。推力軸承的一種形式。
Balance weight	平衡器	A corrective mass used in the static or dynamic balancing of a rotating object. 用于旋轉物體的靜態或動態平衡的校正質量。
Balancing machine	平衡機	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. 一種裝置，用于評估旋轉部件的靜態和動態平衡狀態，并指示為獲得平衡而添加的砝碼的大小和位置。
Ball mill	球磨機	A mill for grinding and pulverizing materials, consisting of a horizontal rotating drum containing loose steel or ceramic balls. 一種用于研磨和粉碎物料的磨機，由裝有松散鋼球或陶瓷球的水平旋轉滾筒組成。
Ball screw and nut	滾珠絲杠和螺母	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. 一種螺母和螺栓組件，具有半圓形螺旋槽，與螺紋相反，在其中運行滾珠軸承。在螺母旋轉時，滾珠沿螺旋線移動并承受軸向載荷。到達凹槽末端的滾珠被循環回起點。這種裝置具有低摩擦和非常小的背隙，并且用于一些轉向機構。
Ballonet	氣囊	An airbag used in a hybrid airship. Helium gas expels air from the ballonet during ascent. Fans draw air in during descent. 混合動力飛艇中使用的安全氣囊。氦氣在上升過程中將空氣從氣囊中排出。風扇在下降過程中吸入空氣。
Band clutch	帶式離合器	A friction clutch in which drive is achieved by a band contracting on to the rim of the clutch. 一種摩擦離合器，其驅動是通過一條帶在離合器邊緣上收縮來實現的。
Bánki turbine	班基渦輪機	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. 一種用于非常低水頭的橫流脈沖式水輪機，其中平板形式的水射流橫向穿過渦輪機，因此穿過轉輪兩次。平行于旋轉軸水平穿過渦輪機的薄轉輪葉片在橫截面上具有輪廓。
Bar	巴（氣壓單位）	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. 一種廣泛使用的（非SI）壓力單位，大約等于海平面上的正常大氣壓。轉換為SI為1bar=105Pa。壓力單位——0oC時75.006厘米高的水銀柱或4oC時約33.45英尺水柱產生的壓力。它等于105帕斯卡。標準大氣壓（海平面）為1.01325bar或1013.25mb。
Barcol hardness test	巴氏硬度測試	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. 一種壓痕測試，類似于肖氏硬度測試，但使用帶有扁平尖端的尖頭壓頭，用于確定硬質塑料和復合材料等材料的硬度。
Barometer	氣壓計	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. 用于測量大氣壓力的儀器。有兩種主要類型——水銀氣壓計和無液氣壓計。
Barrier protection	屏障保護	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. 如果僅將緊固件與環境隔離，則據說緊固件上的涂層可提供屏障保護。例如，油漆提供屏障保護。
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. 在發生增加或減少之前最接近表面的硬度（從芯部到外徑時），分別表示滲碳或脫碳。
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. 在被認為是均勻的條件下生產的一定數量的某些產品或材料。批次通常小于很多。
Batch furnace	間歇式爐	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. 用于一次熱處理單個負載的爐子。對于重型鍛件等大型零件，間歇式爐是必需的，對于需要長周期的復雜合金牌號來說是首選。
Bearing area	承載面積	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. 軸承測試中銷（或孔）直徑和試樣厚度的乘積。（承載面）（單位m2）承載橫向載荷的孔（例如鉚釘孔）的投影面積。
Bearing failure	軸承故障	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. 當橫向載荷除以承載面積產生導致永久塑性變形的應力時，鉚接或螺栓連接中發生的失效。
Bearing strain	軸承應變	The ratio of the deformation of the bearing hole, in the direction of the applied force, to the pin diameter in a bearing test. 軸承孔在作用力方向上的變形與軸承測試中銷直徑的比值。
Bearing strength	承載強度	The maximum bearing stress that a material is capable of sustaining. 材料能夠承受的最大承載應力。
Bearing stress	承受應力	The force per unit of bearing area. 每單位承載面積的力。
Bearing test	軸承測試	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. 一種確定經受鉚接、螺栓連接或類似緊固程序的金屬產品對應力（載荷）的響應的方法。測試的目的是確定材料的承載強度，并測量承載應力與由垂直于表面刺穿板材的圓形橫截面的銷或桿產生的孔的變形。
Bearing yield strength	軸承屈服強度	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. 在軸承測試中，材料在軸承應力與軸承應變的比例之間表現出特定的極限偏差時的軸承應力。
