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詞或詞組	中文	英文解釋中文解釋
Partial annealing	不完全退火	An imprecise term used to denote a treatment given cold-worked material to reduce the strength to a controlled level or to effect stress relief. To be meaningful, the type of material, the degree of cold work, and the time-temperature schedule must be stated. 一個不精確的術語，用于表示冷加工材料的處理，以將強度降低到受控水平或消除應力。為了有意義，必須說明材料類型、冷加工程度和時間-溫度計劃。
Pascal (Pa)	帕斯卡（Pa）	The SI unit of pressure, 1 Pa = 1 N/m2. 壓力的國際單位制，1Pa=1N/m2。
Pascal’s law	帕斯卡定律	When there is a change in pressure at any point in a confined fluid at rest, there is an equal change at every other point in the fluid volume. 當處于靜止狀態的受限流體中任何一點的壓力發生變化時，流體體積中的每一點的變化都相等。
Peel strength (Unit N)	剝離強度（單位：N）	(peel test) The strength of an adhesive bond between two materials as measured by the force required in a given direction to peel apart adhered strips. This force depends on the dimensions and thickness of the adhered strips and their yield stress, together with the fracture toughness of the bond. （剝離試驗）兩種材料之間的粘合強度，通過給定方向上剝離粘合條所需的力來測量。該力取決于粘合條的尺寸和厚度及其屈服應力，以及粘合劑的斷裂韌性。
Percent error	誤差百分比	For testing machines, the ratio, expressed as a percentage, of the error to the correct value of the applied load. 對于試驗機，以百分比表示的誤差與所施加載荷的正確值之比。
Permanent set	永久變形	The deformation or strain remaining in a previously stressed body after release of load. 釋放荷載后，先前受力物體中剩余的變形或應變。
Permissible variation	允許偏差	For testing machines, the maximum allowable error in the value of the quantity indicated. It is convenient to express permissible variation in terms of the percent error. 對于試驗機，所示數量值的最大允許誤差。用誤差百分比表示允許偏差是很方便的。
Physical crack size (ap)	物理裂紋尺寸（ap）	The distance from a reference plane to the observed crack front. This distance may represent an average of several measurements along the crack front. The reference plane depends on the specimen form, and it is normally taken to be either the boundary or a plane containing either the load line or the centerline of a specimen or plate. 從基準面到觀察到的裂紋前沿的距離。該距離可以表示沿裂紋前沿的若干測量的平均值。基準面取決于試樣形狀，通常視為邊界或包含試樣或板的載重線或中心線的平面。
Physical properties	物理性質	Properties of a material the determination of which does not involve the deformation or destruction of the specimen—for example, density, electrical conductivity, coefficient of thermal expansion, magnetic permeability, and lattice parameter. Does not include chemical reactivity or the properties more appropriately regarded as mechanical properties. 不涉及試樣變形或破壞的材料特性，例如密度、電導率、熱膨脹系數、磁導率和晶格參數。不包括化學反應性或更適當地視為機械的性質。
Physical testing	物理測試	Methods used to determine the entire range of physical properties of a material. In addition to density and thermal, electrical, and magnetic properties, physical testing methods can be used to assess simple fundamental physical properties such as color, crystalline form, and melting point. 用于確定材料整個物理特性范圍的方法。除了密度和熱、電、磁特性外，物理測試方法還可用于評估簡單的基本物理特性，如顏色、結晶形式和熔點。
Pin expansion test	插頭膨脹試驗	A test for determining the ability of a tube to be expanded or for revealing the presence of cracks or other longitudinal weaknesses in it, made by forcing a tapered pin into the open end of the tube, similar to flare test. 通過將錐形銷壓入管道開口端來確定管道膨脹能力或揭示其存在裂紋或其他縱向缺陷的試驗，類似于擴口試驗。
