Search Results

Leveraging the power of math models in driveline development requires a deeper appreciation for the multi-disciplinary and wide ranging physical system dynamic behaviors involved. The models have to handle operational demands of multi-configurable systems brought on by hybrid powertrains in general and automatic/manual transmissions, specifically. As a first requirement, system models have to be broken down into physically compatible subsystems, not as the hardware looks but, as the interface dynamics suggest. Transient dynamics, brought on by subsystem power flow disturbances and attendant noise generation and controls challenges must be addressed up front. This paper delves into the levels of detail automotive propulsion system models must possess not only to offer insight to the inner dynamics of a product but, also, make such formulation compatible with modern control system techniques.

This paper outlines the methodology to 1) determine what leak rate specification is appropriate for a given automotive component, 2) arrive at the gas-based leak test method that is best suited for the situation, and 3) perform the requisite calculations to confirm the choice of test method. Also provided are summary tables (based upon actual industry experience) relating component type, typical leak rate specification, test method used, and (production) sensitivity range of the method utilized.

There have been a number of papers written about the dynamic effects of low speed front to rear impacts between motor vehicles during the last several years. This has been an important issue in the field of accident analysis and reconstruction because of the frequency with which the accidents occur and the costs of injuries allegedly associated with them. Several of these papers have discussed the importance of the coefficient of restitution in the accelerations and speed changes that the vehicles undergo in such impacts. These discussions often include data showing the measured restitution for impacts involving various bumper types and closing speeds. However, in most of these studies, the impacts are controlled so that direct bumper to bumper impacts occur. This paper will present the results of several rear impact tests with non-standard impact configurations.

This paper examines the effect that test barriers currently used for frontal and side impact tests have had on collision compatibility between different-sized vehicles. The peak force levels generated by the vehicles’ front structures are one of the significant factors in determining vehicle compatibility. It is shown from principles of mechanics that the use of fixed barriers as a test device may lead to higher force levels for front ends of larger vehicles and thus increase the incompatibility between large and small vehicles. Review of data from various sources supports this conclusion that the peak force levels of vehicles’ front ends have increased in proportion to their test mass. Available crash data is also examined for a relationship between NCAP ratings of vehicles and the likelihood of serious and fatal injuries to occupants of those vehicles. These data do not show any relationship between the frontal NCAP ratings of vehicles and their rate of serious or fatal injuries.

The evasive capabilities of motorcycles and riders are often an important consideration when analyzing a motorcycle crash. Specifically, the longitudinal distance or time required for a motorcycle to move laterally some distance can be of critical interest. Previous publications on this topic have not all measured the same thing and have often included limited test data so their results can be difficult to compare or apply. In addition to reviewing some of the literature on the topic, this paper will present the results of a series of tests conducted with four riders on four motorcycles swerving 2 m (6.5 ft) to their left after passing through a gate at speeds of 40 to 88 km/h (25 to 55 mi/h). The most recent testing involved relatively skilled riders who had faster transitions and greater willingness to lean than the “average” rider generally described in the literature.

Computer Aided Engineering (CAE) plays an important role in the product development. Now a days major decisions like concept selection and design sign off are taken based on CAE. All the Original Equipment Manufacturers (OEMs) are putting consistent efforts to improve accuracy of the CAE results. In recent years confidence on CAE prediction has been increased mainly because of good correlation of CAE predictions with the test results. Defining proper correlation criteria and using a systematic approach helps significantly in building the overall confidence level for predictions given by CAE simulations. Representation of manufacturing effects on material properties and material failure in the simulation is still a big challenge for achieving a good CAE correlation. This paper describes side impact test vs CAE correlation. The important parameters affecting the CAE correlation were discussed.

One of the critical items for a good matching between CAE predictions and actual hardware data is the input parameters variability. A vehicle component, for example, after manufactured shows imperfections that can be translated in small variation on nominal values of geometries and material properties. These variations of physical and geometrical parameters, fundamental data to construct a numerical model, cause impact on dynamic response. Analysis of this impact requires the use of appropriate stochastic methods for structural problems, mainly in correlation analysis between numerical and experimental results. This work assesses Body-in-White Point Mobility and Vibration Transfer Function correlation between CAE predictions and actual vehicle performance, including production variation and test uncertainty data.

