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Mechanical behavior of rock under uniaxial tension:Insights from energy storage and dissipation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2466-2481页

作者： Guanshuang Tan Chunde Ma Junjie Zhang Wenyuan Yang Guiyin Zhang Zihao Kang School of Resources and Safety Engineering Central South UniversityChangsha410083China

Many rock engineering projects show that the growth of tensile cracks is often an important cause of engineering disasters,and the mechanical behavior of rocks is essentially the transmission,storage,dissipation and release of *** investigate the tensile behavior of rock from the perspective of energy,uniaxial tension tests(UTTs)and uniaxial compression tests(UCTs)were carried out on three typical rocks(granite,sandstone and marble).Different unloading points were set before the peak stress to separate elastic energy and dissipated *** input energy density ut,elastic energy density ue,and dissipated energy density ud at each unloading point were calculated by integrating stress-strain *** results show that there is a strong linear relationship between the three energy parameters and the square of the unloading stress in UCT,but this linear relationship is weaker in *** ue and ud increase linearly with the increase in ut in UCT and *** on the phenomenon that ue and ud increase linearly with ut,the applicability of W_(et)^(p) index in UTT was proved and the relative energy storage capacity and absolute energy distribution characteristics of three rocks in UCT and UTT were *** tensile behavior of marble and sandstone in UTT can be divided into two stages vaguely according to the energy distribution,but granite is not the *** addition,based on dissipated energy,the damage evolution of three types of rocks in UCT and UTT was *** study provides some new insights for understanding the tensile behavior of rock.

关键词： uniaxial tension Energy density Mechanical behavior Energy storage coefficient Energy dissipation coefficient

Unified analytical stressstrain curve for quasibrittle geomaterial in uniaxial tension, direct shear and uniaxial compression

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Journal of Central South University of Technology 2006年第1期13卷 99-104页

作者：王学滨 Department of Mechanics and Engineering Sciences Liaoning Technical University Fuxin 123000 China

Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stressstrain curves of quasibrittle geomaterial (such as rock and concrete) in uniaxial tension, direct shear and uniaxial compression were presented, respectively. The three derived stressstrain curves were generalized as a unified formula. Beyond the onset of strain localization, a linear strain-softening constitutive relation for localized band was assigned. The size of the band was controlled by internal or characteristic length according to gradient-dependent plasticity. Elastic strain within the entire specimen was assumed to be uniform and decreased with the increase of plastic strain in localized band. Total strain of the specimen was decomposed into elastic and plastic parts. Plastic strain of the specimen was the average value of plastic strains in localized band over the entire specimen. For different heights, the predicted softening branches of the relative stressstrain curves in uniaxial compression are consistent with the previously experimental results for normal concrete specimens. The present expressions for the post-peak stressdeformation curves in uniaxial tension and direct shear agree with the previously numerical results based on gradient-dependent plasticity.

关键词： stress- strain curve uniaxial tension uniaxial compression direct shear shear band rock concrete

Charactersitics of Stress-strain Curve of High Strength Steel Fiber Reinforced Concrete under uniaxial tension

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Journal of Wuhan University of Technology(Materials Science) 2006年第3期21卷 132-137页

作者：杨萌 State Key Laboratory of Coastal and Offshore Engineering Department of Civil Engineering Dalian University of Technology Dalian 116023China

A whole of 110 specimens divided into 22 groups were tested with varying the volume fraction of steel fibers and the matrix strength of these specimens. The stress-strain behaviors of four types of steel fiber reinforced concrete （SFRC） under uniaxial tension were studied experimentally. When the matrix strength and the fiber content increase, the tensile stress and tensile strain vary differently according to the fiber type. The mechanisms of reinforcing effect for different types of fiber were analyzed and the stress-strain curves of the specimens were plotted. Some experimental factors for stress or strain of SFRC were given. A tensile toughness modulus Re0.5 was introduced to evaluate the toughness characters of SFRC under uniaxial tension. Moreover, the formula of the tensile stress-strain curve of SFRC was regressed. The theoretical curve and the experimental ones fit well, which can be used for references in construction.

