The initial geometry of the tennis racket was created in the postprocessor Patran through a shell element modell of the frame (Left image) and representing the netting by using beam elements. The frame portion of the modell consisted of a five layer thick carbon fibre composite material configuration. The racket was fixated at the hilt in 6 degrees of freedom and a load vertical to the racket head was applied.
The simulation showed (Image), that by applying composite material the results for the bending line of the measurement can be recreated in an adequate manner. By comparison, the use of isotropic material presents results which deviate from the measurement.
The pre-tension of the strings was achieved through a thermally induced change of length. Aside from the calculation of the bending line, the FEM-model was used to calculate the string pre-tension acting on the frame and the string.
The simulation displayed the deformation of the racket frame due to the strin pre-tension. The largest deformation occured in the transverse direction, the lowest deformation in the areas of the lowest frame stiffness (Which is also the area with the smallest change in curvature).
Hereby we were able to show that through the use of Finite Element Models, in combination with the appropriate composite fibre material, a realistic representation of a tennis racket is possible. This allows for the identification of relevant characteristic properties of a racket, and their individual and rapid adaptation of said parameters and a realisitic representation of the occuring effects.
The in the magazine “Digital Engineering” published article written by Jacqueline Dastl (CAE Simulation & Solutions) and Syllvett Trialos (MSC Software) can be downloaded through the link down below.