Pinfold, Martyn Keith (1995) Composite mechanical properties for use in structural analysis. PhD thesis, University of Warwick.

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Abstract

In order to be able to undertake an analysis of a component the designer will
need to know the properties of the material being used. The aim of this work is help
the design engineer such that the mechanical properties of continuous glass fibre
reinforced composite material can be determined and used in the design analysis of
components manufactured from this material.
The literature survey has shown that for the material considered here, then
given the constituent properties, the fibre arrangement and the fibre volume
fraction, the composite mechanical properties may be determined mathematically
by the use of micromechanical equations. The micromechanical prediction of the
mechanical properties of uni-directional, random and woven fibre reinforced
composites has been examined. The variation of these mechanical properties that
may occur in a composite component due to the manufacturing process has been
highlighted as being of importance. This has been studied to determine whether
such a variation is significant by analysing examples of composite components and
plates. The results from these analyses have been correlated with experimental
results and investigated to study the importance of such variations in properties.
Many micromechanical equations have been found in the literature for the
prediction of the mechanical properties of continuous fibre reinforced composite
materials. An accuracy of the predicted properties to within 10% of the
experimental data was concluded to be acceptable and good enough for initial
design purposes as design engineers are not usually able to design to such tight
tolerances. This work has shown that further development of the micromechanical
theories is not the most important problem concerning the prediction of the
mechanical properties. These properties can currently be predicted with
acceptable accuracy from the micromechanical equations already available in the
literature. However, the design engineer is unlikely to have knowledge of the
micromechanical equations necessary to determine the required properties. It is
only by undertaking a large literature survey that the designer would be able to find
this information. Many of the micromechanical equations require the use of an
empirical factor. The knowledge of a value for such a factor is again something that
would not be readily available to the designer. Rather than concentrating upon
improving the micromechanical predictions, this work shows that effort should be
made to understand the influence of other factors upon the mechanical properties
of composite materials. In particular, the behaviour and flow of the material during
the manufacturing process has been highlighted as being of importance as it can
cause a significant variation in the properties. Thus, analyses of composite
components cannot assume that the mechanical properties are constant
throughout, and it is therefore necessary to first model the manufacturing process
to determine the mechanical properties before undertaking a structural analysis.

Item Type:	Thesis (PhD)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Glass fibers, Fibrous composites, Matter -- Properties
Official Date:	April 1995
Dates:	Date Event April 1995 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Smith, Gordon F.
Extent:	xix, 275 p.
Language:	eng

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