John is the instantaneous elastic deformation caused by the instantaneous application of load, ade is a delayed elastic deformation, and 6, is a viscous component. To determine the delayed elastic part, one imagines that the load is instantaneously reduced to zero at time t2. Then, the elastic deformation 6, is instantaneously recovered. As time continues, additional deformation is recovered (Figure 18.12). Since the process of recovery is irre- versible, a residual deformation remains. The nonrecoverable (viscous) deformation developed to time t2 is 6,. At time t2, the total deformation is S2. It consists of the viscous deformation 6, and the delayed elastic deformation 6de. For a particular time t > t2, 6 , can be obtained from the data (Figure 18.12).