Computerisation of Classical Engine Design Techniques using Spreadsheets.
A.C.Erskine, R.Ali, G.G.Lucas, A.Hughes.
Traditionally, engine components have been analysed using models with sufficient simplification to enable solutions to be calculated by hand. With the increasing availability of powerful computers these ‘classical’ techniques are being forgotten in favour of more accurate, but more complex and time consuming, finite element methods. This paper discusses the benefits of using classical analysis techniques and describes a user-friendly, spreadsheet based system for their application.
The Classical Engine Design System (CEDS) is quick and simple to use making parametric studies in the early design stages easy. These can be used to evaluate the feasibility of a design in order to justify time and money spend on further, more detailed analysis.
Microsoft's Excel spreadsheet package, running on a P.C., has been used as a basis for the software. Classical methods have been translated onto spreadsheets, accessible through a system of pull-down menus. These allow the system to be used by people with no experience of Excel itself. Consideration has been given to making the system as simple as possible to learn and to use, while keeping an acceptable level of detail and accuracy, and also to the possibility of adding further spreadsheets at a later date. The current version of the software includes spreadsheets for the analysis of crankshaft torsional vibrations, engine cycle irregularities, crankshaft balancing and for stressing of connecting rods, piston pins, crankshafts and bolted joints. Storage of component details in a database allows combinations of components to be recalled thus taking into account possible ‘knock-on’ effects of altering one particular component on the rest of the engine.