ABSTRACT
Let us select one known configuration of the body as a reference configuration in which the body occupies a known region R of space.* This can be the configuration at any time. We will use a single rectangular Cartesian coordinate system. Let Xk denote the position of a particle in the reference configuration. In a deformed configuration r(t) at time t, this particle occupies a position xk. The motion relative to the fixed reference configuration is described by the mapping:
xk = xk(X,t). (13.1)
The velocity of a particle is
v
x tk
k =
∂ ∂ .
