The aerospace industry experiences a considerable growth in product development costs. Many research works aim at identifying evolution laws characterizing this large-scale phenomenon and at developing design strategies which could help mitigate it. This paper aims to clarify the evolution dynamics governing this phenomenon by studying how the products delivered by these costly projects evolve with time. Increasing complexity is often held responsible for surging costs. If complexity is generally defined as the price to be paid for improving product functionalities, it is rarely specified whether the improvement affects existing functionalities or involves new ones. We aim to identify the patterns of cost growth which can be associated with phenomena of existing functionalities upgrade and new functionalities introduction, and to identify the associated design capabilities that designers need to deploy in order to keep product change and cost growth under control. To that end, we introduce a model which generates curves, each of which featuring a trend of cost growth, specific to a scenario of product evolution and being interpretable as a signature of a strategy used by designers.

For more than two decades, mobile phone industry has shown that innovation is not only functional optimization and combination but can also be a "functional expansion”. Sometimes called radical or disruptive innovation, this phenomenon leads to the development of new method for engineers and designers. However, the intensity remains undemonstrated: is functional expansion a rare phenomenon (few products during very short periods of time) – or is it an intense phenomenon, that even might have accelerated in the last decades? To answer these questions, the paper overcomes two main obstacles: how to measure functional expansion? And what would be a law of functional expansion, that would enable to test the importance and newness of the phenomena? Building on recent advances on the measurement of innovation and on new computational models of design derived from most advanced design theories, this paper presents unique data on functional expansion of 8 consumer products and tests that functional expansion significantly accelerated in the mid 1990s. The paper confirms quantitatively that our societies are now in a new design regime, a regime of innovative design.