Appendix D

A Family of Thermomechanical Processes

In this appendix, we present a particular family of motions and temperatures, given by the following functions of space and time:

x=χ(X,t)=X0+[F0+(tt0)A](XX0),Θ=Θ^(X,t)=Θ0+(tt0)a+[g0+(tt0)a]·F0(XX0),

si1_e  (D.1)

where t0, Θ0, and a are arbitrary constant scalars, X0, g0, and a are arbitrary constant vectors, and F0 and A are arbitrary constant tensors. Loosely speaking, (D.1) gives a family of motions and temperatures with an infinite number of members. From (D.1), with the aid of results (2.99) and (3.22), we can explicitly calculate

F=F^(X,t)=χ(X,t)X=F0+(tt0)A,F.=F^(X,t)t=A,g=g^(X,t)=FTΘ^(X,t)X=[F0+(tt0)A]TF0T[g0+(tt0)a],g.=g^(X,t)t=ATF0T[g0+(tt0)a]+[F0+(tt0)A]TF0Ta,Θ.=Θ^(X,t)t=a+a·F0(XX0).

si2_e

At the particular place X = X0 and time t = t0, the above functions take the values

x=χ(X0,t0)=X0,Θ=Θ^(X0,t0)=Θ0,F=F0,

si3_e

and

F.=A,g=g0,g.=ATF0Tg0+a,Θ.=a.

si4_e

It follows that

L=F.F1=AF01,D=12(L+LT)=12(AF01+F0TAT)

si5_e

at place x = X = X0 and time t = t0.

Recall that t0, Θ0, a, X0, g0, a, F0, and A are arbitrary quantities. We have therefore explicitly exhibited a family of thermomechanical processes (D.1) in which the temperature Θ, deformation gradient F, rate of deformation gradient F.si6_e (or, alternatively, velocity gradient L or rate of deformation D), temperature gradient g, rate of temperature gradient g.si7_e, and rate of temperature Θ.si8_e can be chosen independently at any place and time.

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