Pin or mandrel	銷或心軸	In bend testing, the plunger or tool used in making semiguided, guided, or wrap-around tests to apply the bending force to the inside surface of the bend. In free bends or semiguided bends to an angle of180°, a shim or block of the proper thickness may be placed between the legs of the specimen as bending is completed. This shim or block is also referred to as a pin or mandrel. 在彎曲測試中，用于進行半導向、導向或環繞測試以將彎曲力施加到彎曲內表面的柱塞或工具。在180°角的自由彎曲或半導向彎曲中，彎曲完成后，可在試樣支腿之間放置適當厚度的墊片或墊塊。該墊片或墊塊也稱為銷或心軸。
Piston pump	活塞泵	A positive-displacement pump in the basic configuration of which a piston reciprocates in a cylinder. On the suction stroke, fluid is drawn into a chamber through the inlet valve, which is then open while the outlet valve is closed. On the delivery stroke the fluid is forced out of the chamber through the outlet valve, which then opens while the inlet valve is closed. Both axial and radial configurations are common. 活塞在氣缸中往復運動的一種容積泵。在吸入沖程，流體通過入口閥吸入腔室，然后在出口閥關閉時打開。在輸送沖程中，流體通過出口閥被迫流出腔室，然后出口閥打開，同時入口閥關閉。軸向和徑向配置都很常見。
Pitch	瀝青節距	The nominal distance between two adjacent thread roots or crests. In screw threads, the distance from a point on one thread to a corresponding point on the next thread measured parallel to the axis. In the case of spur gears, indicates the size of the gear teeth and is correctly called diametral pitch. 兩個相鄰螺紋根部或頂部之間的標稱距離。在螺紋中，從一根螺紋上的一點到下一根螺紋對應點的距離，平行于軸線測量。對于正齒輪，表示齒輪齒的尺寸，正確地稱為徑向節距。
Pitch (Unit m)	間距（單位：m）	1. In a cascade of identical turbine or compressor blades, the distance between successive blades measured parallel to the leading edges. 2. For a screw thread, the distance between adjacent thread forms measured parallel to the thread axis. 3. For an aircraft, the vertical relationship between the nose and the horizon. The pitch axis is an axis in the plane of the wings of an aircraft, perpendicular to the centreline, about which the aircraft rotates. Pitch motion is the corresponding up or down movement of the aircraft nose. Pitch attitude is the angle between the centreline of an aircraft and the horizontal. The angle is positive when the nose is above its position when the centreline is horizontal. 1.在相同渦輪或壓縮機葉片的葉柵中，平行于前緣測量的連續葉片之間的距離。2.對于螺紋，平行于螺紋軸線測量的相鄰螺紋形狀之間的距離。3.對于飛機，機頭和水平線之間的垂直關系。俯仰軸是飛機機翼平面內垂直于中心線的軸，飛機繞中心線旋轉。俯仰運動是飛機機頭的相應向上或向下運動。俯仰姿態是飛機中心線與水平線之間的角度。當中心線水平時，當機頭高于其位置時，角度為正。
Pitch angle (Unit °)	俯仰角（單位°）	For a bevel gear, the angle between the axis and the pitch-cone generator. 對于錐齒輪，軸與節錐生成器之間的角度。
Pitch diameter	中徑	For screw threads, the diameter of an imaginary cylinder, the surface of which would pass through the threads at such points that would make the width of the groove and width of the land equal to one half the pitch. 對于螺紋，指一個假想圓柱體的直徑，其表面將在使凹槽寬度和焊盤寬度等于螺距一半的點穿過螺紋。
Pitch-circle diameter (Unit m)	節圓直徑（單位：m）	The diameter of the circle (the pitch circle) centred on a component’s axis, around which holes or bolts are equally spaced. 以部件軸為中心的圓（節圓）的直徑，孔或螺栓圍繞其等距分布。
