الفهرس 
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Abstract
This these provides an approach for studying the dynamic characteristics of a vechicle chassis using different supension with different suspension characteristics.
The considered model in this study is the chassis of the jeep-69.
The problem is firstly investigated by using a very rough lumped system model which is a quarter and half vehicle model under the passive suspension parameters.
The body acceleratain, suspension working space and dynamic trie load are presented, in terms of RMS values and power spectral density, with respect to variable stiffiness and payload.
Then a finite element model is constructed to study the static and dynamic characteristics of the chassis.
An experimental set-up is made and an additional spring damper suspension is fitted in the rig with the original leaf spring to allow a variety in suspension parameter. Sixteen measuring point is fixed to detect the strain and mode shape of the main beam of the chassis using amodern data collector and strain indicator instruments.
A sinusoidal excitation profiles are assumed, and dynamic respone isperformed, then parametric study is performed to estimate the effect of the spring stiffness coefficients on the design to obtain an optimum design for this structure. The effect of different excitation frequencies are also examined.
Results are discussed for different stiffiness values and its effects on the chassis design.
The theoretical results are nearly coincident with those obttained experimentally.
The predicted values of the designed stresses were 10 to 15% higher than those obtained in the tests.