| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| Lap joint | 搭接接头 |
A riveted, welded, or bonded connection between two plates made by overlapping one plate above the other. Lap joints having plates above and below a butt joint avoid the bending moment associated with a simple lap joint. 两块板之间的铆接、焊接或粘结连接，通过将一块板重叠在另一块板上而形成。对接接头上方和下方具有板的搭接接头避免了与简单搭接接头相关的弯矩。 |
| Laser hardening | 激光硬化 |
A surface-hardening process which uses a laser to quickly heat a surface. Heat conduction into the interior of the part will quickly cool the surface, leaving a shallow martensitic layer. Hardening of steel by a moving CO2 or Nd:YAG laser beam focussed down to a few mm in diameter. A point in the surface of an object is rapidly heated into the austenite range and then rapidly cooled to form tempered martensite. 一种使用激光快速加热表面的表面硬化工艺。进入零件内部的热传导将快速冷却表面，留下浅马氏体层。通过移动CO2或Nd:YAG激光束使钢硬化，激光束聚焦至直径几毫米。物体表面的一点迅速加热到奥氏体范围，然后迅速冷却，形成回火马氏体。 |
| Laser sintering | 激光烧结 |
A manufacturing technique by which parts are built layer by layer (each typically 20 μm thick) from plastic or metal (Direct Metal Laser Sintering, DMLS) material in powder form, each layer being sintered by a scanning laser. 一种制造技术，通过这种制造技术，零件由粉末形式的塑料或金属（直接金属激光烧结，DMLS）材料逐层（每个厚度通常为 20 微米）构建，每一层都由扫描激光烧结。 |
| Latent heat | 潜热 |
Thermal energy absorbed or released when a substance undergoes a phase change. 物质发生相变时吸收或释放的热能。 |
| Lathe | 车床 |
A machine tool in which work, gripped in the headstock, is rotated against the cutting tool to produce turned, bored, faced, or threaded components. 一种机床，其中夹持在主轴箱中的工件靠着切削工具旋转，以生产车削、钻孔、端面或螺纹部件。 |
| Lead angle | 导角 |
The angle of the helix of a screw thread or worm thread. It is the measure of the inclination of a screw thread from a plane perpendicular to the axis of the screw. 螺纹或蜗杆螺纹的螺旋角。它是螺纹从垂直于螺钉轴线的平面的倾斜度的量度。 |
| Lead of thread | 螺纹导程 |
On a single threaded screw, the distance the screw or nut advances in one complete revolution. 在单螺纹螺钉上，螺钉或螺母在一整圈中前进的距离。 |
| Lead screw | 丝杠 |
The master screw running along the length of the bed of a lathe from which all screws threads on that machine are cut. Master screw used for cutting a screw thread in a lathe. 沿车床床身长度方向运行的主螺钉，该机床上的所有螺钉和螺纹都从主螺钉上切割下来。用于在车床上切削螺纹的主螺钉。 |
| Least count | 最小计数 |
The smallest value that can be read from an instrument having a graduated scale. Except on instruments provided with a vernier, the least count is that fraction of the smallest division which can be conveniently and reliably estimated; this fraction is ordinarily one-fifth or one-tenth, except where the graduations are very closely spaced. 可从具有刻度尺的仪器中读取的最小值。除配备游标的仪器外，最小计数是可以方便可靠地估计的最小除法的分数；这个分数通常是五分之一或十分之一，除非刻度间隔非常近。 |
| Left hand screw | 左螺旋 |
One that screws into the mating part or advances when turned to the left or counter clockwise. 旋入配合部分或向左或逆时针旋转时前进的螺钉。 |
| Length of engagement | 啮合长度 |
It is the axial measurement within which the external and internal threads have theoretical contact. 它是外螺纹和内螺纹具有理论接触的轴向测量。 |
| Linear (tensile or compressive) strain | 线性（拉伸或压缩）应变 |
The change per unit length due to force in an original linear dimension. An increase in length is considered positive. 由于原始线性尺寸中的力，每单位长度的变化。长度的增加被认为是正的。 |
| Linear-elastic fracture mechanics | 线弹性断裂力学 |
A method of fracture analysis that can determine the stress (or load) required to induce fracture instability in a structure containing a cracklike flaw of known size and shape. 一种断裂分析方法，可确定在含有已知尺寸和形状裂纹状缺陷的结构中引起断裂不稳定性所需的应力（或载荷）。 |
| Liquation temperature | 液化温度 |
The lowest temperature at which partial melting can occur in an alloy that exhibits the greatest possible degree of segregation. 偏析程度最高的合金发生部分熔融的最低温度。 |
| Liquid carburizing | 液体渗碳 |
Surface hardening of steel by immersion into a molten bath consisting of cyanides and other salts. 通过浸入由氰化物和其他盐组成的熔池中对钢进行表面硬化。 |
| Liquid nitriding | 液体氮化 |
A method of surface hardening in which molten nitrogen-bearing, fused-salt baths containing both cyanides and cyanates are exposed to parts at subcritical temperatures. 一种表面硬化方法，其中含有氰化物和氰酸盐的熔融含氮熔盐浴在亚临界温度下暴露于零件。 |
| Load | 负载 |
For testing machines, a force applied to a test piece that is measured in units such as pound-force, newton, or kilogram-force. 对于试验机，施加在试件上的力，以磅力、牛顿或千克力等单位测量。 |
