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Numerical modeling on strain energy evolution in rock system interaction with energy-absorbing prop and rock bolt

International Journal of Mining Science and Technology 2023年第10期33卷 1273-1288页

作者： Yang Hao Chunhui Liu Yu Wu Hai Pu Yanlong Chen Lingling Shen Guichen Li State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China School of Mines China University of Mining and TechnologyXuzhou 221116China

The interaction mechanism between coal and rock masses with supporting materials is significant in roadway control, especially in deep underground mining situations where dynamic hazards frequently happened due to high geo-stress and strong disturbed effects. This paper is to investigate the strain energy evolution in the interaction between coal and rock masses with self-designed energy-absorbing props and rock bolts by numerical modeling with the finite difference method. The interaction between rock and rock bolt/prop is accomplished by the cables element and the interface between the inner and outer props. Roadway excavation and coal extraction conditions in deep mining are numerically employed to investigate deformation, plastic zone ranges, strain energy input, accumulation, dissipation,and release. The effect on strain energy input, accumulation, dissipation, and release with rock deformation, and the plastic zone is addressed. A ratio of strain energy accumulation, dissipation, and release with energy input a, β, γ is to assess the dynamic hazards. The effects on roadway excavation and coal extraction steps of a, β, γ are discussed. The results show that:(1) In deep high geo-stress roadways, the energyabsorbing support system plays a dual role in resisting deformation and reducing the scope of plastic zones in surrounding rock, as well as absorbing energy release in the surrounding rock, especially in the coal extraction state to mitigate disturbed effects.(2) The strain energy input, accumulation is dependent on roadway deformation, the strain energy dissipation is relied on plastic zone area and disturbed effects, and strain energy release density is the difference among the three. The function of energyabsorbing rock bolts and props play a key role to mitigate strain energy release density and amount, especially in coal extraction condition, with a peak density value from 4×10^(4) to 1×10^(4)J/m^(3), and amount value from 3.57×10^(8) to 1.90×10^(6)J.(3) When mining is advanced in small steps, the strai

关键词： strain energy Coal and rock mass energy-absorbing prop and rock bolt strain energy evolution

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A plastic strain energy method exploration between machined surface integrity evolution and torsion fatigue behaviour of low alloy steel

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Chinese Journal of Aeronautics 2022年第10期35卷 412-429页

作者： Yong WANG Xibin WANG Zhibing LIU Shuyao LIU Sitao WANG Hongtao CHEN Ci SONG Yifan BAI Pai WANG Yang LIU School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Fundamental Science for Advanced Machining Beijing Institute of TechnologyBeijing 100081China Beijing North Vehicle Group Corporation Beijing 100072China

To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low alloy steel for service performance,four multistage machining processes were applied to the 45Cr Ni Mo VA steel,including the Rough Turning process(RT),RT+the Finish Turning process(FRT),FRT+the Grinding process(GFRT)and RT+the Finish Turning process on dry cutting condition(FRT0).The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50%when it evolved from the RT process.The lower surface roughness of R1.3μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density,and the crack feature evolved from some specific bulges to flat shear plane characteristics.When the GFRT process evolved from the FRT process,its average fatigue life increased by 1.45 times,compared with the RT process.Plastic strain amplitude decreased by 21%,and the strain energy density decreased by 4%due to more considerable compressive residual stress(-249 MPa).Plastic deformation layer depth had a consistent tendency with surface roughness.In this paper,surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained.A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

关键词： Cyclic hysteresis loop Multistage machining processes strain energy Surface integrity evolution Torsional fatigue

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Mechanical properties and energy evolution of Beishan shallow-layer granite under different unloading paths

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Journal of Mountain Science 2024年第5期21卷 1728-1744页

作者： WANG Chuanle LI Erbing ZHANG Dengke HAN Yang LU Hui HE Kang DU Guangyin School of Transportation Southeast UniversityNanjing 211189China College of Defense Engineering Army Engineering University of PLANanjing 210007China Nanjing Urban Construction Management Group Co. Ltd.Nanjing 210006China College of Field Engineering Army Engineering University of PLANanjing 210007China

Rock has mechanical characteristics and a fracture damage mechanism that are closely related to its loading history and loading path. The mechanical properties, fracture damage features, acoustic emission(AE) characteristics, and strain energy evolution of the Beishan shallow-layer granite used in triaxial unloading tests were investigated in this study. Three groups of triaxial tests, namely, conventional triaxial compression test(Group Ⅰ), maintaining deviatoric stress synchronously unloading confining pressure test(Group Ⅱ), and loading axial pressure synchronously unloading confining pressure test(Group Ⅲ), were carried out for the cylindrical granite specimens. AE monitoring device was utilized in these tests to determine the degree to which the AE waves and AE events reflected the degree of rock damage. In addition, the crack stress thresholds of the specimens were determined by volumetric strain method and AE parameter method, and strain energy evolution of the rock was explored in different damage stages. The results show that the shallow-layer granite experiences brittle failure during the triaxial loading test and unloading test, and the rock has a greater damage degree during the unloading test. The crack stress thresholds of these samples vary greatly between tests, but the threshold ratios of all samples are similar in the same crack damage stage. The Mogi-Coulomb strength criterion can better describe the unloading failure strength of the rock. The evolution of the AE parameter characteristics and strain energy differs between the specimens used in different stress path tests. The dissipative strain energy is the largest in Group Ⅱ and the smallest in Group Ⅰ.

