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In this paper, we present an experimental and analytic procedure for determining the effective leak and vent areas of a full size airbag. Three different bag materials were tested and analyzed: 420 D (72 X 46), 420 D (49 X 49), and 840 D (32 X 32). An airbag model in CAL3D was used to inversely compute the effective leak area based on experimental data. Regression analysis was then performed to find the best fit of mathematical models for estimating effective leak areas as a function of pressure. Following a similar procedure, the effective vent area was also analyzed. Data are presented for a passenger bag and a driver bag. These results are useful for occupant dynamics simulations.

The University of Virginia is investigating the use of a magnetohydrodynamic (MHD) angular rate sensor to measure head angular acceleration in impact testing. Output from the sensor, which measures angular velocity, must be differentiated to produce angular acceleration. As a precursor to their use in actual testing, a torsional pendulum was developed to analyze an MHD sensor's effectiveness in operating under impact conditions. Differentiated and digitally filtered sensor data provided a good match with the vibratory response of the pendulum for various magnitudes of angular acceleration. Subsequent head drop tests verified that MHD sensors are suitable for measuring head angular acceleration in impact testing.

The introduction of the dynamic FMVSS 214 crash test requirement has prompted the need for an economical test method for the development of side impact occupant protection devices. Full scale side impact crash testing is too costly for the development testing of occupant protection components. This paper describes a unique test method for side impact sled testing which utilizes a standard 12-inch HYGE type sled facility. It has been demonstrated, with several hundred tests, to provide high repeatability and good correlation with full vehicle side impact crash tests. An overview of the device and details on how it is used is provided. Typical data correlation between sled tests and crash tests is shown for FMVSS 214(dynamic) testing. EEVC side impact and lateral crash tests into a rigid pole have also been correlated with this device and will be made available upon request.

Side impact crashworthiness development presents a unique challenge to auto safety engineers. One fundamental issue is how to evaluate side impact air bags with a component test that realistically simulates the kinematics of a full scale side impact crash test. This paper presents a test methodology that can be used to evaluate side impact air bags utilizing an accelerator-type sled typically used for frontal impact simulation. The approach uses a “two carriage” system, whereas the struck door and vehicle acceleration profiles are simulated. These acceleration responses are matched through a series of sled variables including thrust column setting, metering pin shape and an on-board pneumatic cylinder which controls the relative response between the two carriages.

Significant dashpanel intrusion is seen in some cars after severe frontal crashes at high speeds or after offset impact with rigid barrier or both. This intrusion may also result in severe steering column displacements and rotation. Knowledge of both responses is critical for designing an efficient vehicle front end that will respond well in crash. The intrusion has an effect on deciding the car front end length, while the column movements have an effect on the driver dummy's response. For reasons of developing efficiency and safety in vehicles and due to lack of published research, studies were conducted to understand the nature of the intrusion phenomenon as well as the mechanics of the steering column movement in the presence of intrusion. This paper describes an experimental investigation on intrusion and steering column movements.

In this paper are presented some results about the dynamic of the wiper systems, vibratory phenomena and some influences of the friction, the weight and the clearances.

Side impact crashworthiness presents a complex problem due to the dynamic interaction between the occupant and the intruding vehicle side structure. As there is a direct impact between the occupant, and the door and B-post trim, small variations in the vehicle structural behaviour can have a significant effect on the dummy response and injury levels. Significant variability in dummy response between crash tests causes problems when evaluating the vehicle side structure and development of side impact restraint systems. A programme of research tests has been conducted at the Motor Industry Research Association (MIRA) using the MIRA - Side Impact System (M-SIS) technique to evaluate the dynamic response of side impact dummies in actual side impact environments. With the implementation of the European side impact legislation in 1998 the effects of variations in dummy location and velocity profile need to be understood.

