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A building-block method, often used for simulating automotive systems, is described in this paper for simulating a driveline system. In the method, a driveline supplier's design responsible components are modeled with explicit FE models. Model accuracy is verified by testing and correlating the components in a free-free condition. Non-design responsible components are modeled using lumped parameters and/or modal models. These components and the validated design responsible components are integrated into a system model and connected using simple lumped parameter connections. Correlation at the system level is performed by making adjustments to the connection parameters and to the parameters of the non-design responsible components. The resulting system model has been used to accurately predict operating responses in a driveline system.

In the design of an automobile, an important consideration is to minimize the amount of “boom” noise that the vehicle occupant could experience. Vehicles equipped with four cylinder engines can experience powertrain boom noise in the 40 to 200 Hz frequency range. Boom noise can also be generated by road input, and it is just as annoying. In this paper, a CAE methodology for predicting boom noise is demonstrated for a vehicle in the early design stage in which only 3-D CAD geometry exists. From the CAD geometry, a detailed finite element (FE) model is constructed. This FE model is then coupled with an acoustic model of the interior cavity. The coupled structural-acoustic model is used to predict acoustic response due to powertrain inputs. As a part of the detailed design process, various design modifications were considered and implemented in the vehicle system model. Many of these modifications proved successful at reducing the boom levels in the vehicle.

Numerous authors have previously published on the effects of system dynamics on gear noise in automotive applications [1,2]. It is now widely understood that the torsional compliances and inertias of propeller shafts and pinion gear sets are a controlling factor in final drive gear noise for rear wheel drive vehicles. Considerable progress has been achieved in using finite element simulations of the driveline dynamics to improve the system in regards to gear noise. However very few published results are available showing the application of dynamic simulation methods to automatic transmissions which require considerations of the complications due to epicyclical gear sets. This paper documents the successful application of finite element dynamics modeling methods to the prediction of gear noise from the gear set in a rear wheel drive automatic transmission. The model was used to investigate the effects of component inertias, stiffnesses, and resonances.

The widespread use of finite element models in assessing system dynamics for NVH evaluation has led to a recognition of the need for improved procedures for correlating models to experimental results. With the greater occurrence of finite element models preceding the first prototype hardware, it is now practical to employ pre-test analysis procedures to guide the execution of the tests in the correlation process. This aids in the efficiency of the test process, ensuring that the test article is neither under nor over instrumented. The test-analysis model (TAM) that results from the pre-test simulation provides a means to compare the test and model both during the test and during the model updating process. This paper discusses procedures for pre-test analyses and demonstrates their application to the correlation of a transmission side cover.

Body acoustic sensitivity, defined as the interior sound pressure due to a unit force applied to the body, has a major influence on the powertrain and road noise of a vehicle. Body acoustic sensitivity can be predicted analytically in the design stage of a vehicle program using structural-acoustic analysis. Recognition and correction of potential problems at this stage is a cost effective approach to improving a vehicle’s NVH performance. This paper describes the structural-acoustic analysis procedure. Techniques for developing the structural and acoustic models and coupling them to form a structural-acoustic system model are discussed. An application of the procedure for prediction and improvement of body acoustic sensitivity is given for a passenger vehicle.

An overview of the analytical noise, vibration, and harshness (NVH) simulations performed to support the design and development of the Nissan Quest mini-van is presented. The use of analytical techniques on this project was unique in that analytical results were used to drive the pre-prototype design efforts, as well as to assist in the prototype development phase. Analytical models were developed, and simulations performed, prior to the release of prototype drawings. The simulation results identified necessary changes which were incorporated into the design. Once prototype vehicles became available, analytical simulations and development testing were used hand-in-hand to minimize development time as well as to optimize the cost, weight, and performance of NVH countermeasures. The extensive use of analytical simulations in the design and development process was critical in achieving the aggressive NVH performance objectives set for the vehicle.