Comparative Review Study on Elastic Properties Modeling for Unidirectional Composite Materials

The aim of this work is to compare from an experimental point of view the determination of in-plane shear strength of unidirectional composite materials by means of two off-axis tests: three-point flexure and tensile. In the case of the off-axis three-point flexure test, the condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some considerations regarding stress and displacement fields are presented. The in-plane shear characterization has been performed on a carbon fiber reinforced unidirectional laminate with several fiber orientation angles: 10°, 20°, 30°, and 45°. Test conditions for both off-axis experimental methods, in order to ensure their applicability, are presented. Off-axis flexure test is considered more suitable than off-axis tensile test for the determination of in-plane shear strength.

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An asymmetrical dynamic model for bridging fiber pull-out of unidirectional composite materials

Meccanica ◽

10.1007/s11012-011-9509-y ◽

2011 ◽

Vol 47 (5) ◽

pp. 1247-1260 ◽

Cited By ~ 3

Author(s):

N. C. Lü ◽

Y. H. Cheng ◽

X. G. Li ◽

J. Cheng

Keyword(s):

Composite Materials ◽

Dynamic Model ◽

Unidirectional Composite ◽

Pull Out

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An evaluation of elastic properties and coefficients of thermal expansion of graphite fibres from macroscopic composite input data

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2004.1358 ◽

2005 ◽

Vol 461 (2054) ◽

pp. 347-369 ◽

Cited By ~ 5

Author(s):

P. Rupnowski ◽

M. Gentz ◽

J. K. Sutter ◽

M. Kumosa

Keyword(s):

Thermal Expansion ◽

Elastic Properties ◽

Input Data ◽

Matrix Material ◽

Unidirectional Composite ◽

Woven Composites ◽

Woven Composite ◽

Temperature Dependent ◽

Fibre Properties ◽

Representative Unit Cell

In this work, a methodology has been presented for the evaluation of stiffness properties and temperature–dependent coefficients of thermal expansion of continuous fibres from the macroscopic properties of either unidirectional or woven composites. The methodology was used to determine the stiffness and thermal properties of T650–35 graphite fibres from the macroscopic input data of unidirectional and woven composites based on the same fibres embedded in a PMR–15 polyimide matrix. In the first part of the analysis, the fibre properties were determined directly from the unidirectional composite macro data using the inversed Eshelby–Mori–Tanaka approach. Subsequently, certain fibre properties were additionally evaluated indirectly from the woven composite, using the finite–element method and the concept of a representative unit cell. It has been shown that the temperature–dependent coefficients of thermal expansion of the fibres can be estimated from the unidirectional composite macro data with significantly smaller errors than in the case of the elastic properties. It has also been shown that the errors in the evaluation of the elastic properties of the fibres from the macro unidirectional composite data could be significantly reduced if the fibres were placed in a stiff matrix material: much stiffer than the polyimide resin. The longitudinal and transverse coefficients of thermal expansions and the shear modulus of the T650–35 fibres determined from the unidirectional composite analysis were successfully verified by investigating the woven composite.

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