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Engineers doing squeak and rattle testing of instrument panels (IP's) have successfully used large electrodynamic vibration systems to identify sources of squeaks and rattles (S&R's). Their successes led to demands to test more IP's, i.e., to increase throughput of IP's to reflect the many design, material, and/or manufacturing process changes that occur, and to do so at any stage of the development, production, or QA process. What is needed is a radically different and portable way to find S&R's in a fraction of the time and at lower capital cost without compromising S&R detection results.

The Kinematic Analysis Methods Computer Program that has been used by Ford Motor Co. to evaluate mechanisms for the past four years has been modified to generate performance curves for windshield wiper linkages directly using a Calcomp Plotter. Problems such as stalling, “jerky” operation, and excessive phase lag between wipers can be detected early in the design stages by careful evaluation of the curves.

Several emission performance tests like Butane Working Capacity (BWC), Cycle Life, and ORVR load tests are required for the certification of a vehicle; these tests are both expensive and time consuming. This paper presents a test process based upon analytical simulation of BWC of an automotive carbon canister in order to greatly reduce the cost incurred in physical tests. The computational model for the fixed-bed system of a carbon canister is based upon non-equilibrium, non-Isothermal, and non-adiabatic algorithm to simulate the real life loading/purging of hydrocarbon vapors from this device.

This paper presents the extended Kalman filter-based sideslip angle estimator design using a nonlinear 5DoF single-track vehicle dynamics model with stochastic modeling of tire forces. Lumped front and rear tire forces have been modeled as first-order random walk state variables. The proposed estimator is primarily designed for vehicle sideslip angle estimation; however it can also be used for estimation of tire forces and cornering stiffness. This estimator design does not rely on linearization of the tire force characteristics, it is robust against the variations of the tire parameters, and does not require the information on coefficient of friction. The estimator performance has been first analyzed by means of computer simulations using the 10DoF two-track vehicle dynamics model and underlying magic formula tire model, and then experimentally validated by using data sets recorded on a test vehicle.

Panel acoustic contribution analysis (PACA) is an advanced engineering tool to improve the NVH quality of vehicles. Using PACA areas of vehicle body panels are categorized according to their contribution to the total sound. Positive contribution areas increase the sound level as vibration amplitude increases, negative contribution areas decrease the sound level as vibration amplitude increases, and neutral areas have no significant effect on the sound level. This knowledge is important to guide vehicle NVH refinement. This paper presents the technical approach of PACA and the results of an experiment used to validate the PACA techniques. Vehicle application results to improve NVH quality and reduce weight are also included.

The dynamic characteristics of a vehicle are an important part of the driver's experience. Ford Motor Company is actively pursuing a leadership role in this arena. To achieve this goal, all the necessary information to complete the vehicle dynamics picture of a vehicle must be gathered in an efficient and well-organized manner. A process was developed to fingerprint a vehicle so that this information could drive vehicle tuning, new Computer Aided Engineering (CAE) models, correlate existing CAE models, support problem resolution and conduct target setting. This paper will discuss a Vehicle Dynamics Fingerprint Process in detail and explain the steps involved.

As evidenced by extensive research work done under contract to the government recently, it is clear that there is a strong federal interest in the limit handling performance of automobiles. Should these efforts come to fruition, manufacturers may be faced with the difficult task of designing vehicles to meet independent and, at times, conflicting handling requirements. Not only must vehicles continue to meet with subjective approval of handling behavior by customers, but they may also be required to meet objective limit performance criteria. Problems arise in that vehicles designed to achieve high levels of limit performance are not guaranteed to be more controllable or subjectively acceptable to customers. This paper shows ways design changes may cause conflicting influences on several measures of performance.

The feasibility of using experimentally determined flow fields at intake valve closing, IVC, as initial conditions for computing the in-cylinder flow dynamics during the compression stroke is demonstrated by means of a computer simulation of the overall approach. A commercial CFD code, STAR-CD, was used for this purpose. The study involved two steps. First, in order to establish a basis for comparison, the in-cylinder flow field throughout the intake and compression strokes, from intake valve opening, IVO, to top dead center, TDC, was computed for a simple engine geometry. Second, experimental initial conditions were simulated by randomly selecting and perturbing a set of velocity vectors from the computed flow field at IVC.

Suspension roll centers are currently used to establish vehicle handling characteristics such as under-steer and feel. Roll centers were developed to help understand vehicle designs on paper. Computers and mechanism simulation software allows vehicle models to be built and analyzed. Analyzing forces and moments may be a better technique as opposed to modeling suspension roll centers. A proposed method is to look directly at forces applied to the vehicle body and moments resulting from the applied forces. This force-moment method includes the effects of load transfer and tread change, which are not accounted for by geometric roll centers.

Present models and methods for simulations of sheet metal forming processes are reviewed in this paper. Because of rapid progress of computer hardware, complex computations, formerly impossible to perform due to high computational cost, are now feasible. Therefore, more realistic and computational intensive models are suggested for finite elements, materials, and frictional forces. Also, simulation methods suitable for sheet metal forming processes are recommended. Four numerical examples at the end of the paper are presented to support the recommendations.

