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.