TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Tchoffo Ngoula, D. A1 - Beier, T. A1 - Vormwald, M. T1 - Cyclic J-integral: Numerical and analytical investigations for surface cracks in weldments N2 - The cyclic J-integral (∆J-integral) is a crack tip parameter of elastic-plastic fracture mechanics which can be used as governing parameter for the description of fatigue crack growth (FCG) in metallic structures. In this contribution, it is applied for modelling FCG in weldments. The ∆J-integral is determined by means of analytical approximation formulas as well as numerical methods. An analytical solution, which takes into account effects of the local ligament plasticity, was derived. This solution is based on well established methods such as R6, BS7910 and SINTAP which were modified for cyclic loading. It incorporates methods for the description of short crack closure behaviour as well as the well known analytical (long) crack closure function of Newman. A specific code was written to evaluate the ∆J-integral numerically in the course of finite element based crack growth simulations. The code was first validated for an infinite plate with centre crack by applying elastic and elastic-plastic material behaviour. Next, the ∆J-integral was calculated for cracks in various butt and cruciform welded joints. The results were compared with the results of the derived analytical approximation formula. A good accordance was achieved between the results. KW - Cyclic J-integral KW - Elastic-plastic fracture mechanics KW - Fatigue crack growth KW - Short cracks KW - Weldments PY - 2018 U6 - https://doi.org/10.1016/j.engfracmech.2017.06.023 SN - 0013-7944 VL - 198 SP - 22 EP - 44 PB - Elsevier AN - OPUS4-46857 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -