Capture and Structure of In-Service Information for Engineering Designers
Author: Jagtap, Santosh
Supervisor: Johnson, Aylmer
Institution: Department of Engineering, University of Cambridge
A fundamental shift is occurring in the manufacture and marketing of aero engines for commercial and defence purposes, away from the selling of products to the provision of services. Aero engines are now effectively leased to airlines, with the manufacturing company remaining responsible for their maintenance and repair throughout their service life. By incorporating in-service experience from existing engines in the design or re-design of components or systems in a new or existing engine, it is hoped to make the engines more economical to operate through better design. A literature review found that there is not a large body of literature on inservice information in general, and about aero engines in particular. Specifically, designers’ in-service information requirements are not examined in detail. Therefore, within the aerospace industry, it is necessary to understand in depth the available inservice information and designers’ requirements regarding this information. The research described in this thesis was carried out in collaboration with a company which designs and manufactures aero engines, with the aims of investigating in detail:
• designers’ in-service information requirements (i.e. in-service information they currently require and in-service information they ought to use) and their use of this information in a design task;
• the available in-service information sources, and their content. Several research methods such as interviews, questionnaires, document analysis, case studies, etc. were carried out within the collaborating company. The findings suggest that the in-service information required by designers (i.e. their current in-service information requirements and in-service information they ought to use) in the design of components or systems of new or existing engines mainly consists of deterioration information, i.e. deterioration mechanisms, deterioration effects, deterioration causes,
etc. Designers access the in-service information in the early phases of the design process. Based on this information, they formulate requirements for their design task, and generate solutions by modifying the conditions that bring about the deterioration mechanisms seen in the in-service information. A key finding of the research is that with a few exceptions the in-service information required by the designers is already available; however, it is in unstructured in its format, and is stored in various disparate and heterogeneous sources. The findings of the research methods employed in this project are used to propose ways to support designers in using in-service information effectively in a design task. The Sym-SAPPhIRE model of causality, which is the output of the development of a generic model of causality found in the reviewed literature, has provided a basis to propose these ways. In addition, a data structure is proposed to store in-service information in a structured format to satisfy designers’ queries regarding this information.