A computer program package named “BRAIN” has been developed to simulate the kinematics and the performance of rolling bearings under various running conditions. The calculation time necessary for running BRAIN software on a PC is very short. Various outputs can be obtained using BRAIN such as running torque, roller skew angle, roller slippage, and PV values. Several experiments have been conducted to confirm the validity of BRAIN. The running torque of a four point contact ball bearing and that of a tapered roller bearing were measured. In addition, the skew of the roller in a needle bearing was measured. These experimental results were compared with the calculation results. The experiments and the calculations showed good agreement.

The backlite molding squeak noise is caused by the stick-slip type of friction between the window molding and the body panel. To predict if the molding would squeak a finite element analysis technique which uses the nonlinear explicit code LS-DYNA3D has been developed. The three dimensional finite element simulation technique is based on the threshold displacement velocity spectrum and the relative movement of the window glass with respect to the body panel. Comparisons between FEA analysis and tests are also presented in this paper.

Current work develops and presents a clear methodology for all stages of adaptive structure design using a commercially available FE program. A procedure for replacing the induced strain actuation of the piezo-elements by mechanical forces is developed and validated numerically using the ANSYSR coupled field piezoelectric 3-D solid elements, as well as experimentally. The use of reduced FE analysis as a spatial discretization tool for controller design is addressed and shown to be advantageous in many cases. Balanced order reduction schemes are applied to the discrete structural model in state space in order to ensure controllability and observability, as well as to maintain a low number of states for the controller design and implementation. Linear quadratic (LQ) and H∞ controller designs are presented and implemented using computer simulations of the controlled structure.

A rollover accident of a bus or a coach is particularly dangerous. Many different aspects must be taken into account in order to reduce occupant injury. The most important criteria are structural resistance, occupant restraint systems and seat anchorages. Spain has complied with ECE R-66 since 1992. For this reason, bus and coach manufacturers have had to improve the structural resistance. IDIADA has developed a simulation procedure using finite element analysis for studying the structural resistance during a rollover. Experimental tests of a representative section of the structure and bending tests of the different beams are conducted in order to evaluate the analysis simulation. Due to the close correlation between the simulation and the real test, IDIADA is currently capable of fully developing structures which comply with ECE R-66 without actually performing a rollover test.

This paper describes a method to design an improved structure for frontal crash. A finite element model has been developed using nonlinear finite element crash code V-CRUSH. Numerical results were experimentally verified using static and dynamic tests. The main objective of the study was to design the structure to dissipate more energy and to reduce intrusion. The design also considered the mean load capacity, mode of collapse and the maximum strength.

The application of aluminum Body-In-White has several technical barriers in press forming, joining, and chemical conversion treatment processes. Among them, the optimization of joining processes with which structural stiffness and durability will be assured might have the key role for the success of aluminum applications to BIW. In this study, stiffness strength and fatigue strength of BIW joints with aluminum sheets were evaluated as a function of joining methods, such as resistance spot welding and weld bonding, via both experimental and analytical routes(FEM). For the evaluation, single-lap joint and T-shaped joint were made, with each joining method, as variation of pitch, sheet thickness and even materials - steel sheets. Based on the experimental and FEM analysis results, the optimum joining method for the aluminum BIW which is suitable for weight saving and has equivalent stiffness and strength to steel is suggested.

Automotive Body Engineering has been one of the most important disciplines in automotive engineering during the past 100 years. A brief historical review will take place highlighting the major automotive trends which have challenged the expertise of the body engineer, including the major contributions of the body engineering profession that brought comfort, convenience and safety to the modern automobile. Finally, the current challenges to body engineering will be discussed. These include the need to drastically reduce program leadtime and control both engineering and product costs. The two areas in which the above stated challenges can be met are as follows: First, the technologies and materials being applied to new vehicle bodies will be discussed. Highlighted, will be the effect upon cost and leadtime reduction. Secondly, the component design process will no longer start with a clean sheet for a new design.

