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Finite element method has been used for modal and vibration / stress analysis of a passenger vehicle. The study vehicle has been discretised taking into account the chassis elements, axles, suspension and tyres. The Lanczos method has been successfully used for the modal analysis. The power spectral density (p.s.d.) of acceleration of a track measured by using three height sensors has been fed as input to the tyres and the dynamic response of the vehicle in terms of acceleration and strain has been computed at all the nodes using finite element modeling and the random vibration concept. The experiments were carried out using piezo-electric accelerometers and strain gauges to measure the vibration and strain levels at critical points of the vehicle. The vibration and strain levels calculated through f.e.m. match well with the experimental values.

In commercial vehicles, exhaust system is normally mounted on frame side members (FSM) using hanger brackets. These exhaust system hanger brackets are tested either as part of full vehicle durability testing or as a subsystem in a rig testing. During initial phases of product development cycle, the hanger brackets are validated for their durability in rig level testing using time domain signals acquired from mule vehicle. These signals are then used in uni-axial, bi-axial or tri-axial rig facilities based on their severity and the availability of test rigs. This paper depicts the simulation method employed to replicate the bi-directional rig testing through modal transient analysis. Finite Element Method (FEM) is applied for numerical analysis of exhaust system assembly using MSC/Nastran software with the inclusion of rubber isolator modeling, meshing guidelines etc. Finite Element Analysis (FEA) results are in good agreement with rig level test results.