Based on BF6M1015CP electronic diesel engine (it is a supercharged, water-cooled engine. It has 6 cylinders and it is for heavy-duty vehicle) and HD4070PR electronic automatic transmission (it covers heavy-duty applications requiring high input horsepower and torque. It contains torque converter module, control module, planetary module and output module. It has 7 forward gears and a power-take -off (PTO) and a retarder), the paper analyzes the shift system of an electronic automatic transmission and sets up a mathematic module of the shifting process. With the model the shifting process is analyzed and the model can be used directly in shifting process control, and the rules of shifting process can be derived. To improve the shift quality, in the paper the different control methods in different phases are used and reviewed that Include the open-loop control, fixed ramp rate, and closed-loop control.

Bollard systems are often used to separate errant vehicular travel from pedestrian and bicycle traffic. Various bollard systems are available for this function, including different installations, functional design, and protection levels. The security-type bollards are used primarily at high-security locations (e.g., military bases and other government installations) around the world. While a protocol exists for testing and rating security bollards, no such protocol or recommended practice or standard currently exists for non-security-type bollards. Non-security, concrete-filled bollards are commonly used by cities/states, local government organizations, and the private sector as “perceived impediments to access” to protect against slow-moving vehicles. There is a general lack of publically available test data to evaluate these non-security bollards and conventional installation procedures.

Subsequent to the presentation of papers regarding head and neck restraints at the 2002 and 2004 SAE Motor Sports Engineering Conference & Expositions, additional testing of both then-existing and newer designs has been conducted at multiple test facilities. This paper consolidates the results of those tests with the results of previous tests, published and unpublished. Previously published testing from those Conferences (Melvin, et al. 2002; Baker 2002; Melvin et al. 2004) evaluated four designs: the Hutchens, D-Cel, HANS® and Isaac® products. All testing employed a 50th percentile male dummy restrained by a six-point harness and a 30 degree offset, 35-mph (56 kph) velocity change producing a nominal 50G deceleration. Unpublished testing using the same protocol was conducted on the Wright Pro Harness design and the White Device in 2002, and two variations of the Isaac® design in 2005.

When qualifying prototype samples in terms of vibration response and dynamic characteristics, an accredited laboratory is required to implement monitoring procedures to assure the validity of the test results. According to ISO17025, such monitoring may include inter-laboratory comparison or proficiency testing. This paper presents a mechanical structure which has been designed specifically to be used as a generic reference sample during such a comparative study in which resonant frequencies of a structure need to be quantified. This paper elaborates on the analysis and design issues, which encompass theoretical analysis, both purely mathematical and by FEM (Finite Element Modeling). In addition, to allow statistical analysis of test data resulting from measurements performed by different test laboratories, the uncertainty budget [1] of the reference value of this sample is determined.

Anti-lock brakes have been implemented on tractor-trailer units for several years. However, a fatal accident involving trailer swing indicated that there is some disagreement within the accident reconstruction industry as to what effects trailer anti-lock brake systems have on the stopping performance, dynamic performance/handling of the trailer, and resultant skid marks left on the roadway. Full-scale testing was conducted on a tractor-trailer unit which was equipped with anti-lock brakes on both the tractor and trailer. Full application braking tests were performed from 65-70 mph concurrent with a lane change. Baseline tests were conducted with all anti-lock systems operational, and the tire marks, amount of trailer swing, and stopping distance were recorded. The test was then repeated with the trailer anti-lock brakes disabled.

The purpose of this study was to determine if quasi-static (QS) bumper force-deformation (F-D) data could be used in a low-speed bumper-to-bumper simulation model (1) in order to reconstruct low-speed crashes. In the simulation model, the bumpers that make contact in a crash are treated as a system. A bumper system is defined as the two bumpers that interact in a crash positioned in their orientation at the time of the crash. A device was built that quasi-statically crushes the bumpers of a bumper system into each other and measures the compression force and the deformation of the bumper system. Three bumper systems were evaluated. Two QS F-D measurements were performed for each bumper system in order to demonstrate the repeatability of the QS F-D measurement. These measurements had a compression phase and a rebound phase. A series of crash tests were performed using each bumper system.

