Investigation of a stress-strain state of a rubber-cable rope with cables of different tensile rigidity

Abstract

Purpose. Establishment of dependences for stress-strain state parameters in a rubber-cable rope with cables of different tensile rigidity and cable breakage. Research methodology. Construction and development of an algorithm for solving a model of a stress-strain state of a rubber-cable rope with ropes of different tensile rigidity and breakage of one cable by using the methods of mechanics of layered composite materials with soft and hard layers. Findings. Analytical expressions are constructed, which allow determining the main stress-strain state indicators in a rope with an odd number of cables, while the middle cable is damaged, and tensile rigidity of the middle cable is half the tensile rigidity of the other cables. Analytical dependencies are established for determining the extreme angles of rubber shear between the cables, what allows determining the most dangerous tension states of a rope with a damaged cable, which has a different rigidity from the other cables. The level of reliability of the developed algorithm for solving the model of a stress-strain state of a rubber-cable rope with cables of different rigidity is confirmed by determining the maximum tensile forces of a rope made of three cables, in which the middle cable has a tensile rigidity half that of the other two. The force distribution coefficients between cables adjacent to the damaged one are equal to 1.25 per unit load on each cable, which corresponds to the only possible case of force distribution between parallel elements under the presented conditions. Scientific novelty. The character of influence of different rigidity and damage of the reinforcing cables on the main parameters of stress-strain state in a rubber-cable rope are established. Practical significance. An algorithm for determining the stress-strain state indicators of a rubber-cable rope, which has an odd number of reinforcing cables, its middle cable is damaged, and the tensile rigidity of the middle cable is different (lower) than the rigidity of the other cables, is developed. This makes it possible to increase the operational safety of rubber-cable ropes in hoisting and transporting machines, in particular when operating at significant lifting heights, and also contributes to justifying the use of a rope design as a stay rope in capital structures.