scholarly journals Effect of Mesh Sensitivity and Cohesive Properties on Simulation of Typha Fiber/Epoxy Microbond Test

Computation ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Ikramullah ◽  
Andri Afrizal ◽  
Syifaul Huzni ◽  
Sulaiman Thalib ◽  
H. P. S. Abdul Khalil ◽  
...  
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Natural Fibers ◽  
Large Data ◽  
Zone Model ◽  
Damage Initiation ◽  
Fine Mesh ◽  
Cohesive Properties ◽  
Macro Scale ◽  
Microbond Test

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.

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.

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.

scholarly journals Microstructural damage evolution and its effect on fracture behavior of concrete subjected to freeze-thaw cycles

2018 ◽  
Vol 27 (8) ◽  
pp. 1272-1288 ◽  
Author(s):  
Yijia Dong ◽  
Chao Su ◽  
Pizhong Qiao ◽  
LZ Sun
Keyword(s):  
Computed Tomography ◽  
Cohesive Zone ◽  
Damage Evolution ◽  
Fracture Behavior ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
X Ray ◽  
Freeze Thaw ◽  
Microstructural Damage ◽  
Macro Scale

Concrete structures in cold regions are exposed to cyclic freezing and thawing environment, leading to degraded mechanical and fracture properties of concrete due to microstructural damage. While the X-ray micro-/nano-computed tomography technology has been implemented to directly observe concrete microstructure and characterize local damage in recent years, the freeze-thawed damage evolution processes and its effect on overall mechanical performance are not well understood. In this paper, the X-ray nano-computed tomography technology and micro-scale cohesive zone model are combined to quantitatively investigate microstructural damage evolution and its effect on fracture behavior of freeze-thawed concrete samples in three-point bending tests. A two-level micro-to-macro scale finite element model is developed based on computed tomography microstructural images with microcracks due to freeze-thaw cycles. The macroscopic load–deflection curves and fracture energies are simulated and compared favorably with experimental results. Simulation results demonstrate that microcracks caused by freeze-thaw actions are the primary reason for degradation of concrete mechanical properties. Fracture behaviors of frost-damaged concrete with different mortar and interfacial transition zone strength and fracture constants are also simulated and discussed. The combined X-ray nano-computed tomography technology and cohesive zone model proposed is effective in characterizing fracture behavior of concrete and capturing freeze-thaw cycle-induced microstructural damage evolution and its effect on fracture process of concrete.

Investigation of damage initiation in high-strength dual-phase steels using cohesive zone model

2016 ◽  
Vol 27 (3) ◽  
pp. 409-438 ◽  
Author(s):  
T Sirinakorn ◽  
V Uthaisangsuk
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
High Strength ◽  
Zone Model ◽  
Dual Phase ◽  
Two Dimensional ◽  
Stress Strain ◽  
Dual Phase Steels ◽  
Damage Initiation ◽  
Representative Volume

Dual-phase steels have been increasingly used for several vehicle structural parts due to their great combination of high strength and good formability. However, for an effective forming process of such steel sheets, their complex failure mechanism on the microscale plays an important role. In this work, damage initiation occurrences in two dual-phase steel grades were examined by a micromechanics-based final element modeling approach. Two-dimensional representative volume element models were applied to take into account amount, morphologies, and distributions of each constituent phase. Uniaxial tensile tests and fractography of the examined steels were carried out in order to characterize crack formation in the microstructure. According to a dislocation-based theory and local alloys partitioning, stress–strain curves were defined for the individual phases and interphases, where geometrically necessary dislocations were present due to austenite–martensite transformation. Cohesive zone model with extended finite element method and two-dimensional damage locus were applied in the representative volume elements for describing crack initiation induced by martensite cracking and ductile fracture of ferrite, respectively. Parameters of the damage models were identified by means of correlation between experimental and final element simulation results. The states of damage initiation of both dual-phase steels were predicted. Local stress, strain, and damage distributions in the dual-phase microstructures were determined and discussed.

Prediction Model for Adhesive Thickness-Dependence of Bonding Structures for Aeronautic Lightweight Alloy

2014 ◽  
Vol 789 ◽  
pp. 580-586
Author(s):  
Wei Xu ◽  
Hui Chen Yu ◽  
Chun Hu Tao
Keyword(s):  
Cohesive Zone ◽  
Adhesive Bonding ◽  
Present Model ◽  
Cohesive Zone Model ◽  
Adhesive Joints ◽  
Thickness Dependence ◽  
Zone Model ◽  
Adhesive Layers ◽  
Cohesive Properties ◽  
Adhesive Thickness

In the present research, the influence of the adhesive thickness on the cohesive properties and the overall strength of metallic adhesive bonding structures were investigated with the cohesive zone model to equivalently simulate the adhesive layers with various thicknesses. A theoretical approach was developed to determine the cohesive parameters for the present model when the adhesive thickness varied. And then some numerical examples were given to explore the adhesive thickness-dependence overall strength of the adhesive joints, followed by the comparison with the existing experimental results. Furthermore, the variations of both the cohesive parameters and the overall strength with the various thicknesses were influenced by the ductility of adhesives, which were investigated finally. The results showed that both the cohesive parameters and overall strength of metallic adhesive bonding structures were dependent on the adhesive thickness. Moreover, the variation of overall strength corresponding to brittle adhesive was more remarkable compared to that of ductile adhesive, especially in the comparatively small thickness range.

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.

A Cohesive Zone Model to Predict Dynamic Tearing of Rubber

2015 ◽  
Vol 43 (4) ◽  
pp. 297-324 ◽  
Author(s):  
Bo Li ◽  
Michelle S. Hoo Fatt
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Strain Energy ◽  
Cohesive Zone Model ◽  
Pure Shear ◽  
Strain Energy Release ◽  
Zone Model ◽  
Element Analysis ◽  
Critical Crack ◽  
Damage Initiation

ABSTRACT Tire failures, such as tread separation and sidewall zipper fracture, occur when internal flaws (cracks) nucleate and grow to a critical size as result of fatigue or cyclic loading. Sudden and catastrophic rupture takes place at this critical crack size because the strain energy release rate exceeds the tear energy of the rubber in the tire. The above-mentioned tire failures can lead to loss of vehicle stability and control, and it is important to develop predictive models and computational tools that address this problem. The objective of this article was to develop a cohesive zone model for rubber to numerically predict crack growth in a rubber component under dynamic tearing. The cohesive zone model for rubber was embedded into the material constitutive equation via a user-defined material subroutine (VUMAT) of ABAQUS. It consisted of three parts: (1) hyperviscoelastic behavior before damage, (2) damage initiation based on the critical strain energy density, and (3) hyperviscoelastic behavior after damage initiation. Crack growth in the tensile strip and pure shear specimens was simulated in ABAQUS Explicit, and good agreement was reported between finite element analysis predictions and test results.

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.

Sign in / Sign up

Export Citation Format

Share Document