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A method is presented to evaluate diesel engine structure borne noise differences caused by component design changes of the engine assembly. A flexible multi-body dynamics model is used to develop loads on the engine due to combustion, piston-liner interactions, and interactions at the main bearings. These loads are applied to an engine finite element model for frequency response analysis. The frequency response analysis is then varied by changing the component design of the engine assembly. Surface velocities and modal participation factors are determined from the frequency response. The participation factors are then used in a modal acoustic transfer analysis to compute the sound power. Comparisons are made between assemblies and to experimental data.

In this paper, a brake damper is modeled with the finite element method to predict its response in a free-free impact modal test. A multi-layer representation of a brake shim is described which captures the dynamic characteristics of a damper, bonded to a brake shoe and lining. Calculations of damping values and natural frequencies are compared to impact modal test results over a wide temperature range. It was found that the finite element model accurately predicts the results from the experiment. A discussion is also given on how the model may be used to develop a material database and automation of the modeling process to analyze any layered brake damper.

This paper will outline the analytical procedure of designing automotive dash panels with laminated metal. A laminated dash is analyzed to determine its proper gauge to maintain the stiffness of the sheet metal original. A custom preprocessor is used to generate a finite element mesh of a laminated design. A static analysis determines the laminate displacement for some given worst case scenario. Displacements are determined for several loading conditions. The laminate skin thickness is then varied to achieve the same displacement as that of the original sheet metal design. A modal test is then simulated on the laminated dash to demonstrate its NVH characteristics. A natural frequency extraction is done to visualize the vibration profile of the part. Damping is seen with a frequency response calculation due to an impact load on the part. The frequency response clearly shows the reduced vibrations associated with the laminated dash.

In this report, two finite element models are presented which predict the vibration characteristics of metal/polymer/metal laminates. The first model uses an approximate elastic solution, while the second model uses a viscoelastic solution. A finite element preprocessor was created to implement both models. With this preprocessor, four complex geometries and a simple plate are investigated. Predictions are made for natural frequencies, damping values, and frequency responses. In addition, the predictions for the plate and one of the geometries is compared to experimental results. It is shown that the two models predict natural frequencies well, but bound experimental damping values. The conservative estimate of damping is given by the viscoelastic model. It is further shown that if the geometry of the component resembles a beam, that both models agree. Based on these observations, recommendations are made to exclusively use the viscoelastic model in design analysis.

In this report, a practical finite element design method is developed for metal/polymer/metal laminates. An analysis is presented which will predict the damping characteristics of laminated structures. Predictions of natural frequencies, loss factors, and frequency responses are compared to experimental data and closed form solutions. The analysis is then used to show a reduced vibration response with the laminated design as compared to a metal design. With the methods presented here, components may be designed which reduce vibrations, noise, and fatigue wear by means of a practical finite element approach. Vibration problems are avoided, allowing other specifications, such as weight or tooling concerns, to be used to size the component.