Shear strength in-plane

In addition to the direct measurements of fiber-matrix interface properties discussed in Section 3.2, a number of testing techniques have been devised to assess the fiber-matrix interface bond quality by inference from the gross mechanical properties such as interlaminar shear strength (ILSS), translaminar or in-plane shear strength, and transverse tensile strength. These testing techniques invariably employ... 

ASTM D 3846 (1985). Test method for in-plane shear strength of reinforced plastics. 

In-Plane Shear Properties. The basic lamina in-plane shear stiffness and strength is characterized using a unidirectional hoop-wound (90°) 0.1 -m nominal internal diameter tube that is loaded in torsion. The test method has been standardized under the ASTM D5448 test method for in-plane shear properties of unidirectional fiber-resin composite cylinders. D5448 provides the specimen and hardware geometry necessary to conduct the test. The lamina in-plane shear curve is typically very nonlinear [51]. The test yields the lamina s in-plane shear strength, t12, in-plane shear strain at failure, y12, and in-plane chord shear modulus, G12. 

FIGURE 13. Temperatme dependence ofinterlaminar and in-plane shear strength of Hi-Nicalon/BSAS composite in air. (Reprinted, from reference 39, with kind permission from Elsevier). 

D3410-87 Compressive properties of unidirectional or crossply fibre resin composites D3518-91 In-plane shear stress-strain response of unidirectional reinforced plastics D3846-79 In-plane shear strength of reinforced plastics... 

Longitudinal tension and compression moduU Shear modulus In-plane shear modulus Second moment of area Major and minor axis second moments of area Span of simply supported beam Longitudinal tension and compression strengths Longitudinal in-plane shear strength Mid-span deflection Point load Shear stiffness ratio... 

In-plane shear strength D3518 D3846 6031 14,130 SACMA SRM 7 Method 101... 

The properties shown in Table 5.3 are axial, transverse and shear moduli, Poisson s ratio, tensile and compressive strengths in the axial and transverse directions, and in-plane shear strength. The Poisson s ratio presented is called the major Poisson s ratio. It is defined as the ratio of the magnitude of transverse strain divided by the magnitude of axial strain when the composite is loaded in the axial direction. Note that transverse moduli and strengths are much lower than corresponding axial values. 

D3846 In-Plane Shear Strength of Reinforced Plastics 4585( )... 

Since the in-plane stresses (Cn, CT22 12) ibe surface ply near the free edge are not constant, the average stresses over a distance of 2t from the free edge were used in the Tsai-Hill criterion for failure prediction. Further, since the surface plies are partially free from constraints (the lamination effect), the in-plane shear strength should be lower than that measured with [ 45]2s specimen. Thus, we took the value S = 14.4 ksi (for AS4/3501-6) reported in most literature. For T300/5208 graphite/epoxy composite we found S = 8.2 ksi was suitable. 

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