THE APPLICATION OF THE COHESIVE ZONE MODEL ON THE ANALYSIS OF MECHANICAL PROPERTIES OF CARBON NANO-TUBE COMPOSITES WITH DEBONDING INTERFACE

2011 ◽  
Author(s):  
WEN-LIANG ZHU ◽  
DONG-MEI LUO
Keyword(s):  
Mechanical Properties ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Carbon Nano Tube

Modeling of Cohesive Zone and Crack Growth in Ni-Al Thin-Film Using MD-XFEM Based Approach

2010 ◽  
Author(s):  
Gaurav Singh ◽  
Vijay Kumar Sutrakar ◽  
D. Roy Mahapatra
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Solid Phase ◽  
Md Simulations ◽  
Failure Behavior ◽  
Mode I ◽  
Zone Model ◽  
Al Thin Film

Intermetallic alloys of Ni-Al have important applications in high temperature anti-corrosive coatings, engine and turbine related materials, and shape memory devices. Predicting failure behavior of these materials is difficult using purely continuum model, since several of the material constants are complicated functions of micro and nano-scale details. This includes solid-solid phase transformation. In the present paper, a framework for analyzing fracture in two-dimensional planar domain is developed using a molecular dynamic (MD) simulation and extended finite element method (XFEM). The framework is then applied to simulate fracture in Ni-Al thin-film. Effect of Ni Al crystallites of various sizes on the mechanical properties is analyzed using direct MD simulations. Initiation and growth of crack under slow (quasi-static) tensile loading in mode-I condition is considered. Mechanical properties at room temperature are estimated via MD simulations, which are further used in the XFEM at the continuum scale. A cohesive zone model for the macroscopic XFEM model is implemented, which directly bridges the molecular length-scale via MD framework. Numerical convergence studies are reported for mode-I crack in initially single crystal B2 Ni-Al thin film.

Chip Formation in Cellular Materials

2002 ◽  
Vol 125 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Ralf Laternser ◽  
Hans-Peter Ga¨nser ◽  
Lars Taenzer ◽  
Alexander Hartmaier
Keyword(s):  
Mechanical Properties ◽  
Chip Formation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Opening ◽  
Cellular Materials ◽  
Point Of View ◽  
Constitutive Behavior ◽  
Zone Model ◽  
Elastoplastic Constitutive Model

The constitutive behavior of cellular materials like wood, especially with respect to the plastic and fracture mechanical properties, differs significantly from that of “classical” materials like steel. From this point of view, it appears interesting to investigate a process like chip formation, where both plasticity and fracture intervene. Finite element simulations of such a process are performed using an elastoplastic constitutive model for isotropic foams to describe the material, and a cohesive zone model to describe the crack. The repartition of the cutting force into the components required for the elasto-plastic deformation of the material and for crack opening is obtained.

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.

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.

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