Recently, Chao Wang from the School of Mechanical Engineering successfully published an academic paper "Artificial thermal strain method: A novel approach for the analysis and fast prediction of the thermal distortion" in the well-known international engineering journal "Journal of Materials Processing Technology" (SCI index, TOP, IF=4.669). Dr. Chao Wang is mainly engaged in the research of thermal-mechanical coupling finite element analysis and optimization design. This study established a rapid prediction model for thermal distortion prediction based on inherent strain theory. The model is capable to realize the rapid prediction of deformation under laser multi-curvature forming, welding of large structural parts, and additive manufacturing. In this study, the growing of inherent strain is studied, the transformation of inherent strain to artificial thermal strain is realized through equivalent moment, and elastic finite element is established to calculate the deformation. This work is collaboration with Duc Truong Pham, Dean of the School of Mechanical Engineering at the University of Birmingham, and he is also the academician of the Royal Academy of Engineering. The study was supported by the Open Fund Project of Jiangsu Key Laboratory of Mechanical and Electrical Product Recycling Technology (RRME201906).

DOI: https://doi.org/10.1016/j.jmatprotec.2020.116937

Paper Title：Artificial Thermal Strain Method: A Novel Approach for the Analysis and Fast Prediction of the Thermal Distortion

Journal：Journal of Materials Processing Technology

Abstract：

Understanding the thermal distortion induced by arc welding, laser, or induction heating is a challenge in academia and industry. This study presents the artificial thermal strain (ATS) method which was modified from strain as boundary (SDB) method, based on inherent strain theory, and its equivalent mechanical model to analyze the distortion mechanism. Experiments and numerical simulation of multi-pass laser bending of alloy 304L were conducted, wherein the various kinds of inherent strain distributions and the boundary of effective inherent strain were examined. Further, the mechanism of bending angle reduction under lower line energy was evaluated by considering the inherent strain redistribution at each pass. The results indicate that the bending angle reduction in multi-pass laser scanning is determined by the size of the inherent strain area at low line energy. Moreover, a simplified plastic finite element model based on the ATS method was developed to predict the welding deformation of plate curvature induced by parallel laser scanning. Additionally, only 210 elements and 7 seconds was cost to perform with the deformation analysis, which indicates that the ATS model is effective in predicting thermal distortion. Meanwhile, the ATS method can provide theoretical guidance and fast prediction for the actual thermal processing in large welded structure and additive manufacturing in the future.

Fig. Transformation of plastic strain distribution into ATS distribution.

Photo with PhD advisor and family members

Wang Chao is a lecturer in School of Mechanical Engineering, Changshu Institute of Technology. He has been to University of Birmingham to do research as an academic visitor for one year. He received his PhD degree in 2017 from Yeungnam University (South Korea). His areas of research interest include finite element analyses of laser welding and optimization by Bee Algorithm.