In this report a system model is described which enables us to predict the vibration behaviour in the frequency range between 0 and 200 Hz for front and rear suspension, engine mounting, powertrain and steering. The body can be considered as rigid mass or as flexible finite element model.

At first the system matrices have to be established. The only way to achieve this for such a complex system is by the finite element method. As programme NASTRAN (Nasa structural analysis) is used. This is a multipurpose programme for very large, complex structures.

The most important step is the idealisation of the real-world structure. This is done by elements as beams, rods, shear panels, plates, shells and solids.

Results of the calculations carried out on the computer CDC Cyber 176 are:

eigen-valuee, vibration mode shapes, frequency response functions, transient response functions and strain energy distribution. All the differential equations describing the vibration system can be established in physical coordinates or in generalised (modal) coordinates.

From a mathematical point of view the use of modal coordinates means decoupling the system of differential equations.

The vehicle phenomena listed below have been investigated by the system models described:

Steering wheel shimmy • Bending vibration of powertrain

Engine shake

Torsional vibration of the powertrain.