Experimental Study On Orthogonal Coupling Resonance Phenomenon Of Aerospace Structures

Vibration environment is an important load that must be considered in the structural design of satellite equipment.At the same time,the ground vibration test of satellite equipment is a key test item to assess whether the satellite equipment can withstand the harsh dynamic environment during the launching phase.When the phenomenon of orthogonal coupling resonance occurs,the vibration response of the structure will be abnormally amplified,which will seriously damage the structure.To this end,we deeply study on the orthogonal coupling resonance phenomenon to deepen our understanding of the orthogonal coupling resonance phenomenon,so as to avoid the phenomenon’s adverse effects on the structure.The main study contents and results are as follows:(1)In order to study the influencing factors and changing laws of the orthogonal coupling resonance phenomenon,eleven vibration test models in two groups are designed and the vibration tests are carried out.According to the vibration test results,it is found that the occurrence of orthogonal coupling resonance phenomenon is independent of the vibration excitation form,structure style,and material,but is related to the section symmetry and vibration direction of the structure.The orthogonal coupling resonance will take place only when the model has the same modal frequency in both the vibration direction and the orthogonal direction.(2)The modal and vibration response simulation analysis are carried out to the FEA model of the vibration test models.By summing up the results of vibration test and comparing them with the simulation analysis results,it is found that orthogonal coupling resonance phenomenon will make structure’s acceleration response become orthogonal coupling and abnormally amplified.The specific laws of how section symmetry and vibration direction affect the orthogonal coupling resonance phenomenon are concluded as well.(3)In order to explore the occurrence mechanism of the orthogonal coupling resonance phenomenon,the dynamic equations of the model are deduced and the steady-state responses are solved under the Coriolis effect according to the characteristics of the vibration response of the model when the orthogonal coupling resonance phenomenon occurs.The steady-state response expressions in the vibration direction and the orthogonal direction of the model show that the two orthogonal modes of the model will excite each other during the vibration process,which explains the occurrence of the orthogonal coupling resonance phenomenon and the reason for abnormal response amplification.(4)Based on the results of experimental study and theoretical analysis of orthogonal coupling resonance phenomenon,an optimal design proposal to avoid and weaken orthogonal coupling resonance phenomenon is proposed.For structures with known vibration load direction in the working environment,it is necessary to adjust the vibration load direction according to the actual section shape and modes of the structure,so as to reduce or avoid the orthogonal mode coupling of the structure;For the working environment with uncertain vibration load direction,the structure should be designed as an asymmetric structure to avoid the phenomenon of orthogonal coupling resonance.