Pitting	點蝕	In tribology, a type of wear characterized by the presence of small, sharp surface cavities formed by processes such as fatigue, local adhesion, wear, corrosion, or cavitation. 在摩擦學中的一種磨損，其特征是存在由疲勞、局部粘附、磨損、腐蝕或空穴等過程形成的小而尖銳的表面空穴。
Planar anisotropy	平面異向性	A variation in physical and/or mechanical properties with respect to direction within the plane of material in sheet form. 在片狀材料平面內，物理和/或機械性能相對于方向的變化。
Plane strain	平面應變	The stress condition in linear-elastic fracture mechanics in which there is zero strain in a direction normal to both the axis of applied tensile stress and the direction of crack growth (i.e., parallel to the crack front); most nearly achieved in loading thick plates along a direction parallel to the plate surface. Under plane-strain conditions, the plane of fracture instability is normal to the axis of the principal tensile stress. 線彈性斷裂力學中的應力條件，其中在垂直于施加拉應力軸和裂紋擴展方向（即平行于裂紋前沿）的方向上存在零應變；最接近于沿平行于板表面的方向加載厚板。在平面應變條件下，斷裂失穩平面垂直于主拉應力軸。
Plane stress	平面應力	The stress condition in linear-elastic fracture mechanics in which the stress in the thickness direction is zero; most nearly achieved in loading very thin sheet along a direction parallel to the surface of the sheet. Under plane-stress conditions, the plane of fracture instability is inclined 45° to the axis of the principal tensile stress. 線彈性斷裂力學中厚度方向上的應力為零的應力條件；在沿著平行于薄片表面的方向加載非常薄的薄片時最接近。在平面應力條件下，斷裂失穩平面與主拉應力軸傾斜45°。
Plane-strain fracture toughness (KIc)	平面應變斷裂韌性（KIc）	The crack extension resistance under conditions of crack-tip plane strain. 裂紋尖端平面應變條件下的裂紋擴展阻力。
Plane-stress fracture toughness (Kc)	平面應力斷裂韌性（Kc）	In linear-elastic fracture mechanics, the value of the crack-extension resistance at the instability condition determined from the tangency between the R-curve and the critical crack-extension force curve of the specimen. 在線彈性斷裂力學中，由試樣的R曲線和臨界裂紋擴展力曲線之間的切線確定的不穩定條件下裂紋擴展阻力的值。
Plastic deformation	塑性變形	The permanent (inelastic) distortion of a material under applied stress that strains the material beyond its elastic limit. 材料在施加應力下的永久（非彈性）變形，使材料應變超過其彈性極限。
Plowing	犁	In tribology, the formation of grooves by plastic deformation of the softer of two surfaces in relative motion. 在摩擦學中，通過相對運動的兩個表面中較軟的表面的塑性變形形成凹槽。
Plug	螺塞	1. An object, usually tapered, used to block a hole to prevent fluid from escaping or flowing. 2. The central moveable part of a valve. 3. In the flow of a yield-stress fluid through a pipe or duct, the central region is often assumed to take the form of a plug with uniform axial velocity. 4. In thermoforming, a shaping tool that forces a heated plastic sheet into a female mould. 1.一種物體，通常為錐形，用于堵塞孔以防止流體逸出或流動。2.閥門的中心可移動部分。3.在屈服應力流體通過管道或管道的流動中，中心區域通常假定為具有均勻軸向速度的塞子形式。4.在熱成型技術中，一種成型工具，將加熱的塑料板壓入陰模中。
Plug gauge	塞規	A steel gauge used to determine the dimension or dimensions of a hole. It may be straight or tapered, and is typically circular, but in principle can have any cross section. 用于確定孔的尺寸的鋼制量規。它可以是直的或錐形的，通常是圓形的，原則上可以有任何橫截面。
