Research on crack propagation of 3D printed material with complex cracks based on the phase-field fracture model

Complex branch cracks in practical engineering structures often have a great impact on structural damage, so the analysis of branch crack propagation is very important. The phase-field fracture model, a particular model for solving crack propagation without any ad hoc criteria, is very effective for complex crack propagation problems. In this research, several tensile experiments of 3D printed material containing designed complex cracks (Y-shaped and N-shaped) have been performed. The i speed 716 high-speed camera is combined with a loading testing machine to capture the real-time whole fracture process in experiments. Based on the phase-field model, the influence of displacement increment and energy decomposition on the simulation results of crack growth is explored. Equilateral Y-shaped center crack specimens in different directions are designed to study the influence of crack angle on crack growth. The results show that the specimens' bearing capacity and propagation form with equilateral Y-shaped cracks change with the orientation of equilateral Y-shaped cracks under tensile load. When the orientation of the equilateral Y-shaped crack is 0 degrees with the x-axis, the specimen is the most resistant to tensile force. When the orientation is 30 degrees, the specimen is the most vulnerable to failure. In practical engineering, the occurrence of cracks at this orientation should be avoided as much as possible. Between 60 degrees and 75 degrees, the crack propagation form changes. The numerical simulations of the tensile failure of the 3D printed material with complex cracks agree with the experiments, and the errors of the maximum force on the failure are smaller than 7%. The model studied in this paper can predict the crack growth of 3D printed material with complex cracks from a qualitative and quantitative perspective.

Automated summary

The research investigates the propagation of complex cracks in 3D printed materials using the phase-field fracture model. Experimental and numerical simulation results reveal the influence of crack angle on crack growth and identify changes in the bearing capacity and propagation form of specimens under different crack orientations.