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Unformatted text preview: Homework #8 Solutions 1. Subscript 1 represents dashpot 1 in the figure, subscript 2 represents dashpot 2, and subscript s represents the spring. For the total strain: T = 1 + s = 1 + 2 For the total stress: T = 1 = s + 2 2. Using the concepts we have talked about in class, this model shows no decrease in stress over time under constant strain. This is because the strain in the spring must always be equal to the total strain, and therefore there is no way for the stress to decrease. We always need a constant stress to maintain the strain in the spring. Alternatively, you could say this model will not work for stress relaxation because the spring prevents instantaneous deformation when the initial strain is applied. Either of these answers is acceptable. In reality, this model can not be used for stress relaxation. Stress relaxation requires imposition of an instantaneous strain. The only kind of element that can be instantaneously strained is a spring. However, the spring in this model can't be instantaneously strained because it is in parallel with a dashpot; for the...
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- Fall '10