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A composite is a material system consisting of two or more phases on a
macroscopic scale, whose mechanical performance and properties are designed to be superior
to those of the constituent materials acting independently. One of the phases
is discontinuous, stiffer, and stronger and is called reinforcement. And the less stiff
and weaker phase is continuous and is called matrix. The low density, high strength,
high stiffness-to-weight ratio, excellent durability and design flexibility of fiber
reinforced composite materials are the primary reasons for their extended use. The
properties of fiber reinforced plastics can be controlled by the appropriate selection of
the substrata parameters such as fiber orientation, volume fraction, fiber spacing
and layer sequence. The required directional properties can be achieved in the case
of fiber reinforced composites by properly selecting fiber orientation, fiber
volume fraction, fiber spacing, and fiber distribution in the matrix and layer sequence. As
a result of this, the designer can have a tailor-made material with the desired
properties. Such a material design reduces the weight and improves the performance of
the composite. For example, the carbon-carbon composites are strong in the
direction of the fiber reinforcement but weak in other directions.
A great number of micromechanical models have been proposed in literature (McCullough,
1990; Halpin, 1992; Sun and Vaidya, 1996; and Zheng, 2001) for predicting
various mechanical properties of composite materials. Several other models have
been proposed such as numerical homogenization
by Sun and Vaidya (1996) and Pericles et al. (1997), and E Finite Element modeling by Sreeramamurthy (1991). In
this paper, the finite element method and response surface model have been adopted
for predicting the engineering constants of Glass Fiber Reinforced Polymer
(GFRP) angle lamina. The typical properties of composite material were taken from
the literature (Issac and Ori, 1994). The aim of the research was to study and develop
the mathematical model equations for predicting engineering constants of GFRP
angle lamina for different fiber angle and fiber volume fractions using Response
Surface Methodology (RSM). The adequacy of the developed model is verified by
using coefficient of determination and Analysis of Variance (ANOVA) method. Based
on experimental results, contours were plotted by using MINITAB-14 statistical
software. The effects of fiber angle and fiber volume fraction were studied through
response surface model. This model is of great importance due to its ability to
predict. Engineering constants of GFRP angle lamina for different fiber angles and fiber
volume fractions were determined. The properties of a composite material can be
controlled by the appropriate selection of the substrata parameters such as fiber
orientation, volume fraction, fiber spacing, and layer sequence. The elastic constants of
fiber reinforced composites with various types of constituents were determined by
Hashin and Rosen (1964), Hashin (1965), Whitney (1967), and Chen and Cheng
(1970). Takashi et al. (1977) experimentally obtained all the independent elastic moduli
of unidirectional carbon-epoxy composites with the tensile and
tensional tests of co-axis and off-axis specimens.
Gorji and Mirzadeh (1989) predicted thermo-elastic properties
in unidirectional composites. Expressions for E1 and G12
were derived using the theory of elasticity approach
of Hyer (1998). Kwak (2005) applied Taguchi and
RSMs for geometric error in the surface grinding process.
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