如何区分：tough, rigid, hard, 谢谢

tough：密度高，不容易打破或摔坏
rigid：抗压高，受外界强大静压力也不走形
hard：硬度高，不容易被其它物体磨损划痕

典型tough但不rigid不hard的物体：青铜
典型rigid但不tough不hard的物体：玻璃
典型hard但不tough不rigid的物体：绿柱石

oxman yah oxman.

according to the stress strain curve, they should be differentiated quite easily

the area under the curve is tough, which means the energy the material could absorb up to fracture.

hardness is the measure of a material's resistance to deformation by surface indentation or by abrasion. If you see from the curve, high hardness means low strain, however, the material may be hard but not tough, since strain is low, the area should be little

rigid, not very sure, seems quite similar to hardness :p