ABSTRACT

This chapter reviews the traditional concept of using a free-body diagram (FBD) as a basis to derive the equations of motion (EQMs) for planar multibody systems. It constructs the FBD for several systems and discusses specific issues associated with each. The chapter identifies the applied and the reaction forces and torques, before constructing the EQMs. It assumes that the motion of all the bodies is fully known, and the unknowns are the reaction forces and one applied force or torque. The chapter performs the process of computing the spring and dampers forces in a more systematic way. It provides the constant data, and the coordinates and velocity of the points of interest. The chapter constructs nine linear algebraic equations that can be solved for the nine unknowns—eight reaction force components and torque, and one applied torque. It computes the acceleration of the mass centers, constructs the array of accelerations, and then evaluates the array of mass times accelerations.