| Failure of mechanical component induced by impact fretting exists widely in power systems, petrochemical equipment, mining machinery, marine machinery, aerospace and other fields, which brings greater security risks to the safe operation of major equipment and greatly shortens its service life. So developing an impact fretting wear tester that may simulate the impact fretting wear conditions has very important scientific value. In this paper, the impact fretting wear tester can evaluate impact wear properties and absorption characteristics of energy of different material structure or metal interface. Besides, it will provide important experimental basis for life prediction research.Based on functional requirements and technical specifications of the tester, a multifunctional impact fretting wear rig was designed. Through the coordinated operation of mechanical structure system, motion control system and data acquisition systems, the testing machine can achieve the functions that controlled by impact contact force or impact energy. And it can realize the measurement of the impact contact force, contact time, interface deformation, impact energy dissipation and the impact velocity. Setting the Zr-4 alloy tube as the research object, changing the outer diameter or wall thickness of the tube that will result in the changing of D/t ratio, and then study the dynamic response and the damage behavior under constant impact energy, finally explore the damage mechanism of it.The research work of the impact fretting wear tester is as follows:(1) Overall design of impact fretting test rigAccording to the requirement analysis result of the test rig and the system principle, mechanical structure and appearance of the servo lifting module, impact fretting module controlled by contact force and impact fretting module controlled by impact energy were designed. Finally, complete the selection, checking, customization, calibration of the core components of the system.(2) Hardware circuit design of the systemFirstly, complete the overall design of the electrical system. Then design the circuit of the servo lift electrical system, voice coil motor control systems, signal acquisition and analysis system. Then design the motion control programming for the servo lift electrical system and voice coil motor control systems. Finally, each system module was debugged. Besides, the acquisition, processing and analysis method of the signals were described.(3) Software design for the systemAt first, needing analysis and overall design of software system were completed. Secondly, achieve the programming of the communicated connection module, parameter setting module, position adjustment module, start and stop module, dynamic data display module, data acquisition and storage module. Finally, each module was integrated and the whole system control interface was designed.In this paper, the impact wear affected by Zr-4 alloy tube’s D/t ratio was also investigated, and the behaviors influenced by the outer diameter and wall thickness were explored. Some conclusion can be found:(1) Under the same outer diameter of the tube, with the D/t value increasing, the contact time will be longer, peak force, energy absorption ratio and degree of the damage will reduce, during the impact wear.(2) Under the same wall thickness of the tube, with the D/t value increasing, the contact time will be shorter, peak force, energy absorption ratio and depth of the wear scar will reduce, during the impact wear.(3) Under the same outer diameter of the tube, with the bending section coefficients value increasing, the bending deformation will reduce, peak force, energy absorption ratio and degree of the damage will increase, during the impact wear. Under the same wall thickness of the tube, with the bending section coefficients value increasing, the bending deformation and energy absorption ratio will reduce.(4) Oxidation and contact fatigue spalling are the mainly wear mechanism of Zr-4 tube under impact wear effect. |
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