Study on Damage Evolution and Resistivity Variation Regularities of Coal Mass Under Multi-Stage Loading

In order to describe resistivity variation regularities during the process of damage evolution of loading coal mass more comprehensively and accurately, electrical resistivity and acoustic emission (AE) characteristics of coal mass were tested by 3532-50 LCR tester and AMSY-6 AE data acquisition system under the condition of multi-stage loading, and resistivity variation characteristics were analyzed with stress changing. The damage evolution process of coal mass was studied by the measurement of the AE parameters, and the resistivity curve was obtained in the damage conditions based on the relationship between the AE damage variable and the resistivity. The results show that resistivity and stress curves of coal mass have a good correspondence during the multi-stage loading, and the resistivity shows a trend of fluctuating downward with the increasing of stress. The resistivity increases sharply to the maximum value when the load increases to the ultimate compressive strength of specimens. AE information can reveal effectively damage evolution process of microcracks formation, expansion and fracture in coal mass under external force, and during multi-stage loading, the cumulative AE ringing counts curve of coal mass have three different types of growth trends: stable stage, sudden change stage, gradual increasing stage. Meanwhile, the relationship between resistivity and AE damage variable is established based on the formula of damage variable under uniaxial compression and combined with continuous damage mechanics, and its rationality is verified.

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A New Method to Calculate Damage Variable with Unload/Load Response Ratio

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1065-1069.2040 ◽

2014 ◽

Vol 1065-1069 ◽

pp. 2040-2043

Author(s):

Juan Zhang ◽

Yuan Zhang ◽

Ke Qiang He ◽

Wei Gong Chen

Keyword(s):

Large Scale ◽

Damage Mechanics ◽

Health Assessment ◽

Damage Variable ◽

Response Ratio ◽

Load Response ◽

Set Up ◽

The University ◽

Theory Of Damage ◽

The Relationship

As an exploration and extension of load/unload response ratio theory, unload/ load response ratio theory (ULRR for short) is introduced firstly, and the relationship between ULRR (Y′) and elastic modulus (E for short) is obtained. Based on the basic theory of damage mechanics,the relationship between ULRR and damage variable (D for short) is set up and analyzed with the relationship between E and D. The unloading and loading experiments on a two-story structure carried out in the University of Naples in Italy are introduced;and calculated damage variable is compared with that calculated by Zhang Langping who put forward Weibull distribution as random distribution function. The results show that damage variable of the structure keep highly consistent with calculations of these two methods. Therefore, the relationship between Y′and D provides a new approach to a health assessment to catastrophic failure of large-scale structures and prediction of engineering.

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Study on Energy Accumulation and Damage Evolution of the Coal and Rock Using Acoustic Emission Test

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.1597 ◽

2011 ◽

Vol 105-107 ◽

pp. 1597-1602 ◽

Cited By ~ 1

Author(s):

You Gang Wang ◽

Xiang Feng Liu

Keyword(s):

Acoustic Emission ◽

Uniaxial Compression ◽

Damage Evolution ◽

Damage Mechanics ◽

Solid Material ◽

Damage Variable ◽

Geometrical Parameters ◽

Compression Process ◽

Energy Accumulation ◽

Ae Energy

Rocks and other rocklike solid materials have inherent defects inside. The defects of rock will be evolved under loading. The evolution process and extent of defects can be described by the damage variable. But which physical or geometrical parameters can be used to define the damage, there has no consistent conclusion domestic and aboard. Moreover, limited by the method of experimental, it is difficult to obtain the parameters to depict the damage variable directly. In order to obtained the evolution law of the interior defects in the solid material, the non-conduct geophysical prospecting measure as AE (Acoustic Emission) will be the leading measure to prospect the interior defects and it’s evolution under outside loading. In the present paper, the AE method was used to obtain the AE parameters during the uniaxial compression process of coal and rock. Therefore, uniaxial compression and AE tests on coal and mudstone were conducted, and the curves among the AE energy accumulation, stress and strain were obtained after analyzing the results of tests data. Based on the principle of damage mechanics and thermodynamics, the damage evolution of coal and rock was deduced through analyzing the experimental results, the curves of damage and AE accumulation were obtained also. By analyzing and fitting the curves of damage and AE energy accumulation, the relation between the AE energy accumulation and stress-strain was obtained and verified through the experimental data.

