scholarly journals Internal Damage Evolution in Double-Network Hydrogels Studied by Microelectrode Technique

2019 ◽  
Vol 52 (18) ◽  
pp. 7114-7122 ◽  
Author(s):  
Honglei Guo ◽  
Wei Hong ◽  
Takayuki Kurokawa ◽  
Takahiro Matsuda ◽  
Zi Liang Wu ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Internal Damage ◽  
Double Network ◽  
Microelectrode Technique

Modeling of Internal Damage Evolution During Actuation Fatigue in Shape Memory Alloys

2018 ◽  
Author(s):  
Francis R. Phillips ◽  
Daniel Martin ◽  
Dimitris C. Lagoudas ◽  
Robert W. Wheeler
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damage Evolution ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Internal Damage ◽  
Functional Fatigue ◽  
Non Linear

Shape memory alloys (SMAs) are unique materials capable of undergoing a thermo-mechanically induced, reversible, crystallographic phase transformation. As SMAs are utilized across a variety of applications, it is necessary to understand the internal changes that occur throughout the lifetime of SMA components. One of the key limitations to the lifetime of a SMA component is the response of SMAs to fatigue. SMAs are subject to two kinds of fatigue, namely structural fatigue due to cyclic mechanical loading which is similar to high cycle fatigue, and functional fatigue due to cyclic phase transformation which typical is limited to the low cycle fatigue regime. In cases where functional fatigue is due to thermally induced phase transformation in contrast to being mechanically induced, this form of fatigue can be further defined as actuation fatigue. Utilizing X-ray computed microtomography, it is shown that during actuation fatigue, internal damage such as cracks or voids, evolves in a non-linear manner. A function is generated to capture this non-linear internal damage evolution and introduced into a SMA constitutive model. Finally, it is shown how the modified SMA constitutive model responds and the ability of the model to predict actuation fatigue lifetime is demonstrated.

Study Asphalt Mixture Damage Characteristics Based on X-CT Technology

2013 ◽  
Vol 831 ◽  
pp. 401-406
Author(s):  
Zhi Yong Wu ◽  
Xiao Ning Zhang ◽  
Hong You ◽  
Cheng Wan
Keyword(s):  
Computerized Tomography ◽  
Damage Evolution ◽  
Asphalt Mixture ◽  
Curvilinear Relationship ◽  
Internal Damage ◽  
X Ray ◽  
Damage Process ◽  
Ct Technology ◽  
Strain Stress ◽  
Important Basis

In order to research the development of the internal cracks and the evolution of damage in asphalt mixture under loads, German Compact-225 type industrial X-ray computerized tomography (X-CT) was used to scan the specimen of asphalt mixture and the visualization of the internal damage process could be achieved, the damage under loads in various stages could be described accurately. Then, the damage evolution process was analyzed by calculating CT numbers, and a curvilinear relationship between the damage variable and the strain-stress was established. The results indicate that X-CT technology can be used as an effective way to detect and analyze the meso-damage of the asphalt mixture and that it further provides an important basis for quantitatively describing the evolution rule of the meso-damage.

Research on Landscape Limestone Damage and Deformation under Uniaxial Compression Based on Acoustic Emission

2013 ◽  
Vol 423-426 ◽  
pp. 914-919 ◽  
Author(s):  
Yong Qin Xiao ◽  
Yi Ping Wan ◽  
Bao Xian Liu
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Detection System ◽  
Damage Model ◽  
Mechanical Damage ◽  
Test System ◽  
Emission Feature ◽  
Internal Damage ◽  
Emission Parameter

In order to establish the relation between acoustic emission parameter and rock mechanical damage mechanism, as well as to better figure out landscape limestone damage and deformation influenced by uniaxial compression, MTS815 rock mechanical electro-hydraulic servo test system and 8CHSPCI-2 acoustic emission and detection system are applied to implement a test and research on damage evolution of limestone under uniaxial compression and the corresponding acoustic emission feature. On this basis, the acoustic emission feature of limestone under uniaxial compression is analyzed. Moreover, based on the damage variable of normalized accumulated emission ringing count, the uniaxial compression limestone damage model based on acoustic emission feature is established, and the damage evolution curve and equation of limestone is figured out as well. Shown by the research, acoustic emission information reflects the internal damage of limestone, and is closely related with densification of inner original fracture, as well as emerging, developing, and merging of new fractures. The acoustic emission feature of limestone perfectly describes its deformation and damage evolution.

Improved Damage Characteristics Identification Method of Concrete CT Images Based on Region Convolutional Neural Network

2019 ◽  
Vol 34 (06) ◽  
pp. 2054018 ◽  
Author(s):  
Liang Zhao ◽  
Chu-Jun Li ◽  
Xiao-Dong Wu ◽  
Di-Tao Niu ◽  
Zhong-Xing Duan ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Ct Images ◽  
Detection Accuracy ◽  
Detection Time ◽  
Feature Maps ◽  
High Quality ◽  
Internal Damage ◽  
Original Algorithm ◽  
Damage Characteristics ◽  
Feature Pyramid

The detection of internal damage characteristics of concrete is an important aspect of damage evolution mechanism in concrete meso-structure. In this paper, the improved Faster R-CNN is used to detect the porosity and cracks in concrete CT images. Based on the Faster R-CNN, ResNet-101 and ResNet-50 are used as the main framework. Feature pyramid network (FPN) and ROI Align are introduced to improve the performance of the model. FPN can generate high quality feature maps. ROI Align solves the region mismatch caused by the quantization operation. Experiments show that the detection accuracy of ResNet-101[Formula: see text]+[Formula: see text]FPN[Formula: see text]+[Formula: see text]ROI Align reaches 87.08%, which is 4.74 higher than that of ResNet-101. The detection accuracy of ResNet-50 [Formula: see text]+[Formula: see text] FPN [Formula: see text]+[Formula: see text] ROI Align reached 81.36%, which is 3.12% points higher than ResNet-50. These two improved algorithms are slower than the original algorithm for the detection time of a single picture. An effective method is provided to analyze concrete meso-damage evolution through the research.

