Optimizing the disassembly sequence of mechanical systems is very useful in order to improve maintenance and recycling activities (i.e. to reduce costs, times and number of operations). A new virtual disassembly environment, based on two different algorithms, is presented. The first analyses the physical constraints that oppose the movement of the mechanical element: starting from its three-dimensional computer-aided design representation, it creates the ‘AND/OR’ graph of a mechanical assembly that represents the space of disassembly solutions. The second algorithm, using a representation based upon binary trees, allows the automatic exploration of the set of all possible sequences. Among these, the optimal one can be identified, choosing a specific target function. The developed methodology provides the theoretical basis for the creation of a computer-aided design tool able to evaluate the ability to disassemble a mechanical complex during the early design phase.

A tailored model for the assessment of environmental benefits achievable by “light-weighting” in the automotive field is presented. The model is based on the Fuel Reduction Value (FRV) coefficient, which expresses the Fuel Consumption (FC) saving involved by a 100 kg mass reduction. The work is composed of two main sections: simulation and environmental modelling. Simulation modelling performs an in-depth calculation of weight-induced FC whose outcome is the FRV evaluated for a wide range of Diesel Turbocharged (DT) vehicle case studies. Environmental modelling converts fuel saving to impact reduction basing on the FRVs obtained by simulations. Results show that for the considered case studies, FRV is within the range 0.115–0.143 and 0.142–0.388 L/100 km × 100 kg, respectively, for mass reduction only and powertrain adaptation (secondary effects). The implementation of FRVs within the environmental modelling represents the added value of the research and makes the model a valuable tool for application to real case studies of automotive lightweight LCA.