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Recent trends in mechanical engineering are focusing on optimization of components with respect both to weight and lifetime by using numerical simulation even in the early design stages. For a reliable prediction of in service performance by simulation, both loading as well as different damage and failure mechanisms that may be activated during operation have to be known. In mechanical engineering applications, cyclic loadings are most common. In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, relative motion of contacting bodies combined with high loads transmitted via the contact surface lead to fretting fatigue failure. In this contribution a few selected results of a currently conducted research project are presented. The aim of this study was to examine the material behavior of a surface stressed steel. The influence of the Fretting regime on fatigue properties has been investigated.

A software package is described which permits the assessment of welded structures under dynamic loadings. Based on the stresses calculated using the Finite Element Method and a database with notch factors of welded seams and S/N-curves the process of this assessment can be automated. Safety factors and damage values can be quickly displayed on the Finite Element structure.

A postprocessor program for the calculation of the fatigue life of components calculated with the finite element method (FEM) is described. Based on the stresses calculated by FEM and the material data of unnotched test specimens, s/n curves in relation to FE nodes are calculated for components taking into account the most varied influencing factors, such as amplitude stress tensor, mean stress tensor, relative stress gradient, surface roughness, technological influences, local plastic deformations etc. The results of the calculations, such as damage distribution and insusceptibility to permanent rupture, are graphically represented in the form of FE colour plots. Besides the possibility of the calculation of the fatigue life of components also costs and time can be reduced during the development phase of vehicles.

For the simulation of driving road- and offroad-vehicles a mathematical model as well as a program have been developed, which allows the prediction of the driving performances, driving time and speed, fuel consumption, exhaust emissions, loading of the drive line and strain on the driver when the vehicle runs on prescribed routes. The driving simulation takes into account engine, tire, gearbox, and general vehicle data, height and outline profiles of the route, visibility, permissible transverse acceleration and wheel or exhaust braking. The aim of the simulation calculations is to find the optimum overall economy for given operating conditions by coordinating the individual elements of the total system of engine-transmission-vehicle. Not only can vehicles be optimized, but existing vehicles can also be easily compared and assessed.

Numerous specifications and tight time schedules in the development of special trucks require the application of comprehensive CAE-methods prior to the cross-country test phase. The methods applied to the development of a complete family of offroad-trucks are presented by the following subjects: stress, fatigue and dynamic analyses based on the finite element method calculation of the comfort by multibody systems mobility analysis system dimensioning, e.g. cooling and brake system prediction of the fuel consumption, gradability, acceleration and loading spectra by a computer driving simulation servo-hydraulic tests of vital parts and sybsystems, based on field data acquisition and processing