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The ride vibration environment of a typical high-speed military tracked vehicle traversing rough off-road terrain is a significant factor due to the magnitude of ride vibrations arising from dynamic terrain-vehicle interactions. In this paper, ride dynamics of a “2+N” degrees of freedom (DOF) tracked vehicle mathematical model has been evaluated for rough off-road terrain modeled as a sinusoidal profile of different pitch and height at constant running speeds. The equations of motion are derived using Newton's laws of motion. A comparison of ride dynamic analysis of the vehicle fitted with conventional passive suspension system and hydrogas suspension system is made.

In recent years graphical dynamic system simulation has become very important in the design and development stage, as new strategies can be examined without expensive measurements. This paper describes the development of a real time simulation model for a turbocharged diesel engine and an automatic transmission of a tracked vehicle using graphical programming environment in Matlab/Simulink. This work is part of a vehicle simulation model which is under development. A Mean Value Engine Model (MVEM) is used for simulation of engine dynamics. A Torque Converter (TC) is used as a fluid coupling between the engine and the transmission gearbox. This model is used to predict the dynamic response, both in steady and transient operation. Various illustrative studies have been conducted to demonstrate the capability of the model to predict the transient system response.

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.

A vehicle's lateral performance and handling characteristics are most important while negotiating a turn. In this paper sensitivity analysis of lateral acceleration and yaw rate for front wheel steering vehicles is carried out in the frequency domain using the first order standard and first order logarithmic sensitivity functions. A simple two degree of freedom model is used for deriving amplitude ratio and phase angle for both yaw rate and lateral acceleration. Vehicle mass, yaw moment of inertia, front and rear tire cornering stiffnesses and distance from the front axle to the centre of gravity are the design variables considered. This study predicts that the strongest parameter is the location of the centre of gravity and the weakest parameters are mass and yaw moment of inertia.

A 3-degrees of freedom rigid body model has been developed to predict the directional response of a light passenger vehicle. An attempt has also been made to modify and use the finite element model developed for determining the vibration response of the vehicle to predict the directional response of the vehicle. The Newmark time integration scheme has been used as solver. The tyre properties such as lateral stiffness, cornering stiffness, self-aligning torque stiffness have been measured using the facilities of (CIRT) Central Institute of Road Transport, Pune. The simulation results of directional response of the vehicle in terms of roll angle, yaw rate and lateral acceleration for the sinusoidal and ramp steering inputs (applicable in tests such as the Slalom test and J-turn manoeuvre respectively) to the vehicle at constant speed have been presented.

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.