Tensile shear loading

The tensile-shear loading was realised in a set-up involving the three specimens of the same batch as follows. The bottom leg of the top specimen was connected to the top leg of the middle specimen with a bolt with a washer of the same thickness as that of the given adhesive layer in order to assure symmetrical loading. The middle specimen was connected in a similar way to the lowest specimen (Fig. 25). 

Tensile shear loading—kAherend tensile loads that produce shear stresses to the bondUne in lap and strap joints. 

In-piane shear ioading (in addition to tensile shear loading) ... 

P(l) This design procedure shall be applied only to tensile shear loaded single-and double-lap and single- and double-strap joints. 

P(2) In-plane loaded single-lap and single-strap joints shall be designed using the corresponding equations for tensile shear loaded Joints and using the parameter conversions indicated in Table 5.6. 

Tensile shear-loaded joints (Fig. la) have the highest strength (see Shear tests). Stress is distributed over the bond area. Joints that have load applied as a shear loading are most resistant to bond failure. 

Figure 5.2 Tensile shear loading (exaggerated to show effect)...

Fatigue resistance is maximised by ensuring that tensile shear loads do not oscillate between compression and tension, and that the elastic shear stress limit of the adhesive is not exceeded... 

For convenience so far we have referred generally to creep curves in the above examples. It has been assumed that one will be using the conect curves for the particular loading configuration. In practice, creep curves obtained under tensile and flexural loading conditions are quite widely available. Obviously it is important to use the creep curves which are appropriate to the particular loading situation. Occasionally it is possible to obtain creep curves for compressive or shear loading but these are less common. 

Orient fibers in direction of loading For tensile and compressive loads along the axial direction of the cylinder, wind helical plies at the lowest possible angle to the shaft axis for in-plane shear loads align fibers at 45 to the shaft axis... 

Two different polyacrylonitrile precursor carbon fibers, an A fiber of low tensile modulus and an HM fiber of intermediate tensile modulus were characterized both as to their surface chemical and morphological composition as well as to their behavior in an epoxy matrix under interfacial shear loading conditions. The fiber surfaces were in two conditions. Untreated fibers were used as they were obtained from the reactors and surface treated fibers had a surface oxidative treatment applied to them. Quantitative differences in surface chemistry as well as interfacial shear strength were measur-ed. 

As with amidoamine and polyamide cured adhesives, epoxy resins cured with aliphatic amines exhibit tensile shear strength that is dependent on the type of filler and concentration. Table 11.10 shows the effect of filler loading on strength of a simple general-purpose, room temperature curing epoxy adhesive composed of liquid DGEBA epoxy mixed with 10 pph of a tertiary amine. 

TABLE 11.10 Effect of Filler Loading on Tensile Shear Strength of DGEBA Adhesive Formulation Cured with 10 pph Tertiary Amine11... 

Adherend stresses in weldbonded joints are lower and more uniform than those for comparable spot welded joints. This provides increased in-plane tensile shear and/or compressive buckling load-carrying ability for a given joint design. The presence of the spot weld provides enhanced out-of-plane load-carrying capability compared to adhesive bonding only. 

When loading this test piece with force F it is noticed that, unlike in the tensile shear test, the force is not applied to an area A (= b x fu), but to a line X... X. The other area of the adhesive layer remains unstressed. Thus, in this case strength cannot be defined as force per area , but the force referring to a line is called peel resistance. If the test piece shown in Figure 10.5 is tom apart by means of force F, and the force over the peeled distance is recorded, the following peel diagram results (Figure 10.6). 

Consider a fiber of length / embedded in a polymer matrix, as shown in Figure 3.49b. One can then write, equating the tensile load on the fiber with the shear load on the interface. 

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