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.

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 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.

Investigation of Cohesive Zone Model Parameters for Steel Used in Shipbuilding Structure

2017 ◽  
Author(s):  
Vikas Chaudhari ◽  
D. M. Kulkarni ◽  
Shivam Rathi ◽  
Akshay Sancheti ◽  
Swadesh Dixit
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Plane Stress ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
High Strength ◽  
Model Parameters ◽  
Zone Model ◽  
Low Carbon ◽  
Two Parameters

Present work deals with the investigation of fracture toughness and modeling parameters need in FEA application for steel use in shipbuilding structure. The investigated steel was 12.5mm thick low carbon high strength steel. Two types of tests were performed, tensile test and fracture test to evaluate mechanical properties and fracture toughness respectively. Cohesive zone model (CZM) was used because it is very computer effective and requires only two parameters, which can be determined in experiments with relative ease. Cohesive zone model with trapezoidal traction law found suitable for the investigated steel. To simulate CZM, bulk section with plane stress elements and bulk section with plane stress with plane strain core scheme are found suitable however bulk section with plane stress with plane strain core scheme gives accurate numerical results.

Micromechanical Simulations on Hygro-Mechanical Properties of Bio-fiber Plastic Composites

2008 ◽  
Vol 1097 ◽  
Author(s):  
Yibin Xue ◽  
Kunpeng Wang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Moisture Content ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Model Parameters ◽  
Zone Model ◽  
Stress Strain ◽  
Plastic Composites ◽  
Plastic Matrix

AbstractThe hygro-mechanical properties of bio-fiber composites comprise two aspects: the coupling between moisture diffusion and mechanical deformations and the coupling of moisture contents and the constitutive behaviors. Bio-fiber is hydrophilic, which absorbs water promptly when environmental moisture content increases; as the moisture content in the fiber increases, its mechanical properties decrease. This paper presents a series of micromechanical simulations to predict the hygro-mechanical behaviors of woodfiber-reinforced plastic composites considering the effects of fiber arrangements on the stress-strain relations and moisture-expansions on three progressively constructed constitutive configurations: 1) the fiber is elastic orthotropic and expandable under moisture variations; the plastic matrix is elastic isotropic and insensitive to environmental moisture variations, and the interface between fiber and matrix is perfectly bounded; 2) the plastic matrix is hyperelastic and expresses a certain degree of damage as deformation progresses; and 3) the interface has a pseudo adhesive layer that obeys Smith and Ferrante's universal binding law implemented as a cohesive zone model in the micromechanical simulation. In configuration II, micromechanical simulations demonstrate significant reductions in the nominal elastic modulus of composites when a nonlinear elastic model for the polymer matrix is assumed. The prediction for stress-strain relationship is found to be comparable to the experimental measurements. A cohesive model in configuration III is introduced to evaluate the possible moisture degradation to the fiber-matrix interface, which results in a reduction in elastic modulus and failure strength of the composite s, as observed in experiments. The cohesive zone model parameters as a function of moisture content in the composites requires more attention in model correlation and guarantee more direct experimental observations.

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