A new coalescence criteria for circular double defects based on the defect spacing ratio

Purpose This paper aims to systematically investigate the coalescence modes and coalescence criteria of circular defects. Design/methodology/approach In this work, a homogeneous plate containing circular double defects was used, and based on the Gurson–Tvergaard–Needleman (GTN) damage model, a series of finite element simulations were conducted. These circular double defects have different sizes, horizontal distances s, and vertical distances h. Then, the coalescence behaviors of these double defects were obtained, and the coalescence results was plotted with the horizontal defect spacing ratio s/(2R + s) as the abscissa and the vertical defect spacing ratio h/(2R + h) as the ordinate. Findings First, the results showed that there are three types of coalescence modes for circular double defects: defect tip is coalesced with defect tip (DT-DT), the middle of defect is coalesced with the middle of defect (DM-DM), and defect tip is coalesced with the middle of defect (DM-DT). Moreover, in the coordinate system constructed with the defect spacing ratio, there is a clear boundary between the defect coalescent area and the independent area. Then, based on the defect spacing ratio, a new coalescence criterion for circular double defects was established. Originality/value A new coalescence criterion for circular double defects is established based on the defect spacing ratios, providing a theoretical basis for evaluating defect interaction and structural integrity.