在各种固体的各种性质中,在外力作用下抵抗破坏和变形的力学性质,如强度、塑性、弹性等,占有特殊地位。这些力学性质直接与物体的结构,与在物体中作用着的分子内聚力和热运动特性有关。固体的强度、塑性和弹性,是判断它用来作为建筑和结构材料、建筑构件、机器和机械零件的可能性的主要而又最有特征的性质。如果不是首先依靠对于材料的力学性质的 In a variety of solid various properties, under the action of external forces to resist damage and deformation of the mechanical properties, such as strength, plasticity, flexibility, occupy a special position. These mechanical properties are directly related to the structure of the object and to the cohesion and thermo-dynamic properties of the molecules acting in the object. The strength, plasticity, and elasticity of a solid are the major and most characteristic of judging its potential as a building and structural material, building element, machine and mechanical part. If not first of all rely on the mechanical properties of the material