关键词： steel fiber reinforced concrete high strength uniaxial tension soften characteristics stress-strain curve

Experimental Study on AE Characteristics of Granite under uniaxial tension at Different Strain Rates

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Journal of Wuhan University of Technology(Materials Science) 2020年第4期35卷 691-698页

作者： WANG Yan WANG Na WANG Zhaozhu CHEN Yuzhi WANG Yao ZHAO Haitao College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China School of Architecture and Civil Engineering Jinling Institute of TechnologyNanjing 211169China

To investigate the acoustic emission(AE)characteristics of quasi-brittle materials like rock and concrete,and to further analyze their damage and failure mechanism under seismic and other dynamic loads,the uniaxial tension test of granite cylinder specimens within the strain rate range of 10^-7-10^-4 s^-1 was monitored by AE technology,and the typical AE characteristic parameters were analyzed using statistical and correlation *** experimental results show that,with the increase of strain rate,the peak of AE hit rate appears earlier and increases;the proportion of AE hits with higher duration or amplitude increases significantly,the b-value shows a decreasing trend,and the distribution of AE frequency-amplitude is increasingly *** addition,the obvious characteristic of double dominant frequency bands was observed in AE waveforms by using spectrum analysis,with the increase of strain rate,the percentage of A-type waveforms corresponding to low dominant frequency band increases,while that of D-type waveforms corresponding to high ones decreases accordingly,which is significance for the further study of the damage and failure mechanism of quasi-brittle materials.

关键词： granite strain rate uniaxial tension AE characteristics spectrum analysis

Size Effect for Normal Strength Concrete in uniaxial tension

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Tsinghua Science and Technology 2004年第6期9卷 700-703,709页

作者：李庆斌尹玉先 Department of Hydraulic and Hydropower Engineering Tsinghua University Beijing 100084 China Department of Urban Engineering Department of Urban Engineering Pingdingshan Institute of Technology Pingdingshan 467001 China

This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface in uniaxial tension. uniaxial tension tests with normal strength concrete measuring the tensile strength of normal strength concrete specimens with different geometrical shapes and different ratios of the aggregate size to the characteristic dimension of the concrete specimen show a significant size effect. The theoretical size effect law prediction agrees well with the experimental data.

关键词： concrete size effect law uniaxial tension aggregate size extreme case

Finite Element Model of a Filament-Wound Composite Tube Subjected to uniaxial tension

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Modern Mechanical Engineering 2017年第4期7卷 91-112页

作者： Gyula Szabó Károly Váradi Dávid Felhos Department of Machine and Product Design Budapest University of Technology and EconomicsBudapestHungary

The aim of this paper is to demonstrate the mechanical behaviour of a filament-wound composite tube subjected to uniaxial tension by finite element analysis. uniaxial tensile test experiments have been carried out on standard specimen and hose piece in order to verify finite element models and material properties and also to assess failure mode of composite plies. Composite reinforcement plies are modeled as linear orthotropic, while elastomer liners are described by hyperelastic material model. Results of finite element models and experiments show good agreement in the initial phase of uniaxial tension, which justifies utilized material models in the operating range. Results of finite element models show that transverse tension and shear load are dominant under tension. It is determined that principal failure mode of reinforcement plies is intra-ply yarn-matrix debonding caused by intensive shear of rubber matrix.

