Engineering prediction of fatigue strength for copper alloy netting structure by experimental method

Abstract

Due to superior corrosion and rust resistance performance, copper alloy aquaculture netting structures are popular in the aquaculture industry. However, due to initial defects such as creases and corners caused by copper alloy weaving, the fatigue performance of copper alloy netting is greatly affected under periodic loads. This paper presents original test results for fatigue strength and ageing performance of copper alloy wire and netting structures. Compared with the fatigue test results of steel and aluminum materials, the fatigue strength of the actual copper alloy netting structure is relatively low with the fatigue ratio σf/σb=0.06 at 106 cycles. The fatigue ratio is only about (1/8–1/4) of that of other metals (σf/σb =(0.4–0.5) for steel and σf/σb =(0.25–0.50) for magnesium alloy). Considering the corrosive environment and ageing effects, metallographic structure and the maximum corrosion depths of copper alloy wire under different ageing conditions were measured and compared systematically. After a series of tests on aging and fatigue, it is concluded that the copper alloy material shows better corrosion resistance and aging resistance in seawater immersion environment than the traditional steel alloy or polymer netting. In seawater environment, the fatigue life of copper alloy netting decreases by only 10%, while the fatigue reduction rate of steel material is about 30% and nylon material is about 80%. The experimental results can provide a reference for the anti-fatigue design of copper alloy netting structure.