During material testing, stress is applied from time \(t_i\) to \(t_f\).
The corresponding strain responses for three different materials are shown in plots P, Q, and R.
Choose the option(s) where the strain response is correctly mapped to its material class.
Show Hint
Elastic → instant deformation and recovery,
Viscous → strain increases linearly with time, no recovery,
Viscoelastic → mix of both: instant plus delayed strain, partial recovery.
The problem involves analyzing strain responses due to applied stress on different material classes: purely elastic, purely viscous, and viscoelastic. We must accurately identify the relationship between the plots and material behaviors based on known characteristics of these materials. Purely elastic materials immediately respond to applied stress and return to their original shape once the stress is removed. They show an instantaneous strain response that ceases immediately after the stress is removed. Purely viscous materials continuously deform over time under constant stress and do not return to their original shape once the stress is removed. The strain response displays a continuous increase during stress application. Viscoelastic materials exhibit both elastic recovery and viscous flow behaviors. The strain response indicates a delayed return to the original shape after the stress is removed.
Plot
Material Type
Explanation
P
Purely viscous
Continuous strain increase, no recovery post-stress.
Q
Viscoelastic
Delayed recovery illustrates both viscous and elastic characteristics.
R
Purely elastic
Immediate strain response and recovery upon stress removal.
Hence, the option "P- purely viscous; Q- viscoelastic; R- purely elastic" correctly maps each strain response to its respective material class.
