Development of a Virtual Orthosis Test Bench

Kurzfassung

Knee orthoses provide vital support for people recovering from cruciate ligament injuries, especially during post-operative period or during conservative treatment. They support the healing process by stabilizing and aligning the injured knee joint. Additionally, these orthoses mitigate the risk of further injuries by safeguarding the knee from excessive strain during rehabilitation. However, the development of new knee orthoses is a time- and labor-intensive process. Following the design phase, a prototype must be manufactured, tested, and evaluated. This process is repeated iteratively until all requirements are met. To accelerate this process, a virtual testing platform would be invaluable. Such a platform can be used to analyse the mechanical behaviour of different prototypes in advance, allowing only the most promising designs to be tested, thus conserving resources. The objective of this study is to develop a virtual test bench to assess the stiffness behavior of knee orthoses under different load conditions. Initially, the compliance of the test frame was determined experimentally, and a simplified simulation model was created and calibrated. A detailed finite element model of the knee orthosis was then developed, incorporating various materials such as isotropic aluminum, foam, and hyperelastic straps as well as kinematics of the orthosis. An explicit solver was employed to calculate the stiffness behavior for three distinct load cases considering the complex friction behaviour. The calculated stiffness values were subsequently compared to experimental data, and the accuracy of the predictions was assessed.