Fraunhofer-Institut für Betriebsfestigkeit. Tätigkeitsbericht 1994

The annual report 1994 of the Fraunhofer-Institute for Strength of Structures under Operational Conditions comprises information on the objectives and organization of the institute as well as on the competence and services provided including lists of project files, publications, lectures and other activities in 1994. Four project reports serve as examples to characterize the typical approaches the institute is offering in more detail: H. Oppermann discusses in his contribution "Improvement of the accuracy of analytical life prediction for metal components considering loading sequence effects" the influence of the order of load events on the fatigue process. As a result, characteristic functions - depending on the shape of specimen and load - are derived and integrated into an existing procedure for life prediction. Subject of the paper "Static and dynamic behavior of elastomer components under large deformations" by U.-J. Görke are various phenomena which are typical for elastomers, th e experimental identification of material parameters for appropriate material models and their implementation in finite element codes. A life prediction method is briefly outlined based on a combination of experimental results of test specimens under oscillating loads and finite element calculations. G. Fischer and V. Grubisic deal with a procedure to derive artificial load sequences based on service measurements of commercial vehicles. These loads are used in a test rig to simulate realistic stresses and strains in the air bellow of pneumatic suspension systems. Finally, H. Kaufmann and C. M. Sonsino in a contribution "Accuracy of life prediction of a steering knuckle based on a local stress concept" discuss divergent results of numerical life time predictions of a real steering knuckle under operational loading, using several state-of-the-art procedures based on results from specimens testing. None of the 6 investigated methods led to a sufficient quality of the prediction, so that t he authors recommend to apply those methods only for predimensioning purposes and to carry out experiments, if heavy oversizing has to be avoided.