Higher-order vibration of thick composite and sandwich plates based on an alternative higher-order model

The transverse stretching vibration of thick sandwich plates, which is attributed to largely different stiffness at the adjacent layers, is a challenging issue, and efficient approach for such issue is less reported in the published literature. Thus, natural frequencies corresponding to stretching vibration modes are generally neglected in engineering design, which might impact structural safety as frequencies of the exciting force are close to transverse stretching vibration frequencies. This paper proposes an alternative higher-order model for dynamic analysis corresponding to the higher-order vibration modes. The proposed model is classified in the displacement-based equivalent single-layer theory, as the number of displacement parameters in the proposed model is independent of the layer number. The continuity of displacements and transverse shear stresses can be fulfilled at the interfaces between the adjacent layers of structures. To demonstrate the capability of the proposed model, typical examples are analyzed by utilizing the proposed model, the three-dimensional finite element method and the chosen higher-order models. By comparing with the exact three-dimensional elasticity solutions, it is found that the proposed model can yield more accurate natural frequencies corresponding to the higher-order displacement modes than the selected models. Moreover, the factors influencing reasonable prediction of the higher-order frequencies are investigated in detail, which can provide a reference for the accurate prediction of the higher-order frequencies.     

一种提高通用处理模块数据完整性的设计方法

航空电子产品中为了满足高安全等级应用的驻留需求，通用处理模块的数据完整性指标需要达到 Level A（10-9）级。基于当前元器件的可靠性和产品设计的复杂度，产品的数据完整性一般在10-3 到10-5 的水平， 无法满足产品的设计需求。本文提出了一种基于数据锁步的设计方法，该方法可用当前的软硬件资源在工程项 目中设计出满足高完整性要求的产品。     

基于适航的通航飞机左边界飞行安全研究

失速/尾旋一直是通航飞机面临的最严重的左边界飞行安全问题，失速/尾旋事故统计结果表明，具备尾旋改出能力，不能避免失速/尾旋造成灾难性后果。为了避免飞机出现无意偏离可控飞行的趋势，通过对“多重防御”理念和基于此理念修订的失速/尾旋条款及其符合性验证方法的解析，提出通过提升飞行员的状态感知、增强飞机抗偏离特性和降低失控危害程度等层面的通航飞机左边界飞行的多重防御体系构建方法。本文提出的方法有助于通航飞机更好的符合新规章中失速尾旋适航条款的要求，达到提升左边界飞行安全的目的。