Pneumatic control valve	氣動控制閥	(pneumatic valve) A valve in which the position of the valve stem, which varies the open area, is determined by the net force generated by compressed air acting on a diaphragm operating against the force of a compression spring. Depending upon the arrangement of the spring, in the event of air-supply failure, the valve may open or close. （氣動閥）一種閥門，其中閥桿的位置隨開口面積的變化而變化，由壓縮空氣作用在隔膜上產生的凈力決定，隔膜克服壓縮彈簧的力進行操作。根據彈簧的布置，在供氣故障的情況下，閥門可以打開或關閉。
Poisson’s ratio (ν)	泊松比（ν）	The absolute value of the ratio of transverse (lateral) strain to the corresponding axial strain resulting from uniformly distributed axial stress below the proportional limit of the material. 橫向（側向）應變與相應軸向應變之比的絕對值，該比值由低于材料比例極限的均勻分布的軸向應力產生。
Pop rivet	拉釘	A hollow rivet that enables a connexion to be made from one side only of an assembly. 一種空心鉚釘，使連接只能從組件的一側進行。
Population	集合	The hypothetical collection of all possible test specimens that could be prepared in the specified way from the material under consideration. Also known as universe. 從所考慮的材料中以規定方式制備的所有可能試樣的假設集合。也稱為體系。
Positive-displacement compressor	容積式壓縮機	Any type of compressor, including piston and rotary-screw types, that delivers a fixed volume of gas at high pressure per unit time. A positive-displacement pump delivers a fixed volume of fluid, usually a liquid, per unit time. 任何類型的壓縮機，包括活塞式和旋轉螺桿式，在單位時間內以高壓輸送固定體積的氣體。容積泵每單位時間輸送固定體積的流體，通常為液體。
Positive-displacement flow meter	容積式流量計	An instrument of high accuracy that determines volumetric flow rate by dividing the flowing fluid into successive fixed volumes, and measuring their times of passage through the meter. 一種高精度儀器，通過將流動的流體分成連續的固定體積并測量其通過流量計的時間來確定體積流量。
Positive-displacement machine	正排量機	A machine that incorporates pistons, valves, etc. to ensure positive admission and delivery of a working fluid and prevent undesired reversal of flow. This class of machine incorporates all reciprocating compressors and expanders and some types of rotary compressor, the Roots blower, agear pump, a lobe pump, and a vane pump. 包含活塞、閥門等的機器，以確保工作流體的正向進入和輸送，并防止不期望的反向流動。這類機器包括所有往復式壓縮機和膨脹機以及一些類型的旋轉壓縮機、羅茨鼓風機、抽水機、凸輪泵和葉片泵。
Power	力能	The rate of doing work or of producing or consuming energy. The unit of power is the watt, W, where 1 W = 1 N m/s. 做功或產生或消耗能量的速度。功率單位為瓦特，W，其中1W=1N m/s。
Pre-stress	預應力	To induce stresses into a component or structure before it is subjected to operating loads. 在部件或結構承受操作載荷之前，將應力引入部件或結構。
Precipitation hardening	沉淀硬化	Hardening caused by the precipitation of a constituent from a supersaturated solid solution. 因成分從過飽和固溶體沉淀而導致的硬化。
Precipitation heat treatment	沉淀熱處理	Artificial aging in which a constituent precipitates from a supersaturated solid solution. 成分從過飽和固溶體沉淀的人工時效。
Precipitation-hardenable stainless steels	沉淀硬化不銹鋼	Precipitation-hardenable stainless steels contain typically 11–18% chromium, 3–10% nickel, 0.05–0.2% carbon, and small additions of manganese, silicon, aluminium, molybdenum, niobium and titanium. These steels can be supplied in a solution-treated condition, which is readily fabricated or machined, and then hardened by an ageing treatment that produces a fine dispersion of second-phase precipitates. They are available in austenitic, semi-austenitic, and martensitic grades. Uses include springs, knives, and pressure vessels. 沉淀硬化不銹鋼通常含有11-18%的鉻、3-10%的鎳、0.05-0.2%的碳以及少量添加的錳、硅、鋁、鉬、鈮和鈦。這些鋼可在固溶處理條件下供應，該條件易于制造或機加工，然后通過時效處理硬化，從而產生細小的第二相沉淀。它們有奧氏體、半奧氏體和馬氏體等級。用途包括彈簧、刀具和壓力容器。
