Bell peel tests

Figure 7. Percent Original Strength Retained, Bell Peel Test.

Floating Roller and BS 5577 Peel Fig. 49 shows a typical peeling rig for the floating roller peel test. The differences between this test and the BS 5577 specification are the peeling angle, which is about 70° for the floating roller or Bell peel test and 90° for the BS 5577 test, and the aluminium alloy used BS 5577 uses a much softer alloy. 

Fig. 10.9. Relative time-to-failure of a seam in the long-term peel test as a function of the melt depth Lq for a given thickness reduction ratio (s/Z-o) The figure has been taken from reference (Luders 2000). Seams with sJLq values of 0.5 (triangles), 0.7 (circles) and 0.9 (squares), thus those within the optimum range of this process parameter, were selected. Each data point represents the average value of 18 to 24 individual seams. The lines of the bell shaped curves lead the eye. Obviously, a very long time-to-failure (about 60 % of the maximum time-to-failure achievable) is achieved only if the Lo values of the seams are within the range of 0.75 mm to 0.95 mm. Based on a more extensive investigation G. Luders suggests a permissible range from 0.75 mm to 0.9 nun...

The most common types of peel test are the T-peel, Bell, and cUmbing-drum methods. Representative test specimens are shown in Fig. 7.21. The values resulting from each test method can be substantially different hence, it is important to specify the test method employed. 

A 90° peel test, such as the Bell peel (ASTM D 3167), is nsed when one adherend is flexible and the other is rigid. The flexible member is peeled at a constant 90° angle throngh a spool arrangement. Thns, the valnes obtained are generally more reproducible. 

Peel ( ) Peel strength for stated test sample configuration, e.g. T peel, floating roller, bell, sandwich, etc. Units vary for different test pieces. 

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