Design and Vibration Study of Heavy Vehicle Medium Duty Transmission Gearbox System

Abstract

Transmission gearbox assembly is the most important part of the vehicle. Heavy vehicle medium duty truck transmission gearbox was selected as research object. Solid model of transmission gearbox assembly was designed in two parts. First part is gear train assembly and second is transmission gearbox housing. Transmission housing is subjected to vibration induced by varying speed, torque, meshing gear excitation and harmonic excitation. Reciprocity principle was used for directly applying the vibration excitation on transmission housing. Gear cast iron FG260 and Grey cast iron HT200 has been selected as transmission housing material. New material Alloy steel AISI 4130 is recommended as future transmission housing material. newlineFinite Element Analysis (FEA) based free vibration analysis was performed to find the fundamental frequencies and mode shapes of transmission housing. Various vibration modes like torsional vibration, axial bending vibration, radial vibration and torsional vibration with axial vibration were identified. Dynamic response of loose transmission gearbox housing was analysed using FEA numerical simulation. Transmission housing is firmly consolidated on vehicle frame using 37 number of connecting bolts. When transmission housing is subjected to 1, 2, 3 and 4 connecting bolt looseness analysis the fundamental frequency decreases by 21% of original frequency. In positional connecting bolts looseness analysis the maximum change in frequency was identified in back positional connecting bolts looseness (16-30) %. Study of loose transmission housing is essential to prevent heavy vibration and noise in transmission assembly. newlineResponse Surface Method (RSM) optimisation method was applied to find the optimised number of connecting bolts using detuning principle. Optimised number of connecting bolt was identified to connect transmission housing on vehicle frame. RSM, FEA based optimisation and simulation analysis shows the effect of design parameters (input) on frequency response (output). Composite material sing