| Load and resistance factor design | 负载和阻力系数设计 |
A design procedure developed for the AISC by the Research Council on Structural Connections. Assigns uncertainties in the strength of (i.e., resistance of) and in the service loads to be placed on a shear joint to estimate the probable strength of the joint. It is a recently defined alternative to the Allowable stress design procedure. 结构连接研究委员会为AISC制定的设计程序。分配剪切接头的强度（即阻力）和工作荷载的不确定性，以估计接头的可能强度。它是最近定义的容许应力设计程序的替代方案。 |
| Load factor (F) | 负载系数（F） |
The ratio between an increase in bolt tension and the external load which has caused the increase. Factors reflecting the probability of an increase in load in a shear joint. Used in load and resistant factor design. 螺栓张力增加与导致增加的外部载荷之间的比率。反映剪切接缝中荷载增加概率的系数。用于载荷和阻力系数设计。 |
| Load range, P | 负载范围P |
In fatigue, the algebraic difference between the maximum and minimum loads in a fatigue cycle. 在疲劳中，疲劳循环中最大和最小载荷之间的代数差。 |
| Load ratio, R | 负载比R |
In fatigue, the algebraic ratio of the minimum to maximum load in a fatigue cycle, that is, R = Pmin/Pmax. Also known as stress ratio. 在疲劳中，疲劳循环中最小载荷与最大载荷的代数比，即 R= Pmin/Pmax。也称为应力比。 |
| Lobe | 凸轮 |
The projecting part such as rotor lobe or the cam lobe. 转子凸角或凸轮凸角等突出部分。 |
| Lock nut | 锁紧螺母 |
A type of nut that is prevented from loosening under vibration. The locking action is accomplished by squeezing, gripping or jamming against the bolt threads. A nut which provides extra resistance to vibration loosening (beyond that produced by proper Preload ), either by providing some form of Prevailing torque, or, in free-spinning lock nuts, by deforming, cramping, or biting into mating parts when fully tightened. 1. A thin auxiliary nut tightened against another nut to prevent loosening. 2. A single nut with special features that prevent loosening. 一种在振动下防止松动的螺母。锁定动作通过挤压、夹紧或卡住螺栓螺纹来完成。通过提供某种形式的主要扭矩，或在自由旋转锁紧螺母中，通过完全拧紧时变形、夹紧或咬入配合零件，提供额外的抗振动松动能力（超出适当预载产生的能力）。1.一个薄的辅助螺母，拧紧到另一个螺母上以防止松动。2.具有防止松动的特殊功能的单个螺母。 |
| Lock-nut pipe thread | 锁紧螺母管螺纹 |
The lock-nut pipe thread is a straight thread of the largest diameter which can be cut on a pipe. Its form is identical with that of the American or Briggs standard taper pipe thread. In general, “Go” gages only are required. These consist of a straight-threaded plug representing the minimum female lock-nut thread, and a straight-threaded ring representing the maximum male lock-nut thread. This thread is used only to hold parts together, or to retain a collar on the pipe. It is never used where a tight threaded joint is required. 锁紧螺母管螺纹是最大直径的直螺纹，可在管道上切割。其形式与美国或布里格斯标准锥管螺纹相同。一般情况下，只需要通规。它们由一个表示最小内螺纹锁紧螺母螺纹的直螺纹塞和一个表示最大外螺纹锁紧螺帽螺纹的直形螺纹环组成。该螺纹仅用于将零件固定在一起，或用于将轴环固定在管道上。切勿使用于需要紧密螺纹接头的情况下。 |
| Lockbolt | 锁紧螺栓 |
A fastener which bears a superficial resemblance to a bolt, but which engages a collar (instead of a nut) with annular grooves (instead of threads). The collar is swaged over the grooves on the male fastener to develop preload. 表面上类似于螺栓的紧固件，但与环槽（而不是螺纹）接合的轴环（而不是螺母）。套环在阳紧固件上的凹槽上锻造，以产生预紧力。 |
| Longitudinal direction | 纵向 |
The principal direction of flow in a worked metal. See also normal direction and transverse direction. 加工金属中的主要流动方向。另请参见法向和横向。 |
| Low-E coating | 低辐射涂层 |
(low-emittance coating) A thin metallic or metal-oxide coating on a glass sheet to absorb and reflect infrared radiation. The coating is applied either by a pyrolytic chemical vapour-deposition process (hard coat), or by sputtering (soft coat). （低辐射涂层）玻璃板上的薄金属或金属氧化物涂层，用于吸收和反射红外辐射。通过热解化学气相沉积工艺（硬涂层）或溅射（软涂层）施加涂层。 |
| Lubricant | 润滑剂 |
Any substance interposed between two surfaces for the purpose of reducing the friction or wear between them. 为了减少两个表面之间的摩擦或磨损而置于两个表面间的任何物质。 |
| Lüders lines | 吕德斯线 |
Elongated surface markings or depressions, often visible with the unaided eye, that form along the length of sheet metal or a tension specimen at an angle of approximately 45° to the loading axis. Caused by localized plastic deformation, they result from discontinuous (inhomogeneous) yielding. Also known as Lüders bands, Hartmann lines, Piobert lines, or stretcher strains. 拉长的表面标记或凹陷，通常肉眼可见，沿金属板或拉伸试样的长度形成，与加载轴的角度约为45°。由于局部塑性变形，它们是不连续（不均匀）屈服的结果。也被称为吕德斯带、哈特曼线、皮奥伯特线或拉伸线。 |