关键词： Filament-Wound Composite Tube uniaxial tension Tensile Test Debonding Damage Finite Element Analysis

Molecular Dynamics Study of tension Process of Ni-Based Superalloy

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Acta Metallurgica Sinica(English Letters) 2020年第5期33卷 741-750页

作者： Hui Li Wan Du Yi Liu Materials Genome Institute Shanghai UniversityShanghai 200444China

To understand the atomistic mechanisms of tension failure of Ni-based superalloy,in this study,the classical molecular dynamics(MD)simulations were used to study the uniaxial tension processes of both the Ni/Ni3 Al interface systems and the pure Ni and Ni3 Al *** examine the effects of interatomic potentials,we adopted embedded atom method(EAM)and reactive force field(ReaxFF)in the MD *** results of EAM simulations showed that the amorphous structures and voids formed near the interface,facilitating further crack propagation within Ni *** EAM potentials also predicted that dislocations were generated and annihilated alternatively,leading to the oscillation of yielding stress during the tension *** ReaxFF simulations predicted more amorphous formation and larger tensile *** atomistic understanding of the defect initiation and propagation during tension process may help to develop the strengthening strategy for controlling the defect evolution under loading.

关键词： Ni-based superalloy Molecular dynamics Embedded atom method(EAM) Reactive force field(ReaxFF) uniaxial tension

Strain Rate Effect of AE Characteristics in the Whole Process of uniaxial Tensile of Mortar

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Journal of Wuhan University of Technology(Materials Science) 2023年第3期38卷 547-556页

作者：王娜王岩 SU Yihui ZHAO Haitao College of Civil Engineering and Transportation Hohai UniversityNanjing 210024China

We completed the uniaxial tensile test of mortar in the range of strain rate from 10^(-6)to 10^(-4)s^(-1)in the section containing softening,and carried out acoustic emission monitoring(AE)simultaneously.A series of AE parameters and spectrum analysis methods were used to identify the damage evolution process and cracking mechanism of mortar at different strain *** results show that,with the increase of strain rate,the peak stress and tensile elastic modulus of mortar increase obviously,and the stress level corresponding to the starting point of AE activity increases significantly as well,which indicates that the mechanical properties and AE characteristics of mortar have obvious strain rate *** the increase of strain rate,the cumulative AE hit decreases gradually,while the average AE hit rate increases significantly,indicating that the increase of strain rate reduces the damage degree of internal microstructure of the specimen,but the crack propagation speed *** the pre-peak stress stage,the average of AE ringing count and signal energy decreases with the increase of strain rate,while the average of duration increases;in the post-peak stress stage(f_(t)-30%f_(t)),the average of the three AE parameters all increase with the increase of strain rate,indicating that the strain rate effect on the damage process of mortar is different before and after peak stress,and the damage mechanism represented by different parameters is also *** the whole process of uniaxial tensile of mortar,with the increase of strain rate,the scatter distribution of AE frequency-amplitude becomes more discrete,and the b-value shows a decreasing *** addition,the average level of AE peak frequency decreases with the increase of strain rate,while that of ca8 band wavelet energy spectrum coefficient *** is indicated that the increase of strain rate enables the crack propagation state of mortar specimen to become unstable,and the width of macrocrack incre

关键词： mortar acoustic emission uniaxial tension strain rate

A Crystal Plasticity Model with Irradiation Effect for the Mechanical Behavior of FCC Metals

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Acta Mechanica Solida Sinica 2019年第6期32卷 675-687页

作者： Jnnfeng Nie Yunpeng Liu Pandong Lin Qihao Xie Zhanli Liu Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Minis try of EducationTsinghua UniversityBeijing 100084China Applied Mechanics Lab. School of Aerospace EngineeringTsinghua UniversityBeijing 100084China Data Science and Information Technology Research Center Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China

In this paper,a crystal plasticity model considering the irradiation effect based on the thermal activation theory is *** evolutions of screw dislocations,edge dislocations,and stacking fault tetrahedrals(SFTs)(induced by irradiation)are included into the *** interactions between dislocations and irradiation-induced SFTs are also *** constitutive model is numerically implemented on the ABAQUS platform through UMAT subroutine and applied to study the irradiation effect on the mechanical behavior of pure *** mechanical properties of single and polycrystalline copper are studied,and the simulation results show that the constitutive model can properly predict the mechanical behavior of irradiated pure *** for polycrystalline copper,the simulation results are in good agreement with the experimental data.

关键词： Crystal plasticity Irradiation effect uniaxial tension Dislocation FCC crystal