Design and fabrication of a biocompatible nanocomposite patch for mechanical reinforcement and stress concentration reduction in cracked bone tissue

This study experimentally investigates the use of a biocompatible nanocomposite patch reinforced with carbon nanotubes (CNTs) to mechanically strengthen cracked bone tissue by mitigating stress concentration. Reducing stress intensity factors (SIFs) in damaged bone is a promising strategy for accelerating fracture healing and limiting crack propagation. A nanocomposite patch composed of chitosan (CS), nanohydroxyapatite (nHAp), and CNTs was fabricated using the solvent casting method. Metacarpal and metatarsal bones containing predefined cracks were prepared as mixed-mode bending (MMB) specimens to determine the critical fracture load. Corresponding finite element models were developed to evaluate mode I and mode II SIFs. The mechanical effectiveness of the nanocomposite patch was assessed by comparing the critical SIFs of cracked bone specimens with and without patch reinforcement. The results demonstrate that the applied patch significantly reduces stress concentration at the crack tip, thereby enhancing the mechanical resistance of the bone tissue. Furthermore, the applicability of the maximum tangential stress (MTS) criterion for mixed-mode I/II fracture assessment in bone was examined and validated. This work presents a mechanical proof-of-concept for the use of nanocomposite patches as reinforcement strategies in cracked bone structures.