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In the present study, several welded beam and plate specimens are fabricated using an electrical resistance type spot welder and studied experimentally applying the frequency response function approach. The experimental data is used to guide the dynamic finite element modeling effort, and to determine the weld joint representation that most accurately characterizes the measured dynamic response. The results reveal the compliant nature of the spot welds at higher frequencies and in applications consisting of more complex geometrical structures and boundary conditions. This finding shows the inadequacy in the classical rigid element representation that is widely used in current dynamic modeling practices.

The changes of dynamic frequency response, commonly used to determine the dynamic characteristic of built-up structures, were studied over the entire fatigue failure process for tensile-shear spot-welded joints. The results of an experimental study showed that the natural frequency varies non-linearly with the fatigue damage fraction. This behavior was modeled using finite element analysis of a progressively growing crack, initiating at the joining surface, then progressing to the outside surface of the specimen, and finally extending from the spot weld nugget. The relationship between dynamic frequency response and crack propagation may be applied to study effect of aging (high mileage) in NVH quality.

Reduction of noise transmitted through laminated glass with interlayer is of interest to vehicle applications. Altering the structure of the interlayer can impact sound transmission loss particularly at the coincidence frequency. This study investigates the feasibility of including a porous layer within the laminated glass to act as an acoustic damper. To understand the underlying physics controlling transmission loss in laminated glass design, an approach utilizing transfer matrices is used for modeling each layer in the laminated glass. These transfer matrices are used to relate the acoustic characteristics of two points within a layer. For any two layers in contact, an interface matrix is defined that relates the acoustic fields of the layers depending on their individual characteristics. The solid layer is modeled as an elastic element and the sound propagation through the porous materials is described using the Biot theory.

Spiral bevel gears are commonly used in heavy-duty trucks and buses. An integrated dynamic model of the spiral bevel gears with mixed elastohydrodynamic lubrication is proposed in this study. First, loaded tooth contact analysis was performed to evaluate the kinematic parameters and calculate the mesh force variation for one mesh cycle. These kinematic quantities are used in the mixed elastohydrodynamic lubrication (EHL) calculation to determine the EHL parameters such as pressure, film thickness, and shear distribution considering the surface roughness profile of the spiral bevel gears. Then, the EHL pressure and film thickness are used in the calculation of the coefficient of friction, damping, and oil film elastohydrodynamic lubrication stiffness. Last, these tribological parameters are used in the dynamic calculation of the spiral bevel gears.

The tooth surface error will affect the contact pattern and transmission error of the hypoid gear, which may result in an unfavorable dynamic response. The tooth surface error can be generated by machine tool errors, such as blade wear. The most common forms of blade wear are the positive cutter radius and the positive blade angle error. In addition, in the cutting process of face-hobbed hypoid gear, the continuous indexing motion will aggravate the blade wear due to the alternating cutting force. Most previous studies on the influence of hypoid gear tool errors only focus on the contact pattern and static transmission error. However, there are very few studies about the effect of tool errors on hypoid gear dynamic responses. In this paper, a hypoid gear tooth surface, mesh, and linear dynamic model with tool errors were established. The tooth surface deviation distribution of different tool errors was analyzed.