Fatigue life improvement of a welded structure with topology optimization
Heikkilä, Taneli Eero Juhani
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This master’s thesis deals with topology optimization as a tool for fatigue life improvement of a welded structure. Welded structures are prone to failure due to fatigue caused by cyclic loads. Optimizing structures against fatigue with topology optimization has very few practical examples in literature, but it has proven as promising technique. In this work we utilize rainflow cycle counting method, Palmgren-Miner damage sum and effective notch stress method to create constraint function for weld seam fatigue stress to attain optimal design in terms of fatigue strength and stiffness. The method was then adapted on Ponsse C44+ parallel crane boom head design to improve fatigue life of the structure. Structure was optimized using ANSYS and GENESIS topology optimization software with custom made fatigue constraint function. Results show significant reduction on stress ranges at the weld seam.