Stress stateofa composite tractive element with cable rigidity variable over length considering bending on a drum with curved generatrix

Abstract

Purpose. Establishment of dependencies for parameters of a stress-strain state of a composite tractive element taking into account bending of a rope with cable rigidity variable over length on a drum with a curved generatrix. Research methodology. Development of a method for calculating the influence of a complex of factors on a stress-strain state of a rope by constructing and solving a model of a stress-strain state of a composite tractive element with cable tensile rigidity variable over length, cable base breakages and a non-cylindrical drum shape, using the methods of mechanics of layered composite materials with soft and hard layers. Findings. Analytical dependencies are obtained in a closed form and allow determining the maximum quantitative indicators of a stress-strain state of a rope of a combined structure with a broken cable, rigidity different from the main cables and variable along rope length in a straight rope part and in a part of interaction with a curved drum of a hoisting machine. Analytical dependencies are established for determining the maximum angles of rubber shear between cables, which allows determining the dangerous tangential stresses in a tractive element for cases of flat rope tension, rope bending on a convex drum, and bending on a convex drum of a rope with cables of reduced tensile rigidity. The results of solving the problem of determining the distribution of forces in a rope with cables of different rigidity by the developed method absolutely coincide with the only possible distribution of forces in a sample of three cables, which allows considering the developed algorithm reliable to describe the mechanism of redistribution of forces between cables with different tensile rigidity, including in the event of cable breakage, and the obtained results are reliable. Scientific novelty. A method of calculating the influence of a complex of factors on a stress-strain state of a rope is developed. The dependencies of parameters of a stress-strain state of a composite tractive element are established, taking into account rope bending, which has cable base breakages and cable rigidity variable over length, on a drum with a curved generatrix. Practical significance. A method for determining the indicators of a stress-strain state of a composite tractive element, which has cable base breakages and cable rigidity variable over length, including for bending on a non-cylindrical drum, is developed. This makes it possible to increase the operational safety of a composite tractive element in hoisting and transporting machines, in particular at significant hoisting heights, and also contributes to justifying the use of a rope design as a stay rope in capital structures.