The mathematical model and results of tooth contact analysis (TCA) of the Wildhaber-Novikov (W-N) gear are given in Ref. [I] [F. L. Litvin and C.-B. Tsay, Trans. ASME, J. mech. Trans. Auto. Des. 556-564 (December l9SS)]. A finite element method (FEM), using the SAP IV package, is employed to the W-N gear stress analysis. An automatic nodal points and meshes generating (AMG) computer program has been developed. By utilizing the mathematical model of the W-N gear and the AMG computerprogram, nodal points and meshes for finite element analysis can be obtained automatically.By applying the results of TCA, the location and direction of applied loading on gear teeth can be defined. Root bending stresses of pinion and gear with different loading positions have been analyzed. Effects on root stresses due to variations of fillet radius and normal pressure angle of pinion have also been investigated.

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The propagation of surface acoustic waves in two types of tunable magneto-electro-elastic phononic crystal structures is investigated, for which Terfenol-D rods are vertically deposited on the piezoelectric substrate or embedded in the piezoelectric substrate. The bandgaps of the phononic crystal structures are analyzed by using the finite element method considering the nonlinear physical characteristics of Terfenol-D under a magnetic field and compressive pre-stress. Furthermore, through a detailed discussion of the calculated results, it is shown that the bandgaps of surface acoustic waves can be enlarged and new bandgaps will appear under an appropriate magnitude of magnetic field and compressive stress. Therefore, the present numerical model may provide relevant guidance for adjusting the bandgaps of surface acoustic waves in a two-dimensional magneto-electro-elastic phononic crystal.

In this study, we developed a novel multi-scale model to predict the aging performance of particle-filled polymer composites (PFPCs) under thermo-oxidative aging conditions. To investigate the aging behavior, high-temperature accelerated aging tests were conducted in combination with macroscopic and microscopic characterization. At the microscopic level, the crosslinking density of the polymer matrix is calculated using the closed-loop chain reaction of polymer oxidation. In addition, the theory of polymer physics was used to determine the relationship between crosslinking density and elastic modulus. Relationships between elastic modulus and dewetting strain were analyzed at the macroscopic level. Based on the observations and analyses, a multi-scale model was developed to predict the aging performance of PFPCs. The predicted results show good agreement with the test results, which verifies the reliability of the model.

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