Modal Analysis Using Learning Management System (LMS) Test Equipment on a Fluid Dynamic Subjected High-Speed Vehicle Chassis Frame

Abstract

The experimental technique used to determine the dynamic characteristics of a high-speed vehicle's chassis frame constructed of a T-45 tube is described in this study. To do this, an experimental free-free modal analysis was performed to obtain the natural frequencies at different modes of the chassis. The flow regimen under which the vehicle chassis was subjected was determined using the Mach model. 4 measurements were taken for each node, to obtain an accurate mean value at each nodal point. The results obtained showed that the vehicle did not exceed Mach 0.3 and as such operated in the subsonic regimen. Force/time, acceleration/time, coherence analysis, and frequency response function of the impact hammer on the node was carried out. The result was used to identify the stress-concentrated area at different modes of the frame's construction and provide suitable modelling recommendations for the redesign of the chassis. A total of 9 mode shapes and their associated natural frequencies were obtained on the high-speed chassis frame. Furthermore, the fluid flow was observed to be in the subsonic incompressible flow regime. After the computation and simulation on the LMS test equipment, it was observed that Mode 1, Mode 2 and Mode 3 all exhibited the same mode shapes, a twisting mode but at different Natural frequencies. It was recommended that a further simulation be carried out but with analytical software to compare and validate the results.