Wedge cleavage tests

Cleavage strength BS 5350 Part Cl 1986 ASTM 01062-72(83) ASTM 03433-75(85) ASTM 03762-79(83) ) Compact tension specimen ) Parallel- or tapered doublecantilever-beam joint for determining the adhesive fracture energy, G c Wedge cleavage test (for aluminium adherends)... 

Joint fracture toughness. The initial mode I fracture toughness K 1C, obtained from the mean of several tests using wedge cleavage specimens, an example of which is depicted in Fig. A.5, should not be less than 0.5 MN The tests should be carried out at 20 °C... 

Structural adhesives. Cleavage test using wedge. 

Figure 37 Cleavage test also called crack propagation (ISO 10354) or BOEING wedge test (a) test specimen (all dimensions in mm) (b) wedge (c) Test specimen after the test wedge has been pushed inside the test specimen (at a speed of 1 mm/min, for instance) original opening was o, which increased by Aa so that crack propagation was Aa (Aa is measured very accurately with a microscope).

In common with most polymeric materials, adhesives and sealants are sensitive to the rate of applied force. There are several different types of impact test for adhesives. The most common test (similar in application to the Izod impact test for plastic materials) has been withdrawn without replacement however, the test was not widely used in a production situation due to the difficulty in achieving reproducible results. A more informative test for impact is the cleavage test in which the test specimen is subject to an impact force through a wedge (refer to Table 24). This can be initiated by a pendulum impact machine with an impact energy range of 50-300 J and an impact speed of 3-5.5 m/s. 

ISO 11343, 1993, Adhesives—Determination of dynamic resistance to cleavage of high strength adhesive bonds under impact conditions- Wedge impact method The method is mainly aimed for the characterisation of metal substrates suitable for automotive applications. An instrumented impact testing machine (pendulum type) of 50-300 J and. 3-5.5ms maximum capacity is required for this test. A blunt wedge of approximately 1 mm tip radius and included angle of 8 is impact driven into a bonded joint at 3 ms" for aluminum alloy adherends and 2 ms" for steel adherends. The impact event should be... 

Cleavage resistance, wedge test Curve strain/stress, elongation at break Impact resistance and resiliency Creep under constant load Hardness Hexibility... 

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