In-plane shear properties

ASTM D 4255 (1983). Guide for testing in plane shear properties of composite laminates. 

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. 

Experiments that probe the in-plane shear properties have been performed by using Iosipescu test specimens.26 A summary of experimental results... 

ASTM D4255. 1994. In-plane shear properties of eompo.site laminates. 

Lee S, Munroe M, In-plane shear properties of graphite/epoxy composites for aerospace applications evaluation of test methods by the decision analysis method, Aeronautical Note NAE-AS22, NRC No.23778, Mechanical Engineering Department, University of Ottawa, Canada, Oct 1984. 

A relevant contribution to the conposite prcperties dqiends on the matrix characteristics. Hie major role of the matrix in a fiber rehnorced conposite is to transfer stresses between the fibers to provide, a barrier to adverse oivironmeit and protect die surface of the fibers fi om tte mechanical and chemical aggression. While the contribution of the fibers mainly affects die teisile propM es of the conposite, the matrix is responsible of off-axis pixpeties and interiaminar shear as well as in plane shear properties. Furth more die processability and the eventual defects of a conposite stnmgly on the physical charactoistics of the matrix such as... 

Lee, B.L., Holl, M.W. Effects of moisture and thermal cycling on in-plane shear properties of graphite fibre-reinforced cyanale estta- resin composites. Compos. A Appl. Sci. Manuf. 27, 1015-1022 (1996)... 

ASTM D 4255/D 4255M-01 (2(X)7), Standard test method for in-plane shear properties of polymer matrix composite materials by the rail shear method, ASTM, West Conshohocken, PA. 

Table 4.2 summarises some basic properties of PEEK-based APC2 thermoplastic composites from Cytec. The properties of finished components can be tailored by controlling fibre orientation during the layup process. Eull characterisation of a thermoplastic composite will include measurement of in-plane shear properties, open hole tensile and compressive failure, interlaminar fracture toughness and compression after impact. Cytec also produces TPC based on PEKK [20]. 

In-plane shear properties In simple shear loading, two parallel faces move in opposite parallel directions. In pure shear, the plane is subjected to tensile forces on one axis and compressive forces of equal magnitude on the orthogonal axis. Many different techniques have been proposed for the determination of the in-plane and through-plane shear properties with variations appropriate to composite plates, rods and tubes [1]. Inter-laminar shear strength The inter-laminar shear strength (ILSS) test is a three-point bend test at very... 

It is critical that surface treatment conditions be optimized to composite properties since overtreatment as well as undertreatment will degrade composite properties. Typically composite interlaminar shear strength (ILSS), in-plane shear, and transverse tension ate used to assess the effectiveness of surface treatment. More recently damage tolerance properties such as edge delamination strength, open hole compression, and compression after impact have become more important in evaluating the toughness of composite parts. 

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... 

The composite s resin-dominated material properties are in-plane shear, interlaminar shear, transverse tension/compression, and mode I and II fracture toughness. These properties are... 

The lamina s transverse compressive/tensile properties are determined from a hoop wound (90°) cylinder loaded in axial compression and/or tension. The test methods have been standardized under ASTM D5450 and D5449. The tube geometry and manufacturing procedures are similar to those used in the lamina s in-plane shear tests. 

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... 

Sawada Y, Shindo A, Torsional properties of carbon-fibers, Carbon, 30(4), 619-629, 1992. Swanson SR, Merrick M, Toombes GR, Comparison of torsion tube and losipescu in-plane shear test results for a carbon fibre reinforced epoxy composite, Composites, 16, 8220, 1985. 

Depending on a material, single smectic monolayers can exist in two different modificati(His, liquid-like and hexatic like. Properties of these monolayers are shown in Table 5.1. Upon melting, a two-dimensional hexatic layer undergoes the transition into the liquid-like layer. It is spectacular that hexatic layers like liquid layers do not support the in-plane shear [14]. The layer can be sheared by as small force (stress) as is wished. 

Reinforced plastics, particularly laminates, are anisotropic (i.e., their properties differ depending on the direction of measurement). For example, a laminate made of fabric has physical properties controlled by the weave of the fabric and the number and density of the threads in the warp and fill directions. Both of these values are different from the values of the z or thickness direction. This is clearly evident in the shear properties. Thermal expansion and thermal conductivity properties are also anisotropic, hi the x, y, and z planes of the laminate, the thermal expansion values differ. Even the reinforcing fibers themselves may have anisotropic properties. 

The engineering properties of interest are the elastic constants in the principal material coordinates. If we restrict ourselves to transversely isotropic materials, the elastic properties needed are Ei, Ei, v, and G23, i.e. the axial modulus, the transverse modulus, the major Poisson s ratio, the in-plane shear modulus and the transverse shear modulus, respectively. All the elastic properties can be obtained from these five elastic constants. Since experimental evaluation of these parameters is costly and time-consuming, it becomes important to have analytical models to compute these parameters based on the elastic constants of the individual constituents of the composite. The goal of micromechanics here is to find the elastic constants of the composite as functions of the elastic constants of its constituents, as... 

Kriz and Stinchcomb [32] published experimental data for unidirectional graphite/epoxy composites. These results illustrate the case when the fibres are transversely isotropic. The elastic properties of the matrix are = 5.28 GPa and T = 0.354, and for the fibres E = 232 GPa, E = 15 GPa, 0(2 = 24 GPa, v 2 = 0.279 and v 3 = 0.49. In Figs 11.21-11.25 are plotted the predictions against the experimental data for , , G12, G23 and V23, i.e. the longitudinal or axial modulus, the transverse modulus, the in-plane shear modulus, the transverse shear modulus and the transverse Poisson s ratio, respectively. 

The determination of the in-plane elastic properties involves four values El, E2, V12 and G12. The measurement of longitudinal and transverse moduli and Poisson s ratio Ey, E2, V12) is made using tensile coupons oriented at 0° and 90°. These tests are quite straightforward to perform and to analyse when measuring the elastic properties. For the in-plane shear modulus (G12) off-axis, 45° and losipescu test coupons are used, but these tests are not so straightforward to analyse since a complex stress/strain state is induced in the coupons further details on this subject are well documented in the literature [33-37]. 

The mechanical properties of adhesive joints are primarily determined by applying an in-plane shear stress to the assemblies. Fig. 23 shows the single lap shear configuration recommended in ASTM D 1002, Federal Specification MMM-A 132 and Federal Test Method Standard No. 175. 

D 3713 MEASURING RESPONSE TO SMALL FLAME IGNITION D 3748 EVALUATING HD RIGID CELLULAR PLASTICS D 3810 EXTINGUISHING CHARACTERISTICS-VERT POSITION D 3835 RHEOLOGICAL PROPERTIES/CAPILLARY RHEOMTR D 3846 IN PLANE SHEAR OF REINFORCED PLASTICS D 3895 COPPER INDUCED OXIDATIVE INDUCTION BY DSC D 3914 IN PLANE SHEAR OF RODS D 3916 TENSILE OF PLASTIC ROD... 

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. 

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