Evaluation of the Safety Performance and Weight Reduction Using CFRP Modified Automotive Structures in NHTSA's Frontal Oblique Impact Test

摘要

In a project conducted for NHTSA during 2016-2017, finite element analysis simulations were conducted representing NHTSA's right and left oblique impact configurations being developed for possible use in the agency's New Car Assessment Program. For the study using this test procedure, simulations were conducted representing an offset moving deformable barrier impacting a stationary 2015 Toyota Camry with a 35 percent overlap and an angle of 15 degrees (from collinear) at a speed of 90 km/h. In the NHTSA project, the model was successfully used to develop structural countermeasures in order to reduce occupant compartment intrusion for the new oblique impact configuration. Higher strength steel materials and modification of component thicknesses allowed the reduction of occupant compartment intrusion by more than 50%. As part of this effort, George Mason University (GMU) calculated mass and relative material expense comparisons to traditional materials. As a result, three optimized models using traditional materials were created. The accomplished reduction of occupant compartment intrusion ranged from 52% to 69% and the associated added mass ranged from 7.3 kg to 17.3 kg. The significant reduction in intrusion was achieved without unintended consequences, i.e., no considerable increases in the vehicle pulse severity for oblique and co-linear crash configurations were observed. Following these results, the American Chemistry Council (ACC) commissioned this subsequent study to determine if the vehicle could be lightweighted and provide a similar reduction of occupant compartment intrusion for NHTSA's right and left oblique impact configurations using carbon fiber reinforced plastic (CFRP) composite materials. Different thicknesses for relevant components were evaluated and associated reductions in intrusion, associated changes in mass, and associated critical areas with material failure were determined. As a result of using selected components made out of a composite material, a similar reduction in occupant compartment intrusion was achieved in NHTSA's right and left oblique impact configuration as realized for the best high strength steel model. In using the CFRP composite material, the associated change in mass was a reduction of 7 kg of the baseline vehicle as compared to an increase of 17 kg in the baseline vehicle mass when using more traditional countermeasures—higher component thicknesses and use of high strength steel materials. The developed and incorporated countermeasures using composite materials were also evaluated to determine if they produced unintended consequences in other impact configurations. The developed FE models, which showed reduced occupant compartment intrusion due to components made out of the CFRP composite material in NHTSA's oblique crash configuration, were also evaluated in NHTSA's NCAP full overlap and in the Insurance Institute for Highway Safety (IIHS) partial overlap crash configurations. No unintended consequences were observed when the results were analyzed with respect to vehicle pulse and intrusion when compared to the results using the baseline simulation model. In addition to the above technical achievements, in partnership with Honda R&D Americas and LSTC; other efforts are underway. These include the development of a material constitutive model of the composite material for use in modeling and subsequent simulation in automotive crash applications. Also, validation efforts using CFRP components will be undertaken.