Dynamic Response Analysis And Fatigue Life Prediction Of Composite Laminate Under Noise Loading

In recent years, with the rapid development of aerospace field, there are some studies for the aircraft structures. And more attentions have also paid on the noise fatigue problems for aircraft structures. Composite laminates with the high intensity have been widely used in all types of aircrafts. But thinness laminate may have noise fatigue failure when a high dB noise is applied on the laminate. The sonic problems are relevant to the dynamic response, damage accumulation and failure of composites under noise loading. And the dynamic response analysis of laminate under noise loading is the foundation for the sonic fatigue analysis. The acoustic pressure is far lower than the strength of the laminates, but the factors including resonance and wide frequency range of noise should be taken into account. Therefore, the response analysis of laminated plates with different boundary conditions and different structure configurations is required to be further analyzed. It is a long history to study the noise problem. And the sound insulation and noise reduction are widely investigated. But few references are about the noise response. The noise response analysis for the laminates with holes and delamination is required to be studied urgently in the application. Based on the noise response analysis, the sonic fatigue damage and life analysis for laminates is essential to evaluate the composite structures in the engineering.In this thesis, the noise response mechanisms of the composite laminates are introduced, and the dynamic response model of the composite laminates is established. The equilibrium differential equation, the modal equation and the stress strain response equation of laminated plates are deduced.Using ABAQUS finite element software, natural frequency for two kinds of laminates, C/SiC and T300/HD03, is calculated. The effect of different boundary conditions, holes and hierarchical on the natural frequency, of C/SiC composite laminated, is studied. And the natural frequency of the T300/HD03 laminates with different ply angle and ply location is analyzed. At the same time, the numerical results are verified by the experimental data from other references.Finally, based on the stress strain response equation and the calculation of natural frequency, noise response model of the laminate plate is established. The effect of the air, frequency variation, different sound pressure and different boundary conditions on the response of the laminate plate is studied. In addition, the different root mean square value, the fatigue life and the cumulative damage are analyzed.In this thesis, the noise response calculation method and noise fatigue damage analysis for the composite laminates are provided, which can be helpful to analyze and solve sonic fatigue problem fot aerospace composite laminates structure and to improve significantly the serviceability of structure.