Belt drive	帶傳動	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). 通過穿過滑輪的連續平帶或帶齒柔性帶（帶）將運動從一根軸傳遞到另一根軸。與鏈條傳動相比，皮帶傳動往往用于低扭矩應用。由于普通傳動帶的拉伸可能會導致傳動松弛（皮帶蠕變）或主動或從動皮帶輪上的皮帶打滑（皮帶打滑），從而導致傳動功率降低。
Belt furnace	帶式爐	A continuous-type furnace which uses a mesh-type or cast-link belt to carry parts through the furnace. 一種連續式爐，它使用網狀或鑄造鏈帶將零件運送通過爐子。
Bend test	彎曲試驗	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. 確定待成形金屬（通常為薄板、帶材、板材或線材）的相對延展性或確定金屬的堅固性和韌性（例如，焊接后）的試驗。試樣通常在規定的直徑上重復彎曲一個規定的角度，然后在規定的循環次數內彎曲。彎曲試驗有四種一般類型，根據施加在試樣上的力進行彎曲的方式命名：自由彎曲、引導彎曲、半引導彎曲和環繞彎曲。
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. 對于穩定流動的流體（液體或氣體），壓力、每單位體積的動能和每單位體積的勢能之和在流體中的任何點都是恒定的。使用這種關系，可以通過在兩個點測量流體的壓力來測量流體的速度，就像使用壓力計或皮托管一樣。
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. 通過在形成β相的溫度范圍內加熱某些鈦合金，然后以適當的速率冷卻以防止其分解，從而產生β相。
Bias pressure (Unit Pa)	偏壓（單位Pa）	In a fluidic device controlled by pressure difference, the magnitude of that difference. 在由壓力差控制的流體裝置中，該差值的大小。
Biaxial stress	雙軸應力	Generalized loading of a body in a single plane with no loading normal to it. 物體在一個平面內的廣義載荷，沒有垂直于它的載荷。
Bimetallic strip	雙金屬片	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. 將兩種膨脹系數不同的金屬焊接、鉚接或釬焊在一起形成的帶材，當溫度變化時，帶材會卷曲。典型的組合是鋼和銅或鋼和黃銅。
Binary vapour cycle	二元蒸氣循環	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. 一種動力循環，它將相對低溫的蒸汽循環（底部循環）與高溫循環（頂部循環）相結合，其中使用了諸如汞、鈉或鉀之類的工作流體。
Biodiesel	生物柴油	A substitute for diesel fuel derived from the oily seeds of sunflowers, oilseed rape, soya beans, etc. 從向日葵、油菜、大豆等的油性種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.來自特定種植的能源作物（包括甘蔗、玉米、小麥和大米）以及木材、稻草和動物糞便（包括污水、糞便和動物垃圾）等材料的能源。2.有時用于同時涵蓋生物質和生物燃料的術語。
Bioengineering	生物工程	(biological engineering) The application of engineering principles to biology, medicine, agriculture, etc. （生物工程）工程原理在生物學、醫學、農業等方面的應用。
Biomechanics	生物力學	The application of mechanical-engineering principles, including thermodynamics, fluid mechanics, and solid mechanics together with materials engineering, to biological systems. 機械工程原理（包括熱力學、流體力學和固體力學以及材料工程）在生物系統中的應用。
Biomedical engineering	生物醫學工程	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. 工程原理和方法在醫學領域的應用。涉及機械工程的例子包括假肢和心臟、心肺機、假眼和骨科植入物（如髖關節和用于穩定骨折骨骼的銷釘）的設計和建造。
Black annealing	黑退火	Box annealing or pot annealing ferrous alloy sheet, strip, wire to impart a black color to the oxidized surface. 對鐵合金板、帶、線進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. 通過將金屬浸入熱氧化鹽或鹽溶液中產生的黑色飾面。
Blade compressor	葉片式壓縮機	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. 一種無油雙作用旋轉式壓縮機，其中連接到旋轉外殼內表面的傾斜葉片穿過圓盤上的槽，該槽繞垂直于外殼的軸旋轉，但偏離外殼。空氣通過殼體中的孔進入，并通過殼體的端口離開。
Blank carburizing	毛坯滲碳	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. 在不引入碳的情況下模擬滲碳操作。這通常通過使用惰性材料代替滲碳劑或通過在鐵合金上施加合適的保護涂層來實現。
Blank nitriding	空白滲氮	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. 在不引入氮氣的情況下模擬氮化操作。這通常通過使用惰性材料代替氮化劑或通過在鐵合金上施加合適的保護涂層來實現。
