【摘 要】
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Accurate prediction of dynamic characteristics is quite critical to understand the strength of layered structures.Nevertheless,the existing five-unknown higher-order theories encounter dif-ficulties to forecast accurately the dynamic response of sandwich
【机 构】
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School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China
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Accurate prediction of dynamic characteristics is quite critical to understand the strength of layered structures.Nevertheless,the existing five-unknown higher-order theories encounter dif-ficulties 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 sand-wich 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 pre-sented 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 mod-els,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 fre-quencies 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.
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