Precision	精確	The closeness of agreement between the results of individual replicated measurements or tests. The standard deviation of the error of measurement may be used as a measure of “imprecision.” 單個重復測量或測試結果之間的一致性。測量誤差的標準偏差可用作“不精確性”的度量
Preheating	預熱	Heating before some further thermal or mechanical treatment. For tool steel, heating to an intermediate temperature immediately before final austenitizing. For some nonferrous alloys, heating to a high temperature for a long time, to homogenize the structure before working. In welding and related processes, heating to an intermediate temperature for a short time immediately before welding, brazing, soldering, cutting, or thermal spraying. 在進一步熱處理或機械處理之前加熱。對于工具鋼，在最終奧氏體化之前立即加熱至中間溫度。對于一些非鐵合金，在工作前長時間加熱到高溫，以使結構均勻化。在焊接和相關工藝中，在焊接、釬焊、釬焊、切割或熱噴涂之前，立即加熱到中間溫度。
Preload	預載	The tension created in a threaded fastener when the nut is first tightened. Often used interchangeably, but incorrectly, with Working load or bolt force or bolt tension 第一次擰緊螺母時螺紋緊固件中產生的張力。經常與工作載荷或螺栓力或螺栓張力互換使用但容易使用不當。
Preload accuracy	預載精度	A measure of the precision with which a given tool or procedure creates preload in a bolt when the bolt is tightened. A common torque wrench, for example, is said to produce preload with an accuracy of +30%. The mean preload, however, may not be that which the designer intended, or may not be what he should have intended. Accuracy as used here, in other words, is synonymous with Scatter. 當螺栓擰緊時，給定工具或程序在螺栓中產生預緊力的精度度量。例如，一個普通的扭矩扳手據說可以產生精度為+30%的預載。然而，平均預載可能不是設計者預期的。這里使用的準確度是分散度的同義詞。
Preload adjustments	預載調整	Preloads may be applied directly by axial loading or indirectly by turning of the nut or bolt. When preload is applied by turning of nuts or bolts, a torsion load component is added to the desired axial bolt load. 預載荷可通過軸向載荷直接施加，或通過轉動螺母或螺栓間接施加。當通過轉動螺母或螺栓施加預載荷時，扭轉載荷分量被添加到所需的軸向螺栓載荷中。
Preload relaxation	預載松弛	Local yielding, due to excess bearing stress under nuts and bolt heads (caused by high local spots, rough surface finish, and lack of perfect squareness of bolt and nut bearing surfaces), may result in preload relaxation after preloads are first applied to a bolt. 由于螺母和螺栓頭下的軸承應力過大（由局部斑點高、表面粗糙以及螺栓和螺母軸承表面缺乏完美的方正度造成），局部屈服可能會在首次向螺栓施加預載荷后導致預載荷松弛。
Press quenching	壓淬	A quench in which hot dies are pressed and aligned with a part before the quenching process begins. Then the part is placed in contact with a quenching medium in a controlled manner. This process avoids part distortion. 一種淬火方法，在淬火過程開始之前，熱模具被壓制并與零件對齊。然后將零件以受控方式放置在與淬火介質接觸的位置。該過程避免了零件變形。
Pressure (p) (Unit Pa)	壓力（p）（單位Pa）	In thermodynamics and fluid mechanics, the compressive force exerted by the fluid per unit area. The pressure exerted by a fluid on a surface acts normal to the surface. 在熱力學和流體力學中，每單位面積流體施加的壓縮力。流體施加在表面上的壓力垂直于表面。
Pressure chamber	壓力室	A chamber in which components or devices can be subjected to high or low fluid (liquid or gas) pressure. 部件或裝置可承受高或低流體（液體或氣體）壓力的腔室。