This paper identifies and analyzes steady-state and transient tire properties affecting vehicle directional response characteristics. The study is limited to the relationship between lateral force and slip angle. It shows fundamental differences between steady-state and transient properties. Tire transient properties are described by a force-slip angle loop with cornering stiffness and dynamic lateral force offset as parameters. Cornering stiffness is presented as a variable that changes with speed and steer rate. An interrelationship between cornering stiffness and dynamic lateral force offset resulting from the time lag between lateral force and slip angle is shown. Ramp steer techniques for measuring transient tire properties on a road trailer and on an external drum machine are described. A need for transient tire data for computer simulations of vehicle transient steer maneuvers is shown.

Traction drive continuously variable transmissions (TCVTs) are under active investigation by a number of OEMs and suppliers. Along with advances in control systems and metallurgy, improved traction fluids will be key to successful implementation of this technology. Traction fluids will need to function over a wide range of temperatures and contact pressures. Contact pressures may reach as high as 4 GPa, while temperatures may range from about - 40 C to about 140 C. It is widely recognized that low temperature fluidity at start-up is an issue, since fluids which give high traction coefficients and adequate viscosity under normal operating temperatures generally exhibit high viscosity at low temperatures. However, fe published data are available on traction behavior at temperatures below about 20 C and at contact pressures above about 2 GPa.

An experiment has been conducted to study the effect of vehicle alignment, tire construction and operational conditions on tire treadwear. The Taguchi approach was used to compose the experimental design and to analyze the data. The treadwear testing was conducted on the indoor test machine; this test duplicates the treadwear pattern observed during road test. The responses of interest were total wear, irregular wear patterns, and diagonal wear. The study quantified the relative importance of different factors to treadwear and also the degree of wear irregularity.

A tire on a vehicle is not a separate entity to be considered only in itself. The tire is part of the entire vehicle and this entire vehicle must be considered in making tire selections. Just as important are the components of a tire and the various parameters to be considered in tire design. Care must be taken that any attempt to optimize a single parameter does not jeopardize the overall quality.

Thermophysical properties of materials used in the design of automotive interiors are needed for computer simulation of climate conditions inside the vehicle. These properties are required for assessment of the vehicle occupants' thermal sensation as they come in contact with the vehicle interior components, such as steering wheels, arm rests, instruments panel and seats. This paper presents the results of an investigation into the thermophysical properties of materials which are required for solving the non-linear Fourier equations with any boundary conditions and taking into account materials' specific heat, volume density, thermal conductivity, and thermal optical properties (spectral and total emissivity and absorptivity). The model and results of the computer simulation will be published in a separate paper.

Structural composite materials offer automotive engineers an excellent opportunity to produce automotive components that achieve weight savings, improved NVH (noise, vibration, and harshness) and inherent corrosion protection. Components designed and fabricated from automotive structural composite systems have demonstrated these capabilities during laboratory and in-service durability testing. Components evaluated to date have been employed in areas of the vehicle not likely to encounter high temperatures and with controlled exposure to harsh environments. More extensive use of structural composites will demand that future structural components be located in areas where they will likely encounter a wider range of temperature extremes as well as increased exposure to various environmental and automotive fluids.

The Vehicle Handling Model (VHM) is representative of a new type of vehicle dynamics programs which can be easily used on a personal computer by vehicle development engineers. It consists of a simulation kernel which solves the vehicle equations of motion and a hypertext GUI which controls the model data input, execution, and post processing. The vehicle model has 5 DOF, including the vehicle lateral, vertical, yaw, pitch, and roll motions. The simulation also includes suspension compliance, a simple non-linear tire model, a wind gust model and a human driver model to provide realistic vehicle and steering inputs. The simulation program was generated by AUTOSIM which uses a high level description of the system to generate Fortran source code. The GUI allows an engineer to setup the model, run the analysis, and display the results with just a few clicks of the mouse.

A simple CAE method of predicting the performance of a component during sine testing has been developed and applied to the practical case of an automotive component. The slow frequency sweep rate during a test is represented as a sequence of steady state conditions. Direct frequency response analysis at the limited number of frequencies is conducted and results used as a basis for prediction of fatigue damage using the Palmgren-Miner rule. The total damage during the test is calculated by linear summation of the damage during each frequency interval. This technique is completely general and can be applied even if there are multiple inputs to the component. A simple extension enables application to engine testing and other cases where excitation may be expressed as a Fourier series expansion of periodic excitations.

The Ford Motor Company Advanced Engineering Center contains 100,000 square feet of sound and vibration laboratories, induding full vehicle chassis dynamometers, powertrain dynamometers, and sound quality evaluation chambers. The facility houses the first U.S. All-Wheel-Drive NVH Chassis Dynamometer (4 independent motor drive), the first U.S. All-Wheel-Drive NVH Powertrain Dynamometer (4 independent motor drive) and other unique elements, such as innovative wedge construction for the acoustic chambers.

Seat Effective Amplitude Transmissibility (SEAT) values can be obtained from direct measurements at seat track and top or estimated from transmissibility data and seat track input. Vertical transmissibility was measured for sixteen seats and six subjects on the Ford Vehicle Vibration Simulator, and these 96 functions used to estimate the seat top response for rough road input. SEAT values were calculated, and good correlation to values computed from direct seat top measurements obtained (R2 of 0.86). Averaging transmissibilities and direct seat measurements over the 6 subjects to obtain correlations for the 16 seats improved R2 to 0.94, validating this approach.