ABSTRACT
A mechanical system becomes a structure when the number of degrees of freedom (DoF) is zero. This chapter discusses two computational procedures for correcting the initial conditions. It discusses how to determine the friction force between two contacting bodies. The chapter performs some form of matrix factorization, such as Gaussian elimination or L-U factorization with pivoting, on the Jacobian matrix of the constraints. It introduces a simple approximation process that could be considered as a crude finite-element representation for a deformable body. A multibody system is said to be in a state of static equilibrium when all the accelerations are zeros; however, the velocities could be either zeros or nonzeros but constants. Forward dynamic analysis of constrained equations of motion requires a set of initial conditions on coordinates and velocities that satisfy the corresponding constraints. A friction formula is a function of several parameters, the relative velocity, and the normal force between two contacting bodies.
