Research On Bending Fatigue Characteristics Of Wire Rope And Test System

Wire rope is used widely in various engineering fields as a flexural member with high strength and impact resistance, while the fatigue damage phenomenon thereof would result significant security risk in practice. Because of the complex wire ripe structure and various working conditions, as well as a number of factors impacting on the bending fatigue of wire rope,it is difficult to obtain a desired result through only theoretical analysis. Therefore,the effective research method is to combine the theoretical analysis and experimental study.Now, there are few researches about the bending fatigue characteristics of wire rope, even less systematic experimental basis. In order to assure the security and reliability of wire rope in use, it has great theoretical value and practical significance to study the bending fatigue characteristic of wire rope and the testing system.The paper establishes mathematics and mechanics models for a length of wire rope bending around the pulley, over the study object of 6×7IWS wipe rope. On this basis, main factors for the bending fatigue characteristic of the wire rope are studied. In consideration of the factors above,this paper presents a testing scheme on the bending fatigue of the wire rope,in accordance with which,a further study is performed subsequently and thus a testing system for wire rope bending fatigue with hydraulic-driving automatic control, high load and a large travel is designed.The main work of the paper focuses on the following aspects:First, on the basis of space and differential geometry, the mathematics and mechanics models for the length of wire rope bending around the pulley are made and the bending stress distribution thereof is analyzed. After that, finite element emulations on the length of wire rope based on ANSYS Workbench, to study the factors impacting on the bending fatigue of wire rope.Secondly, in according to the above factors impacting on the bending fatigue of wire rope, the scheme of wire rope bending fatigue is studied including the design of primary testing factors and experimental flow specification. The design objective and technical requirements are determined, over which the general scheme of the testing system for wire rope bending fatigue is obtained, that is: loading under a constant large load with high precision is achieved in the system via a hydraulic cylinder whose pressure is adjusted by an electronic pump; a reciprocating motion with a large travel is realized by being driven back and forth via a dual-cylinder; and the control flow of the system in different load modes is designed.Then,a loading system,a driving system,a monitoring system are designed in detail respectively. Specifically, a pressure compensation algorithm based on neural network is designed to compensate the pressure of the loading system, thereby offsetting the effect of temperature on loading precision, and therefore guaranteeing the error precision of the loading system. Furthermore, a control strategy of dual-cylinder synergy is presented,the dual-cylinder driving system is simulated through AMEsim, to verify the stability of the driving system; Additionally, the human-computer interface procedure based on MFC testing system is designed, and the test database system is designed through SQL Server, to achieve the function of monitoring and recording the test data, processing analysis, managing inquiry,maintaining the testing system and the like.Finally, function debugging and performance testing in relation to the wire rope bending fatigue testing system are made. Specifically, the functions of each subsystem of the testing system are debugged respectively which comprises loading function debugging, driving function debugging and monitoring software performance debugging, to verify the veracity of loading performance and the stability of the driving system. Additionally, taking the combined loading for example, the testing system is debugged in combination, to achieve a continuous automatic control even under a high load and a large travel.