Yijung Chen

Testing and Modeling of Mounts for Improved Safety Design and Crashworthiness Analysis

This paper describes (1) the findings from the implementation of a component test methodology for body, engine and transmission mounts [1-3], and (2) the associated CAE model development and mount design robustness enhancement. A series of component tests on light truck body, engine and transmission mounts have been conducted to not only obtain their characteristics as inputs for crashworthiness analysis, but also drive mount design direction for frontal impacts. In this paper, the lessons learned from implementation of the mount testing and modeling methodology [1-3] are reported in three areas: firstly, improvement of test setup and data collection over an existing approach to achieve test robustness, time efficiency and cost effectiveness; secondly, the confirmation of the thread effect on body mount performance for improved body mount design; and thirdly, the confirmation of a dual spring modeling methodology for better simulating engine and transmission mounts based on test finding and existing practice. Component test results and the new mount modeling methodology are incorporated into full vehicle CAE models for crashworthiness analysis of frontal crashes. Simulated results with implementation of the mount modeling methodology, when compared with full vehicle test data, indicate that the quality and the prediction accuracy of the full vehicle CAE models have been improved. Both the test and CAE methodology are implemented into vehicle program for support in crash safety analysis.

Rigid Angular Impact Responses of a Generic Steel Vehicle Front Bumper and Crush Can: Correlation of Two Velocity-Measurement Techniques

This study presents experimental investigations of generic steel vehicle front bumper and crush can (FBCC) assemblies subjected to a 30° front-angular impact. There is a lack of studies regarding component level tests with FBCCs. As vehicles aim to decrease weight by applying lighter-weight material to vehicle structures, component level studies become important. Computer aided models will then be valuable tools to assess performance of these structures. Thus, a novel component level test procedure is valuable to aid in CAE correlation. A sled-on-sled testing method was used to perform all the tests reported here. Impact speed was optimized to minimize bottoming-out force for this type of test. The speed of the impactor-sled was obtained based on two measurement techniques, namely: high-speed cameras and accelerometers. Several high-speed cameras were used at different locations. The sled and bumper motions were monitored using video targets. A triaxial accelerometer system was utilized to measure off-axis accelerations of the sled-beam. The results showed that good correlation exists between the two methods for measuring the sled velocity. The accelerometer data were used to generate force-time history plots based on Newton’s second law. The force-time history and force-displacement curves from different FBCC specimens were consistent and in good agreement with respect to each other with a low coefficient of variation calculated.

Force-Time History Assessment of a Generic Steel Vehicle Front Bumper and Crush Can Subjected to a Rigid Center Pole Impact

In this study, generic steel vehicle front bumper and crush cans (FBCC) were impacted against a rigid pole. The majority of studies regarding pole impact tests are related to full vehicle testing. There is a lack of studies regarding component level tests with FBCCs. Component level studies are important as vehicles utilize lighter-weight materials to vehicle structures in order to decrease weight. Computer aided models will then be helpful to assess performance of these structures. Thus, a novel component-level test procedure is valuable to aid in CAE correlation. A sled-on-sled testing method was used to conduct the tests. Two approaches were considered to assess force-time history, namely: direct force measurement and Newton’s second law. Applied impact force was directly measured by a load wall located behind the rigid pole. The load wall consisted of two uniaxial PCB 1204-03A load cells. Each load cell had a diameter of 6.06″ (153.9 mm) and load capacity of 50 klb (222 kN). A total of six accelerometers were used in the sled system. The off-axis accelerations of the sled-beam were also measured using a triaxial accelerometer system mounted on the left side of the beam. Two types of damped accelerometers were used in this study: Endevco 7264-2000 G piezoresistive and Measurement Specialties A40.