Pressure control valve	壓力控制閥	A valve used to set the pressure level in a pressure vessel or piping system. 用于設置壓力容器或管道系統中壓力水平的閥門。
Pressure difference (Unit Pa)	壓差（單位Pa）	(pressure differential, Δp) The difference between two pressures, one of which may be a reference pressure such as barometric pressure. In many flow processes, the pressure difference is more important than the absolute pressure level. （壓差，Δp）兩個壓力之間的差值，其中一個壓力可以是參考壓力，如大氣壓力。在許多流動過程中，壓差比絕對壓力水平更重要。
Pressure gauge	壓力表	An instrument used to measure absolute or gauge pressure. The sensing element may be a tube which deflects when pressurized, as in a Bourdon gauge, a bellows as in an aneroid barometer, a piezoelectric crystal, a piezoresistive element, etc. 測量絕對壓力或表壓的儀器。傳感元件可以是加壓時會偏轉的管，如波登壓力表、無液氣壓計中的波紋管、壓電晶體、壓阻元件等。
Pressure loss (Unit Pa)	壓力損失（單位Pa）	The loss in stagnation pressure in internal flow due to wall friction and minor losses in fittings. 壁面摩擦引起的內部流動停滯壓力損失和配件的微小損失。
Pressure rating (Unit Pa or bar)	額定壓力（單位Pa或bar）	The internal pressure at which a pressure vessel, boiler, tank, piping, etc. is designed to operate safely. 壓力容器、鍋爐、儲罐、管道等設計用于安全運行的內部壓力。
Pressure ratio	壓力比	One pressure divided by another which may be a reference pressure. In many flow and thermodynamic processes, the pressure ratio is more important than the absolute pressure levels. For example, in compressible gas flow the Mach number is determined by the ratio of the stagnation pressure to the static pressure. 一個壓力除以另一個壓力，該壓力可以是參考壓力。在許多流動和熱力學過程中，壓力比比絕對壓力水平更重要。例如，在可壓縮氣流中，馬赫數由停滯壓力與靜壓之比決定。
Pressure recovery (Unit Pa)	壓力恢復（單位Pa）	The progressive increase in static pressure for unseparated flow through a diverging nozzle or diffuser. 通過發散噴嘴或擴散器的未分離流的靜壓逐漸增加。
Pressure regulator	壓力調節器	(pressure-regulating valve) A device installed in a pneumatic or gas system to maintain the downstream pressure at the required level. （壓力調節閥）安裝在氣動或氣體系統中以將下游壓力保持在所需水平的裝置。
Pressure snubber	壓力緩沖器	(pressure-pulse snubber) A device used for filtering, dampening, and the protection of transducers, pressure gauges, and switches, from pressure surges, pressure spikes, and water hammer. A typical design uses a fixed mesh or porous metal disc installed in an inline body. In a piston-type pressure-gauge snubber, a piston is forced against an orifice leading to the gauge. （壓力脈沖緩沖器）一種用于過濾、阻尼和保護傳感器、壓力表和開關免受壓力浪涌、壓力尖峰和水錘影響的裝置。典型的設計使用安裝在內聯閥體中的固定網格或多孔金屬盤。在活塞式壓力表緩沖器中，活塞被壓靠在通向壓力表的孔口上。
Pressure storage tank	壓力貯存器	(pressure vessel) A closed container for storing gases or volatile liquids, such as liquefied gases, at pressures significantly above atmospheric pressure. Such tanks are commonly cylindrical with domed ends, spherical, spheroidal, torispherical or hemispherical. （壓力容器）密閉容器：在大氣壓以上的壓力下儲存氣體或揮發性液體，如液化氣體的密閉容器。此類貯存器通常為圓柱形，具有半球形端部、球形、球面或半球形。
Pressure surface	壓力面	The high-pressure surface of an aerofoil, turbine, or compressor blade. In normal aircraft applications, this is the lower surface of a wing. For applications, such as to high-performance motor vehicles, where the aerofoil is inverted to generate downforce, it is the upper surface. 機翼、渦輪或壓縮機葉片的高壓表面。在正常的飛機應用中，這是機翼的下表面。對于高性能機動車輛等應用，機翼翻轉以產生下壓力，它是上表面。
