Anelasticity standard anelastic solid

Analog Model for Standard Anelastic Solid. To find the dependence of <5 on frequency, a model that relates the stress and strain and their time derivatives must... 

Figure 8.19 Analog model for a standard anelastic solid.

If the standard linear solid (SLS) is unloaded from a constant stress, the spring (modulus ,) closes immediately and the elastic strain is removed. The anelastic strain then decays to zero as the second spring closes the dashpot, i.e., there is complete recovery. Under the action of a constant strain, the SLS model will also show stress relaxation but, in this case, the time constant, Tf =rf /(E +E2). In applying a constant stress to the SLS model, the strain can be considered to lag behind the stress, both on loading and unloading. This lag concept is also very important in considering the effect of a dynamic stress or strain. 

Some materials demonstrate anelastic behavior and this is often modeled by a spring in series with a parallel spring and dashpot unit (standard linear solid, SLS). 

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