Asymmetric Shielding Mechanisms in the Mixed-Mode Fracture of a Glass/Epoxy Interface

1998 ◽  
Vol 65 (1) ◽  
pp. 25-29 ◽  
Author(s):  
J. G. Swadener ◽  
K. M. Liechti
Keyword(s):  
Cohesive Zone Model ◽  
Hydrostatic Stress ◽  
Crack Opening ◽  
Shielding Effect ◽  
Mixed Mode Fracture ◽  
Zone Model ◽  
Element Analysis ◽  
Rate Dependent ◽  
Numerical Predictions ◽  
Wide Range

An asymmetric increase in the apparent values of the interfacial fracture toughness with increasing mode II component of loading has been observed by several investigators. In this study, cracks were grown in a steady-state manner along the glass/epoxy interface in sandwich specimens in order to determine the mechanisms responsible for the shielding effect. Finite element analysis using a hydrostatic stress and strain rate dependent plasticity model for the epoxy and a cohesive zone model for the interface shows that plastic dissipation in the epoxy accounts for the asymmetric shielding seen in these experiments which cover a wide range of mode mix. Numerical predictions of normal crack-opening displacements yielded results that were consistent with measured values which were made as close as 0.3 μm from the crack tip.

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.

Progressive failure analysis of scarf-repaired composite laminate based on damage constitutive model

2016 ◽  
Vol 233 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Qiuyi Shen ◽  
Zhenghao Zhu ◽  
Yi Liu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Composite Laminate ◽  
Damage Mechanics ◽  
Cohesive Zone Model ◽  
Load Capacity ◽  
Three Dimensional ◽  
Zone Model ◽  
State Variables ◽  
Element Analysis

A three-dimensional finite element model for scarf-repaired composite laminate was established on continuum damage model to predict the load capacity under tensile loading. The mixed-mode cohesive zone model was adopted to the debonding behavior analysis of adhesive. Damage condition and failure of laminates and adhesive were subsequently addressed. A three-dimensional bilinear constitutive model was developed for composite materials based on damage mechanics and applied to damage evolution and loading capacity analyses by quantifying damage level through damage state variables. The numerical analyses were implemented with ABAQUS finite element analysis by coding the constitutive model into material subroutine VUMAT. Good agreement between the numerical and experimental results shows the accuracy and adaptability of the model.

scholarly journals On the influence of delamination on laminated paperboard creasing and folding

2012 ◽  
Vol 370 (1965) ◽  
pp. 1912-1924 ◽  
Author(s):  
Lars A. A. Beex ◽  
Ron H. J. Peerlings
Keyword(s):  
Cohesive Zone ◽  
Mechanical Model ◽  
Cohesive Zone Model ◽  
Packaging Material ◽  
Friction Model ◽  
Zone Model ◽  
General Mechanics ◽  
Single Fold ◽  
Wide Range

Laminated paperboard is used as a packaging material for a wide range of products. During production of the packaging, the fold lines are first defined in a so-called creasing (or scoring) operation in order to obtain uncracked folds. During creasing as well as folding, cracking of the board is to be avoided. A mechanical model for a single fold line has been proposed in a previous study (Beex & Peerlings 2009 Int. J. Solids Struct. 46 , 4192–4207) to investigate the general mechanics of creasing and folding, as well as which precise mechanisms trigger the breaking of the top layer. In the present study, we employ this modelling to study the influence of delamination on creasing and folding. The results reveal the separate role of the cohesive zone model and the friction model in the description of delamination. They also show how the amount of delamination behaviour should be controlled to obtain the desired high folding stiffness without breaking of the top layer.

scholarly journals Rate-Dependent Cohesive Zone Model for Fracture Simulation of Soda-Lime Glass Plate

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 749 ◽  
Author(s):  
Dong Li ◽  
Demin Wei
Keyword(s):  
Strain Rate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Glass Plate ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Zone Model ◽  
Rate Dependent ◽  
Fracture Simulation ◽  
The Impact

In this paper, rate-dependent cohesive zone model was established to numerical simulate the fracture process of soda-lime glass under impact loading. Soda-lime glass is widely used in architecture and automobile industry due to its transparency. To improve the accuracy of fracture simulation of soda-lime glass under impact loading, strain rate effect was taken into consideration and a rate-dependent cohesive zone model was established. Tensile-shear mixed mode fracture was also taken account. The rate-dependent cohesive zone model was implemented in the commercial finite element code ABAQUS/Explicit with the user subroutine VUMAT. The fracture behavior of a monolithic glass plate impacted by a hemispherical impactor was simulated. The simulation results demonstrated that the rate-dependent cohesive zone model is more suitable to describe the impact failure characteristics of a monolithic glass plate, compared to cohesive zone model without consideration of strain rate. Moreover, the effect of the strain rate sensitivity coefficient C, the mesh size of glass plate and the impact velocity on the fracture characteristics were studied.

