FEMFAT

FEMFAT performs fatigue analyses in combination with widely used finite element programs. Commonly used interfaces to multi-body, optimization and measurement systems are employed to ensure full and convenient integration into the customer’s CAE processes. FEMFAT provides engineers with reliable information on the fatigue life of structures to improve critical locations and/or reduce the total weight at an early stage of the design process, long before time and cost consuming tests are scheduled. This results in high-level accurate prototypes and less tests.

FEMFAT takes many important and interacting fatigue influences into consideration; for example material properties, notches, mean stresses, surface roughness, surface boundary layers, temperature field, plasticity, mechanical and/or chemical surface treatments, component sizes, special behaviour of welds, spot welds, self piercing rivets, multi-axial loading, static, dynamic, linear, non linear effects and much more. It is possible to use combinations of modules to solve problems correctly.

Methods and Verification

The methods used in FEMFAT are based on the latest scientific findings of the German FKM guidelines, on the work of Huck / Thrainer / Schutz (synthetic S/N curves), on the local stress-strain model (TU - Darmstadt), on the R1MS concept for assessment of welding seams and on ECS-proprietary methods, for example spot joints. In addition to this, methods applicable to FEM were developed, such as computing notch influence in terms of the relative stress gradient or consideration of the interaction of different stress tensors by using the critical cutting plane method. All these hypothesis have been checked by comparing numerous test series with fatigue analysis results and have been verified during many years of practical use.