CHAPTER ELEVEN - VIBRATIONS

Abstract

This chapter focuses on automobile vibrations. Vibrations of a complete automobile, or part of an automobile, can occur in a variety of ways and arise from a variety of sources. The motion of a single rigid body can be specified in terms of component linear motions along three axes mutually at right angles, together with component rotations about the axes. The motion of a single rigid body has six component motions and six degrees of freedom. Excitation can arise from the unbalance of the engine, torsional fluctuations in the engine output, cam forces on the valve tappets, or whirling of certain transmission parts. Vibrational characteristics broadly fall into the categories of system representation, analysis of the system representation, and deductions drawn from the analysis. A system is generally represented by a number of vibrating masses, constrained by elastic members and dampers and acted on by disturbing forces. A vehicle in complex form is considered to consist of a main body mass suspended on springs so that each wheel is independent and its motion is damped. A reciprocating engine crankshaft is subjected to torques at each crank that develop during the combustion process and which are transmitted by the reciprocating mechanism.