It is well known that the mechanical properties of human bones change with aging, accompanied with the geometrical changes. While structure model index (SMI) is often employed to quantitatively evaluate the bone shapes, it is impossible that changes in shapes of bodies with concave and convex faces are accurately distinguished. In this study, SMI was extended to solve the problem, and this extended version of SMI (ESMI) was adapted to vertebral body models, where the models were built based on young and old aged vertebrae. Uniaxial compressive deformations of the vertebral body models were also numerically simulated by finite element method, and the relationship between the shapes and stress concentration factors was organized by ESMI. The results showed that ESMI distinguish shape changes of vertebral bodies more accurately than SMI, and the ease of stress concentration depending on the diameter of narrow part in vertebral body was successfully evaluated by ESMI.

In bimetallic rolls widely used in steel rolling industries, the compressive residual stress at the roll surface improves the roll fatigue life, but the tensile residual stress at the roll center sometimes reduces the roll strength. By controlling the residual stress, sleeve bimetallic rolls can be used more advantageously because the sleeve can be changed even after the sleeve’s wear amount exceeds the use limit. In this paper, therefore, two manufacturing processes are considered to investigate the residual stress. Method 1 is machining the roll inside after heat treatment. Method 2 is machining the roll inside first before heat treatment. By applying FEM, the residual stresses of sleeve rolls are compared to find out the suitable manufacturing method. The results show that method 2 is better than method 1 since the tensile residual stress can be reduced at the center of the sleeve.

In the past research, it was clarified that the preload single-row angular contact ball bearings in the fixed position preload changes increase significantly due to thermal expansion. However, the amount of change in this preload is considered to depend on the contact angle. Therefore, in this study, three types of single-row angular contact ball bearings 7306 with different contact angles were assembled with fixed-position preload, and the change in preload during rotation was measured. As a result, it was clarified that the larger the contact angle, the larger the calorific value, and the larger the contact angle, the larger the preload release amount. In addition, no preload loss occurred when preload was repeated with an axial load smaller than the previous load.