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Research on the Damage Evolution Process of Steel Wire with Pre-Corroded Defects in Cable-Stayed Bridges

Applied Sciences ◽

10.3390/app9153113 ◽

2019 ◽

Vol 9 (15) ◽

pp. 3113 ◽

Cited By ~ 2

Author(s):

Ying Wang ◽

Yuqian Zheng

Keyword(s):

Fatigue Life ◽

Fatigue Damage ◽

Damage Evolution ◽

Damage Mechanics ◽

Steel Wire ◽

Evolution Process ◽

Fe Model ◽

Steel Wires ◽

Abaqus Software ◽

Cable Stayed Bridges

A numerical simulation method is presented in this paper to study the damage evolution and failure process of high-strength steel wires with pre-corrosion defects in cable-stayed bridges under fatigue loads. This method was based on the mechanism of crack nucleation accelerated by corrosion pits, in which cellular automata (CA) and finite element (FE) simulation methods were used. First, based on the continuum damage mechanics (CDM) theory, a fatigue damage model suitable for steel wire with pre-corroded defects was established to describe the evolution process of the microscopic damage of steel wires, and a user-defined material subroutine (UMAT) was written using formula translator (FORTRAN) language. Then, in MATLAB, the shape and position of random pitting defects on the steel wire surface were generated using 3D CA technology. Afterwards, a pitting defect model was successively inputted into AutoCAD, Rhino and ABAQUS software to obtain the FE model of steel wire with initial pitting defects or initial damage. Finally, the life-and-death element method and the UMAT program were used to simulate the fatigue damage evolution process of the steel wire with initial defects in ABAQUS software, and the fatigue life of the steel wire was obtained. The results show that the proposed strategy and algorithm can effectively describe the fatigue damage evolution process of the steel wire with initial pitting defects under the action of a fatigue load, and the simulated fatigue life is in good agreement with the experimental results. The obtained stress-life (S-N) curves of the steel wire with different corrosion degrees show that the influence of pit corrosion on fatigue life is much greater than that of the mass loss caused by corrosion. By comparing the irregular pit model with regular pit models, it can be found that the irregular shape angle is the main reason for the smaller fatigue life and the larger stress concentration in the irregular pit model than in the regular pit model.

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Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

International Journal of Damage Mechanics ◽

10.1177/1056789521991193 ◽

2021 ◽

pp. 105678952199119

Author(s):

Kai Yang ◽

Qixiang Yan ◽

Chuan Zhang ◽

Wang Wu ◽

Fei Wan

Keyword(s):

Mechanical Properties ◽

Acoustic Emission ◽

Water Content ◽

Damage Evolution ◽

Damage Assessment ◽

Triaxial Compression ◽

Confining Pressure ◽

Damage Variable ◽

Natural State ◽

Carbonaceous Shale

To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

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Diagnosis of damage evolution process for asphalt mixtures using pattern recognition with acoustic emission signals

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.122536 ◽

2021 ◽

Vol 280 ◽

pp. 122536

Author(s):

Xin Qiu ◽

Jingxian Xu ◽

Wenyi Xu ◽

Qing Yang ◽

Feng Wang ◽

...

