Determination of Natural Frequencies through Modal and Harmonic Analysis of Space Frame Race Car Chassis Based on ANSYS

Abstract

Space frame chassis the preferred choice of chassis design due to its low cost, high strength, lightweight and safe qualities, which made it suitable for a single-seat race car application and an important aspect in the construction of the space frame race car chassis. Key sections of a space frame race car chassis consist of front and main hoops, side impact protection and crush zone sub-frame. These sections are pivotal in the safety aspect of the driver during emergency situation. This research introduces several methods of dynamic analysis to investigate the mode shape and natural frequencies in the chassis structure. Two methods are mainly used in the study, modal analysis and harmonic analysis with both analyses are performed using Finite Element (FE) method through Finite Element Analysis (FEA) software packaged, ANSYS v13 APDL Mechanical. The study identified five mode shapes extracted using Block Lanczos method, all mode shapes vibrated at a frequency above 150 Hz with the characteristic of each mode shapes is further explained in this study. Amplitude vs. frequency graph is generated from harmonic analysis is utilised to determine the resonance frequency. The highest amplitude occurred in the third natural frequency with an amplitude of 0.375 mm. The outcome of this analysis can be used as a reference in improving the chassis design and performance against dynamic behaviour of the structure by introducing stiffener on part of the chassis imposed with the highest displacement.