The Manufacture Of The Wire Rope Fatigue Test Bench And Estimation For Wire Rope Life

Wire ropes are key components in many engineering field, and when using it in some process will be prone to fatigue, wear, and even the phenomenon such as fracture, which can lead to engineering accident, so it is necessary to use scientific and reasonable model for wire rope life prediction to make a beforehand assessment of the bearing capacity and safety coefficient ; At the same time due to the complexity of its structure, uncertainty working condition and bad work environment,there are many factors to influence the service life of wire rope . It is difficult to get a satisfactory result only through the theoretical analysis,therefore, in order to ensure the wire rope can work be safe, reliable and efficient, It has important theoretical value and practical significance to study the fatigue status by adopting the combination of theoretical analysis and experiment.In this paper,6 x 31 SW + FC wire as the research object The necessity of the wire rope fatigue test bench and wire rope life assessment's theoretical research are analyzed, and reviews the current situation of wire rope fatigue test bench, kinetics of wire and wire rope life assessment's theoretical research, meanwhile designs the wire rope fatigue test bench for larger load conditions, and on this basis, the wire rope life assessment's theory has been carried on the thorough research.First of all, according to the characteristics of wire rope structure and its working environment, and developed the overall program of the wire rope fatigue testing. Meanwhile carry on the detailed design of the test bench's structure of tension,drives and other important components and a 3 D modeling for the bench. Make a finite element analysis for its structure based on ANSYS . The analysis results show that the stiffness and strength of the wire rope fatigue test bench meet the requirements under the given conditions. In addition, the main technical parameters of the hydraulic system is determined by the analysis and calculation of the test bench's operation condition,and on the basis of these made the hydraulic system design.Secondly,the paper studies the wire rope's dynamics and mechanics model. Simplified the force relationship of wire rope fatigue test bench as two degrees of freedom dynamic model,according to the second category Lagrange dynamics method to establish dynamics equation of wire rope,its tension relationships with the variation changing was derived under the test condition. Based on Costello's elastic theory to establish wire rope's mechanical equilibrium equation, analyzed the stress of steel wire, and on this basis, established a straight and bending a spiral and secondary spiral steel wire mechanics model,lay a foundation for the wire rope fatigue life estimation.Then, established a spiral and secondary spiral space curve equation of straight and bending on the basis of the principle of coordinate transformation and carried out wire rope solid model by UG. Using the Matlab software to make the fitting calculation of space curve's curvature and torsion to get the equation of curvature and torsion. Based on ANSYS,respectively, the straight line and bending section of wire were carried on the finite element analysis, take finite element simulation results compared with mechanical model calculation results, which verify the wire rope mechanical model is correct.Finally, based on the stress field intensity method to estimate fatigue life of wire rope.According to the result of finite element analysis of wire rope, determined the risk site of wire rope fracture, and combined with mechanical models established wire rope tensile, bending moment, torque load spectrum of dangerous parts, on this basis, wire rope fatigue life is calculated according to the linear fatigue cumulative damage theory, and the theoretical results with the test data were analyzed. The results show that: for 6 x 31 sw type + FC wire,90 t test load is the critical point for high cycle fatigue and low cycle fatigue, in all fatigue area, wire rope fatigue life prediction results are close to test results , and proved the feasibility of stress field intensity method to estimate the fatigue life of wire rope.This design that a large-diameter rope overloaded conditions of fatigue test bench offers a reference for the manufacture of fatigue test prototype, while providing a test platform for the cable fatigue testing. In addition, based on the stress field method of rope fatigue life prediction can effectively calculate the life of the cable, thus providing a theoretical guidance for safe use of ropes.