Analysis And Experimental Study On Vibration Characteristics Of Exhaust Pipe Of Automobile Air Conditioning

In the process of vehicle driving,the automobile air conditioning system will be stimulated by various complex loads such as engine and compressor.If the design of the pipeline system does not meet the requirements,fatigue fracture will occur in the air conditioning pipeline under the excitation,which will seriously affect the safety of the vehicle.With the continuous improvement of users' requirements on the comfort and reliability of automobile driving,a lot of theoretical and experimental studies have been carried out on automobile air conditioning pipeline in China,but the actual pipeline structure will still fail.Therefore,it is necessary to study the vibration characteristics of automobile air conditioning pipeline to ensure the reliability of automobile air conditioning system.In this paper,combined with the practical problems in the design and development of new automobile air conditioning exhaust pipes,the following aspects are studied:The development process,working principle and vibration research of automobile air conditioning piping system at home and abroad were summarized by referring to relevant literature.The importance of the study on the vibration characteristics of automobile air conditioning system is discussed.The modal analysis theory of single-degree-of-freedom system and multi-degree-of-freedom system and the response analysis theory of single-degree-of-freedom system are studied,and the modal analysis and harmonic response analysis of the classical cantilever beam model are given.In this paper,the model of exhaust pipe of automobile air conditioning is equivalent simplified,the finite element model of exhaust pipe is established,and the material nonlinearity and contact nonlinearity and their treatment methods are studied and discussed.The modal analysis of the finite element analysis model is carried out according to the actual working condition,and the natural frequency and modal mode of the pipeline are obtained.The vibration characteristics of the pipeline are analyzed with the effective mass and the participation coefficient,and the influencing factors of the modal analysis results are discussed.By comparing the direct integration method with the modal superposition method,the harmonic response analysis based on the modal superposition method is carried out,and the data post-processing is carried out on the response data to complete the result data conversion of different excitation methods.Finally,the vibration test of the vibration table of the exhaust pipe was carried out to obtain the actual resonance position of the exhaust pipe.The test results were compared with the simulation results,and the causes of the errors were analyzed.In this paper,the finite element simulation and vibration test of the exhaust pipe are completed by combining with the vibration analysis theory,and the response results are processed to obtain the frequency response data.The bidirectional check of the air conditioning exhaust pipe is carried out through simulation and experiment,and the feasibility of a new design scheme of the exhaust pipe is verified,which points out the direction for the further optimization of the pipeline and has important research significance.