Compression shear tests

Compression shear tests are also commonly used. ASTM D 2182 describes a simple compression specimen geometry and the compression shear test apparatus. The compression shear design also reduces bending and, therefore, peeling at the edges of the laps. Higher and more realistic strength values are obtained with the compression shear specimen over the standard lap shear specimen. 

The results of the drained triaxial compression shear tests with the same initial states and different temperatures (22 °C and 90 °C) are compared for several overconsolidation ratios (OCR) (Figure 2). The initial confining pressure was 600 kPa. 

In Germany, standards have been published describing the Compression Shear Test (DIN 54452), Dynamic Viscosity Determination of Anaerobic Adhesives by Rotational Viscometer (DIN 54453), Initial Breakaway Test at Bonded Threads (DIN 54454), and Torsion Shear Test (DIN 54455). DIN 54455 is particularly interesting since it is one of a very few tests in which a nut and bolt (MIO) are seated to a measured torque before the anaerobic sealant is allowed to cure. 

In order to gain some knowledge about the degradation of the adhesive layer during the delamination test, the specimens which successfully passed the test were further tested in compression shear (Fig. 24). For these tests, blocks with a cross section of 50 by 50 mm were cut out of the tested specimens. As a control, specimens of a similar size were cut from the part of the original sample which had not been subjected to the delamination tests. The compression shear tests conhrmed that the five adhesive layers which passed the delamination tests did not suffer any degradation during the harsh treatment. Their shear resistance was hardly reduced after the harsh delamination tests. 

Figure 24. Compression shear tests with a 3 mm thick elastic adhesive layer (no. 027). The left picture shows the test set-np, whilst the right picture shows the extraordinary large shear deformation of the adhesive layer.

Figure 4. Test sample design for compressive shear testing according to EN 302-4 (2004) [9].

Compression shear tests are also commonly used. ASTM D2182 (withdrawn 1983) describes sample geometry similar to the lap-shear specimen... 

Compressive shear tests are similar to lap shear tests except that compressive, rather than tensile, forces are applied to the sample until failure. Compressive loading may provide better alignment of adhesive bonds and also may reduce stress nonuniformities caused by the bending adherends. 

Another compressive shear test used for wood joints is ASTM D905-49. Test joints are prepared by bonding two blocks of wood, free from defects, with the grain of each block parallel to the length direction. Test specimens are cut from this bonded joint and tested in a special shearing apparatus (Figure 13). Loads are applied using a crosshead movement of 0.015 inch/min. The shear stress is calculated with the failure load and bonded shear area. 

DIN 54452 Testing of adhesives for metals and adhesively bonded metal joints compression shear test. 

D-0905. Test Method for Strength Properties of Adhesive Bonds in shear by Compression Loading (Fig. 8). A basic compression shear test which is widely used in screening wood glues. It is also used in specifications D-3110 (on nonstructural wood laminating ad hesives), D-2559 and D-3024 (on exterior and interior structural wood laminating adhesives respectively) and D-4317 (on polyvinyl acetate based wood adhesives). 

D-4501. Test Method for Shear Strength of Adhesive Bonds Between Rigid Substrates by the Block-Shear Method. Fig. 9 shows the two specimen configurations and the test head for this new, general-purpose, compression shear test which should be suitable for testing adhesives for plastics, metals, glass, wood, and other substrates. 

K. Schneider, B. Lauke, W. Beckert (2001) Compression shear test (CST) - a convenient apparatus for the estimation of apparent shear strength of composite materials, Appl. Compos. Mater. 8,43. 

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