Precise and detailed finite element models of the grabber in closed, unequally closed and open position with different angles were built to simulate the cyclic working conditions. Based on the stress differences in different working load cycles, the fatigue life of the grab could be calculated. The detailed dimensions and improvement in the weld procedure of the required design update could be validated and after repair, the fatigue vulnerability of the modified grab design was removed.
The fatigue check was performed according to the NEN 2018/2019 standard (the Dutch equivalent of the DIN15018 with the same calculation procedure as the FEM 1.001) which in this case was specified in the original purchase procedure. The importance of the possibility to calculate even according to the guidelines of older standards was in this project again underlined.