Search Results

Structure enhancement based on data monitored in a traditional side impact evaluation is primarily a trial and error exercise resulting in a large number of computer runs. This is because how the structure gets loaded and the degree of contribution of local structural components to resist the impact while absorbing energy during a side collision is not completely known. Developing real time complete load profiles on a body side during the time span of an impact is not an easy task and these loads cannot be calculated from that calculated at the barrier mounting plate. This paper highlights the load distribution, calculated by a procedure using computer aided engineering (CAE) tools, on a typical 2-door vehicle body side when struck by moving deformable barriers used in the insurance institute for highway safety (IIHS), EuroNCAP and LINCAP side impact evaluations.

Driven by a tight vehicle development schedule and unique performance and styling goals for the new Ford GT, a Ford-Lear team delivered a complete interior and electrical package in just 12 months. The team used new materials, processes and suppliers, and produced what may be the industry's first structural instrument panel.

This paper describes a new concept for a Ford GT instrument panel (IP) based on structural magnesium components, which resulted in what may be the industry's first structural IP (primary load path). Two US-patent applications are ongoing. Design criteria included cost, corrosion protection, crashworthiness assessments, noise vibration harshness (NVH) performance, and durability. Die casting requirements included feasibility for production, coating strategy and assembly constraints. The magnesium die-cast crosscar beam, radio box and console top help meet the vehicle weight target. The casting components use an AM60 alloy that has the necessary elongation properties required for crashworthiness. The resulting IP design has many unique features and the flexibility present in die-casting that would not be possible using conventional steel stampings and assembly techniques.

Ford GT 2005 vehicle was designed for performance, timing, cost, and styling to preserve Ford GT40 vintage look. In this vehicle program, many advanced manufacturing processes and light materials were deployed including aluminum and magnesium. This paper briefly explains one unique design concept for a Ford GT instrument panel comprised of a structural magnesium cross-car beam and other components, i.e. radio box and console top, which is believed to be the industry's first structural I/P from vehicle crash load and path perspectives. The magnesium I/P design criteria include magnesium casting properties, cost, corrosion protection, crashworthiness assessments, noise vibration harshness performance, and durability. Magnesium die casting requirements include high pressure die cast process with low casting porosity and sound quality, casting dimensional stability, corrosion protection and coating strategy, joining and assembly constraints.

The dynamics of vehicle front end crash are studied using the ADAMS dynamic simulation code. The analysis is carried out in three dimensions and can capture the behavior associated with an asymmetrical structure or impact mode. Subroutines which allow the modeling of structural crush and plastic hinge formation, contact forces and friction forces are discussed. The method is relatively inexpensive, but does require a good understanding of the problem on the part of the analyst. A discussion of the techniques that are used to model the structural system is given. The results of the analysis are compared with experimental data and the correlation is very encouraging.

Sudden tire deflation, or blow-out, is sometimes cited as the cause of a crash. Safety researchers have previously attempted to study the loss of vehicle control resulting from a blow-out with some success using computer simulation. However, the simplified models used in these studies did little to expose the true transient nature of the handling problem created by a blown tire. New developments in vehicle simulation technology have made possible the detailed analysis of transient vehicle behavior during and after a blow-out. This paper presents the results of an experimental blow-out study with a comparison to computer simulations. In the experiments, a vehicle was driven under steady state conditions and a blow-out was induced at the right rear tire. Various driver steering and braking inputs were attempted, and the vehicle response was recorded. These events were then simulated using EDVSM. A comparison between experimental and simulated results is presented.

According to accident analysis, submarining is responsible for most of the frontal car crash AIS 3+ abdominal injuries sustained by restrained occupants. Submarining is characterized by an initial position of the lap belt on the iliac spine. During the crash, the pelvis slips under the lap belt which loads the abdomen. The order of magnitude of the abdominal deflection rate was reported by Uriot to be approximately 4 m/s. In addition, the use of active restraint devices such as pretensioners in recent cars lead to the need for the investigation of Out-Of-Position injuries. OOP is defined by an initial position of the lap belt on the abdomen instead of the pelvis resulting in a direct loading of the abdomen during pretensioning and the crash. In that case, the penetration speed of the belt into the abdomen was reported by Trosseille to be approximately 8 to 12 m/s. The aim of this study was to characterize the response of the human abdomen in submarining and OOP.

This paper will provide an overview of the work progress of the advanced offset frontal crash protection group of IHRA. It resumes, including tables, the strategy of the group to cope with the assigned task. This is the commitment to achieve an harmonized frontal crash protection procedure taking into account the different world wide views in this field.

This paper describes the risk of injury to the rider in a crash using a statistical model based on real-world accident data. We analyzed the road traffic accidents data in Los Angeles and Hanover. Logistic regression modeling technique was used to clarify the relationship among probabilities of minor, serious, fatal injury risk to the rider, and the influence of risk factors in accidents involving opposing vehicle contact point, motorcycle contact point, opposing vehicle speed, motorcycle speed, relative heading angle of impact, and helmet use. The odds ratio, which was adjusted for risk factors simultaneously, was estimated by using the developed technique, and was compared with the effects of risk factors individually. The results showed that there was a statistically significant relationship between minor and serious injuries and opposing vehicle speed, motorcycle speed and opposing vehicle contact point.

Today’s automotive world has moved towards an age where safety of a vehicle is given the topmost priority. Many stringent crash norms and testing methodology has been defined in order to evaluate the safety of a vehicle prior to its launch in a particular market. If the vehicle fails to meet any of these criteria then it is debarred from that particular market. With such stringent norms and regulations in place it becomes quite important on the engineer’s part to define the structural requirements and protect the space to meet the same. If the concept level platform definition is done properly it becomes very easy to achieve the crash targets with less cost and weight impact.

