Computer aided engineering
Computer Aided Engineering (CAE) is a term used for a variety of engineering analysis
and software tools which will be dealt with in the following sections. Of these, the
technology that is typically of greatest interest to the rubber technologist working on
tyres is tyre structural modelling using FEA.
Computer aided manufacture (CAM)
Though some robotic manufacturing systems have been purported to be in use in the tyre
industry, a more common application for CAM is in the manufacture of metal tyre moulds.The use of CAM for metal machining is well documented elsewhere. One of the most important aspects for the effective use of CAM, however, is the integration between the CAM initialisation and a CAD system used for creating the mould drawings.
Computer aided design (CAD)
CAD systems are used in a variety of engineering and manufacturing operations. These
systems speed the process of creating and modifying the drawings of the tyre profile and
tread pattern. Linking CAD systems with CAM systems enables automation of tyre mould manufacturing.
Computational fluid dynamics (CFD)
The tread pattern affects how a tyre wears and provides traction in a variety of environmental conditions. CFD is used for hydroplaning (aquaplaning) analysis. In this type of analysis, the deformable tyre structure and tread pattern are made to move over, or through, a standing body of water. The analysis may also be applied to materials such as mud or snow, but the properties of these media are not well documented for input to a general purpose mathematical model. The technology in this field is being actively researched and commercial software is continually being improved.
Vehicle dynamics analysis (VDA)
The dimensions and structural response of a tyre affect how it performs when used on a
vehicle. VDA programmes are used to examine the behaviour of a vehicle with tyres. The
primary objective of such an analysis is to understand the vehicle motion as it might be
affected by a change in tyre performance parameters. Tyre performance modelling includes vehicle handling simulations as well as structural dynamics and vibrational response of the vehicle system. The typical VDA uses simplified models of the tyre behaviour and typically does not have a sophisticated geometric representation of the tyre shape or structure.
Finite element analysis (FEA)
The CAD programs for using a computer system to describe tyre profiles and tread patterns presume that the desired shapes are known to the designer. However, in order to utilize shape and construction changes in the tyre to meet various performance criteria, a
structural analysis program is required. The current technology for structural analysis is
FEA in which the overall structure is mathematically represented by small volumetric
elements with simplified geometry and material properties.
The complex geometric shape of the tyre, typically produced with CAD software, is
provided to another computer programme, which creates a model of the internal structure
in a step called ‘pre-processing’. This model is then analysed by another programme, the
FEA ‘solver’ programme itself, which performs the mathematical computations of the
physical relationships represented by the tyre during use. Finally, a computer programme
extracts and displays information about the performance of the tyre that was represented
by the mathematical model in a step called ‘post-processing’.
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