Influence Of Interface Defects on Ultrasonic Reflection/Transmission Characteristics of Thick Adhesive Layer Composite Bonding Structure

Author(s):  
Bing LIU ◽  
Bin WU ◽  
Yan LYU ◽  
Guo-rong SONG ◽  
Xie-hong SONG ◽  
...  
2013 ◽  
Vol 281 ◽  
pp. 448-452 ◽  
Author(s):  
Chang Liang Li ◽  
Da Zhi Jiang ◽  
Jing Cheng Zeng

In this work, the hybrid fabrics of carbon and quartz fibers as filters were adopted in PMI core sandwich structures for low-observable radomes. The advantages of fabric composite frequency selective surfaces (FCFSSs) are easily fabricated by braiding and shaped into curved surfaces. This paper mainly studied the electromagnetic (EM) transmission characteristics of the low-observable radome wall with composite FSS by 3-dimensional electromagnetic analysis software. First of all, the accuracy of the simulation model composed of up and down composite face sheets, a layer of composite FSS and PMI core was validated by comparing with experimental results. Then, the studies on electromagnetic transmission characteristics of the sandwich structure with composite FSS and the sensitivity analysis about the thickness and permittivity of face sheets and PMI core were carried out. The results show that the sandwich structure with single layer composite FSS can realize the function of frequency selection, limit the reflection at the resonance frequency and decrease the sensitivity of EM transmission loss about the thickness of sandwich structures.


2013 ◽  
Vol 275-277 ◽  
pp. 819-824
Author(s):  
Chun An Ai ◽  
Yu Liu ◽  
Xu Zhi Gao ◽  
Li Jian

According to bonding strength weakening in SRM bonding structure, the decreases of elastic modulus in adhesive layer have been used to characterise the bonding strength weakening in adhesive layer. Ultrasonic propagation characteristics with bonding strength weakening in adhesive layer has been simulated. Based on analysing the relation between reflection coefficient and incident angle, the optimal test strategy has been put forward. According to test strategy, the experiment of ultrasonic oblique incidence has been done to test bonding strength weakening, the average energy of reflected wave from test points has been taken as signal property to characterise reflection coefficient. The results show that the energy of reflected wave can reflect the extent of bonding strength weakening, can effectively achieve quantitative test of strength weakening.


Procedia CIRP ◽  
2018 ◽  
Vol 76 ◽  
pp. 100-105
Author(s):  
Xiao Chen ◽  
Zhijing Zhang ◽  
Xin Jin ◽  
Muzheng Xiao ◽  
Huan Guo ◽  
...  

Author(s):  
L. Wan ◽  
R. F. Egerton

INTRODUCTION Recently, a new compound carbon nitride (CNx) has captured the attention of materials scientists, resulting from the prediction of a metastable crystal structure β-C3N4. Calculations showed that the mechanical properties of β-C3N4 are close to those of diamond. Various methods, including high pressure synthesis, ion beam deposition, chemical vapor deposition, plasma enhanced evaporation, and reactive sputtering, have been used in an attempt to make this compound. In this paper, we present the results of electron energy loss spectroscopy (EELS) analysis of composition and bonding structure of CNX films deposited by two different methods.SPECIMEN PREPARATION Specimens were prepared by arc-discharge evaporation and reactive sputtering. The apparatus for evaporation is similar to the traditional setup of vacuum arc-discharge evaporation, but working in a 0.05 torr ambient of nitrogen or ammonia. A bias was applied between the carbon source and the substrate in order to generate more ions and electrons and change their energy. During deposition, this bias causes a secondary discharge between the source and the substrate.


2019 ◽  
pp. 97-104
Author(s):  
Mikhail V. Tarasenkov ◽  
Egor S. Poznakharev ◽  
Vladimir V. Belov

The simulation program by the Monte Carlo method of pulse reactions of bistatic atmospheric aerosol-gas channels of optical-electronic communication systems (OECS) is created on the basis of the modified double local estimation algorithm. It is used in a series of numerical experiments in order to evaluate statistically the transfer characteristics of these channels depending on the optical characteristics of an atmosphere plane-parallel model for wavelengths λ = 0.3, 0.5, and 0.9 μm at a meteorological visibility range SM = 10 and 50 km. The results are obtained for a set of basic distances between the light source and the light receiver up to 50 km and for the angular orientations of the optical axes of a laser radiation beam and of the receiving system in a wide range of their values. The dependences of the pulse reactions maximum values over-the-horizon channels of the OECS on the variations of these parameters are established.


Author(s):  
Luiz Felipe Ribas Motta ◽  
Guilherme Silva Prado ◽  
Venicio Silva Araujo ◽  
Heinsten Frederich Leal dos Santos

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