Fractal Study for Micro-Crack of Mud-Shale

2016 ◽  
Vol 719 ◽  
pp. 28-32 ◽  
Author(s):  
Ping Wang ◽  
Zhan Qu ◽  
Ying Cui
Keyword(s):  
Fractal Dimension ◽  
Damage Evolution ◽  
Fracture Behavior ◽  
Quantitative Description ◽  
Bearing Surface ◽  
Internal Damage ◽  
Fractal Method ◽  
Fractal Characteristics ◽  
Evolution Behavior ◽  
Evolution Trend

The structure, distribution and evolution of micro-crack within the mud-shale are studied in this paper. The micro-fracture behavior of mud-shale has fractal characteristics. Fractal method is used to quantitative description of the damage evolution behavior of the mud-shale. The study shows that the variation of the fractal dimension in the domain of the bearing surface can reflect the internal damage evolution trend of the mud-shale. The fractal dimension has a nonlinear relationship with the applied stress.

Damage Mechanics Implementation of Material Design Simulator for Layered Ceramic Composites

2006 ◽  
Vol 324-325 ◽  
pp. 1083-1086
Author(s):  
Jae Myung Lee ◽  
Jung Kwan Seo ◽  
Dae Suk Han ◽  
Myung Hyun Kim ◽  
Hong Chae Park
Keyword(s):  
Damage Evolution ◽  
Evaluation System ◽  
Damage Mechanics ◽  
Numerical Technique ◽  
Cost Effective ◽  
Material Design ◽  
Ceramic Composites ◽  
Internal Damage ◽  
Automatic Data ◽  
Damage Evolution Equation

The objective of this study is to establish a numerical technique applicable for the assessment of damage characteristics of laminate ceramic. A numerical simulator, which can be used for the optimal material design, was developed based on the damage mechanics approach. To evaluate the internal damage evolution behavior within composite material, generalized damage evolution equation was developed and implemented in way of finite element method. By virtue of an automatic data interface between the commercial FEA results and damage calculation, a simple and cost-effective damage evaluation system is constructed. It was found that the developed system can be used for the evaluation of the material performance of composite.

Fatigue Damage Model for Numerical Assessment of Fatigue Characteristics

2008 ◽  
Vol 580-582 ◽  
pp. 663-666 ◽  
Author(s):  
Chi Seung Lee ◽  
Myung Hyun Kim ◽  
Min Sung Chun ◽  
Tak Kee Lee ◽  
Jae Myung Lee
Keyword(s):  
Damage Evolution ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Numerical Technique ◽  
Damage Model ◽  
Internal Damage ◽  
Numerical Assessment ◽  
Fatigue Characteristics ◽  
Evolution Behavior ◽  
Relationship Assessment

The aim of this study is the development of a numerical technique applicable for the fatigue assessment based on the damage mechanics approach. The generalized elasto-visco-plastic constitutive equation, which can consider the internal damage evolution behavior, is developed in order to numerically evaluate the material fatigue responses. Explicit information of the relationships between the mechanical properties and material constants, which are required for the mechanical constitutive and damage evolution equations, are derived. The performance of the developed technique has been verified using the S-N relationship assessment for STS304 stainless steel.

How chain dynamics affects crack initiation in double-network gels

2021 ◽  
Vol 118 (49) ◽  
pp. e2111880118
Author(s):  
Yong Zheng ◽  
Takahiro Matsuda ◽  
Tasuku Nakajima ◽  
Wei Cui ◽  
Ye Zhang ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Damage Zone ◽  
Soft Materials ◽  
Polymer Dynamics ◽  
Internal Damage ◽  
Double Network ◽  
Solvent Viscosity ◽  
Elastic Networks ◽  
Unique Material

Double-network gels are a class of tough soft materials comprising two elastic networks with contrasting structures. The formation of a large internal damage zone ahead of the crack tip by the rupturing of the brittle network accounts for the large crack resistance of the materials. Understanding what determines the damage zone is the central question of the fracture mechanics of double-network gels. In this work, we found that at the onset of crack propagation, the size of necking zone, in which the brittle network breaks into fragments and the stretchable network is highly stretched, distinctly decreases with the increase of the solvent viscosity, resulting in a reduction in the fracture toughness of the material. This is in sharp contrast to the tensile behavior of the material that does not change with the solvent viscosity. This result suggests that the dynamics of stretchable network strands, triggered by the rupture of the brittle network, plays a role. To account for this solvent viscosity effect on the crack initiation, a delayed blunting mechanism regarding the polymer dynamics effect is proposed. The discovery on the role of the polymer dynamic adds an important missing piece to the fracture mechanism of this unique material.

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