Effects of the impactor geometrical shape on the non-linear low-velocity impact response of sandwich plate with CNTRC face sheets

In this study, non-linear low-velocity impact response of a simply supported sandwich plate with CNTRC face sheets subjected to the impactors with different geometrical shapes is investigated. It has been assumed that the sandwich plate is made up of two face sheets reinforced with CNTs graded along their thickness as X profile and a homogeneous core. In CNT-reinforced layers, a micromechanical model has been used to obtain the effective material properties and the analysis is performed in the framework of the Reddy's higher order shear deformation theory with regard to thermal effects. An analytical model is proposed to capture the response performance of the three-layer sandwich plates under different thermal environments. Through the proposed analytical study, in order to characterize the contact force between the sandwich plate and the impactors, the modified Hertz contact law is utilized. Rayleigh-Ritz method is applied to the Hamilton principle in order to find the set of equations of motion for the impactor as well as the CNTRC sandwich plate. Afterwards, the solution in the time domain is obtained based on Newmark's numerical time integration scheme. After validating the proposed approach, in order to examine the influences of various involved parameters, different parametric studies are conducted. It has been demonstrated that the variation of the initial kinetic energy as one of the parameters under study has a significant effect on the central displacement, contact force, and indentation in both conical and cylindrical impactors and the change in the radius of the cylinder has an insignificant effect on the central displacement. As well, in the case of equal masses, the cylindrical impactor causes more amount of indentation with respect to conical.

A RAIL CENTRAL DISPLACEMENT METHOD ABOUT GB-SAR

This paper presents a new method to correct rail errors of Ground Based Synthetic Aperture Radar (GB-SAR) in the discontinue mode. Generally, “light positioning” is performed to mark the GB-SAR position in the dis-continuous observation mode. Usually we assume there is no difference between the marked position and the real installation position. But in fact, it is hard to keep the GB-SAR positions of two campaigns the same, so repositioning errors can’t be neglected. In order to solve this problem, we propose an algorithm to correct the rail error after analyzing the GB-SAR rail error geometry. Results of the simulation experiment and the real experiment of a landslide in Lvliang, Shanxi, China, show the proposed method achieves an mm-level precision, enabling the D-GBSAR mode to be used in engineering projects.

A RAIL CENTRAL DISPLACEMENT METHOD ABOUT GB-SAR

This paper presents a new method to correct rail errors of Ground Based Synthetic Aperture Radar (GB-SAR) in the discontinue mode. Generally, “light positioning” is performed to mark the GB-SAR position in the dis-continuous observation mode. Usually we assume there is no difference between the marked position and the real installation position. But in fact, it is hard to keep the GB-SAR positions of two campaigns the same, so repositioning errors can’t be neglected. In order to solve this problem, we propose an algorithm to correct the rail error after analyzing the GB-SAR rail error geometry. Results of the simulation experiment and the real experiment of a landslide in Lvliang, Shanxi, China, show the proposed method achieves an mm-level precision, enabling the D-GBSAR mode to be used in engineering projects.

Dynamic Test Experimental Studies on Printing Pressure Based on Two-Dimensional Holospectum

a proper printing pressure is a basic condition for realizing offset printing and is also quality guarantee of printed products. The printing pressure should be adjusted on time according to different thickness of paper and requirements. At present, the printing pressure is mainly tested statically and pre-commissioned by experiences, so it can not reflect size of the real printing pressure and no dynamic commissioning can be carried out. In this paper, the hoho-spectrum analysis method was adopted to analyze the vibration displacement signals of cylinders, so as to obtain central displacement of two cylinders and distance and to indirectly obtain pressure between the two cylinders. The test results showed that the method could test the printing pressure effectively and dynamically.

A Variable Optical Attenuator With Tunable Mirror Curvature

A novel variable optical attenuator is proposed, fabricated, and tested here. The attenuation effect is achieved by changing the curvature of a reflection mirror membrane. In order to demonstrate the proposed principle, concave mirrors with different radii are first used to confirm the attenuation effect. Then a thermal bimorph structure with membrane is used to deform the mirror membrane at different input voltages to show the variable attenuation effect. The size of the mirror membrane, which is made of low-stress Nitride (1.0 μm) with Cr/Au (0.4 μm) on the top surface, is 800 μm × 800 μm. The major two materials in bimorph actuator are low-stress Nitride and Al (1.2 μm). Two other materials, Poly-Si (0.4 μm) and SiO2 (0.5μm), act as the heating and insulation layers in the bimorph beams, respectively. The minimum insertion loss of the attenuator is found to be 0.74 –dB. The attenuation and deflections of the mirror membrane at the central part are calibrated at different input voltages. It shows that and the attenuation is more than 40 –dB at input voltage of 44 V when the central displacement of the mirror membrane is about 16 μm.