Design of energy absorbing plastic brackets to meet rear crash regulation ECE R42 2019-28-0041
ECE R 42 uniform is a provision concerning the approval of vehicles with regard to their front and rear protective devices. Invention of low speed impact plastic brackets is related to rear bumper impact as per ECE R42 at a vehicle speed of 2.5 KMPH. Current bumper collision system uses several separate components assembled together. These components include a soft energy absorber which must go through iterative design and testing process which results in a comparatively high material cost. The invention involves the design of an energy dissipating method in slow speed rear impact with use of plastic brackets. The impact energy during the crash is controlled using innovative initial and secondary crash zones. The initial pendulum impact is on the bumper mounting sheet metal bracket which absorbs part of the energy. The proposed bracket design is capable to absorb the low speed impact energy during crash without the use of any additional parts. The bracket geometry is designed for maximum energy absorption during collapse. The design is also optimized to reduce the size of the bracket to limit the part weight and cost. Comparatively the proposed bracket size is lesser than existing conventional designs due to its unique geometry and the sharing of crash energy strategy. This clever strategy of splitting the impact into two zones, helped the plastic bracket to effectively absorb and dissipate the remaining crash energy. This division of crash zones also helped to optimize the size of the plastic bracket to minimum limit as opposed to the conventional designs.
A low-cost plastic bracket geometry using POM material is designed and successfully tested. The comparison between the existing design and the proposed design was done and was found that the new design had significant saving in terms of cost.