Dynamic Verification of a Grid Structure Numerical Model Consisting of Different Stiffness Parts

The work presents the results of experimental and numerical investigations into the natural frequencies of grid structure containing parts made of materials with significantly different elastic modulus. A good example of such structure is human thorax. Firstly, the elastic properties of bone and cartilage materials were obtained by using bending and compression tests. The elastic modulus of the compact substance of the bone is 8…12 GPa, coastal cartilage – 70…90 MPa. The maximum failure force and bending strength were defined under the bending impact test (using a drop tower impact system). This bone strength is ∼175 MPa (1.5...2 times more of the values obtained in static bending). Then, a three-dimensional model of a human thorax was developed allowing one to predict their mode shapes and the natural frequencies using the finite element method (ANSYS software). The verification of the model was carried out by comparing the experimental (in vivo) and numerical natural frequencies of a human thorax.