Specific energy analysis for the manufacturing of light-weight automobile body

Abstract

This manuscript analyses the specific energy requirements to produce two hybridised vehicle structures on current automotive assembly lines. It provides quantitative and specific electric (kWhr/vehicle) and fossil-fuel (MMBtu/vehicle) energy predictions of the body-in-white (BIW) manufacturing processes including body panel forming, welding, painting, and final assembly, in addition to the facility heating ventilation and air conditioning or HVAC consumption. Two hybridised BIW design criteria are analysed; the first is based on minimising the added cost per unit weight saved (+$/‒kg), while the second is based on maximising the percentage of weight saved (% ‒kg). Also a new criterion; that is the added specific-energy per unit weight-saved or (+kWhr/vehicle/‒kg) is proposed. The light-weight structures comprise body parts made of aluminium and steel. To compute energy consumptions, the study utilises the energy performance index (EPI) stochastic model in addition to complementing it with a panel-forming energy model. Cost analysis is also provided for all the major vehicle body-panels using an in-house Excel macro. The study reverse engineers a passenger vehicle BIW using a full-size coordinate measuring machine (CMM). The presented work further highlights the monetary value of the associated emissions when increasing the specific energy.