Prediction of the bearing capacity of the hip joint endoprosthesis from the С/C composites

The article evaluates the bearing capacity of the hip joint endoprosthesis made of carbon/carbon (С/C) composites under anatomical load. С/C is made on the basis of carbon fiber Ural N/400-22 and phenolformaldehyde resin novolachny type RP-010. A significant complexity in modeling an endoprosthesis is the prediction of the properties of С/C. The complexity of mathematical modeling based on the mechanics of composite materials consists in the impossibility of experimentally determining the mechanical characteristics of a pyrocarbon matrix. The pyrocarbon matrix does not exist in its pure form separately from the composite material. The mechanical characteristics of the С/C are calculated, mathematical models of bone tissue and endoprosthesis are constructed, taking into account the complex composite structure. The femur is represented by a combination of cortical and spongy tissue. The femur in the study was fixed along the lateral and medial condyles of the femur. This fixation corresponds to the contact spot of the condyle with the lateral and medial menisci. The hypothesis is confirmed that the weakest component in the С/C is the pyrocarbon matrix. The position of the highest values of normal and tangential stresses are revealed. The position of concentration of tangential stresses coincide with the areas of destruction of the endoprosthesis during compression testing, which were previously visually identified. New design and technological requirements for the structure have been identified, which will contribute to increasing the reliability of the endoprosthesis.