High strain rate deformation of explosion-welded Ti6Al4V/pure titanium

Multilayer materials are widely used in military, automobile and aerospace industries. In this paper, the response of an explosion-welded Ti6Al4V/pure titanium with a flat interface to dynamic loading is investigated. An SHPB apparatus is used. Then, the dynamic behaviour of a bimetal sample is explored with a DIC system coupled to the SHPB. Result indicates that in the bimetal sample pure titanium is deformed and failed before Ti6Al4V. The stress curve of the sample shows two different peaks in a striker velocity higher than the 18.3 m/s. When the incident wave encounters the interface of the Ti6Al4V/pure titanium sample, only a small fraction of the wave is reflected owing to similar impedance. Using the direct interpretation stress-strain curve is unreasonable in this case because of unhomogenised plastic deformation. The microstructure of the sample is investigated after loading. An adiabatic shear band is formed in the pure titanium side before failure, and the interface of the sample remains intact under different loading conditions. The FEM simulation result for the sample is in good agreement with experimental observations.     

Responses of HFR-LWC beams under close-range blast loadings accompanying membrane action

The load-carrying capacities and failure patterns of reinforced concrete components can be significantly changed by membrane effects. However, limited work has been carried out to investigate the blast resistance of Hybrid Fiber Reinforced Lightweight Aggregate Concrete (HFR-LWC) members accompanying membrane action. This paper presents a theoretical approach to quantitatively depicting the membrane behavior and its contribution on the behavior of HFR-LWC beams under close-range blast loadings, and the suitability of the proposed model is validated by a series of field tests. An improved Single-Degree-of-Freedom (SDOF) model was employed to describe the dynamic responses of beam-like members under blast loadings accompanying membrane action, where the mass-load coefficient is determined according to the nonuniformly distributed load induced by close-range explosion, and the membrane action is characterized by an in-plane (longitudinal) force and a resisting moment. The elasto-plastic and recovery responses of HFR-LWC beams under the combined action of blast load and membrane force were analyzed by the promoted model. A specially built end-constrain clamp was developed to provide membrane action for the beam member when they are subjected to blast load simultaneously. It is demonstrated that the analytical displacement-time histories are in good agreement with experimental results before peak deflections and that the improved SDOF model is an acceptable tool for predicting the behavior of HFR-LWC beams under blast loadings accompanying membrane action.     

数据采集中脉冲丢失补偿算法

针对测试中遇到的脉冲丢失问题,采用脉冲边沿、脉冲到达时间和脉冲间隔等特征量,设计了快速进行脉冲丢失位置定位和补偿的算法。仿真结果表明,该算法能有效地解决脉冲丢失的问题,对脉冲敏感型的数据分析和故障诊断具有重要意义。     

一种改善雷达测距测角精度的窄带补偿方法

多通道间幅相不一致会影响三维成像雷达的成像质量。针对步进频率体制三维成像雷达,分析了系统窄带部分通道间幅相不一致对目标三维(距离、方位角、俯仰角)成像的影响,并提出了一种基于中频注入补偿信号的补偿方法。