Energy absorption of a car roof reinforced with a grid stiffened composite panel in the event of a rollover

Abstract

Rollovers tend to be very severe crashes because of the energy required to roll a vehicle over unlike front and side crashes. This study is an effort towards reducing the severity of a rollover crash by strengthening the roof of a passenger car. The main focus of this thesis is to study the effect of reinforcing the roof of a car, in the event of a rollover. An Eglass/polypropylene isogrid composite panel, which is known for high specific energy absorption under impact, is used in reinforcing the roof of a ford Taurus car and the force-displacement response of the roof structure is observed in contrast to the same while without the roof reinforcement. The non-linear Finite Element Analysis (FEA) simulation of this rollover event is performed in LS DYNA computer code. The simulation setup is done in accordance with Federal Motor Vehicle Standard (FMVSS) No. 216, which is a static study of roof strength in the case of rollover accidents. A study of roof strength characteristics under dynamic loading, involving rollover forces and velocities, is also carried out. The simulation in the latter case involves dropping the car, inverted at a certain pitch and roll offset against gravity from a certain predetermined height onto a concrete surface. The results of the above simulations show that Isogrid composite panels are excellent reinforcements for a car roof, stiffening the roof and increasing its resistance to crush in a rollover accident. This study will help in recommending the use of isogrid panels in the design of car roofs with better roof crush characteristics.