Keyword(s):

Pattern Recognition ◽

Acoustic Emission ◽

Damage Evolution ◽

Asphalt Mixtures ◽

Evolution Process

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A Study on Estimation of Internal Pressure Creep Life Using Small Punch Creep (SPC) Tests for Boiler Pipes

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77336 ◽

2009 ◽

Author(s):

Toshimi Kobayashi ◽

Toru Izaki ◽

Junichi Kusumoto ◽

Akihiro Kanaya

Keyword(s):

Internal Pressure ◽

Residual Life ◽

Test Results ◽

Creep Life ◽

Creep Tests ◽

Good Correspondence ◽

Small Punch ◽

Uniaxial Creep ◽

Wide Range ◽

The Relationship

The small punch creep (SPC) test is possible to predict residual creep life at a high accuracy. But, the results of SPC tests cannot be compared with uniaxial creep or internal pressure creep results directly. In this report, the relationship between SPC test results and uniaxial creep test results in ASME A335 P11 (1.25Cr-0.5Mo Steel) was studied. The obtained relationship between SPC load and equivalent uniaxial creep stress formed a simple linear equation under the wide range of test temperature and test period. Then, the SPC results can be compared with uniaxial results by converting SPC loads to the equivalent uniaxial creep stresses. The relationship between SPC test results and internal pressure creep tests results was also studied. The internal creep life of as-received P11 pipe was almost same as SPC result when the hoop stress was converted to the SPC load. The creep lives of internal pressure creep influenced materials also showed good correspondence with SPC results. Therefore SPC can estimate the residual life of internal pressure creep influenced materials.

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Finite Element Simulation of the Creep Behavior of 2.25Cr-1Mo-0.25V Steel Based on Continuum Damage Mechanics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.750.266 ◽

2015 ◽

Vol 750 ◽

pp. 266-271 ◽

Cited By ~ 1

Author(s):

Yu Zhou ◽

Xue Dong Chen ◽

Zhi Chao Fan ◽

Yi Chun Han

Keyword(s):

Genetic Algorithm ◽

Finite Element ◽

Creep Behavior ◽

Constitutive Equations ◽

Damage Evolution ◽

Damage Mechanics ◽

Creep Damage ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Element Simulation

The creep behavior of 2.25Cr-1Mo-0.25V ferritic steel was investigated using a set of physically-based creep damage constitutive equations. The material constants were determined according to the creep experimental data, using an efficient genetic algorithm. The user-defined subroutine for creep damage evolution was developed based on the commercial finite element software ANSYS and its user programmable features (UPFs), and the numerical simulation of the stress distribution and the damage evolution of the semi V-type notched specimen during creep were studied. The results showed that the genetic algorithm is a very efficient optimization approach for the parameter identification of the creep damage constitutive equations, and finite element simulation based on continuum damage mechanics can be used to analyze and predict the creep damage evolution under multi-axial stress states.

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Theoretical damage characterisation and damage evolution process of intact rocks based on linear energy dissipation law under uniaxial compression

International Journal of Rock Mechanics and Mining Sciences ◽

10.1016/j.ijrmms.2021.104858 ◽

2021 ◽

Vol 146 ◽

pp. 104858

Author(s):

Fengqiang Gong ◽

Peilei Zhang ◽

Song Luo ◽

Jianchun Li ◽

Da Huang

Keyword(s):

Energy Dissipation ◽

Uniaxial Compression ◽

Damage Evolution ◽

Evolution Process

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Simulation Optimization of Backrest Mechanism of Separable Bed Chair System

International Journal of Circuits, Systems and Signal Processing ◽

10.46300/9106.2021.15.121 ◽

2021 ◽

Vol 15 ◽

pp. 1114-1123

Author(s):

Meng Ning ◽

Zhi Wu ◽

Lianjie Chen ◽

Fan Zhang ◽

Huitao Chen

Keyword(s):

Sudden Change ◽

Optimal Solution ◽

Simulation Software ◽

Final Solution ◽

Integration System ◽

Modeling And Analysis ◽

Movement Characteristics ◽

Fixed Structure ◽

The Relationship ◽

Research And Design

Research and design an intelligent bed and chair integration system for assisting inconvenient mobility and aging population. The system consists of a removable detached wheelchair and a c-shaped bed with a fixed structure. The user can switch freely between the mobile wheelchair and the bed to meet the user's requirements of free movement and repositioning.Through the simulation software to analyze the movement characteristics of the bed backboard, the angle of the take-off and landing of the backboard and the sudden change of the take-off and abrupt angular velocity will cause the user to have dizziness and discomfort. In the case of determining the speed of the driving push rod, the relationship between mechanism parameters and installation parameters is the key to affect the lifting rate of the rear plate. Modeling and analysis of each mechanism is performed to determine the relationship between the mechanism parameters and the take-off and landing speed of the backplane. After optimizing the mechanism, the simulation is compared again to obtain the optimal solution. Finally, the optimal solution parameter is the final solution to improve the overall comfort of the nursing bed.

