Shear strength short-beam

Flexural Properties of Plastics and Electrical Insulating Materials Bearing Strength Short Beam Shear... 

ISO 14130 1997 Fibre-reinforced plastic composites - Determination of apparent interlaminar shear strength by short-beam method ISO 15024 2001 Fibre-reinforced plastic composites - Determination of mode I interlaminar fracture toughness, GIC, for unidirectionally reinforced materials... 

Apart from the short beam shear test, which measures the interlaminar shear properties, many different specimen geometry and loading configurations are available in the literature for the translaminar or in-plane strength measurements. These include the losipescu shear test, the 45°]5 tensile test, the [10°] off-axis tensile test, the rail-shear tests, the cross-beam sandwich test and the thin-walled tube torsion test. Since the state of shear stress in the test areas of the specimens is seldom pure or uniform in most of these techniques, the results obtained are likely to be inconsistent. In addition to the above shear tests, the transverse tension test is another simple popular method to assess the bond quality of bulk composites. Some of these methods are more widely used than others due to their simplicity in specimen preparation and data reduction methodology. 

ASTM D 2344 (1989). Test method for apparent interlaminar shear strength of parallel fiber composites by short-beam method. 

Fig. 5.5. Normalized irKerfacial shear strength of unsized (bare) and sized E-glass fiber-epoxy matrix eomposites measured from the interfaeial testing system (ITS, equivalent to fiber push-out test), short beam shear (SBS) test, 0° flexural test and 90° flexural test. After Drown et al. (1991).

As with tensile properties, both compressive strength and modulus depend on the fiber content and hber orientation (see Table 5.8). The interlaminar shear strength reported in Table 5.8 is a measure of the shear strength in the thickness direction of the SMC sheet. It is determined by three-point flexural testing of beams with short span-to-depth ratios and is considered to be a quality-control test for molded composites. 

The degree of bonding analysis has been verified for both compression molding and online consolidation of thermoplastic composites. In these studies, composite test specimens were consolidated under controlled processing conditions. The most common types of tests performed to measure the interply bond strength were the interlaminar (short beam) shear test [21,25] or the lap shear test [12,21,26]. 

Short beam tests provided information on the apparent interlaminar shear strength (ILSS) of laminates made with bare and sized E-glass fibers. In all cases, the specimens failed in shear at or near the midplane, allowing comparisons between fiber types. The ILSS, SD, and number of specimens tested are given in Table 5. 

Figure 7. Normalized values for the interfacia] shear strength as measured by the ITS plotted against the short beam shear strength (SBS), 0° flexure strength, and 90° flexure strength for the bare and Epoxy-sized fibers.

It was concluded that the actual values of interlaminar shear strength obtained by a short-beam method agreed well with the theoretical values. 

The apparent inierlantinar shear lest uses a short beam flexure loading mode to measure the shear strength along the plane of lamination. The analysis of the test is... 

BS EN ISO 14.130. Fibre-reinforced plastic composites- Determination of apparent interlaminar shear strength by short-beam method. 

In the broad sense, interlaminar adhesion means the adhesion between any laminations of similar or dissimilar materials and hence could be taken to include just about any adhesion test. One particular type for fiber-reinforced plastics, which is known as interlaminar shear strength, is normally considered as a short beam flexural test (sec Chapters 9 and 18). A method peculiar to laminated plastics tube is given in BS 2782, Method 346A [59] and called cohesion between layers of laminated tube. A sample of tube is subjected to compression to induce shear forces between layers and delamination observed by eye,... 

Figure 3. Flexural strength, flexural modulus, and short beam shear at 550°F of non-post cured P13N/boron specimens after aging at 550° F...

Interlaminar shear testing was carried out using the short beam shear technique in 3-point bending at a displacement rate of 0.02 /minute from room temperature to 1300 C. Results of the interlaminar shear strength [31] forthe 0/90° cross-ply Nicalon/BN/SiC/BS AS composites, containing 38-40 volume per cent of fibers are given in Table 5. The failure mode for all the test specimens was shear. 

O. Unal and N. P. Bansal, Interlaminar Shear Strength of a Unidirectional Fiber-Reinforced Celsian Composite by Short-Beam and Double-Notched Shear Tests, Ceram. Eng. Sci. Proc., 22 [3] 585 95 (2001). 

As there are no fibers aligned in the through-thickness direction of 2-D fiber-reinforced composites, a possible mode of failure is by shear between the fabric plies. Hence, interlaminar shear strength is an important property. Tests were conducted using the ASTM D2344-84 short beam method. The average interlaminar shear strength from five samples was measured to be 62 MPa at room temperature. 

Shear Properties - Double notch shear testing is preferred to short-beam shear, because of the multiple stress condition for the short beam shear geometry. In the double notch shear (DNS) test, the compression load translates into an interlaminar shear stress along the midplane connecting the two notches in the composite (See Figure 3). Table 3 lists the ultimate double notch shear strengths for the two sets of composite test bars. 

FIGURE 8. Short beam shear test to determine the yield shear strength (Tei of WHIPOX CMC (a) and cyclic fatigue test showing degradation if the toad exceeds (Tei (b). 

D2344-84 Apparent interlaminar shear strength of parallel fibre composites by short beam method D3039-76 Tensile properties of fibre—resin composites... 

D4475- Apparent horizontal shear strength of pultruded reinforced plastic rods by the short beam 85 method... 

Fiber Strength Modulus Short beam shear... 

Measurement of the interlaminar shear strength (ILSS) by short beam... 

Under three point bend loading of a composite (beam), cracks may be developed due to tensile stresses at the lower stratus of the specimen as well as compression stresses at the upper one, or due to interlaminar shear. The type of failure depends on the ratio of span to depth (L/D). Short beam specimens usually fail in shear and long ones by tensile or compression stresses. For interlaminar shear strength (ILSS) tests, a L/D = 5 was chosen (ASTM-D-2344-76). In case of flexural strength tests, this ratio was fixed to 40 (DIN 29971). 

---