Damage initiation and fracture analysis of honeycomb core single cantilever beam sandwich specimens

2020 ◽  
pp. 109963622090982 ◽  
Author(s):  
Vishnu Saseendran ◽  
Pirashandan Varatharaj ◽  
Shenal Perera ◽  
Waruna Seneviratne

Fracture testing and analysis of aerospace grade honeycomb core sandwich constructions using a single cantilever beam test methodology is presented here. Influence of various parameters such as facesheet thickness, core density, honeycomb cell-size, and core thickness were studied. A Winkler-based foundation model was used to calculate compliance and energy-release rate, and further compare with finite element model and experiments. A cohesive zone model was developed to predict the disbond initiation and simulate the interface crack propagation in the single cantilever beam sandwich specimen. The mode I interface fracture toughness obtained from the translating base single cantilever beam setup was provided as input in this cohesive zone model. It is shown that the presented cohesive zone approach is robust, and is able to capture the debonding phenomenon for majority of the honeycomb core specimens.

Author(s):  
Hussain Altammar ◽  
Sudhir Kaul ◽  
Anoop Dhingra

Damage detection and diagnostics is a key area of research in structural analysis. This paper presents results from the analysis of mixed-mode damage initiation in a composite beam under thermal and mechanical loads. A finite element model in conjunction with a cohesive zone model (CZM) is used in order to determine the location of joint separation as well as the contribution of each mode in damage (debonding) initiation. The composite beam is modeled by using two layers of aluminum that are bonded together through a layer of adhesive. Simulation results show that the model can successfully detect the location of damage under a thermo-mechanical load. The model can also be used to determine the severity of damage due to a thermal load, a mechanical load and a thermo-mechanical load. It is observed that integrating thermal analysis has a significant influence on the fracture energy.


Author(s):  
Chris Bassindale ◽  
Xin Wang ◽  
William R. Tyson ◽  
Su Xu

Abstract In this work, the cohesive zone model (CZM) was used to examine the transferability of the crack tip opening angle (CTOA) from small-scale to full-scale geometries. The pipe steel STPG370 was modeled. A drop-weight tear test (DWTT) model and pipe model were studied using the finite element code ABAQUS 2017x. The cohesive zone model was used to simulate crack propagation in 3D. The CZM parameters were calibrated based on matching the surface CTOA measured from a DWTT finite element model to the surface CTOA measured from the experimental DWTT specimen. The mid-thickness CTOA of the DWTT model was in good agreement with the experimental value determined from E3039 and the University of Tokyo group’s load-displacement data. The CZM parameters were then applied to the pipe model. The internal pressure distribution and decay during the pipe fracture process was modeled using the experimental data and implemented through a user-subroutine (VDLOAD). The mid-thickness CTOA from the DWTT model was similar to the mid-thickness CTOA from the pipe model. The average surface CTOA of the pipe model was in good agreement with the average experimental value. The results give confidence in the transferability of the CTOA between small-scale specimens and full-scale pipe.


Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1531 ◽  
Author(s):  
Guilpin ◽  
Franciere ◽  
Barton ◽  
Blacklock ◽  
Birkett

Adhesive bonding of polyethylene gas pipelines is receiving increasing attention as a replacement for traditional electrofusion welding due to its potential to produce rapid and low-cost joints with structural integrity and pressure tight sealing. In this paper a mode-dependent cohesive zone model for the simulation of adhesively bonded medium density polyethylene (MDPE) pipeline joints is directly determined by following three consecutive steps. Firstly, the bulk stress–strain response of the MDPE adherend was obtained via tensile testing to provide a multi-linear numerical approximation to simulate the plastic deformation of the material. Secondly, the mechanical responses of double cantilever beam and end-notched flexure test specimens were utilised for the direct extraction of the energy release rate and cohesive strength of the adhesive in failure mode I and II. Finally, these material properties were used as inputs to develop a finite element model using a cohesive zone model with triangular shape traction separation law. The developed model was successfully validated against experimental tensile lap-shear test results and was able to accurately predict the strength of adhesively-bonded MPDE pipeline joints with a maximum variation of <3%.