关键词： Beishan granite Unloading test Mechanical properties Damage mechanism Acoustic emission strain energy

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Multiple damage detection in complex bridges based on strain energy extracted from single point measurement

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Frontiers of Structural and Civil Engineering 2020年第3期14卷 722-730页

作者： Alireza ARABHA NAJAFABADI Farhad DANESHJOO Hamid Reza AHMADI Department of Structural Engineering RoadHousing&Urban Development Research CenterTehran 13145-1696Iran Department of Structural Engineering Faculty of Civil and Environmental EngineeringTarbiat Modares UniversityTehran 14115-397Iran Department of Civil Engineering Faculty of EngineeringUniversity of MaraghehMaragheh 55136-553Iran

strain energy of the structure can be changed with the damage at the damage location.The accurate detection of the damage location using this index in a force system is dependent on the degree of accuracy in determining the structure deformation function before and after damage.The use of modal-based methods to identify damage in complex bridges is always associated with problems due to the need to consider the effects of higher modes and the adverse effct of operational conditions on the extraction of structural modal parameters.In this paper,the deformation of the structure was determined by the concept of influence line using the Betti-Maxwell theory.Then two damage detection indicators were developed based on strain energy variations.These indices were presented separately for bending and torsion changes.Finite element analysis of a five-span concrete curved bridge was done to validate the stated methods.Damage was simulated by decreasing stiffness at different sections of the deck.The response regarding displacement ofa point on the deck was measured along each span by passing a moving load on the bridge at very low speeds.Indicators of the strain energy extracted from displacement influence line and the strain energy extracted from the rotational displacement influence line(SERIL)were calculated for the studied bridge.The results show that the proposed methods have well identified the location of the damage by significantly reducing the number of sensors required to record the response.Also,the location of symmetric damages is detected with high resolution using SERIL.

关键词： damage detection strain energy infuence line complex bridges rotation displacement

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Accurate theoretical evaluation of strain energy of all-carboatomic ring(cyclo[2n]carbon),boron nitride ring,and cyclic polyacetylene

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Chinese Physics B 2022年第12期31卷 357-363页

作者：卢天刘泽玉陈沁雪 Beijing Kein Research Center for Natural Sciences Beijing 100024China School of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

Cyclocarbon fully consists of sp-hybridized carbon atoms,which shows quite unusual electronic and geometric structures compared to common molecules.In this work,we systematically studied strain energy(SE)of cyclocarbons of different sizes using regression analysis method based on electronic energies evaluated at the very accurate DLPNO-CCSD(T)/ccp VTZ theoretical level.In addition,ring strain of two systems closely related to cyclocarbon,boron nitride(BN)ring,and cyclic polyacetylene(c-PA),is also explored.Very ideal relationships between SE and number of repeat units(n)are built for cyclo[2n]carbon,B_(n)N_(n),and[2n]c-PA as SE=555.0·n^(-1),145.1·n^(-1),and 629.8·n^(-1)kcal·mol^(-1),respectively,and the underlying reasons of the difference and similarity in their SEs are discussed from electronic structure perspective.In addition,force constant of harmonic potential of C-C-C angles in cyclocarbon is derived based on SE values,the result is found to be 56.23 kcal·mol^(-1)·rad^(-2).The possibility of constructing homodesmotic reactions to calculate SEs of cyclocarbons is also explored in this work,although this method is far less rigorous than the regression analysis method,its result is qualitatively correct and has the advantage of much lower computational cost.In addition,comparisons show thatωB97XD/def2-TZVP is a good inexpensive alternative to the DLPNO-CCSD(T)/cc-p VTZ for evaluating energies used in deriving SE,while the popular and very cheap B3LYP/6-31G(d)level should be used with caution for systems with global electron conjugation such as c-PA.

关键词： strain energy ring strain cyclocarbon boron nitride ring cyclic polyacetylene quantum chemistry

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Using strain energy-based prediction of effective elastic properties in topology optimization of material microstructures

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Acta Mechanica Sinica 2007年第1期23卷 77-89页

作者： Weihong Zhang Gaoming Dai Fengwen Wang Shiping Sun Hicham Bassir Institute of Mechatronic Engineering Northwestern Polytechnical University Xi'an 710072 China FEMTO-ST Department of LMARC UMR--CNRS 6174 25000 Besancon France

An alternative strain energy method is proposed for the prediction of effective elastic properties of orthotropic materials in this paper. The method is implemented in the topology optimization procedure to design cellular solids. A comparative study is made between the strain energy method and the well-known homogenization method. Numerical results show that both methods agree well in the numerical prediction and sensitivity analysis of effective elastic tensor when homogeneous boundary conditions are properly specified. Two dimensional and three dimensional microstructures are optimized for maximum stiffness designs by combining the proposed method with the dual optimization algorithm of convex programming. Satisfactory results are obtained for a variety of design cases.

