This research article presents the crashworthiness response of carbon fiber composite front bumper crush can (FBCC) assembly subjected to 40% offset frontal impact loading. Automobile manufacturers continue to strive for overall vehicle weight reduction while maintaining or enhancing safety performance. Therefore, the physical testing of lightweight materials becomes extremely important under a crash scenario in order to apply them to automotive structures to reduce the overall weight of the vehicle. In this study carbon fiber/epoxy lightweight composite material is chosen to develop frontal bumper beam crush can assemblies. Due to lack of available studies on carbon fiber composite FBCCs assemblies under frontal offset crash scenario, a new component-level experimental study is conducted in order to develop data that will provide assistance to CAE models for better correlation. A sled-on-sled testing method was utilized to perform tests in this study. 40 % offset frontal tests on FBCC structures were conducted by utilizing three high-speed cameras (HSCs), several accelerometers and load wall. Impact histories i.e. crash pulse, force-time history, force-displacement, impact characteristics and deformation patterns from all FBCC tests were consistent. The standard deviation and coefficient of variance for the energy absorbed were very low suggesting the repeatability of the 40% offset tests. Excellent correlation was achieved between video tracking and accelerometers results for time histories of displacement and velocity. Post-impact photographs showed the progressive crushing of composite crush cans, bumper beam/crush can adhesive joint failure located on unimpacted side and breakage of the bumper beam due to the production of shear stresses as it is stretched due to its curvature after hitting the sled.

This research study highlights the testing method and relevant results for assessing impact performance of a carbon fiber composite front bumper crush can (FBCC) assembly subjected to full frontal crash loading. It becomes extremely important to study the behavior of lightweight composite components under a crash scenario in order to apply them to automotive structures to reduce the overall weight of the vehicle. Computer-aided engineering (CAE) models are extremely important tools to virtually validate the physical testing by assessing the performances of these structures. Due to lack of available studies on carbon fiber composite FBCCs assemblies under the frontal crash scenario, a new component-level test approach would provide assistance to CAE models and better correlation between results can be made. In this study, all the tests were performed by utilizing a sled-on-sled testing method. An extreme care was taken to ensure that there is no bottoming-out force for this type of test while adjusting the impact speed of sled. Full frontal tests on FBCC structures were conducted by utilizing five high-speed cameras (HSCs), several accelerometers and a load wall. Excellent correlation was achieved between video tracking and accelerometers results for time histories of displacement and velocity. The standard deviation and coefficient of variance for the energy absorbed were very low suggesting the repeatability of the full frontal tests. The impact histories of FBCC specimens were consistent and in excellent agreement with respect to each other. Post-impact photographs showed the consistent crushing of composite crush cans and breakage of the bumper beam from middle due to the production of tensile stresses stretched caused by straightening of the bumper curvature after hitting the load wall.

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This study compares the deformation characteristics of steel and carbon fiber composite (CFC) front bumper crush can (FBCC) assemblies when subjected to a full-overlap frontal impact into a rigid wall. Both the steel and composite bumper tests were conducted using a sled-on-sled testing method. Several high-speed cameras (HSCs) and accelerometers were used to gather kinematics data. The applied forces were measured using a load cell wall. For each test, the collective set of data was filtered, sorted, and analyzed to compare the performance of the steel and CFC bumpers. Similarities in Acceleration-Time plots suggested resemblance in the deformation patterns for both types of bumper systems. The difference observed in the velocity and displacement time-histories was because of the brittle nature of the composite material. The velocity-time history of the CFC FBCC had two distinct patterns, events suggesting adhesive bond failure between the bumper beam and the crush cans, which was validated through video tracking. Post-impact photographs showed a clear difference between the material behavior of composite and steel bumpers when subjected to high-velocity impact. The steel bumper beam was bent uniformly with intact, equally crushed crush cans. The composite beam was cracked in the middle and was detached from the crush cans.