scholarly journals Predicting interlaminar damage behaviour of fibre-metal laminates containing adhesive joints under bending loads

2021 ◽  
pp. 073168442110517
Author(s):  
Ahmad SM Al-Azzawi ◽  
Luiz F Kawashita ◽  
Carol A Featherston
Keyword(s):  
Cohesive Zone ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Adhesive Joints ◽  
Interfacial Shear ◽  
Zone Model ◽  
Shear Stresses ◽  
Bending Loads ◽  
Fibre Metal ◽  
Fibre Metal Laminate

This study includes experimental and numerical investigations on fibre-metal laminate structures containing adhesive joints under static bending loads. Experimental tests were carried out on Glare® 4B specimens manufactured in-house and containing doubler joint features. Numerical analyses were performed using Abaqus software including damage in the glass fibre reinforced polymer layers, ductile damage in the resin pockets (FM94 epoxy) and plasticity in the metal layers. A new cohesive zone model coupling friction and interfacial shear under through-thickness compressive stress has been developed to simulate delamination initiation and growth at the metal/fibre interfaces with the adhesive joint under flexural loading. This model is implemented through a user-defined VUMAT subroutine in the Abaqus/Explicit software and includes two main approaches, firstly, combining friction and interfacial shear stresses created in the interlaminar layers of the fibre-metal laminate as a result of through-thickness stresses and secondly, considering elastic-plastic damage behaviour using a new cohesive zone model based on the trapezoidal law (which provides more accurate results for the simulation of toughened epoxy matrices than the commonly used bilinear cohesive zone model). Numerical results have been validated against experimental data from 4-point bending tests and a good correlation observed with respect to both crack initiation and evolution. Delamination and shear failure were noted to be the predominant failure modes under bending stresses as expected. This is due to the higher mode-II stresses introduced during bending which cause different damage evolution behaviour to that seen for axial stresses. Finite element results revealed that both friction and shear strength parameters generated from through-thickness compression stresses have a significant effect in predicting damage in fibre-metal laminate structures under this type of loading.

Experimental and numerical analysis of dual-adhesive stepped-lap aluminum joints

2020 ◽  
Vol 234 (5) ◽  
pp. 454-464
Author(s):  
CL Ferreira ◽  
RDSG Campilho ◽  
RDF Moreira
Keyword(s):  
Cohesive Zone ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Stress Gradient ◽  
Maximum Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Zone Model ◽  
Behavior Prediction ◽  
Adhesive Bonds

The use of adhesive bonds has attracted considerable interest from the scientific community. Stepped-lap joints have the advantage of decreasing stress gradients along the bond length, although the outer steps still encounter stress levels above the steps in the inner zone of the joint. One possible way to reduce this stress gradient is to combine this type of joint with the use of two adhesives. This work consists of an experimental and numerical evaluation of stepped-lap dual-adhesive joints between aluminum adherends, for various overlap lengths ( LO), and comparison with stepped-lap single-adhesive joints. The adhesives Araldite® AV138, Araldite® 2015, and Sikaforce® 7752 were evaluated. Numerically, cohesive zone models with a triangular damage law were applied in the joint behavior prediction. The analysis of the results is presented in the form of failure modes, stress analysis, damage variable analysis, load–displacement ( P–δ) curves and maximum load ( Pm), and energy required to failure ( U). It was concluded that, in general, cohesive zone model presented precise predictions. In general, no significant increase in strength was achieved with dual-adhesive joint but, on the other hand, significant energy increases were obtained.

scholarly journals Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

2020 ◽  
Vol 10 (19) ◽  
pp. 6640
Author(s):  
Zhonghua Shi ◽  
Zhenhang Kang ◽  
Qiang Xie ◽  
Yuan Tian ◽  
Yueqing Zhao ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Lead Zirconate ◽  
Efficiency Factor ◽  
Zone Model ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Total Energy Density ◽  
Average Shear

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

scholarly journals Strength prediction of adhesive joints after cyclic moisture conditioning using a cohesive zone model

2011 ◽  
Vol 78 (16) ◽  
pp. 2746-2760 ◽  
Author(s):  
A. Mubashar ◽  
I.A. Ashcroft ◽  
G.W. Critchlow ◽  
A.D. Crocombe
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Adhesive Joints ◽  
Strength Prediction ◽  
Zone Model

Cohesive Zone Model for Moist Adhesive Joints

2018 ◽  
pp. 405-426
Author(s):  
Olaf Hesebeck ◽  
Florian Goldschmidt ◽  
Stefan Diebels
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Adhesive Joints ◽  
Zone Model

scholarly journals Numerical Representation of Multiple Premature Failures in Steel-Plated RC Beams

2017 ◽  
Vol 14 (04) ◽  
pp. 1750035 ◽  
Author(s):  
Mohammad Arsalan Khan ◽  
Jamal El-Rimawi ◽  
Vadim V. Silberschmidt
Keyword(s):  
Crack Initiation ◽  
Cohesive Zone ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Numerical Representation ◽  
Rc Beams ◽  
Premature Failure ◽  
Different Types ◽  
Complete Failure

Realizing the importance of widely used technique of plating for flexural retrofitting of reinforced concrete (RC) beams and its drawbacks due to premature failure(s), present work concentrates in developing a finite element tool model capable of successfully capturing multiple premature failure modes and their corresponding behaviors. The model is simple but focused; the capability and accuracy of the results have been validated through test literature, particularly focusing on the load capacities of beams at progressive stages of failure modes; which is from crack initiation through to complete failure, such as the load of crack initiation, first crack and complete failure. Acceptable accuracy is shown in terms of crack type(s), crack patterns, sequence, location and direction of propagation through the innovative use of cohesive zone model (CZM). The model clearly explains that debonding and peeling, although originating from a same location for most cases, are extensions of different types of cracks.

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