ABSTRACT


Author: David Barberá Tomás.
Supervisors: Ernesto de los Reyes López; Fernando Jiménez Sáez
Phd Programme: Engineering and Innovation Projects.

The Product Life Cycle Theory (hereinafter PLCT) characterizes the technological change experienced by a product throughout its life cycle as a sequence of variation-selection. Thus, the initial stages of the life cycle of a product are characterized by high technological variety, because there is high uncertainty concerning the performance of the different technological solutions proposed. However, this uncertainty is reduced over time, and this causes the reduction of variety in more mature stages of the life cycle, as the emergence of a single and hegemonic design (the so called ‘dominant design’) appears. The most commonly used example to illustrate PLCT is the early history of automobile: while in 1900, at the beginning of its development, three different solutions were present in the market with similar market shares (the car with electric engine, gasoline engine or steam engine), in 1920 the gasoine engine have been selected as the dominant design.
 
But in PLCT the variety-selection sequence is conceived as a ahistorical sequence. That is, it assumes that all the variety is present in the market at the same time and does not take into account the different moments of introduction in the market  of these rival variants, and its  influence in the later emergence of the dominant design. This doctoral thesis aims to complete the theoretical framework of PLCT, for making it able to include the inherent historicity of the emergence of new technologies. We compare the evolutionary patterns that are derived from our theoretical framework with the technological evolution of a surgical prosthesis, the artificial disc for the spine. In our case, the different moments of introduction in the market of the two major proposed technological solutions is due to the smaller “technological resistance” of one of them, whose structure was inspired by another trauma implant, the hip prosthesis. 

To operationalize the concept of "technological resistance” we have proposed a different sequence to that of variety-selection. The variety-selection sequence is a strictly "population" sequence. That is, describes the different frequencies of these solutions along the life cycle: in the early stages different solutions will have different frequencies of occurrence, none of which greatly exceeds the other; but in the more mature stages the frequency of one of them (the dominant design) is much higher than the rest. However, such measures do not refer to the internal nature of design, nor explain the reasons for the historical moments of introduction of the different technology options at the beginning of the cycle. It simply shows the decline of this variety as the cycle progresses and emerges a dominant design. Our sequence is 'internal': describes the technological changes in terms of their nature. By nature of technological change we mean changes in the technical characteristics of a product, the services it provides, and/or the complexity of the relationships between them. Our theoretical framework is synthesized in a sequence that describes the different chronological changes of these technical and service characteristics throughout the product life cycle. In this way we aim to identify the particular link in the sequence where the resistance lies, stagnating the technological evolution of the latter varieties of the product. Specifically, we found the reason for the lower resistence of the artificial disc inspired by the hip prostheses in the reduced complexity of the redesign that followed the clinical failures of the first primitive design . These failures involved the addition of new components that try to improve the performance of the original design, but while in the disc inspired by the hip prostheses these new components  did not add a higher level of complexity to the product, in the rival design the technological resistance was located precisely in the effort to undo the complexity wich follows the introduction of new components. In the discs inspired by the hip prostheses this effort of reducing complexity was unnecessary, because it had already been done before, in the technological development of hip prosthesis.