An Inverse Analysis-Based Optimal Selection of Cohesive Zone Model for Metallic Materials

2018 ◽  
Vol 10 (02) ◽  
pp. 1850015 ◽  
Author(s):  
Guanghui Zhao ◽  
Ju Li ◽  
Y. X. Zhang ◽  
Zheng Liang ◽  
Chunhui Yang
Keyword(s):  
Cohesive Zone ◽  
Inverse Analysis ◽  
Cohesive Zone Model ◽  
Steel Grade ◽  
Zone Model ◽  
Fe Model ◽  
Metallic Materials ◽  
Fracture Behaviors ◽  
Fracture Tests ◽  
Selection Of

Five different cohesive zone models (CZMs), including bilinear, polynomial, trapezoidal, exponential, and PPR (Park–Paulino–Roesler) models, which are commonly used in simulating fracture failure of metallic materials, are evaluated in this paper. The cohesive parameters of these CZMs are determined by an inverse analysis based on the modified Levenberg–Marquardt method. A finite element (FE) model is developed by employing these CZMs and used to predict fracture behaviors of steel grade 120, which is frequently used for the tool joints of drill pipes. Tensile and fracture tests are conducted to determine material properties and fracture behaviors of the steel grade 120, and the fracture behavior obtained from the experiment is used to determine the CZM parameters and validate the FE model. It is found that the five CZMs, with the cohesive parameters determined by the inverse analysis, can be used to simulate the ductile fracture process of the steel, and that among the five CZMs, the exponential CZM provides the closest results to the experimental data.

scholarly journals Finite Element Multibody Simulation of a Breathing Crack in a Rotor with a Cohesive Zone Model

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Rugerri Toni Liong ◽  
Carsten Proppe
Keyword(s):  
Finite Element ◽  
Crack Closure ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Fe Model ◽  
Multibody Simulation ◽  
Closure Model ◽  
Breathing Mechanism ◽  
Cracked Shaft

The breathing mechanism of a transversely cracked shaft and its influence on a rotor system that appears due to shaft weight and inertia forces is studied. The presence of a crack reduces the stiffness of the rotor system and introduces a stiffness variation during the revolution of the shaft. Here, 3D finite element (FE) model and multibody simulation (MBS) are introduced to predict and to analyse the breathing mechanism on a transverse cracked shaft. It is based on a cohesive zone model (CZM) instead of linear-elastic fracture mechanics (LEFM). First, the elastic cracked shaft is modelled by 3D FE. As a second step, the 3D FE model of the shaft is transferred into an MBS model in order to analyze the dynamic loads, due to the crack, and the inertia force acting during rotation at different rotating speeds. Finally, the vibration responses in the centroid of the shaft obtained from MBS have been exported into FE model in order to observe the breathing mechanism. A bilinear crack closure model is proposed. The accuracy of the bilinear crack closure model and the solution techniques have been demonstrated by a comparison with the corresponding results of previous publications.

Estimating the Cohesive Zone Model Parameters of Carbon Nanotube–Polymer Interface for Machining Simulations

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lingyun Jiang ◽  
Chandra Nath ◽  
Johnson Samuel ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Weight Fraction ◽  
Model Parameters ◽  
Zone Model ◽  
Fe Model ◽  
Polymer Interface ◽  
Two Parameters

The failure mechanisms encountered during the machining of carbon nanotube (CNT) polymer composites are primarily governed by the strength of the CNT–polymer interface. Therefore, the interface should be explicitly modeled in microstructure-level machining simulations for these composites. One way of effectively capturing the behavior of this interface is by the use of a cohesive zone model (CZM) that is characterized by two parameters, viz., interfacial strength and interfacial fracture energy. The objective of this study is to estimate these two CZM parameters of the interface using an inverse iterative finite element (FE) approach. A microstructure-level 3D FE model for nanoindentation simulation has been developed where the composite microstructure is modeled using three distinct phases, viz., the CNT, the polymer, and the interface. The unknown CZM parameters of the interface are then determined by minimizing the root mean square (RMS) error between the simulated and the experimental nanoindentation load–displacement curves for a 2 wt. % CNT–polyvinyl alcohol (PVA) composite sample at room temperature and quasi-static strain state of up to 0.04 s−1, and then validated using the 1 wt. % and 4 wt. % CNT–PVA composites. The results indicate that for well-dispersed and aligned CNT–PVA composites, the CZM parameters of the interface are independent of the CNT loading in the weight fraction range of 1–4%.

Physics Based Formulation of a Cohesive Zone Model for Ductile Fracture

2015 ◽  
Vol 651-653 ◽  
pp. 993-999 ◽  
Author(s):  
Tuncay Yalcinkaya ◽  
Alan Cocks
Keyword(s):  
Ductile Fracture ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Volume Element ◽  
Cohesive Zone Modeling ◽  
Mode I ◽  
Zone Model ◽  
Metallic Materials ◽  
Bound Solution ◽  
Zone Modeling

This paper addresses a physics based derivation of mode-I and mode-II traction separation relations in the context of cohesive zone modeling of ductile fracture of metallic materials. The formulation is based on the growth of an array of pores idealized as cylinders which are considered as therepresentative volume elements. An upper bound solution is applied for the deformation of the representative volume element and different traction-separation relations are obtained through different assumptions.

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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