Strength and Failure of Synthetic Webbing of Unitizing Sling Assemblies in the Initial State and after Overloading

The results of full-scale tests of unitizing multiple-leg sling assemblies loaded with a trapezoidal waveform are considered. Mechanical behavior of the sling webbing material was evaluated by comparing its strength in the initial state and after overloading. A parameter to estimate the damage accumulated in the polymer material held under load is proposed, which makes it possible to determine the residual strength of the webbing at a known loading history. Under cyclic loading of slings the webbing strength markedly deteriorates, which leads to a decrease in the actual value of the sling safety factor. Design calculations of lifting capacity for unitizing sling assemblies should be performed with regard for the breaking force of their webbing tested after overloading.