Fracture Behavior of Type 2 and Type 3 Arc-Shaped Microcrack Penetration Subjected to Implant–Bone Interface Loading

Femur bone fracture is mainly caused by sports injuries or accidents and has become serious attention in orthopedic trauma. The unique cortical bone microstructures and features contribute to complex fracture behavior. This paper presents the investigation of Type 2 and Type 3 arch-shaped microcrack penetration based on von Mises stress and stress intensity factor (SIF) parameters around the microcrack tips penetration in Haversian system cortical bones. The fracture model was constructed based on bone continuum mechanics theory named Kachanov theory of elastic interaction. It aims to determine the level of stress amplification and stress shielding for the transition of Type 2 to Type 3 for heterogeneous cortical bone fracture model. A total of eight microcrack extension points (CP1–8) were constructed based on 1-mm 2 Haversian system model, subjected to the force of 10 N in Mode I and Mode II loading. Finite element (FE) analysis was then performed to evaluate the von Mises stress around the crack end tips and SIF under the assumption of bone damage, D < 1. The study found that the greatest von Mises stress value was observed at the CP4 (175.766 MPa) and CP8 (213.264 MPa) for Mode I loading and CP4 (106.037 MPa) for Mode II loading. In terms of fracture parameter, the critical SIF magnitude was peaked at CP4 (1272.8 MPa*m 1/2 ) and CP8 (1369.0 MPa*m 1/2 ) for Mode I loading and CP5 (402.29 MPa*m 1/2 ) for Mode II loading. The results show that the transition of Type 2 (straight crack) to Type 3 (arch crack) microcrack penetration in Haversian system experienced the multilevel of stress amplification (CP1–CP4, CP6–8) and stress shielding (CP4–CP6) to represent the bone micro-damage level.