Optimal mechanical properties of composite material and pressure socket analysis for through-knee amputation

• Layer Configuration Innovation: The study introduces hybrid layer structures (e.g., 4P+2C+4P, 4P+4C+4P) and quantifies their direct mechanical and fatigue performance impact, offering a new approach for socket optimization. • Comprehensive Comparative Framework: The study provides detailed insights into the impact of different reinforcement strategies on yield stress, ultimate strength, and modulus of elasticity. • Fatigue Life Assessment at Million-Cycle Level: The use of high-cycle fatigue testing (up to 10⁶ cycles) provides long-term performance validation, which is rarely reported in prosthetic socket studies. • Biomechanical Interface Pressure Analysis: The investigation of pressure distribution at the limb-socket interface in correlation with muscular anatomy is a novel addition that addresses patient comfort from a structural design perspective. • Validated Numerical Analysis: The integration of experimental results with finite element modeling adds value by confirming the reliability of the optimized configuration (Group E), including deformation and safety factor analysis. The study measures the mechanical and fatigue characteristics of prosthetic sockets for through-knee amputation using five groups of composite material layers with an acrylic lamination matrix reinforced with air exclusion technology to avoid forming bubbles. The yield stress, ultimate stress, and modulus of elasticity increased in different groups due to different layers of carbon fiber and glass fiber. The fatigue limit for 8 layers of perlon was 18 MPa, while adding layers of glass fibers increased the fatigue limit to 35 MPa and 60 MPa for two and four layers, respectively, and adding two and four layers of carbon fibers did not break at the 1*10 6 cycle number, indicating that they are excellent for life and suitable for wearing socket prostheses. The interface pressure using the F-socket test reaches its maximum at the back of the stump (175 KPa) and front (160 KPa), ideal for patient comfort due to the large leg muscle that can bear more pressure than other walls. The best results of numerical analysis for group E (perlon and carbon fibers) indicate a total deformation of 1.219 mm, with a safety factor of 2.995, acceptable for medical applications.