Härtill 4 uppsatser

Diss. (sammanfattning) Stockholm : Kungliga Tekniska högskolan, 2023

This thesis explores how the systemic-level environmental footprint of light-duty vehicles could be reduced through integrative design using the Life Cycle Energy Optimisation (LCEO) methodology. This methodology aims at finding a design solution that uses a minimum amount of cumulative energy demand over the different phases of the vehicle's life cycle; while complying with a set of functional constraints, thereby avoiding any sub-optimal energy demand shifts between the vehicle's different life cycle phases. This thesis further develops the LCEO methodology and expands its scope through four main methodological contributions. This work also contributes in establishing the methodology as a standalone design approach and provides guidelines for its most effective use. Initially, an End-of-Life (EOL) model, based on the substitution with a correction factor method, is included to estimate the energy credits and burdens that originate from EOL vehicle processing. Multiple recycling scenarios with varying levels of induced recyclate material property degradation were built, and their associated resulting optimal vehicle subsystem designs were compared to those associated with landfilling and incineration with energy recovery scenarios. The results show how the structural material use patterns, as well as the very mechanisms enabling the embodiment of the Life Cycle Energy (LCE) optimal designs, are impacted by taking into consideration the effect of a vehicle's EOL phase. In particular, the material intensity-space allocation trade-off was identified as a key factor in the realisation of the LCE optimal designs. This coupling existing between optimal use of material and space allocation was further explored by functionally expanding the LCEO methodology's scope to handle aerodynamic functional requirements. This involved the definition of a novel allocation strategy for the energy necessary to overcome aerodynamic drag, as well as the development of a parametrised vehicle body model that ensures that the LCE knock-on effects of aerodynamically motivated design decisions are fully accounted for at the targeted subsystem level.