An advanced five-unknown higher-order theory for free vibration of composite and sandwich plates

Accurate prediction of dynamic characteristics is quite critical to understand the strength of layered structures. Nevertheless, the existing five-unknown higher-order theories encounter difficulties to forecast accurately the dynamic response of sandwich structures. Therefore, a new five-unknown higher-order theory is developed for free vibration analysis of composite and sandwich plates, which possesses the same degree of freedom as those of other five-unknown higher-order theories. The developed model can meet beforehand interlaminar continuity conditions and the free-surface conditions of transverse shear stresses. To assess capability of the proposed model, analytical solution for such composite structures with simply-supported conditions has been presented by employing Hamilton’s principle, which is utilized for analysis of mechanical behaviors of composite and sandwich plates. Compared with the three-dimensional (3D) elasticity solutions, 3D finite element results and the results obtained from the chosen five-unknown higher-order models, the proposed model can yield accurately natural frequencies of composite and sandwich plates. Even for the thick plates, the higher-order frequencies calculated from the proposed model are in good agreement with the 3D finite element results. By studying effect of the thickness/length ratios on natural frequencies, it is found that the proposed model is adaptable to predicting natural frequencies of the sandwich plates with the thickness/length ratios between 1/4 and 1/100. In addition, some factors influencing accuracy of five-unknown higher-order models have been investigated in detail. Finally, by means of numerical analysis and discussion, some conclusions have been drawn as well, which can serve as a reference for other investigators.     

ON THE STABILITY OF ANISOTROPIC VISCOELASTIC THIN PLATES

Uptonow,someanalyses['~'Jhavebeendoneoncreepbucklingofviscoelasticstruc-tures.However,nomethodhaseverbeengiventodeterminethedurablecriticalloadofvis-coelasticstructuressubjectedtoadurableload.OnlyTroyanovskii['jsubmittedamethodtode-terminethedurablecriticalloadofisotropicviscoelasticthinplatesbutgavenoexample.Thededucingandcalculatingmethodinthispapercanbeusedtoresolvethecreepbucklingques-tionsofotheranisotropicviscoelasticplatesandshells.lAnalysisThecreepbucklingofanorthotropicviscoelastict…     

半平板周期断裂问题

本文讨论裂纹在交线上的周期半平板焊接问题,求得了平衡应力场的封闭解,给出了一些数值结果。     

复合材料舷窗大开口结构强度研究

复合材料舷窗结构作为飞行器的重要组成部件,对其强度进行研究具有重要意义。采用试验与数值模拟相结合的方法对舷窗结构的力学行为进行研究,首先得到结构件的极限剪切载荷,然后建立基于连续介质损伤力学(CDM)的数值模型进行仿真模拟。结果表明:所建立的数值模型可以准确预测结构件的强度值及损伤破坏部位。     

Impact of aperture on dynamic response of sandwich plates with aluminium face-sheets and PMI core based on an alternative finite element formulation and experiments

Apertures generally exist in the sandwich structures attributing to mechanical connection and lightweight, which might induce failure of such structures. Thus, it is required to realize the impact of aperture on mechanical behaviors of sandwich structures. If transverse shear deformations are unable to be described accurately, the reasonable prediction of dynamic behaviors of the form-core sandwich plates with apertures will meet severe challenges due to a large difference of transverse shear mo...