Hygrothermal Vibration Analysis Of Composite Honeycomb Panel Based On Progressive Damage

The specific strength and specific stiffness of composite honeycomb panels are better than those of metal structures.They are widely used in the primary and secondary loadbearing structures of aircraft.However,due to the special structural characteristics of the honeycomb structure,its performance will be affected by other environmental factors such as moisture,heat,and impact,resulting in damage.Therefore,it is very important to study the influence of temperature and humidity on the vibration characteristics of honeycomb panels at different damage stages for the design or repair of honeycomb panels.In this paper,the composite honeycomb core laminates are studied,and the constitutive relationship of honeycomb laminates under hygrothermal environment is deduced.The progressive damage analysis method is introduced to theoretically analyze and predict the damage process.At the same time,the influence of hygrothermal environment on the vibration characteristics of honeycomb laminates at different damage stages is explored by simulation analysis.Based on the theory of segmented shear deformation,the vibration control equation of honeycomb plate under hygrothermal environment is derived and the natural frequency is solved.Through finite element simulation,Sandwich equivalent model is used to analyze the vibration characteristics of damaged composite honeycomb panel under hygrothermal conditions.Conclusion : 1)The increase of temperature or moisture absorption will reduce the natural frequency of honeycomb panel.When the moisture absorption reaches 0.5 %,the damaged honeycomb panel will produce buckling effect and affect the change trend of natural frequency.2)The hygrothermal strain generated by the honeycomb panel does not cause damage expansion and failure of the damaged adhesive layer,but the damage area increases,which reduces the overall stiffness of the honeycomb panel and the natural frequency of each order.3)When the combined effect of damp and heat,the overall stiffness of the honeycomb panel is significantly reduced,and the influence on the vibration characteristics of the honeycomb panel is more obvious.Finally,the progressive damage analysis of composite honeycomb panel was carried out,the loss criterion was introduced,the constitutive relationship was improved,the progressive failure model was established,and the vibration characteristics of different damage states from damage generation to expansion and final failure were studied under different temperature and humidity and their combined effects.The results show that: 1)The increase of temperature or humidity will lead to the decrease of failure load of honeycomb panel,and the influence of humidity is more obvious.2)The increase of temperature or moisture absorption makes the natural frequencies of the damaged honeycomb panel decrease,and the first-order natural frequency decreases most obviously.The influence of temperature or humidity will aggravate the decreasing trend of natural frequency.3)In the process of honeycomb plate loading from damage initiation to failure,damage expansion will lead to the degradation of material performance parameters,which will greatly reduce the overall stiffness and strength of honeycomb plate,resulting in the decrease of its natural frequency.