A modified cohesive zone model for a high-speed expanding crack

2014 ◽  
Vol 37 (9) ◽  
pp. 1013-1024 ◽  
Author(s):  
J. Wu ◽  
C. Q. Ru
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Zone Model

Multiscale cohesive zone modeling and simulation of high-speed impact, penetration, and fragmentation

2018 ◽  
Vol 03 (01n02) ◽  
pp. 1850003
Author(s):  
Chao Wang ◽  
Dandan Lyu
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Spall Fracture ◽  
Weak Formulation ◽  
High Speed Impact ◽  
Different Characteristics

In this work, a multiscale cohesive zone model (MCZM) is developed to simulate the high-speed penetration induced dynamic fracture process such as fragmentation in crystalline solids. This model describes bulk material as a local quasi-continuum medium which follows the Cauchy–Born rule while cohesive zone element is governed by an interface depletion potential, such that the cohesive zone constitutive descriptions are genetically consistent with that of bulk element. This multiscale method proved to be effective in describing material inhomogeneities and it is constructed and implemented in a cohesive finite element Galerkin weak formulation. Numerical simulations of high-speed penetration with different shape of penetrators, i.e., square, circle and parabola nose penetrators are performed. Results show that the proposed MCZM can successfully capture spall fracture, the penetration process and different characteristics of fragmentation under different shape of penetrators.

Application of Multiscale Cohesive Zone Model to Simulate Fracture in Polycrystalline Solids

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jing Qian ◽  
Shaofan Li
Keyword(s):  
Material Properties ◽  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Small Scale ◽  
Zone Model ◽  
Transgranular Fracture ◽  
Spall Fracture ◽  
High Speed Impact ◽  
Polycrystalline Solids

In this work, we apply the multiscale cohesive method (Zeng and Li, 2010, “A Multiscale Cohesive Zone Model and Simulations of Fracture,” Comput. Methods Appl. Mech. Eng., 199, pp. 547–556) to simulate fracture and crack propagations in polycrystalline solids. The multiscale cohesive method uses fundamental principles of colloidal physics and micromechanics homogenization techniques to link the atomistic binding potential with the mesoscale material properties of the cohesive zone and hence, the method can provide an effective means to describe heterogeneous material properties at a small scale by taking into account the effect of inhomogeneities such as grain boundaries, bimaterial interfaces, slip lines, and inclusions. In particular, the depletion potential of the cohesive interface is made consistent with the atomistic potential inside the bulk material and it provides microstructure-based interface potentials in both normal and tangential directions with respect to finite element boundary separations. Voronoi tessellations have been utilized to generate different randomly shaped microstructure in studying the effect of polycrystalline grain morphology. Numerical simulations on crack propagation for various cohesive strengths are presented and it demonstrates the ability to capture the transition from the intergranular fracture to the transgranular fracture. A convergence test is conducted to study the possible size-effect of the method. Finally, a high-speed impact example is reported. The example demonstrates the advantages of multiscale cohesive method in simulating the spall fracture under high-speed impact loads.

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.

Sign in / Sign up

Export Citation Format

Share Document