求翻译：当材料在外力作用下不能产生位移时，它的几何形状和尺寸将发生变化，这种形变就称为应变（Strain）。材料发生形变时内部产生了大小相等但方向相反的反作用力抵抗外力．把分布内力在一点的集度称为应力（Stress），应力与微面积的乘积即微内力．或物体由于外因(受力、湿度变化等)而变形时，在物体内各部分之间产生相互作用的内力，以抵抗这种外因的作用，并力图使物体从变形后的位置回复到变形前的位置。是什么意思？

When the material under external force can not produce displacement, its geometric shape and size will change, this deformation is called strain (Strain). Material deformation occurs when the internal generated equal but opposite reaction force to resist. The distribution point set in the degree of

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When material is cannot produce displacement under external force, geometric shapes and sizes it will changing this deformation is known as strain (Strain). Material deformation occurred inside when the equal but opposite reaction against external forces. Internal force distribution of a set of poin

When the material under external force can not produce displacement, its geometric shape and size will change, this deformation is called strain (Strain). Material deformation occurs when the internal generated equal but opposite reaction force to resist. The distribution point set in the degree of