A SIMPLIFIED MESHLESS METHODS FOR BRITTLE FRACTURE OF CONCRETE

2013 ◽  
Vol 10 (03) ◽  
pp. 1350007 ◽  
Author(s):  
N. SAGARESAN
Keyword(s):  
Brittle Fracture ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Meshless Methods ◽  
Nonlinear Material ◽  
Zone Model ◽  
Discrete Crack ◽  
Fracture Modeling ◽  
Consistent Linearization

A simplified meshless methods for brittle fracture and nonlinear material is presented. In this method, the crack is modeled by a set of discrete crack segments crossing the entire domain of influence of the meshless shape functions. The key advantage of this method is its simplicity since no representation of the crack topology is needed. A nonlocal stress tensor around the crack tip is used as fracture criterion. A neo-Hooke material in the bulk material is used and a cohesive zone model is employed once discrete cracks occur. We also present consistent linearization of the cohesive zone model. The method is applied to fracture modeling in concrete that is accompanied by excessive cracking and therefore methods that represent the crack path have major drawbacks. We demonstrate the accuracy of the proposed method for complex problems involving mode-I and mixed mode failure.

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.

A comparative study of cohesive zone models for predicting delamination fracture behaviors of arterial wall

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 467-477
Author(s):  
Ting Miao ◽  
Liqiong Tian ◽  
Xiaochang Leng ◽  
Zhangmu Miao ◽  
Jingjing Wang ◽  
...  
Keyword(s):  
Comparative Study ◽  
Cohesive Zone ◽  
Arterial Wall ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Zone Model ◽  
Fracture Failure ◽  
Delamination Fracture ◽  
Cohesive Models ◽  
Arterial Tissue

AbstractArterial tissue delamination, manifested as the fracture failure between arterial layers, is an important process of the atherosclerotic plaque rupture, leading to potential life-threatening clinical consequences. Numerous models have been used to characterize the arterial tissue delamination fracture failure. However, only a few have investigated the effect of cohesive zone model (CZM) shapes on predicting the delamination behavior of the arterial wall. In this study, four types of CZMs (triangular, trapezoidal, linear–exponential, and exponential–linear) were investigated to compare their prediction of the arterial wall fracture failure. The Holzapfel–Gasser–Ogden (HGO) model was adopted for modeling the mechanical behavior of the aortic bulk material. The CZMs optimized during the comparison of the aortic media delamination simulations were also used to perform the comparative study of the mouse plaque delamination and human fibrous cap delamination. The results show that: (1) the numerical predicted the relationships of force–displacement in the delamination behaviors based on the triangular, trapezoidal, linear–exponential, and exponential–linear CZMs match well with the experimental measurements. (2) The traction–separation relationship results simulated by the four types of CZMs could react well as the corresponding CZM shapes. (3) The predicted load–load point displacement curves using the triangular and exponential–linear CZMs are in good agreement with the experimental data, relative to the other two shapes of CZMs. All these provide a new method combined with the factor of shape in the cohesive models to simulate the crack propagation behaviors and can capture the arterial tissue failure response well.

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.

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