Which one of the following pairs is NOT correctly matched?
A
Visco-elastic – small plastic zone
B
Orthotropic material – different properties in three perpendicular directions
C
Strain hardening material – stiffening effect felt at some stage
D
Isotropic material – same physical property in all directions at a point
Correct Answer: Visco-elastic – small plastic zone
Visco-elastic material exhibit a mixture of creep and elastic after effects at room temperature. Thus their behaviour is time dependent. Materials with different properties in different directions are called anisotropic. Orthotropic material is a special case of an anisotropic material in three mutually perpendicular directions. However, these are symmetric about any axis.