Abstract
To overcome the fatigue safety problem of transmission tower cross arms caused by the wind-induced vibrations, an experimental study on the high-cycle fatigue performance of a new type of GFRP-steel sleeve composite cross arms was carried out. A total of six specimens were subjected to 500 thousand cyclic loadings based on the practical engineering background. The stress state was monitored, and a variety of load-displacement-time curves, the energy dissipation capacity, and the dynamic strain were analyzed to examine the effects of fatigue loading. After the fatigue test, the specimens without significant fatigue failure were evaluated to derive the residual bearing capacity. Based on the residual strength theory, the cumulative damage was examined, and the fatigue life was predicted under various loading conditions to ensure the reliability of composite cross arms. It is shown that the new type full-scale GFRP-steel sleeve composite cross arms can demonstrate a high level of safety redundancy on antifatigue performance and can be expected for wide application in power transmission towers.
Highlights
Glass-fiber-reinforced polymers (GFRPs) have been applied in manufacturing power transmission engineering widely as a replacement of conventional materials because of its unique advantages of high strength-toweight ratio, resistance to corrosion, lower transportation, and installation and maintenance costs [1, 2]
The summary of test results is shown in Table 2, in which there was no significant fatigue failure occurred of GFRP-steel composite cross arms during the 500 thousand high-cycle fatigue test. en, the axial compression test was carried out to derive the residual ultimate bearing capacity of the specimens
From GZ-1 to GZ-6 except for GZ-4, the predicted fatigue lives decrease apparently with the increase in fatigue loads. e average fatigue life predicted by the average residual ultimate bearing capacity is more than 5.5 million cycles, indicating that the GFRP composite cross arms can resist the multimillion fatigue loads caused by the windinduced vibrations of 1.3 times of the ultimate windy condition (30 m/s). e overall prediction result shows that the GFRP-steel sleeve composite cross arms can demonstrate high level of safety redundancy on antifatigue performance and can be expected for wide application in transmission towers
Summary
Glass-fiber-reinforced polymers (GFRPs) have been applied in manufacturing power transmission engineering widely as a replacement of conventional materials (wood, concrete, and steel) because of its unique advantages of high strength-toweight ratio, resistance to corrosion, lower transportation, and installation and maintenance costs [1, 2]. Many scholars have studied the fatigue problem of composite materials to the different extent, such as fatigue mechanics behavior, residual strength, and fatigue life prediction [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. An experimental study on high-cycle fatigue properties of a new type of full-scale GFRP-steel sleeve composite cross arms was conducted. Based on the modified residual strength theory, the cumulative damage was assessed to predict the fatigue life of GFRP-steel sleeve composite cross arms
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