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詞或詞組	中文	英文解釋中文解釋
J-integral	J-積分	A mathematical expression describing a line or surface integral that encloses the crack front from one crack surface to the other, used to characterize the fracture toughness of a material having appreciable plasticity before fracture. The J-integral eliminates the need to describe the behavior of the material near the crack tip by considering the local stress-strain field around the crack front; JIc is the critical value of the J-integral required to initiate crack extension from a preexisting crack. 描述從一個裂紋表面到另一個裂紋正面的線或表面積分的數學表達式，用于表征斷裂前具有可觀塑性的材料的斷裂韌性。J積分通過考慮裂紋前緣周圍的局部應力應變場，無需描述裂紋尖端附近材料的行為；JIc是從先前存在的裂紋開始裂紋擴展所需的J積分的臨界值。
Jack	杰克裝置	A lifting device that exerts large forces over small displacements, achieved by mechanical gearing or hydraulics. 通過機械傳動或液壓裝置在小位移上施加大力的提升裝置。
Joint	關節接合處	The part of a robot arm permitting either rotational or translational motion. Each joint provides a single degree of freedom, and thus a minimum of six is required if the robot is to be able to position and orientate the end effector anywhere within the workspace. A joint is described by four parameters: the joint angle, joint offset, joint twist, and link length. The joint angle is the angle between an extrapolation of the previous link length and the present link length, measured positive anticlockwise in a plane normal to the joint axis. This is variable in a rotational joint and fixed in a translational joint. The joint offset is the distance between the link length for the previous link and that for the present link, measured along the joint axis. This is variable for a translational joint and fixed for a rotational joint. The joint twist for the nth joint is the angle between the axes of joints Jn?and Jn+1, measured positive anticlockwise in a plane normal to the link length and viewed from the position of the Jn+1?joint. The link length is the mutually perpendicular distance between planes passing through the axes of joint Jn?and Jn+1. Both the joint twist and link length are fixed in all joints. 機器人手臂上允許旋轉或平移運動的部分。每個接合處都有自由度，如果機器人要能夠在工作空間內的任何位置定位和定向末端執行器，則至少需要六個接合處具有自由度。關節接合處由四個參數描述：關節角度、關節偏移、關節扭曲和鏈接長度。關節角度是在垂直于關節軸的平面內逆時針測量的先前連桿長度和當前連桿長度的外推之間的角度。這在旋轉關節中是可變的，在平移關節中是固定的。關節偏移是沿關節軸測量的前一個連桿和當前連桿的連桿長度之間的距離。這對于平移關節是可變的，對于旋轉關節是固定的。第n個關節的關節扭曲是關節Jn和Jn+1軸之間的角度，在垂直于連桿長度的平面內逆時針測量，從Jn+2關節的位置觀察。連桿長度是穿過關節軸Jn和Jn+1的平面之間相互垂直的距離。關節扭曲和連桿長度在所有關節中都是固定的。
Joint diagrams	接合處關系圖	Mathematical diagrams which illustrate the forces on and deflections of fasteners and joint members. 說明緊固件和連接件上的力和變形的數學圖。
Joint space	關節空間	The description of the position and orientation of a robot in terms of the rotational angles and translational positions of the joints. Kinematic analysis, normally using homogeneous transforms, allows conversion between this description and the end‐effector position and orientation in x,y,z space. 根據關節的旋轉角度和平移位置描述機器人的位置和方向。通常使用齊次變換的運動學分析允許在該描述與x、y、z空間中的末端執行器位置和方向之間進行轉換。
Joule	焦耳	The SI unit of energy. One joule is the work done by a force of one newton acting over a distance of one metre. The symbol is J, where 1 J = 1 N m. 國際單位制能量單位。一焦耳是一牛頓的力在一米的距離上所做的功。符號為J，其中1j=1m。
Junker machine	容克機	A test machine, first proposed by Gerhard Junker, for testing the vibration resistance of fasteners. 由Gerhard Junker首次提出的測試機，用于測試緊固件的抗振性。