Kelvin spring-and-dashpot models

Spring-and-dashpot models are extended by the Voigt-Kelvin (V-K) model, which broadens linear viscoelastic concepts. The spring and dashpot are always in parallel. The V-K spring-and-dashpot models are useful for understanding creep behavior [11]. 

Total strain e in a Voigt-Kelvin spring-and-dashpot model [11] is 

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