| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| J-integral | J-积分 |
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. 描述从一个裂纹表面到另一个裂纹正面的线或表面积分的数学表达式，用于表征断裂前具有可观塑性的材料的断裂韧性。J积分通过考虑裂纹前缘周围的局部应力应变场，无需描述裂纹尖端附近材料的行为；JIc是从先前存在的裂纹开始裂纹扩展所需的J积分的临界值。 |
| Jack | 杰克装置 |
A lifting device that exerts large forces over small displacements, achieved by mechanical gearing or hydraulics. 通过机械传动或液压装置在小位移上施加大力的提升装置。 |
| Joint | 关节接合处 |
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. 机器人手臂上允许旋转或平移运动的部分。每个接合处都有自由度，如果机器人要能够在工作空间内的任何位置定位和定向末端执行器，则至少需要六个接合处具有自由度。关节接合处由四个参数描述：关节角度、关节偏移、关节扭曲和链接长度。关节角度是在垂直于关节轴的平面内逆时针测量的先前连杆长度和当前连杆长度的外推之间的角度。这在旋转关节中是可变的，在平移关节中是固定的。关节偏移是沿关节轴测量的前一个连杆和当前连杆的连杆长度之间的距离。这对于平移关节是可变的，对于旋转关节是固定的。第n个关节的关节扭曲是关节Jn和Jn+1轴之间的角度，在垂直于连杆长度的平面内逆时针测量，从Jn+2关节的位置观察。连杆长度是穿过关节轴Jn和Jn+1的平面之间相互垂直的距离。关节扭曲和连杆长度在所有关节中都是固定的。 |
| Joint diagrams | 接合处关系图 |
Mathematical diagrams which illustrate the forces on and deflections of fasteners and joint members. 说明紧固件和连接件上的力和变形的数学图。 |
| Joint space | 关节空间 |
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. 根据关节的旋转角度和平移位置描述机器人的位置和方向。通常使用齐次变换的运动学分析允许在该描述与x、y、z空间中的末端执行器位置和方向之间进行转换。 |
| 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. 国际单位制能量单位。一焦耳是一牛顿的力在一米的距离上所做的功。符号为J，其中1j=1m。 |
| Junker machine | 容克机 |
A test machine, first proposed by Gerhard Junker, for testing the vibration resistance of fasteners. 由Gerhard Junker首次提出的测试机，用于测试紧固件的抗振性。 |