Simulation method for precision bonding structure with micron scale adhesive layer

In order to study the interfacial adhesive material simulation method of a sandwich structure with aluminum alloy panels and a low-density foam core under edgewise compression condition, two finite element models were defined using material model no. 185 (MAT 185) adhesive element and tiebreak contact, respectively, by LS-DYNA. Under the conditions of different loading rates, and element sizes, the effects of peak load, energy absorption, failure mode of adhesive layer and the influence degree of the changing condition on the calculated results were compared between the two models, and then compared with the experiment results and theoretical results. The higher the loading rate was, or the smaller the element size was, the higher the peak load was. The simulation results obtained using MAT 185 were closer to the experimental results under the edgewise compression condition.

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Propagation of Non-Linear Lamb Waves in Adhesive Joint with Micro-Cracks Distributing Randomly

Applied Sciences ◽

10.3390/app10030741 ◽

2020 ◽

Vol 10 (3) ◽

pp. 741 ◽

Cited By ~ 2

Author(s):

Xiaoyang Li ◽

Guoshuang Shui ◽

Youxuan Zhao ◽

Yue-Sheng Wang

Keyword(s):

Adhesive Joint ◽

Lamb Waves ◽

Damage Zone ◽

Adhesive Layer ◽

Propagation Distance ◽

Element Model ◽

Matching Condition ◽

Simulation Method ◽

Micro Cracks ◽

Non Linear

With the advantages of uniform stress transfer and weight reduction, adhesive joints are widely used in engineering. The propagation of non-linear Lamb waves in an adhesive joint with micro-cracks distributing in a random way is systematically investigated by using the numerical simulation method in this paper. A finite element model of the tri-layer adhesive structure with micro-cracks distributing randomly is established, and the Lamb wave mode pair with a matching condition of the phase velocity is chosen to examine the interaction of the micro-cracks with Lamb waves. The results show that the micro-cracks within the adhesive layer will lead to the generation of second harmonics. We also find that the Acoustic Non-linearity Parameters (ANP) increase with the propagation distance in the micro-crack damage zone and the density of the micro-cracks. However, ANPs are less concerned with the friction coefficients of the surface of micro-cracks. This numerical research reveals that non-linear Lamb waves can be employed to effectively characterize the micro-cracks related damages within an adhesive joint.

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Full Waveform Simulation Method of Elastic Wave for Multi-layer Bonding Structure

2020 IEEE Far East NDT New Technology & Application Forum (FENDT) ◽

10.1109/fendt50467.2020.9337544 ◽

2020 ◽

Author(s):

Yi Hu ◽

Shi-Yuan Zhou ◽

Lu-Hang Liu ◽

Fu-Qiang Han ◽

Chun-Guang Xu

Keyword(s):

Elastic Wave ◽

Simulation Method ◽

Bonding Structure ◽

Full Waveform ◽

Waveform Simulation

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Research of Ultrasonic Oblique Incidence for Testing Bonding Strength Weakening in SRM

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.819 ◽

2013 ◽

Vol 275-277 ◽

pp. 819-824

Author(s):

Chun An Ai ◽

Yu Liu ◽

Xu Zhi Gao ◽

Li Jian

Keyword(s):

Reflection Coefficient ◽

Bonding Strength ◽

Oblique Incidence ◽

Incident Angle ◽

Average Energy ◽

Adhesive Layer ◽

Optimal Test ◽

Bonding Structure ◽

Test Strategy ◽

Reflected Wave

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.

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Preparation and characterization of thin films of carbon nitride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136891 ◽

1995 ◽

Vol 53 ◽

pp. 104-105

Author(s):

L. Wan ◽

R. F. Egerton

Keyword(s):

Carbon Nitride ◽

Arc Discharge ◽

Ion Beam ◽

Chemical Vapor ◽

Reactive Sputtering ◽

Vacuum Arc ◽

Specimen Preparation ◽

Bonding Structure ◽

Electron Energy Loss

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.

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Power of Modified Brown-Forsythe and Mixed-Model Approaches in Split-Plot Designs

Methodology ◽

10.1027/1614-2241/a000124 ◽

2017 ◽

Vol 13 (1) ◽

pp. 9-22 ◽

Cited By ~ 1

Author(s):

Pablo Livacic-Rojas ◽

Guillermo Vallejo ◽

Paula Fernández ◽

Ellián Tuero-Herrero

Keyword(s):

Repeated Measures ◽

Statistical Power ◽

Mixed Model ◽

Covariance Structure ◽

Simulation Method ◽

Future Research ◽

Repeated Measures Design ◽

Fixed And Random Effects ◽

Split Plot ◽

High Level

Abstract. Low precision of the inferences of data analyzed with univariate or multivariate models of the Analysis of Variance (ANOVA) in repeated-measures design is associated to the absence of normality distribution of data, nonspherical covariance structures and free variation of the variance and covariance, the lack of knowledge of the error structure underlying the data, and the wrong choice of covariance structure from different selectors. In this study, levels of statistical power presented the Modified Brown Forsythe (MBF) and two procedures with the Mixed-Model Approaches (the Akaike’s Criterion, the Correctly Identified Model [CIM]) are compared. The data were analyzed using Monte Carlo simulation method with the statistical package SAS 9.2, a split-plot design, and considering six manipulated variables. The results show that the procedures exhibit high statistical power levels for within and interactional effects, and moderate and low levels for the between-groups effects under the different conditions analyzed. For the latter, only the Modified Brown Forsythe shows high level of power mainly for groups with 30 cases and Unstructured (UN) and Autoregressive Heterogeneity (ARH) matrices. For this reason, we recommend using this procedure since it exhibits higher levels of power for all effects and does not require a matrix type that underlies the structure of the data. Future research needs to be done in order to compare the power with corrected selectors using single-level and multilevel designs for fixed and random effects.

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