Blanking shear test	落料剪力試驗	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. 一種用于確定板材全厚度剪切強度的方法，包括使用簡單的沖模方法從扁平帶材中沖裁出圓盤。也稱為沖切試驗。
Blind rivet	盲孔鉚釘	A rivet that enables a connexion to be made from one side only of an assembly. 一種鉚釘，可以僅從組件的一側進行連接。
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. 通過使用內部氣壓使一端密封的管子（型坯）靠在型腔模具的壁上膨脹來制造中空聚合物物體（例如瓶子）。
Blowing	吹氣	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. 氣體通過有氣流的多孔表面轉移的過程。該效應用于減少表面摩擦和增加傳熱，例如在渦輪葉片冷卻的過程中。
Blue annealing	藍色退火	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. 在開放式爐中將熱軋鐵板加熱到轉變范圍內的溫度，然后在空氣中冷卻，以軟化金屬。在表面上形成藍色氧化物是偶然的。
Blue brittleness	藍色脆性	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. 當淬火鋼在250–350°C范圍內回火（在部件表面產生藍色色調的溫度）時，延展性異常損失。某些鋼在加熱到約205至370°C（400至700°F）范圍內的某個溫度后表現出脆性，特別是在高溫下加工鋼時。鎮靜鋼幾乎沒有這種脆性。
Blueing	發藍	Application of blue dye (‘engineers’ blue’) to identify high spots on surfaces in contact, or for marking out. 應用藍色染料（“工程師藍”）來識別接觸表面上的高點，或用于標記。
Boiler and Pressure Vessel Code	鍋爐和壓力容器規范	A large and complex document, maintained and published by the American Society of Mechanical Engineers. The code 一份龐大而復雜的文件，由美國機械工程師協會出版和維護。
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. （機械螺栓）外螺紋圓柱狀緊固件：一端有頭的緊固件，通過裝配零件上的孔插入，然后通過擰緊到螺紋上的螺母固定在一起。螺栓頭部下方有一個無螺紋區域，因此當位于孔中時，橫向載荷由兩個接觸的平面圓柱面承擔。相反，使用沿其長度具有螺紋的機器螺釘，會導致螺紋支撐在孔的平面上。正式情況下，螺紋緊固件設計用于與螺母一起使用。
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. 一種已形成頭部但未切割螺紋的桿，可根據需要從中制造螺栓或螺釘。
Bolt gage	螺栓量規	An ultrasonic instrument used to measure the stress or strain in bolts. 用于測量螺栓應力或應變的超聲波儀器。
Bolt length	螺栓長度	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. 螺栓長度應為平行于產品軸線測量的從頭部的支承面到包括點在內的螺栓末端的距離。
Bolt stress (Unit Pa)	螺栓應力（單位Pa）	The axial tensile stress induced in a bolt by tightening. 通過擰緊在螺栓中產生的軸向拉應力。
Bond strength (Unit Pa)	結合強度（單位Pa）	The tensile, compressive or shear stress at which joints fail, e.g. by fracture or excessive deformation. 接頭失效的拉伸、壓縮或剪切應力，例如斷裂或過度變形。
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. 在使氧化最小化的條件下，在密封容器中對金屬或合金進行退火。在對鐵合金進行箱式退火時，通常將裝料緩慢加熱至低于轉變范圍的溫度，但有時會高于或低于轉變范圍，然后緩慢冷卻；這個過程也稱為緊密退火或罐式退火。
Boyle’s law	波義耳定律	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. 在給定的絕對溫度T下，氣體的壓力p與其體積的乘積是恒定的。與查爾斯定律一起，它產生了理想的氣體方程p=Mrt，其中m是氣體的質量，R是特定的氣體常數。恒溫下氣體的體積與壓力成反比。這意味著隨著壓力的增加，氣體的體積會減少。
Brake fluid	制動液	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. 用于將力傳遞到盤式制動器中的活塞或鼓式制動器中的輪缸的液壓油。要求包括高沸點和低吸濕性。
Brake lining	制動襯片	The replaceable friction material that covers a brake shoe in an internally expanding brake. 在內膨脹制動器中覆蓋制動的可更換摩擦材料。
Brayton cycle	布雷頓循環	(Joule cycle) An air standard cycle that is the ideal cycle for a gasturbine engine. As shown on the diagram of pressure (p) ?s specific volume (?), 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. （焦耳循環）一種空氣標準循環，是燃氣輪機發動機的理想循環。循環可以擴展到包括再生、再熱和中冷。
