| Abstract Scope |
Heat effects including part distortion and residual stresses are major factors deteriorating the manufacturing accuracy and structural integrity of fusion welded or additively manufactured products, which have attracted considerable attention from research communities in process modeling and control. For decades, the sequentially coupled thermo-mechanical finite element analysis (FEA) is widely adopted for welding process simulation because the one-way coupling scheme is more efficient in the case of implicit iteration. However, such computational framework faces the bottleneck of scalability in large-scale analysis due to the exponential growth of computational burden with the increase of elements in a FEA model.
In the present study, a fully coupled approach with explicit integration was developed to simulate fusion process induced temperature, distortion, and residual stresses. A material density scaling and heat capacity inverse scaling technique was proposed to accelerate the thermal and mechanical analysis simultaneously, by maintaining the actual property of thermal diffusivity in the spatial and time domain. The scaling factor was optimized by a sensitivity study based on different heat input, melt pool size and plate thickness. To effectively model the springback during clamp removal or local cutting, both the direct explicit analysis and the transfer analysis from explicit to implicit were investigated.
The proposed modeling framework was successfully implemented on a general-purpose CAE software. Numerical examples of arc welding, wire arc additive manufacturing as well as selective laser melting were analyzed to verify the computational accuracy and efficiency of the fully coupled approach. Owing to the nature of explicit scheme, the proposed approach will be more powerful in solving large-scale welding and additive manufacturing problems. The ideal parallel performance of the explicit code will unleash the computing power of the massive-core CPUs and GPUs. The limitations and future development were discussed to conclude the presentation. |