Associate Professor Xu Wu has published research paper at JMPS

   Recently, Associate Professor Xu Wuchang of the Department of Aircraft Design of the School of Aeronautics and Astronautics and his team published the paper "A finite crack growth energy release rate for elastic-plastic fracture" in the Journal of the Mechanics and Physics of Solids (JMPS). In this paper, from the perspective of energy conservation and crack propagation work, the finite crack propagation energy release rate of elastic-plastic fracture is proposed to overcome the limitations of Irwin-Orowan-Griffith criterion that fracture toughness is related to specimen geometry and size, loading history and type. It provides a new method for elastoplastic fracture analysis and residual strength analysis of aircraft structures with extensive fatigue damage.

  In this paper, a finite crack growth energy release rate is proposed by assuming a finite crack growth, which is conveniently applicable to finite element analysis. The effect of the plastic dissipation on the crack growth is considered in the driving force. Elastic-plastic finite element analysis is used to apply the present energy release rate. Compared to the experiment results, it is shown that for a fixed finite crack growth, a constant critical energy release rate can well predict the stable crack growths and residual strengths of sheets with single and various collinear cracks subjected to different types of loads. The present finite crack growth energy release rate is conceptually simple, has a solid physical foundation, and would be appealing for ductile crack growth analysis.

Fig. 1. Crack closure for elastic-plastic material.

Fig. 2. Predicted and experimental results of the CT test subjected to monotonic displacement loading and cyclic loading.

Fig. 3. Predicted and experimental load-crack growth relationships.

Fig. 4. Experimental and predicted load-crack growth relationships for sheets with multiple collinear cracks.

  The finite crack propagation energy release rate of elastoplastic fracture proposed in this paper has a solid theoretical basis, clear physical significance, convenient combination with finite element, and is expected to be more widely used in engineering. The research was supported by the National Natural Science Foundation of China and the Shanghai Natural Science Foundation. Associate Professor Xu Wu and Master Ren Yanshen from Shanghai Jiao Tong University, Professor Liu Bin from Tsinghua University, and Dr. Xiao Si from Southern University of Science and Technology are co-authors of this paper.

Paper link：https://doi.org/10.1016/j.jmps.2023.105447