Breaking load	斷裂載荷	The maximum load (or force) applied to a test specimen or structural member loaded to rupture. 施加到加載到破裂的試樣或結構構件上的最大載荷（或力）。
Breaking load (Unit N)	斷裂負荷（單位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. 在某個點施加到導致斷裂的部件或結構的載荷。斷裂應力（斷裂強度）是構件斷裂時的平均應力，由斷裂載荷除以其作用的面積給出。
Breaking stress	斷裂應力	The stress at failure. Also known as rupture stress. 失效時的應力。也稱為破裂應力。
Breaks	斷裂	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”或超過屈服點的老化材料中出現折痕或隆起。根據斷裂的起源，它可能被稱為交叉斷裂、線圈斷裂、邊緣斷裂或貼紙斷裂。
Bright annealing	光亮退火	Annealing in a protective medium to prevent discoloration of the bright surface. 在保護介質中退火以防止光亮表面變色。
Bright nitriding	光亮氮化	Nitriding in a protective medium to prevent discoloration of the bright surface. 在保護介質中氮化，以防止光亮表面變色。
Brine quenching	鹽水淬火	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. 一種淬火，其中鹽水（鹽水-氯化物、碳酸鹽和氰化物）是淬火介質。添加鹽提高了水在淬火過程的氣相或熱階段的效率。
British Standards Institution (BSI)	英國標準協會（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. 負責為制成品及其設計、制造和測試制定和發布標準規范（英國標準）的英國機構。
British thermal unit (BTU, Btu)	英熱單位（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. 一種已被淘汰的（非SI）英制能量單位，定義為將68°F的一磅純水的溫度升高1°F所需的能量。轉換為SI為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. 脆性材料通常會突然斷裂，不會產生永久變形。脆性材料的例子有一些鑄鐵、玻璃、混凝土和一些塑料。如果螺栓在拉伸時僅超過其屈服點一小部分就會斷裂，則稱其為脆性螺栓。
Brittle fracture	脆性斷裂	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. 部件或結構在全局彈性載荷范圍內的斷裂，以便可以將破碎的碎片重新裝配以恢復原始物品。固體的分離伴隨著很少或沒有宏觀塑性變形。通常，脆性斷裂通過快速裂紋擴展發生，能量消耗比韌性斷裂少。
Brittle lacquer coating	脆性漆涂層	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. 一種漆，當涂在未加載的車身上時，從車身加載時在漆中產生的裂紋圖案中顯示出最大拉應力的方向。
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. 1.一種杯形葉片，所述杯形葉片具有附接到沖擊式水輪機（例如沖擊式水輪機臺）的轉輪的外圍的中央分隔脊。2.壓縮機或渦輪機中的轉子葉片。
Bulk density (Unit kg/m3)	容重（單位kg/m3）	The average density of a mass of granular or powdered material at ambient conditions. 在環境條件下大量粒狀或粉狀材料的平均密度。
Bulk velocity	體積速度	(average velocity, V) (Unit m/s) For fluid flow in a pipe or duct, the average flow velocity, given by V = ?/ρA where ? is the mass flow rate, ρ is the fluid density, and A is the duct cross-sectional area. （平均速度，V）（單位m/s）對于管道或管道中的流體流動，平均流速，由V=?/ρA給出，其中?是質量流量，ρ是流體密度，A是管道截面積。
Burning	燃燒化	(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）通過加熱導致初期熔化或晶間氧化而永久損壞金屬或合金。參見過熱、晶界液化。（2）在磨削過程中，使工件熱到足以引起變色或通過回火或硬化改變微觀結構。
Butt joint	對接接頭	The end-to-end joining of two plates either by welding or by overlapping plates that are bolted or riveted. 通過焊接或通過螺栓或鉚接的重疊板將兩塊板端對端連接。
Butterfly valve	蝶閥	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. 閥瓣在與管道軸線成直角的軸上旋轉以調節流量的閥門。當打開時，圓盤與水流邊緣并提供有限的阻力。關閉時，閥瓣被壓在閥體內的閥座上。
Bypass flow meter	旁通流量計	(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. （分流流量計）安裝在管道旁路中的流量計，它本身可能是流量計的一部分。孔板用于確保一部分主流通過旁路。
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. 在渦扇發動機中，旁通流的質量流量與通過發動機核心的質量流量之比。
Bypass valve	旁通閥	A valve that directs flow through a bypass. 引導流過旁路的閥門。