Pressure tap	測壓口	A small hole in the wall of a pipe or pressure vessel to which is attached a tube, the other end of which is connected to one side of a pressure transducer. 管子或壓力容器壁上的小孔，與管子相連，管子的另一端與壓力傳感器的一側相連。
Pressure-relief valve	減壓閥	A valve that limits the maximum pressure in a pressure vessel or fluid-power system to a specified level. 將壓力容器或流體動力系統中的最大壓力限制在規定水平的閥門。
Prevailing torque	有效扭矩	Torque required to run a nut down against the joint when some obstruction, such as a plastic insert in the threads, or a noncircular thread, or other, has been introduced to help the fastener resist vibration loosening. Prevailing torque, unlike normal torque on a nut or bolt, is not proportional to the Preload in the fastener. 當引入了一些障礙物（如螺紋中的塑料插件或非圓螺紋或其他障礙物）以幫助緊固件抵抗振動松動時，將螺母向下壓靠接頭所需的扭矩。與螺母或螺栓上的正常扭矩不同，主要扭矩與緊固件中的預載不成比例。
Principal stress (normal)	主應力（正常）	The maximum or minimum value of the normal stressat a point in a plane considered with respect to all possible orientations of the considered plane. On such principal planes the shear stress is zero. There are three principal stresses on three mutually perpendicular planes. The state of stress at a point may be: (1) uniaxial, a state of stress in which two of the three principal stresses are zero; (2) biaxial, a state of stress in which only one of the three principal stresses is zero; or (3) triaxial, a state of stress in which none of the principal stresses is zero. Multiaxial stress refers to either biaxial or triaxial stress. 相對于所考慮平面的所有可能方向，所考慮平面中某點處的法向應力的最大值或最小值。在這樣的主平面上，剪切應力為零。在三個相互垂直的平面上有三個主應力。一點的應力狀態可以是：（1）單軸，三個主應力中的兩個為零的應力；（2）雙軸，三個主應力中只有一個為零的應力狀態；或（3）三軸，即主應力均不為零的應力狀態。多軸應力是指雙軸或三軸應力。
Process annealing	中間退火	An imprecise term denoting various treatments used to improve workability. For the term to be meaningful, the condition of the material and the time-temperature cycle used must be stated. 一個不精確的術語，表示用于改善可加工性的各種處理方法。為了使術語有意義，必須說明材料的條件和使用的時間-溫度循環。
Profile	輪廓	The shape of a cross section of an object, such as an aerofoil or cam. 物體的橫截面形狀，如機翼或凸輪。
Profiling machine	仿形機	(profile milling machine) A milling machine in which the cutter is guided by the contour of a pattern having the required shape. （仿形銑床）銑刀由具有所需形狀的圖案輪廓引導的銑床。
Profilometer	輪廓儀	An instrument used to quantify the roughness of a surface. For a contact profilometer, a diamond stylus sweeps across the surface along a series of parallel lines. Noncontact profilometers use optical techniques to map the surface irregularities. 用于量化表面粗糙度的儀器。對于接觸式輪廓儀，鉆石觸針沿一系列平行線掃過表面。非接觸式輪廓儀使用光學技術繪制表面不規則。
Progressive aging	漸進時效	Aging by increasing the temperature in steps or continuously during the aging cycle. 通過在時效周期中逐步或連續升高溫度進行增加時效。
Proof load	驗證載荷（單位 N）	The maximum, safe, static, tensile load which can be placed on a fastener without yielding it. Sometimes given as a force (in lb or N) sometimes as a stress (in psi or MPa). The test load in quality control to which different components made of different materials must be subjected without failing in order to perform properly. 可施加在緊固件上而不使其屈服的最大安全靜態拉伸載荷。有時以力（lb或N）表示，有時以應力（psi或MPa）表示。質量控制中的測試負荷，由不同材料制成的不同部件必須經受該負荷，才能正常運行。