The accuracy of the speed change reported by Generation 1 Toyota Corolla Event Data Recorders (EDR) in low-speed front and rear-end collisions has previously been studied. It was found that the EDRs underestimated speed change in frontal collisions and overestimated speed change in rear-end collisions. The source of the uncertainty was modeled using a threshold acceleration and bias model. This study compares the response of Generation 1, 2 and 3 Toyota EDRs from Toyota Corolla, Camry and Prius models. 19 Toyota airbag control modules (ACMs) were mounted on a linear sled. The ACMs underwent a series of frontal and rear-end haversine crash pulses of varying severity, duration and peak acceleration. The accuracy and trigger thresholds of the different models and generations of EDRs were compared. There were different accuracy trends found between the early Generation 1 and the more modern Generation 2 and 3 EDRs.

Study on the braking torque allocation of the ABS (Anti-lock Brake System) of the electro-hydraulic brake system in the distributed drive electric vehicles, using a hierarchical control structure, of which the lower controller takes a braking torque allocation strategy based on frequency, so as to achieve a good braking effect. The lower controller uses the strategies which are based on the filter principle or the weighted least squares algorithm. To the former, Butterworth filter is selected to execute the braking torque allocation. Then the ABS braking torque allocation strategy based on Butterworth filter and the weighted least squares are designed and analyzed respectively, finally their braking effects are simulated and contrasted in Simulink and AMESim.

Disc herniations in the spine are commonly associated with degenerative changes, and the prevalence increases with increasing age. With increasing number of older people on U.S. roads, we can expect an increase in clinical findings of disc herniations in occupants involved in rear impacts. Whether these findings suggest a causal relationship is the subject of this study. We examined the reported occurrence of all spine injuries in the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) database from 1993 to 2014. There were over 4,000 occupants that fit the inclusion criteria. The findings in this study showed that, in the weighted data of 2.9 million occupants, the most common spine injury is an acute muscle strain of the neck, followed by strain of the low back. The delta-V of a rear impact is a reliable indicator of the rate of acute cervical strain in occupants exposed to such impacts.

ISO 26262, an international functional safety standard of electrical and/or electronic systems (E/E systems) for motor vehicles, was published in November 2011 and it is expected that the scope will be extended to motorcycles in a second edition of ISO 26262 going to be published in 2018. ISO/DIS 26262 second edition published in 2016 has Part 12 as a new part in order to apply ISO 26262 to motorcycle. Proper estimation of Exposure, Controllability, and Severity in accordance with ISO/DIS 26262 Part 12, are key factors to determine Motorcycle Safety Integrity Level. To estimate precise these factors, there would be a case that it might not be appropriate to apply studies done for passenger car to motorcycle, and it would be necessary to apply motorcycle specific knowledge and estimation methods. In our previous studies we clarified these motorcycle specific issues and studied the method for the adaptation.

The goal of this study was to use naturalistic driving data to characterize the motion of vehicles making right turns at signalized intersections. Right-turn maneuvers from 13 intersections were extracted from the Second Strategic Highway Research Program (SHRP2) database and categorized based on whether or not the vehicle came to a stop prior to making its turn. Out of the vehicles that did stop, those that were the first and second in line at the intersection were isolated. This resulted in 186 stopped first-in-line turns, 91 stopped second-in-line turns, and 353 no stop turns. Independent variables regarding the maneuver, including driver’s sex and age, vehicle type, speed, and longitudinal and lateral acceleration were extracted. The on-board video was reviewed to categorize the road as dry/wet and if it was day/night. Aerial photographs of the intersections were obtained, and the inner radius of the curve was measured using the curb as a reference.

Modern advances in the technical developments of Advanced Driver Assistance Systems (ADAS) have elevated autonomous vehicle (AV) operations to a new height. Vehicles equipped with sensor based ADAS have been positively contributing to safer roads. As the automotive industry strives for SAE Level 5 full driving autonomy, challenges inevitably arise to ensure ADAS performance and reliability in all driving scenarios, especially in adverse weather conditions, during which ADAS sensors such as optical cameras and LiDARs suffer performance degradation, leading to inaccuracy and inability to provide crucial environmental information for object detection. Currently, the difficulty to simulate realistic and dynamic adverse weather scenarios experienced by vehicles in a controlled environment becomes one of the challenges that hinders further ADAS development.