Quantitative biomechanical analysis of sharp force injuries to the head using finite element simulation.

In sharp force injury cases, assessments of applied force and injury severity primarily rely on empirical judgment, lacking quantitative and objective data support. This study aims to construct a high-fidelity finite element (FE) head model, validate it using 3D-printed biomimetic skull experiments, and investigate the relationship between momentum and injury severity in sharp instrument stabs to the head, thereby providing scientific evidence for case analysis. A high-fidelity FE head model was reconstructed based on the Total Human Model for Safety (THUMS) model. Biomimetic skulls were 3D-printed using PEEK material. Experimental data obtained from slashing with a Chinese kitchen knife were collected via sensors and motion capture systems, using the erosion failure model to simulate wound formation. Following model validation, the approach was applied to a real stabbing fatality case to systematically simulate stabbing processes under varying momenta (0.75-11.25 kg·m/s). FE model validation demonstrated close alignment between simulation and experimental results, with errors in wound dimensions and slashing force within 15.0%. Case reconstruction revealed that the minimum momentum required to reproduce penetrating injury in the homicide case was 9.75 kg·m/s. In the present simulation framework, momentum values of 0.75 kg·m/s, 2.25 kg·m/s, and 5.25 kg·m/s were associated with minor, moderate, and serious skull injuries, respectively. This study provides a biomechanical framework for quantitative simulation and illustrative case reconstruction of sharp force injuries. The real-case application serves primarily as an example of the proposed biomechanical reconstruction approach, which may enhance the objectivity of injury severity assessment when integrated with other forensic evidence and provide reproducible biomechanical support for case investigation.