Target Weighing Approach: Study to evaluate the benefits of a methodical approach in comparison to classical company processes for the identification of lightweight design potentials
Editor: Ekströmer, Philip; Schütte, Simon and Ölvander, Johan
Author: Revfi, Sven; Albers, Albert; Stegmiller, Marcus
Institution: Karlsruhe Institute of Technology
In order to achieve weight targets, the product developer can rely on the five lightweight design strategies concept, material, form, manufacturing and conditional lightweight design. However, lightweight design activities often focus on material and form lightweight design, i.e. the optimisation of individual subsystems. But a combination of subsystem optima does not inevitably lead to an overall system optimum. For this reason, the optimisation of the overall system must be carried out by cross-subsystem approaches (concept lightweight design).One such approach, which serves for the systematic identification and evaluation of holistic, cross-subsystem lightweight design potentials, is the ""Target Weighing Approach (TWA)"". Thereby, the reference product to be examined is analysed with regard to its functions. Subsequently, the percentage contribution of the subsystems to the fulfilment of the functions is determined in a Function-Mass-Matrix and thus a weight per function is determined. Based on this, ""too heavy"" functions are determined which offer possible lightweight design potentials. This paper presents the results of a study conducted as part of the Live Lab ""IP -Integrated Product Development"". In this Live Lab, selected students go through a product development process(in cooperation with a chosen industrial company)from the analysis phase through the generation of product profiles to the production of prototypes. The aim of the study was to identify lightweight design potentials of an application-oriented system (underbody of an automobile) and to develop related initial concept ideas. For the study, 37 students were split into two groups of four development teams. One group was taught in the TWA and forced to use the method for achieving the goal. The development teams of the other group were organised by subsystem responsibilities in analogy to a classic corporate structure, i.e. one person per development team is responsible for one subsystem. As in real corporate environment, the individual members of the development teams were locally separated and only allowed to interact at defined points in time. This simulates corporate-typical meetings where product developers from different departments exchange information about the project and make decisions. At the end of the study, the most promising concept idea per development team was presented and a questionnaire with seven questions was handed out. Here, the influencing factors for the identification of lightweight design potentials (communication, distinct analysis phase, understanding of subsystem interactions, cross-system thinking, detachment from existing restrictions (interfaces) of the reference product) identified by the authors prior to the study were queried. The results showed that the development teams supported by the TWA achieved a greater understanding of the overall system and were therefore able to recognise the lightweight design potential of the system more comprehensively. On the one hand, this was due to better communication and a more detailed analysis phase compared to the peer group. On the other hand, they had a better overview of subsystem interactions and were able to think independently of existing interfaces.