The “Extended Target Weighing Approach” (ETWA) presented here describes a holistic, cross-subsystem, function-based lightweight design method - in terms of conceptual lightweight design - for the identification and evaluation of lightweight design potentials in the concept phase of product development. It systematically extends the existing “Target Weighing Approach” (TWA), in order to balance key factors mass, costs and CO2 emissions. During the application of the method, concept ideas are generated which have to be evaluated with regard to their potential.
The selection of concept alternatives to be pursued in the early phase of product development often depends on the experience of the product developer. Therefore, the potential of some concepts is not recognized correctly or the risk according to the intended solution caused by missing knowledge or uncertainties is misjudged. This paper presents a method for the evaluation of technological uncertainties of concept ideas based on the PGE - Product Generation Engineering. Four factors - Impact, Carryover Variation Share, Reference Product - Technology and Reference Product - Application Scenario - to assess the total technological uncertainty of a concept idea are described. The total technological technological uncertainty of a concept idea is gained by summing up the values for the influencing factors. In the context of this paper, the method is used for the Extended Target Weighing Approach to evaluate generated concept ideas in terms of their technological uncertainties. The capabilities of the proposed method to evaluate uncertainties in the context of the ETWA are demonstrated in a real world application scenario as a part of the EU-project AffordabLe LIghtweight Automobiles AlliaNCE (ALLIANCE). Based on an existing product generation of a vehicles front part, lightweight design potential and the linked efforts -costs and CO2-emissions- of two concepts are analyzed in regard to the technological uncertainties. It is shown how decision making in the development process can be supported during an early phase of concept design.