An improved design of apparatus for multi-specimen bending fatigue and fatigue behaviour for laminated composites

Abstract

A previously designed fatigue apparatus to test bending fatigue behaviours of glass-fiber reinforced plastic materials is improved in the scope of this research. The advantages of the improved test apparatus are as follows: It can teste 16 samples instead of 10. The square section axis was used to connect the samples more rigid by instead of the round section. So, a good balance and less vibration were obtained on the apparatus. More functional infrared sensors were used instead of proximity sensors that are sensitive to repeated cycling. While the load stress ratio is R = 0 or 1 (two alternative), with a developed adjustable support device, it is R = - 1, 0 and 1 (three alternatives). The fatigue behaviours of two groups (A and E) of composite fiber samples which have different directions but the same volumes were tested by this new apparatus. As a result, it was observed that the directions of the fibers have an important effect on the fatigue strength.