Multiscale Finite Element Modeling of Alumina Ceramics Undergoing Laser-Assisted Machining

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Xiangyang Dong ◽  
Yung C. Shin
Keyword(s):  
Finite Element ◽  
High Temperatures ◽  
Cutting Forces ◽  
Cohesive Zone Model ◽  
Multiscale Approach ◽  
Zone Model ◽  
Alumina Ceramics ◽  
Weight Percentage ◽  
Laser Assisted Machining ◽  
Wide Range

Alumina ceramics, due to their excellent properties of high hardness, corrosion resistance, and low thermal expansion coefficient, are important industrial materials with a wide range of applications, but these materials also present difficulty in machining with low material removal rates and high tool wear. This study is concerned with laser-assisted machining (LAM) of high weight percentage of alumina ceramics to improve the machinability by a single point cutting tool while reducing the cutting forces. A multiscale model is developed for simulating the machining of alumina ceramics. In the polycrystalline form, the properties of alumina ceramics are strongly related to the glass interface existing in their microstructure, particularly at high temperatures. The interface is characterized by a cohesive zone model (CZM) with the traction–separation law while the alumina grains are modeled as continuum elements with isotropic properties separated by the interface. Bulk deformation and brittle failure are considered for the alumina grains. Molecular dynamics (MD) simulations are carried out to obtain the atomistic structures and parameterize traction–separation laws for the interfaces of different compositions of alumina ceramics at high temperatures. The generated parameterized traction–separation laws are then incorporated into a finite element model in Abaqus to simulate the intergranular cracks. For validation purposes, simulated results of the multiscale approach are compared with the experimental measurements of the cutting forces. The model is successful in predicting cutting forces with respect to the different weight percentage and composition of alumina ceramics at high temperatures in LAM processes.

scholarly journals A novel approach to modelling the bond characteristics between CFRP fabrics and steel plate joints under quasi-static tensile loads

2021 ◽  
Author(s):  
Hemad Hamedi ◽  
ATA Kamyabi-Gol
Keyword(s):  
Cohesive Zone Model ◽  
Failure Load ◽  
Steel Structures ◽  
Experimental Tests ◽  
Critical Distance ◽  
Zone Model ◽  
Element Analysis ◽  
Novel Approach ◽  
Externally Bonded ◽  
Static Tensile

Abstract Carbon fiber reinforced polymer (CFRP) materials have been effectively used as externally bonded sheets to repair damaged steel structures such as airplanes and ships. In this study, a series of double strap joints with different bonding lengths are considered and examined to experimentally and theoretically assess the effective bond length. Various models exist in the literature which are used to predict the strength of steel and CFRP joints under various loading conditions. Non-linear Lagrange stress method (NLS) which is a novel stress-based method for predicting the failure load values is presented for the first time. This approach is based on 2D and 3D linear elastic finite element analysis. Relying only on two experimental tests, the new approach proposed here can quickly and easily predict the failure load in steel/CFRP samples. In this methodology, it is assumed that the adhesive joint will fail as the normal stress along the adhesive mid-line reaches a predetermined value at a critical distance. In addition, experimental data on steel/CFRP joints gathered from the literature are compared to predictions using the NLS method. It was found that results from the theoretical predictions (NLS) were in good agreement with experimental tests conducted on double strap joints. It was also revealed that the average accuracy of the NLS method is superior to other methods such as cohesive zone model and Hart-Smith. The results revealed that under the best conditions, the NLS model is 5 times more accurate than existing models.

Numerical Investigation of the Damage Behavior of S355 EBW by Cohesive Zone Modeling

2015 ◽  
Vol 1102 ◽  
pp. 149-153 ◽  
Author(s):  
H.Y. Tu ◽  
Ulrich Weber ◽  
Siegfried Schmauder
Keyword(s):  
Tensile Test ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Opening ◽  
Compact Tension ◽  
Initial Crack ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Opening Displacement ◽  
Zone Modeling

In this paper, the cohesive zone model is used to study the fracture behavior of an electron beam welded (EBW) steel joint. Mechanical properties of different weld regions are derived from the tensile test results of flat specimens, which are obtained from the respective weld regions. Based on the tensile test of notched round specimens, the cohesive strength T0can be fixed. With the fixed T0value, the cohesive model is applied to compact tension (C(T)) specimens with the initial crack located at different positions of weldment with different cohesive energy values Γ0. Numerical simulations are compared with the experimental results in the form of force vs. Crack Opening Displacement (COD) curves as well as fracture resistance (JR) curves.

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