Beyond Design: Ergonomic Numerical Evaluation of a Biomimetic Breast Prosthesis for Daily Use

External breast prostheses remain the primary noninvasive alternative after mastectomy; however, most commercial designs do not adequately reproduce natural breast biomechanics, heat dissipation, and ventilation behavior during daily activities. This study presents an integrated numerical framework for the ergonomic evaluation of a biomimetic external breast prosthesis under realistic use conditions. A multilayer prosthesis-torso assembly was generated through 3D digitization and modeled using nonlinear hyperelastic finite element formulations. The proposed design incorporated biomimetic lobular internal architecture and microsphere-based posterior ventilation configurations to improve load distribution and heat dissipation. Dynamic behavior was evaluated through modal, harmonic, and spectral analyses, while thermal and airflow simulations were used to assess interface temperature reduction and ventilation efficiency. The results showed physiologically acceptable dynamic displacements, without critical stress concentrations and natural frequencies outside dominant gait excitation ranges. Additionally, biomimetic ventilation configurations reduced contact temperatures by up to 6.58 °C compared with conventional commercial geometries. Overall, the proposed architecture demonstrated mechanical stability, improved thermal performance, ergonomic compatibility, and potential for personalized prosthesis design.