Proof strength? (Unit Pa)	驗證強度（單位Pa）	(proof stress, Rp, Rp,) The yield strength (offset yield strength) at some fixed value of the permanent strain given by the intersection of a line offset from, but parallel to, the elastic loading line and the engineering stress-engineering strain curve. The offset is arbitrary but is usually 0.1, 0.2, or 0.5% permanent strain (the proof strain). Used for materials which do not exhibit a sharply defined yield point. The notation Rp0.2?or Rp0.2?is employed for the 0.2% proof stress. （驗證應力，Rp）在永久應變的某個固定值下的屈服強度（偏移屈服強度），由偏離但平行于彈性加載線的線與工程應力-工程應變曲線的交點給出。偏移是任意的，但通常為0.1、0.2或0.5%的永久應變（驗證應變）。用于沒有明確定義屈服點的材料。對于0.2%的驗證應力，采用符號Rp0.2。
Proof stress	彈性極限應力	(1) The stress that will cause a specified small permanent set in a material. (2) A specified stress to be applied to a member or structure to indicate its ability to withstand service loads. （1）在材料中引起規定的小永久變形的應力。（2）施加在構件或結構上的規定應力，以表明其承受工作荷載的能力。
Proportional limit	比例極限	The greatest stress a material is capable of developing without a deviation from straight-line proportionality between stress and strain. 材料能夠產生的最大應力不偏離應力和應變之間的直線比例。
Prying	撬動	The magnification of an External load by a pseudolever action when that load is an Eccentric tensile load. 當外部荷載為偏心拉伸荷載時，通過偽杠桿作用放大外部荷載。
PSI (pounds per square inch)	PSI（磅/平方英寸）	Pressure measurement. Psia (pounds per square inch absolute) measures actual pressure with no allowance for atmospheric pressure. Psig (pounds per square inch gauge) measures pressure with the gauge set to zero (0) at atmospheric pressure (14.7 psia). In other words psig = psia – 14.7. 壓力測量。Psia（絕對磅/平方英寸）測量實際壓力，不考慮大氣壓力。Psig（磅/平方英寸表壓）在大氣壓（14.7 psia）下，將表壓設置為零（0）時測量壓力。換句話說，psig=psia–14.7。
Pulley	帶輪	A free or driven wheel on a shaft with an appropriately shaped rim to carry a flat belt, vee belt, notched belt, rope, or chain. Used to transmit power or motion. 軸上的自由輪或從動輪，具有適當形狀的輪緣，以承載平皮帶、V形皮帶、槽口皮帶、繩索或鏈條。用于傳遞動力或運動。
Pulse	脈沖	An increase or decrease in the magnitude of a physical quantity, such as pressure, voltage, or force, with a time scale short compared with other time scales in a process, after which there is a return to the original level. 物理量的大小的增加或減少，如壓力、電壓或力，與過程中的其他時間尺度相比，時間尺度較短，之后返回到原始水平。
Pump	泵	A machine designed to cause a liquid, gas, vapour, or slurry to flow due to the reciprocating motion of pistons, rotation of vanes, or rotation of an impeller. 通過活塞的往復運動、葉片的旋轉或葉輪的旋轉而使液體、氣體、蒸汽或泥漿流動的機器。
Punch	沖床	1. A hand tool with a sharp point, used to mark the position of a hole centre in a workpiece prior to drilling. 2. A flat-ended tool with sharp edges, used to shear out a hole in a plate that is supported underneath on a die having a slightly larger same-shaped orifice. 1.一種帶有尖頭的手動工具，用于在鉆孔前標記工件中孔中心的位置。2.一種具有銳邊的平頭工具，用于剪切板上的孔，該板支撐在具有稍大相同形狀孔口的模具下方。
Push rod	推桿	A rod which opens and closes a valve via a valve rocker in an overhead-valve piston engine. The rod is actuated by a camshaft located in the crankcase. 在頂置氣門活塞發動機中，通過氣門搖臂打開和關閉氣門的桿。連桿由曲軸箱中的凸輪軸驅動。