FEA (finite element analysis) is widely accepted as a verification method for the design of new medical products. However, only a limited number of organizations are using FEA as an everyday design tool. A combined system consisting of nitinol and polymers (coronary angioplasty scoring catheter) was developed and optimized using Three dimensional FEA modeling based on a commercially available software package (ANSYS, Canonsburg, PA). Selected structural features were determined using the above model in an interactive manner. Once validated, the model was used to predict the system compliance and response for different loading conditions.

The analysis consists of several sequential steps that simulate the actual manufacturing processes of the device. The design requirements were highly non linear due to material nonlinearity, large deformations and the presence of contact elements in the manufacturing process simulation. Different types of elements were combined and a full Newton-Raphson algorithm was used to solve the problem. Convergence was enhanced by using incremental load equilibrium iterations. Using FEA as an interactive design tool substantially reduced the number of design iterations and helped in determining the Nitinol/Polymer interface, the desired safety margins and the fatigue resistance of the device.