Thermo-Mechanical Analysis of Mixed-Mode Damage: Cohesive Zone Modeling

2015 ◽  
Author(s):  
Hussain Altammar ◽  
Sudhir Kaul ◽  
Anoop Dhingra
Keyword(s):  
Cohesive Zone ◽  
Composite Beam ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Mechanical Load ◽  
Element Model ◽  
Mechanical Analysis ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Damage Initiation

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.

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
Keyword(s):  
Cantilever Beam ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Interface Fracture ◽  
Zone Model ◽  
Honeycomb Core ◽  
Damage Initiation ◽  
Foundation Model ◽  
Honeycomb Cell

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.

A cohesive zone model for predicting the initiation of Mode II delamination in composites under cyclic loading

2020 ◽  
pp. 073168442094966
Author(s):  
Roham Rafiee ◽  
Sina Sotoudeh
Keyword(s):  
Numerical Simulation ◽  
Cyclic Loading ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Cohesive Elements ◽  
Damage Criterion ◽  
Damage Initiation ◽  
Number Of Cycles

A new approach for simulating delamination initiation under cyclic loading is proposed. This approach is based on the hysteresis cohesive zone modeling and the gradual degradation of interface properties. The initiation of delamination is predicted based on the monotonic traction–separation law of the interface. A damage criterion is proposed that depends on the bilinear traction–separation law and interlaminar stiffness is degraded by defining a damage parameter as a function of number of cycles and bilinear traction–separation law parameters. Numerical simulation is accomplished by implementing 2D finite element modeling for the case of double-notched specimen. Four-node zero-thickness interfacial cohesive elements are defined to capture the delamination behavior of midplane in the specimen. The results of numerical simulation are compared with available experimental data and a good agreement is observed. The main novelty of this research lies on assuming a cycle-by-cycle irreversible decrease in interlaminar stiffness prior to damage initiation and applying a damage criterion based on the bilinear traction–separation law in order to predict the number of cycles for initiation of delamination.

scholarly journals An Improved Cohesive Zone Model for Interface Mixed-Mode Fractures of Railway Slab Tracks

2021 ◽  
Vol 11 (1) ◽  
pp. 456
Author(s):  
Yanglong Zhong ◽  
Liang Gao ◽  
Xiaopei Cai ◽  
Bolun An ◽  
Zhihan Zhang ◽  
...  
Keyword(s):  
Interface Crack ◽  
Cohesive Zone ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Complex Loading ◽  
Bending Test ◽  
Mixed Mode Fracture ◽  
Zone Model ◽  
Slab Track ◽  
Interfacial Cracks

The interface crack of a slab track is a fracture of mixed-mode that experiences a complex loading–unloading–reloading process. A reasonable simulation of the interaction between the layers of slab tracks is the key to studying the interface crack. However, the existing models of interface disease of slab track have problems, such as the stress oscillation of the crack tip and self-repairing, which do not simulate the mixed mode of interface cracks accurately. Aiming at these shortcomings, we propose an improved cohesive zone model combined with an unloading/reloading relationship based on the original Park–Paulino–Roesler (PPR) model in this paper. It is shown that the improved model guaranteed the consistency of the cohesive constitutive model and described the mixed-mode fracture better. This conclusion is based on the assessment of work-of-separation and the simulation of the mixed-mode bending test. Through the test of loading, unloading, and reloading, we observed that the improved unloading/reloading relationship effectively eliminated the issue of self-repairing and preserved all essential features. The proposed model provides a tool for the study of interface cracking mechanism of ballastless tracks and theoretical guidance for the monitoring, maintenance, and repair of layer defects, such as interfacial cracks and slab arches.

Examination of the Transferability of CTOA From Small-Scale DWTT to Full-Scale Pipe Geometries Using a Cohesive Zone Model

2020 ◽  
Author(s):  
Chris Bassindale ◽  
Xin Wang ◽  
William R. Tyson ◽  
Su Xu
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Full Scale ◽  
Opening Angle ◽  
Small Scale ◽  
Zone Model ◽  
Pipe Model ◽  
Good Agreement

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.

scholarly journals A Numerical and Experimental Study of Adhesively-Bonded Polyethylene Pipelines

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1531 ◽  
Author(s):  
Guilpin ◽  
Franciere ◽  
Barton ◽  
Blacklock ◽  
Birkett
Keyword(s):  
Cohesive Zone ◽  
Adhesive Bonding ◽  
Structural Integrity ◽  
Cohesive Zone Model ◽  
Low Cost ◽  
Element Model ◽  
Zone Model ◽  
Adhesively Bonded ◽  
Lap Shear ◽  
Lap Shear Test

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%.

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