This paper describes the development of a new sled system that can address many safety-related issues pertaining to the racing industry. The system was designed to re-create acceleration and velocity levels similar to levels evident in race car crashes. The sled utilizes equipment typically used in passenger car crash research with the primary change to a specially designed lightweight carriage. This paper will overview the system and the types of crash events that can be simulated. Readers of this paper will gain a much broader understanding of accelerator sled testing and the issues related to the simulation of high speed crashes using physical testing.

This paper presents a 2D model for frontal vehicle-to-vehicle crashes that can be used for fleet modeling. It presents the derivational details and a preliminary assessment of the model. The model is based on rigid-body collision principles, enhanced adequately to represent energy dissipation and lateral engagement that plays a significant role in oblique frontal vehicle-to-vehicle crashes. The model employs the restitution and the apparent friction in order to represent dissipation and engagement respectively. It employs the impulse ellipse to identify the physical character of the crash, based on the principal directions of impulse. The enhancement of the rigid body collision model with restitution and apparent friction is based on collision simulations that use very simple finite element vehicle representations. The dependence of the restitution and the apparent friction on the incidence angle, the frontal offset, and the mass ratio, as predicted by the 2D model, has been presented.

A great deal of data is available concerning accident simulation tests with test dummies or cadavers but in comparison there is very little material on tests involving living volunteers. This paper describes crash tests and sled tests with human test persons and Hybrid II dummies. To obtain a realistic accident simulation the tests were run with standard Audi 80 vehicles fitted with the standard seat belt systems. The results clearly demonstrate that none of the test persons sustain any kind of physical injury at a precisely defined level of accident severity (vehicle-to-vehicle crash at a collision speed of approx. 30 mph). In some cases considerable differences are revealed between the loadings imposed on the dummies and the human test persons.

A 50th percentile male pelvis finite element model was designed for impact simulation. Shell elements represented the pelvic bone, which geometry was taken into account. Non linear viscous springs accounted for soft tissues connecting skin to bone structure, and body segments inertia around the pelvis were represented using rigid bodies. Geometric and mechanical characteristics were taken either from litterature or by identification to in house experimental results. Three dimensional movements were reproduced by the model for static lateral loading and dynamic lateral impact simulation at two different velocities, 3.5 and 6.5 m/s, with a good agreement with experimental results. This model takes into account pelvic bone geometry, allowing an appreciation of its deformation and therefore injury risk.

In statistical modeling, cross-validation refers to the practice of fitting a model with part of the available data, and then using predictions of the unused data to test and improve the fitted model. In accident reconstruction, cross-validation is possible when two different measurements can be used to estimate the same accident feature, such as when measured skidmark length and pedestrian throw distance each provide an estimate of impact speed. In this case a Bayesian cross-validation can be carried out by (1) using one measurement and Bayes theorem to compute a posterior distribution for the impact speed, (2) using this posterior distribution to compute a predictive distribution for the second measurement, and then (3) comparing the actual second measurement to this predictive distribution. An actual measurement falling in an extreme tail of the predictive distribution suggests a weakness in the assumptions governing the reconstruction.

The injury-reducing functions of crash padding are discussed as they relate to head impact. The bony structure of the cranial vault (above eyebrows) is strong under localized impact compared with the face. Padding used to protect the cranial vault from impact has the primary function of absorbing energy to reduce the possibility of brain damage. On the other hand, padding for facial protection has the primary function of providing uniform load distribution on the face. The pad understructure then supplies the needed energy absorbing capacity. Test procedures to measure both energy absorption and load distribution are described, and evaluation criteria are shown. Other factors that affect padding, such as temperature and cover stock material, are discussed.

A test fixture for use on the Hyge Sled was fabricated to NHTSA specifications, matching the fixture used at Heidelberg University to measure forces on cadavers in side impact configurations. Tests were conducted at 16, 22, 24, and 32 km/h to simulate both the APR cadaver drop tests and Heidelberg sled tests. Comparisons to the cadaver data were made with the Ford Side Impact Body Block and the APR and SID dummies. Test results are shown and discussed.

Biomechanical data on the response of the face to localized and distributed loads are analyzed to provide performance goals for a biomechanically realistic face. Previously proposed facial injury assessment techniques and dummy modifications are reviewed with emphasis on their biomechanical realism. A modification to the Hybrid III dummy, called the GM Hybrid III Deformable Face, is described. The modification produces biomechanically realistic frontal impact response for both localized and distributed facial loads and provides for contact force determination using conventional Hybrid III instrumentation. The modification retains the anthropometric and inertial properties and the forehead impact response of the standard Hybrid III head.

Choosing the correct thermoplastic for an instrument panel application requires a thorough understanding of the environmental and performance conditions. In the case of a high speed event, such as an airbag deployment or a knee bolster intrusion, standard static tensile properties may not adequately define the material performance. The engineer needs to understand the materials sensitivity to high strain rate extremes. The subject of this paper is the enhancement of part performance through the testing and knowledge of material performance over a range of strain rates.

Newer automobiles have complex dynamic and stability controls due to regulations, competition, and safety concerns. More systems require testing at the subcomponent level to ensure proper operation in the final vehicle assembly. Many of the stability and navigation features originally designed for aircraft components are now being incorporated into automobiles. Certain types of motion test simulators were originally designed for testing aircraft sensors as: gyroscopes, inertial navigation systems (INS), inertial measurement units (IMU), and attitude heading and reference systems (AHARS) This same type of equipment is now used for automotive testing as: airbag fuse sensors, anti-skid sensors, rollover sensors, vehicle stabilization systems, active suspension sensors, and navigation systems.