Dynamic Analysis of an Automobile Lower Suspension Arm Using Experiment and Numerical Technique

Abstract

All machines, vehicles and buildings are subjected to dynamic forces that cause vibration. Most practical noise and vibration problems are related to resonance phenomena where the operational forces excite one or more modes of vibration. Modes of vibration that lie within the frequency range of the operational dynamic forces always represent potential problems. Mode shapes are the dominant motion of a structure at each of its natural or resonant frequencies. Modes are an inherent property of a structure and do not depend on the forces acting on it. On the other hand, operational deflection shapes do show the effects of forces or loads, and may contain contributions due to several modes of vibration. Modal analysis is an efficient tool for describing, understanding, and modelling structural dynamics (Sitton, 1997). The dynamic behaviour of a structure in a given frequency range can be modelled as a set of individual modes of vibration. The modal parameters that describe each mode are: natural frequency or resonance frequency, (modal) damping, and mode shape. The modal parameters of all the modes, within the frequency range of interest, represent a complete dynamic description of the structure. By using the modal parameters for the component, the model can subsequently be used to come up with possible solutions to individual problems (Agneni & Coppotelli, 2004). Published studies have demonstrated the different purposes from performing modal analysis. Initially, Wamsler & Rose (2004) found the mode shapes and study the dynamic behavior of structure in automotive applications. Gibson (2003), presented a comparison of actual dynamic modal test data to the analytically predicted mode shapes and natural frequencies for a missile and its launcher structure that was created in MSC.Patran/MSC.Nastran. Then Guan et al. (2005) evaluated the modal parameters of a dynamic tire then carried out the dynamic responses of tire running over cleats with different speeds. In other study, Leclere et al. (2005) performed modal analysis on a finite element (FE) model of engine block and validated the experimental results. Hosseini et al. (2007) performed experimental modal analysis of crankshaft to validate the numerical results. In particular, studies using a computational model to estimate component fatigue have been actively developed because of the low cost and time savings associated with the estimation (Yim & Lee, 1996; Lee et al., 2000; Kim et al., 2002; Jung et al., 2005). Recently, Choi et al.