Computation ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Ikramullah ◽  
Andri Afrizal ◽  
Syifaul Huzni ◽  
Sulaiman Thalib ◽  
H. P. S. Abdul Khalil ◽  
...  

The microbond test for natural fibers is difficult to conduct experimentally due to several challenges including controlling the gap distance of the blade, the meniscus shape, and the large data spread. In this study, a finite element simulation was performed to investigate the effects of the bonding characteristics in the interface between the fiber and matrix on the Typha fiber/epoxy microbond test. Our aim was to obtain the accurate mesh and cohesive properties via simulation of the Typha fiber/epoxy microbond test using the cohesive zone model technique. The axisymmetric model was generated to model the microbond test specimen with a cohesive layer between the fiber and matrix. The cohesive parameter and mesh type were varied to determine the appropriate cohesive properties and mesh type. The fine mesh with 61,016 elements and cohesive properties including stiffness coefficients Knn = 2700 N/mm3, Ktt = 2700 N/mm3, and Kss = 2700 N/mm3; fracture energy of 15.15 N/mm; and damage initiation tnn = 270 N/mm2, ttt = 270 N/mm2, and tss = 270 N/mm2 were the most suitable. The cohesive zone model can describe the debonding process in the simulation of the Typha fiber/epoxy microbond test. Therefore, the results of the Typha fiber/epoxy microbond simulation can be used in the simulation of Typha fiber reinforced composites at the macro-scale.


Author(s):  
Yong Chen ◽  
Wang Wenhao ◽  
Wei Dong ◽  
Mo Li ◽  
Lei Lei

Accumulation of ice on aeroengine components could cause serious aircraft accidents. An understanding of the adhesion characteristics of ice-substrate interfaces is essential in order to design reliable anti-icing and de-icing systems. The main purpose of this paper is on the application of a bilinear cohesive zone model to simulate the interface between ice and aluminum by using ANSYS software. A finite element model which coupled with the cohesive zone model is built and some factors that affect the Al/ice tensile strength are discussed. These factors include interface roughness, initial damage of the interface, which is caused by the existence of bubbles. The adhesion strength between ice and aluminum are predicted and analyzed. This model could be used to further study on the mechanisms responsible for the non-linear relationship between the surface roughness and ice adhesion strength.


2019 ◽  
Vol 953 ◽  
pp. 65-71
Author(s):  
Xiao Ming Yu ◽  
Bin Zhang ◽  
Jia Min Shen ◽  
Yue Li ◽  
Sai Sai Liu

A finite element model on the single fiber pull-out test of short fiber reinforced rubber matrix sealing composites (SFRC) were established. The effects of the interphase properties on the interfacial stress distribution and initial debonding strain are investigated based on the cohesive zone model (CZM). The influences of interphase thicknesses and elastic modulus on the interfacial debonding behavior of SFRC are obtained. The results show that the interfacial initial debonding strain increases with the increasement of interphase thickness, and it decreases with the increasement of interphase elastic modulus. An interphase thickness of 0.4 μm and an interphase elastic modulus of about 750 MPa are optimal to restrain the initiation of the interfacial debonding.


2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Nuri Setyo Taufiqqurrahman ◽  
Mas Irfan Purbawanto Hidayat ◽  
Amaliya Rasyida

Author(s):  
Javed Iqbal

Abstract: This study describes the development of Continuum and Discrete Damage Models in commercial finite element code Abaqus/Standard. The Concrete Damage Plasticity Model has been simulated, analysed, and compared the result with the experimental data. For verification, the Cohesive Zone Model has been simulated and analysed. Furthermore, the Extended Finite Element Model and concrete damage model are discussed and compared. The continuum damage model tends to simulate the complex fracture behaviour like crack initiation and propagation along with the invariance of the result, while the cohesive zone model can simulate and propagate the crack as well as the good agreement of the result. Further work in the proposed numerical models can better simulate the fracture behaviour of asphalt concrete in near future. Keywords: Model, Concrete, Cohesive Zone, Finite element, Abaqus.


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