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CONTINUUM MECHANICS for ENGINEERS

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9.5 A proposed model consists of a Kelvin unit in parallel with a Maxwell<br />

unit. Determine the constitutive equation <strong>for</strong> this model.<br />

Answer:<br />

9.6 For the four-parameter model shown, determine<br />

(a) the constitutive equation<br />

(b) the relaxation function, G(t). [Note that G(t) is the sum of the G(t)’s<br />

of the parallel joined units.]<br />

Answer: (a)<br />

( ) + ( )<br />

˙ σ + σ/ τ = ηγ˙˙ + G + G + η / τ γ˙ G / τ γ<br />

2 1 1 2 1 2 1 2<br />

( ) + ( )<br />

˙ σ + σ/ τ = η ˙˙ γ + G + G + η / τ γ˙ G / τ γ<br />

2 3 1 2 3 2 1 2<br />

(b) G(t) = G1 + Ge +<br />

t − /τ 2<br />

2 ηδ 3 () t

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