Design Method And Experimental Study Of The Vibration Isolator For An Aero-engine Controller

Aero-engine electronic controller is one of the core components of the engine, and its reliability directly affects the reliability of the engine and the whole aircraft. During the work process, the controller suffers from vibrations and impact loads, such as the impact load caused by an aircraft to make a maneuver or landing, the narrow band sinusoidal load generated by the engine rotor system and the wideband random load generated by background excitation, etc. In order to ensure the electronic controller can work normally in complex vibration environment, there are two solutions: one is to reinforce the controller directly, another is to adopt the vibration isolation and shock resistance technology, and to install the vibration isolator between the controller and the mounting position. The cost of the first method is high, and the effect is very limited. The second method is relatively easy to implement, and the device has a simple structure, which has been widely used in aviation engine at home and abroad. In the domestic aero-engine controller, the design of the vibration isolator mainly depends on the experience and test to complete, lack of theoretical design method and process, and it is difficult to ensure the product development schedule, and the stability and reliability of the products. Therefore, it is necessary to make a thorough study of the vibration isolator used by the controller, in order to establish a scientific theory and method for the design of the isolator.In this paper, a type of GQJ vibration isolator is used as the research object, and the methods of theoretical analysis and experimental test are used to study the system. The main work and contributions of this paper are as follows:1. The forward design theory and design process of the vibration isolator are established. According to the forward design ideas of the vibration isolator, the axial and lateral characteristics of the conical spring, the establishment of the vibration isolation device analysis model, the deformation and stress of the vibration isolator in the static equilibrium state and the dynamic load process, and the fatigue life estimation of the vibration isolator are studied. The forward design flow of the vibration isolator is finally formed.2. Carry forward the optimization design of the isolator, with using the established top-down design process. In the situation of more design parameters and large parameter changes, carry out the top-down design process with the orthogonal design method, the uniform design method and the exhaustive method. In the two experimental design methods, two iteratives of design are carried out, and the first iterative design is carried out in a large range, then the number of design parameters are reduced to a more precise design. Compared the design results of the three methods, we find that the design parameters of the corresponding values are relatively close, which indicating the experimental design methods are effective, and can replace the exhaustive method in the design process of vibration isolator. Taking into account of uncertainty of processing, the sensitivity of design parameters and the robustness of the isolator’s design scheme are analyzed.3. According to the selected design scheme, we have made many vibration isolators, and then test those performance and fatigue life. Firstly, the spring characteristics, the dry friction force and the dynamic characteristics of the isolators are tested and compared with the design state. Secondly, four vibration isolators, which meet the design requirements and have same performance, are selected from the processed vibration isolators, and then an accelerated test is conducted with the four devices to evaluate the fatigue life of the isolators. Finally, the vibration isolators are tested again and the performance are compared before and after the accelerated test. We also have observed and analyzed the fracture shape of the spring to determine the spring break mode, and given a few suggestions to improve the fatigue life of the isolators.