Effects of structural details on brittle crack arrestability in thick cross-joint components under different propagation scenarios

• Brittle crack propagation is experimentally observed in PMMA cross-joint component. • Three tested scenarios: no slit (S0), coaming-to-deck (S1), deck-to-coaming (S2). • Crack propagation/arrest behaviour is successfully recorded by a high-speed camera. • The s-method-based numerical framework is used to simulate crack behaviour. • Compared with S0, S1 showed enhanced arrestability, but S2 had little effect. Brittle fracture poses significant risks in large container ships; therefore, enhancing brittle crack arrestability is essential for structural integrity. While structural design offers a promising route, a critical gap remains: the lack of quantitative understanding regarding how realistic crack propagation scenarios influence brittle crack arrestability. This study addresses this gap by investigating thick cross-joint components—critical welded details that connect the deck plate and hatch coaming and play a decisive role in maintaining the safety of container ships—under three realistic scenarios: Scenario Zero (S0), without discontinuities, simulating full penetration welding; Scenario One (S1), with discontinuities, crack propagation from hatch coaming to deck; Scenario Two (S2), also with discontinuities but in the reverse direction. Specimens were designed for crack arrest tests to simulate these scenarios using PMMA capable of capturing high-speed crack propagation/arrest behaviour, similar to that observed in steel, in situ. Experimental results demonstrated that discontinuities significantly improved crack arrestability in S1 but had negligible effect in S2. To further analyse these effects, a high-fidelity s-version-finite-element-based framework was employed to simulate high-speed crack propagation/arrest behaviour. Numerical results revealed that, compared to S0, discontinuities reduced the dynamic stress intensity factor by up to 44% in S1—equivalent to using materials with an arrest toughness increased by nearly 80%—while showing negligible effect in S2. These findings provide the quantitative and mechanistic clarification of how structural details affect brittle crack arrestability and offer both scientific insight and practical design guidance for improving the safety of large welded marine structures.