Prediction of Crash Performance of Adhesively Bonded Vehicle Front Rails
2022-01-1051
03/29/2022
- Content
- Adhesive bonding provides a versatile strategy for joining metallic as well as non-metallic substrates, and also offers the functionality for joining dissimilar materials. For problems of elastic behavior and small strains in vehicle unibody structures such as designing for NVH (Noise, Vibration and Harshness), adhesive bonding of sheet metal parts along flanges provides enhanced stiffening of body and improved acoustics due to sealing of openings between flanges. However, due to the brittle nature of adhesives, they remain susceptible to failure under impact loading conditions which can cause crumpling of sheet metal parts resulting in plasticity and large strains. The viability of structural adhesives as a sole or predominant mode of joining stamped sheet metal panels into closed hollow sections such as hat sections thus remains suspect and requires further investigation. The mechanical behavior of adhesives tends to be significantly different as compared to ductile and isotropic metals such as steel and aluminum. As modern vehicle design is primarily driven by CAE (Computer-Aided Engineering) methodologies, it is also important to ensure that the failure modes of adhesives under normal (peel) and shear stresses are adequately captured. To address the issues mentioned i.e. gathering insight into the performance of a structural adhesive, in the present case epoxy-based, under impact loading conditions, and simulation of its behavior along with adopted steel substrates in an explicit FEA code viz. LS-DYNA, a systematic experimental and numerical study is carried out comprising: (a) testing of single lap shear and peel joints in a UTM and prediction of the mechanical behaviors of the joints till failure using a cohesive zone material modeling approach for the adhesive with independent Mode I and Mode II fracture criteria, (b) axial impact testing of double-hat section components with conventional spot welds, the latter replaced with only adhesive-bonding along flanges, and hybrid joining consisting of adhesive-bonding and sparse spot welds, and prediction of the detailed impact responses and deformation, and (c) finally, implementation of the adhesive-based joining strategies in front rails of a validated finite element model of a commercially produced unibody passenger car and assessment of their performance vis-à-vis the baseline vehicle in full frontal NCAP test mode against a rigid barrier.
- Citation
- Ramachandra, S., Deb, D., and Chou, C., "Prediction of Crash Performance of Adhesively Bonded Vehicle Front Rails," SAE Technical Paper 2022-01-1051, 2022, .