关键词： Cellular solids Material design Homogenization method strain energy Topology optimization

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A method of determining effective elastic properties of honeycomb cores based on equal strain energy

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Chinese Journal of Aeronautics 2017年第2期30卷 766-779页

作者： Qiu Cheng Guan Zhidong Jiang Siyuan Li Zengshan School of Aeronautic Science and Engineering Beihang University Bejing 100083 China

A computational homogenization technique（CHT） based on the finite element method（FEM） is discussed to predict the effective elastic properties of honeycomb structures.The need of periodic boundary conditions（BCs） is revealed through the analysis for in-plane and out-of-plane shear moduli of models with different cell numbers.After applying periodic BCs on the representative volume element（RVE）,comparison between the volume-average stress method and the boundary stress method is performed,and a new method based on the equality of strain energy to obtain all non-zero components of the stiffness tensor is proposed.Results of finite element（FE） analysis show that the volume-average stress and the boundary stress keep a consistency over different cell geometries and forms.The strain energy method obtains values that differ from those of the volume-average method for non-diagonal terms in the stiffness matrix.Analysis has been done on numerical results for thin-wall honeycombs and different geometries of angles between oblique and vertical walls.The inaccuracy of the volume-average method in terms of the strain energy is shown by numerical benchmarks.

关键词： Elastic properties Homogenization Honeycomb strain energy Unit cells

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Experimental and Numerical Study on the Shear Strength and strain energy of Rock Under Constant Shear Stress and Unloading Normal Stress

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Computer Modeling in Engineering & Sciences 2021年第4期127卷 79-97页

作者： Tantan Zhu Da Huang Jianxun Chen Yanbin Luo Longfei Xu School of Highway Chang’an UniversityXi’an710064China College of Geological Engineering and Geomatics Chang’an UniversityXi’an710064China School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China

Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stress conditions,a new stress path for direct shear tests was proposed to model the unloading of stress caused by excavation and other processes.The effects of the initial stresses(i.e.,the normal stress and shear stress before unloading)on the shear behavior and energy conversion were investigated using laboratory tests and numerical simulations.The shear strength of a rock under constant stress or under unloading normal stress conforms to the Mohr Coulomb criterion.As the initial normal stress increases,the cohesion decreases linearly and the tangent of the internal friction angle increases linearly.Compared with the results of the tests under constant normal stress,the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are larger.A strength envelope surface can be used to describe the relationship between the initial stresses and the failure normal stress.Shear dilatancy can decrease the total energy of the direct shear test under constant normal stress or unloading normal stress,particularly when the stress levels(the initial stresses in the test under unloading normal stress or the normal stress in the test under constant normal stress)are high.The ratio of the dissipated energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses.The direct shear test under constant normal stress can be considered to be a special case of a direct shear test under unloading normal stress with an unloading amount of zero.

关键词： Unloading normal stress direct shear test strain energy energy conversion

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Planar Cardinal Spline Curves with Minimum strain energy

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Communications in Mathematical Research 2018年第4期34卷 329-334页

作者： li jun-cheng ma fu-ming College of Mathematics and Finance Hunan University of HumanitiesScience and TechnologyLoudiHunan417000 不详

In this paper, we focus on how to use strain energy minimization to obtain the optimal value of the fl＇ee parameter of the planar Cardinal spline curves. The unique solution can be easily obtained by minimizing an ap... 详细信息

关键词： Cardinal spline Catnmll-Rom spline nlinimization strain energy fair curve

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Prediction of cutting force in ultra-precision machining of nonferrous metals based on strain energy

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Nanotechnology and Precision Engineering 2021年第4期4卷 1-11页

作者： Ying Wang Zewei Yuan Tianzheng Wu Heran Yan School of Mechanical Engineering Shenyang University of TechnologyShenyang 110870China

The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account of factors such as size effects,the undeformed cutting thickness,the tool blunt radius,and the tool rake angle.Therefore,this paper proposes a new theoretical calculation model for accurately predicting the cutting force in ultra-precision machining,taking account of such factors.The model is first used to analyze the material deformation of the workpiece and the cutting force distribution along the cutting edge of a diamond tool.The size of the strain zone in different cutting deformation zones is then determined by using the distribution of strain work per unit volume and considering the characteristics of the stress distribution in these different deformation zones.Finally,the cutting force during ultra-precision machining is predicted precisely by calculating the material strain energy in different zones.A finite element analysis and experimental data on ultra-precision cutting of copper and aluminum are used to verify the predictions of the theoretical model.The results show that the error in the cutting force between the calculation results and predictions of the model is less than 14%.The effects of the rake face stress distribution of the diamond tool,the close contact zone,and material elastic recovery can be fully taken into account by the theoretical model.Thus,the proposed theoretical calculation method can effectively predict the cutting force in ultra-precision machining.

关键词： Ultra-precision cutting Diamond tool Cutting force strain energy Finite element analysis

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