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《高文舉》版本考述

中正漢學研究 ◽

10.53106/2306036020210600370010 ◽

2021 ◽

Vol 37 (37) ◽

pp. 281-332

Author(s):

柯香君柯香君

Keyword(s):

The Other ◽

Evolution Process ◽

Cultural Characteristics ◽

Original Stories ◽

Other Hand ◽

The One ◽

The Relationship ◽

Work First

「高文舉故事」始自形成，便以多元樣貌流播於各地聲腔，依據本文所較析的四個版本，彼此間存在著複雜關係，或有獨立發展者，如南管戲《高文舉》，或有屬古本系統者，如《水雲亭還魂記》，或有保留南戲原貌者莆仙戲《高文舉》，乃至於集大成者「文林閣本」《高文舉珍珠記》。南戲《高文舉》已亡佚，其中以《高文舉珍珠記》之影響最為深遠。「高文舉故事」主要情節有三：「珍珠米糷」、「還魂訴冤」、「包拯斷案」。在「文林閣本」與「莆仙本」皆有「珍珠米糷」、「龍圖斷案」，而「還魂本」有「玉真還魂」、「龍圖斷案」，至於「南管本」則一概具無，可知「南管本」在高文舉故事流變過程中之獨特性。本文主要針對各版本間之「關目情節」、「曲文賓白」等詳實比勘，剖析「高文舉」在不同聲腔劇種間之承繼與創新，並試圖重構各地聲腔在「高文舉」演化過程中之地位與價值。  Gao Wen Jyu of southern opera has been disappeared and present versions include Zhen Zhu Ji (Yi Yang tune), Gao Wen Jyu of Southern Pipes (Quan tune), Gao Wen Jyu of Pu Xian (Hsin Hua tune) and Revival After Death of Shui Yun Pavilion (Qing Yang tune). Among others, Zhen Zhu Ji is the most influential one. The plots such as “Window Meeting” and “Zhen Zhu Mi Lan” are not only the selected Zhe Zi operas for the later generations, but also the adapted texts of local operas. Main plots of “story of Gao Wen Jyu” are below: “Zhen Zhu Mi Lan”, “Revival After Death to Appeal for Justice” and “Master Pao’s Judgment”. Zhen Zhu Ji and “version of Pu Xian” include “Zhen Zhu Mi Lan” and “Master Pag’s Judgment”. “Version of revival after death” includes “Revival After Death of Yu Chen” and “Master Pao’s Judgment”. “Version of Southern Pipes” does not include the above. Hence, it shows the uniqueness of “version of Southern Pipes” in the evolution of “story of Gao Wen Jyu”. Varieties of plots result in the richness of “story of Gao Wen Jyu”. The process of spread reveals flexibility and regionality of local common systematic tunes and varieties of operas. This study will treat four versions of Gao Wen Jyu as the subjects to significantly compare and analyze the original stories and difference and similarity of related work. First, it explores present versions to recognize the evolution of the story “Gao Wen Jyu”; secondly, it precisely compares “plots” and “singing and talking” of the versions to analyze the inheritance and innovation of “story of Gao Wen Jyu” in different common systematic tunes and varieties of Chinese operas. It, on the one hand, clarifies the relationship and origin of different versions of “Gao Wen Jyu” and, on the other hand, probes into cultural characteristics of “time” and “region” of operas; finally, it attmpets to reconstruct the positions and values of common systematic tunes in different regions in the evolution process of “Gao Wen Jyu”.

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