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.

Cohesive Zone Model and GTN Model Collation for Ductile Crack Growth

2007 ◽  
Vol 567-568 ◽  
pp. 145-148
Author(s):  
Vladislav Kozák ◽  
Ivo Dlouhý ◽  
Zdeněk Chlup
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Interface Elements ◽  
Ductile Crack Growth ◽  
Propagation Analysis ◽  
Wide Range ◽  
Finite Element Package

The micromechanical modelling encounters a problem that is different from basic assumptions of continuum mechanics. The material is not uniform on the microscale level and the material within an element has its own complex microstructure. Therefore the concept of a representative volume element (RVE) has been introduced. The general advantage, compared to conventional fracture mechanics, is that, in principle, the parameters of the respective models depend only on the material and not on the geometry. These concepts guarantee transferability from specimen to components over a wide range of dimensions and geometries. The prediction of crack propagation through interface elements based on the fracture mechanics approach (damage) and cohesive zone model is presented. The cohesive model for crack propagation analysis is incorporated into finite element package by interface elements which separations are controlled by the traction-separation law.

Cohesive Zone Modeling of Stable Crack Propagation in Highly Ductile Steel

2018 ◽  
Vol 774 ◽  
pp. 167-172 ◽  
Author(s):  
Andreas Burgold ◽  
Stephan Roth ◽  
Meinhard Kuna
Keyword(s):  
Cohesive Zone ◽  
Large Scale ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Minor Effect ◽  
Stable Crack Propagation ◽  
Wide Range ◽  
Separation Relation ◽  
A Minor

A recent cohesive zone model is applied to the simulation of crack extension in austenitic stainless steel under large scale yielding conditions. The shape of the corresponding exponential traction-separation-relation can be modified in a wide range. In order to investigate the sensitivity regarding the cohesive zone parameters, a systematic parametric study is performed. The shape of the traction-separation envelope has a minor effect on the results compared to the cohesive strength and the work of separation. The aim is to fit experimental data by an appropriate choice of these parameters. Therefore, not only force-displacement curves should be used, but also crack growth resistance curves should be employed. A promising strategy for parameter identification is derived.

A Superposition Framework for Discrete Dislocation Plasticity

2004 ◽  
Vol 71 (6) ◽  
pp. 805-815 ◽  
Author(s):  
M. P. O’Day ◽  
W. A. Curtin
Keyword(s):  
Boundary Conditions ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Bimaterial Interface ◽  
Homogeneous Material ◽  
Plastic Behavior ◽  
Zone Model ◽  
Discrete Dislocation ◽  
Wide Range

A superposition technique is introduced that allows for the application of discrete dislocation (DD) plasticity to a wide range of thermomechanical problems with reduced computational effort. Problems involving regions of differing elastic and/or plastic behavior are solved by superposing the solutions to i) DD models only for those regions of the structure where dislocation phenomena are permitted subject to either zero traction or displacement at every point on the boundary and ii) an elastic (EL) (or elastic/cohesive-zone) model of the entire structure subject to all desired loading and boundary conditions. The DD subproblem is solved with standard DD machinery for an elastically homogeneous material. The EL subproblem requires only a standard elastic or elastic/cohesive-zone finite element (FE) calculation. The subproblems are coupled: the negative of the tractions developed at the boundaries of the DD subproblem are applied as body forces in the EL subproblem, while the stress field of the EL subproblem contributes a driving force to the dislocations in the DD subproblem structure. This decomposition and the generic boundary conditions of the DD subproblem permit the DD machinery to be easily applied as a “black-box” constitutive material description in an otherwise elastic FE formulation and to be used in a broader scope of applications due to the overall enhanced computational efficiency. The method is validated against prior results for crack growth along a plastic/rigid bimaterial interface. Preliminary results for crack growth along a metal/ceramic bimaterial interface are presented.

scholarly journals On the Representativeness of the Cohesive Zone Model in the Simulation of the Delamination Problem

2019 ◽  
Vol 3 (1) ◽  
pp. 22 ◽  
Author(s):  
Elena Sitnikova ◽  
Dafei Li ◽  
Jiahu Wei ◽  
Xiaosu Yi ◽  
Shuguang Li
Keyword(s):  
Energy Release ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Critical Energy ◽  
Physical Reality ◽  
Zone Model ◽  
Release Rates ◽  
Fe Modelling ◽  
Wide Range ◽  
Energy Release Rates

With the development of finite element (FE) codes, numerical modelling of delamination is often considered to be somewhat commonplace in modern engineering. However, the readily available modelling techniques often undermine the truthful understanding of the nature of the problem. In particular, a critical review of the representativeness of the numerical model is often diverted to merely a matter of numerical accuracy. The objective of this paper is to scrutinise the representativeness of cohesive zone modelling (CZM), which is readily available in most of the modern FE codes and is used extensively. By concentrating on obtaining the converged solution for the most basic types of delamination, a wide range of modelling complications are addressed systematically, through which complete clarity is brought to their FE modelling. The representativeness of the obtained predictions, i.e., their ability to reproduce the physical reality of the delamination process, is investigated by conducting a basic verification of the results, where the capability of the model to reproduce its input data in terms of critical energy release rates is assessed. It is revealed that even with converged solutions, input values of the critical energy release rates for the simple cases considered are not reproduced precisely, indicating that representativeness of the CZM for more general applications must not be taken for granted.

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.

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.

Cohesive Zone Model for the Interface of Multiwalled Carbon Nanotubes and Copper: Molecular Dynamics Simulation

2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Ibrahim Awad ◽  
Leila Ladani
Keyword(s):  
Carbon Nanotubes ◽  
Normal Stress ◽  
Multiwalled Carbon Nanotubes ◽  
Cohesive Zone ◽  
Large Scale ◽  
Cohesive Zone Model ◽  
Dynamics Simulation ◽  
Zone Model ◽  
Multiwalled Carbon ◽  
Significant Difference

Due to their superior mechanical and electrical properties, multiwalled carbon nanotubes (MWCNTs) have the potential to be used in many nano-/micro-electronic applications, e.g., through silicon vias (TSVs), interconnects, transistors, etc. In particular, use of MWCNT bundles inside annular cylinders of copper (Cu) as TSV is proposed in this study. However, the significant difference in scale makes it difficult to evaluate the interfacial mechanical integrity. Cohesive zone models (CZM) are typically used at large scale to determine the mechanical adherence at the interface. However, at molecular level, no routine technique is available. Molecular dynamic (MD) simulations is used to determine the stresses that are required to separate MWCNTs from a copper slab and generate normal stress–displacement curves for CZM. Only van der Waals (vdW) interaction is considered for MWCNT/Cu interface. A displacement controlled loading was applied in a direction perpendicular to MWCNT's axis in different cases with different number of walls and at different temperatures and CZM is obtained for each case. Furthermore, their effect on the CZM key parameters (normal cohesive strength (σmax) and the corresponding displacement (δn) has been studied. By increasing the number of the walls of the MWCNT, σmax was found to nonlinearly decrease. Displacement at maximum stress, δn, showed a nonlinear decrease as well with increasing the number of walls. Temperature effect on the stress–displacement curves was studied. When temperature was increased beyond 1 K, no relationship was found between the maximum normal stress and temperature. Likewise, the displacement at maximum load did not show any dependency to temperature.

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