Identifying factors affecting rope durability

Abstract

When a rope is in use, tensile stresses arise in its cross-sections due to the end load, bending stresses as it passes through pulleys and drums, torsional stresses, and contact stresses. The loads applied to the rope can be either static or dynamic. When calculating crane ropes, static tensile loads are determined without taking into account bending and torsion stresses. This approach underestimates the stress state of the rope and can lead to reduced rope durability. Goal. The purpose of the study was to determine the factors that actually affect the durability of crane ropes. When winding a rope onto a drum or when bending a rope on pulley blocks, a deviation of the ropes from the plane of rotation of the blocks occurs. As deflection angles increase, very negative aspects can arise due to the fact that the deflected rope slides along the side of the block groove, which itself wears out and leads to wear on the block groove. Methodology. The actual operating conditions for ropes differ significantly from those on a test machine. However, experimental studies conducted by scientists have made it possible to determine the impact of various factors on rope durability. To determine the effect of the rope deflection angle, a machine with a rocker mechanism was manufactured to study the rope’s durability. At the same time, the work of the rope was studied at different angles of deflection from 3 to 7. Results. The research carried out enabled the identification of new dependencies that account for the distance between blocks, thereby refining the calculation. Experimental studies fully confirmed the obtained refined calculation. Originality. The resulting formulas allow taking into account the distance between the blocks and therefore are more accurate. Practical value. The results presented in the article allow us to obtain a more accurate calculation of the durability of the rope, taking into account the influence of the angle of deflection of the rope on the block.