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The fatigue behavior of many structures, e.g. chassis components, or frame structures, often is restricted by the fatigue life of their welded joints. The fatigue of welds depends on the stress and strain histories in the toes and roots of the weld. Numerous research projects in the past have shown that knowing these stress histories (notch stresses) allows good fatigue prediction for welds. But the roots and toes are geometrically complex and of course also depending on the real welding process and therefore it efforts a lot of manual modeling to achieve local notch stresses by Finite Element simulation. Due to this methods have been developed to simplify the modeling effort and evaluate the local stresses and fatigue from the local load situation in the weld joint itself. These methods had been restricted to sheet structures modeled by shell-elements. In thick structures more and more modeling by solid elements is used in practice.

The need of weight reduction for fuel reduction and CO₂ regulations enforces the use of light-weight materials for structural parts also. The importance of reinforced composites will grow in this area. While the structural behavior and the simulation up to high strain-rate processes for those materials have been in the focus of investigation for many years, nowadays the simulation of high cycle fatigue behavior is getting important as well. Efficient fatigue analysis for metals was developed by understanding the microscopic behavior (crack nucleation and initiation) and bringing it to the macroscopic level by combining it with the matching test data (SN curves, etc.). Similar approaches can be applied to composite materials as well.

In the last decades the development time of vehicles has been drastically reduced due to the application of advanced numerical and experimental methods. Specifications concerning durability and other functional attributes for every new model improve for every vehicle. In particular, for machines and components under variable multiaxial loading, fatigue evaluation is one of the most important steps in the design process. Appropriate material testing and simulation is the key to efficient life prediction. However, the life of automotive components, power plants and other high-temperature facilities depends mostly on thermo-mechanical fatigue (TMF). This is due to the normally variable service conditions, which contain the phases of startup, full load, partial load and shut-down.

During the last ten years, there is a significant tendency in automotive design to use lower aspect ratio tires and meanwhile also more and more run-flat tires. In appropriate publications, the influences of these tire types on the dynamic loads - transferred from the road passing wheel center into the car - have been investigated pretty well, including comparative wheel force transducer measurements as well as simulation results. It could be shown that the fatigue input into the vehicle tends to increase when using low aspect ratio tires and particularly when using run-flat tires. But which influences do we get for the loading and fatigue behavior of the respective rims? While the influences on the vehicle are relatively easy to detect by using wheel force transducers, the local forces acting on the rim flange (when for example passing a high obstacle) are much more difficult to detect (in measurement as well as in simulation).

Product designers worldwide are confronted with highly competitive though conflicting demands to deliver more complex products with increased quality in ever shorter development cycles. Optimizing design performance with purely test-based approaches is no longer an option and numerical simulation methods are widely used to model, assess and improve the product design based on virtual prototypes. However, variability in design parameters and in operating conditions leads to scatter in actual performances and must be incorporated in the simulation process to guarantee the robustness of the design. This paper presents the application of state-of-the-art robust design techniques to a vehicle suspension system. A multibody model of a vehicle with a virtual test ground has been created to predict the durability response of three main components of the suspension system.

While CAE methods allow improving nominal product design using virtual prototypes, uncertainty and variability in properties and manufacturing processes lead to scatter in actual performances. Uncertainty must hence be incorporated in the CAE process to guarantee the robustness and reliability of the design. This paper presents an overview of uncertainty-based design in automotive and aerospace engineering. Fuzzy methods take uncertainty into account, whereas reliability analysis and a reliability-based design optimization framework can deal with variability. Key enabling technologies to alleviate the computational burden, such as workflow automation, substructuring and design of experiments, are discussed, and industrial applications are presented.

Recently, LMS has developed a new approach for fatigue life prediction of seam welds, which automatically combines quite accurate solid element based techniques with fast shell element-based structural analysis. Pre-modeled welded joint details are delivered in a user-extensible library, which is combined with regular shell element meshes as used in the transportation industries. Detection of the seam welds in the structure is mostly automatic. This new approach is implemented in LMS Virtual.Lab, the integrated environment for functional performance engineering.