Dynamic Vibration Characteristics Analysis of Truck Transmission Gearbox Casing with Fixed Constraint of Vehicle Frame Based on FEA

Abstract Truck transmission gearbox casing is subjected to vibration induced by the harmonic excitation, meshing excitation, load fluctuations, gear defects, varying speed and torque conditions. Noise and vibrations are the reasons for the transmission failure. The transmission gearbox casing vibrations are the resultant of internal excitation caused by the gear meshing process and transmission error. This internal excitation produces a dynamic mesh force, which is transmitted to the casing through the shafts and bearings. The objective of this research work is to simulate the relation between dynamic vibrations of transmission and fixed constraint of vehicle frame. Transmission casing is tightly fixed on vehicle frame using connecting bolts. 37 connecting bolts were used to fix the casing on vehicle frame. If connecting bolts were loosened, it causes heavy vibration and deformation. For transmissions type multi degree freedom system the natural frequency and vibration mode are important modal parameters. First 10 inherent natural frequencies and corresponding mode shapes were evaluated. Grey cast iron HT200 was used as casing material. FEA based numerical simulation method was used to find the dynamic response of the casing. The numerical simulation method used reciprocity principle to apply the mesh forces transmitted to the casing and to determine the main responsible forces for the vibration of the casing. The FEA simulation results show that the natural frequency of one bolt unconstraint condition varies from (1637.2 – 2674) Hz. The analysis results were verified with experimental result available in literature.