A study of frontal collisions using the NASS data base showed that there were four times as many arm injuries to belt restrained drivers who had an air bag deploy than for the drivers who were simply belted. By far, the distal forearm/hand was the most commonly injured region. Hard copy review identified two modes of arm injury related to the deploying air bag: 1) The arm is directly contacted by the air bag module and/or flap cover, and 2) The arm is flung away and contacts an interior car surface. Based on the field studies, a mechanical device called the Research Arm Injury Device (RAID) was fabricated to assess the aggressivity of air bags from different manufacturers. Results from static air bag deployment tests with the RAID suggested that the RAID was able to clearly distinguish between the aggressive and non-aggressive air bags. Maximum moments ranging between 100 Nm and 650 Nm, and hand fling velocity ranging between 30 and 120 km/h were measured on the RAID in these tests.

Three-dimensional simulation models of a driver's right upper extremity interacting with a deploying airbag have been set up and run with the Articulated Total Body program. The goal of this study is to examine the significance of various occupant and airbag parameters during deployment, such as grip strength, upper extremity position, shoulder compliance, flap position, flap aggressivity, and deployment speed. Given a range of 250 N to 650 N, the grip strength did not affect the resultant loads. Also, the contact force and torque at the e.g. of the forearm are not sensitive to shoulder joint compliance. The flap aggressivity and the position of the airbag module relative to the upper extremity are most important in affecting the interaction. This study is used to justify cadaveric experiments involving disarticulated upper extremities.

This paper reports recent developments made at Pininfarina in the aeroacoustic field with the aim of reducing the background noise in the test section of its full scale wind tunnel as well as for improving the measuring techniques which are used during the acoustic development of new cars. The first part of the paper describes the changes made to the wind tunnel drive-line, i.e. new motor, new low-noise fan and new acoustic treatments. The new background noise levels are reported and compared with the old values, already published in ref. (2). The second part describes the three acoustic techniques (acoustic intensimetry, acoustic holography and acoustic mirror) which have been developed or improved in the meantime, to measure the exterior noise of new cars from the first stage of their design. Examples of results of these measurements are reported as well as an indication of the capabilities and limitations of each technique.

In order to assess the head and neck kinetics of human subjects exposed to low-speed rear-end impacts, a method for measuring the magnitude and line of action of the force between the head and the head restraint was required. In addition to being accurate and repeatable, the design was required to maintain original seat back and head restraint geometry, mass, stiffness, and height adjustment. This paper presents a design using strain gauges applied to the head restraint tubes, upper seat back, and custom replacements for brackets attaching the head restraint to the seat back. The background theory and free-body analysis, the analog math circuitry, and a dynamic calibration procedure are presented. Overall force magnitude and line-of-action errors are quantified, and a sample output from a human subject undergoing a rear-end collision with a speed change of 8 km/h is presented.

A time cost effective methodology has been developed for the prediction of the A-pillar vortex formation and the side and the rear window flow separation for the purpose of wind noise assessment. This methodology combines a simplified Computational Fluid Dynamics (CFD) model and wind tunnel test data by CFD post-processing tools. The solution of the simplified CFD model provides background data for the whole flow field, but it lacks detail features such as mirror, sealing groove and glass in-set, which are locally important but difficult to mesh and require a very fine mesh resolution. The wind tunnel test data was taken in the specific areas of interest at the A-pillar, side window, rear window area, and roof from a real automotive. Then the wind tunnel test data was superposed upon the simplified CFD model to correct the numerical error due to geometry simplification and insufficient mesh resolution.

Objective of the present work is the development and validation of a computational methodology for the prediction of flow-induced noise around a vehicle. The technique employed makes use of the Lighthill's acoustic analogy revised for low Mach number flows and consists of two steps: prediction of noise sources over the body surface by means of a suitable Computational Fluid Dynamics (CFD) technique and subsequent prediction of the radiated noise by solving the Ffowks-Williams Hawkings equation. For testing the methodology flows around a cylinder and a test shape, generating the type of flows occuring around the A-pillar of a car, have been employed. Results are compared with experimental data. The paper demonstrates the feasibility of computational prediction of aerodynamic noise even for turbulent high Reynolds number flows.