Design And Practice Of Rotary Bending Fatigue Test System For Aircraft Tube Fittings And Assemblies

There are three types of bending fatigue test systems: simple beam bending fatigue test system,cantilever bending fatigue test system and rotary bending fatigue test system.Since the first two test methods can only be bent in the vertical plane,the peak load of the alternating stress is only the highest and the lowest two points,which is far from the actual working environment of the catheter assembly.In contrast,only the rotation Fatigue test method can be achieved 360 ° all-round assessment of the loading,eliminating the impact of random factors,closer to the actual working environment.Reference to the Ministry of Aviation aircraft hydraulic pipe and its connection bending fatigue test standards(HB6442-90),Aircraft Hydraulic tubing joints and fittings-Rotary flexure test-first edition(ISO7257-1983),Aircraft-Hydraulic tubing joints and fittings-rotary flexure test(ISO7257-2016)and other relevant standards,Based on the air deflector bending fatigue testing machine type ?,a new type of air duct bending bending fatigue testing machine is designed,which includes a complete fatigue testing system including tail rotor four degree of freedom adjustment mechanism.The tailrest four degrees of freedom adjustment mechanism to achieve the adjustment from the four degrees of freedom to carry out the initial calibration of the test piece,the strain difference in the control of ± 10 micro-strain range,the goal of improving the test accuracy and expanding the scope of the test object;Through the optimization of the structure of the offset plate and so on,the improvement of the machining precision of the important parts of the testing machine has achieved the effect of reducing the vibration on the experiment,which not only reduces the noise,improves the working environment,but also increases the speed of the motor from 1600 r / min To 2300 r / min,as well as the introduction of linear bearings,so that the preparatory work to shorten the previous five times more,are higher to enhance the work efficiency;NI strain detection system and test load value real-time monitoring system to solve the resistance strain gauge operation process is complex,and the experimental process of the amount of change in the amount of observation is not intuitive and convenient.The design of the improved testing machine,through the catheter test to test,to achieve the desired goal,to improve the test accuracy,operation more easily and easily,almost ruled out because the initial calibration accuracy is not high on the experimental results,reducing noise,improve the working environment,improve work efficiency,and expand the scope of the test object.