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A methodology to determine the elastic properties of anisotropic rocks from a single uniaxial compression test

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1166-1183页

作者： Morteza Nejati Marie Luise Texas Dambly Martin Osaar Department of Earth sciences ETH ZurichZurichSwitzerland Geothermal Energy and Geofluids Department of Earth SciencesETH ZurichZurichSwitzerland

This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test.We first give the mathematical proof that a uniaxial compression test provides only four independent strain equations.As a result,the exact determination of all five independent elastic constants from only one test is not possible.An approximate determination of the Young’s moduli and the poisson’s ratios is however practical and efficient when adding the saint-Venant relation as the fifth equation.Explicit formulae are then developed to calculate both secant and tangent definitions of the five elastic constants from a minimum of four strain measurements.The results of this new methodology applied on three granitic samples demonstrate a significant stress-induced nonlinear behavior,where the tangent moduli increase by a factor of three to four when the rock is loaded up to 20 MPa.The static elastic constants obtained from the uniaxial compression test are also found to be significantly smaller than the dynamic ones obtained from the ultrasonic measurements.

关键词： Transversely isotropic rock Elastic constants Young’s modulus poisson’s ratio seismic anisotropy Uniaxial compression Granite

Mechanical Response of Honeycomb structures Under Impact

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Journal of Beijing Institute of Technology 2020年第1期29卷 1-8页

作者： Yaxin Guo Mengqi Yuan Hang Zhang Xinming Qian state Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing 100081China

A honeycomb structure with a negative poisson’s ratio(NPR)was designed,fabricated,and analyzed for utilization in personal protective clothing(PPC).The mechanical properties were investigated using a quasi-static mechanical testing and the Hopkinson pressure bar experimental system,and results were compared with similar samples containing regular hexagonal and regular quadrilateral honeycomb structures.The experimental results showed that under quasi-static loadings,the concave honeycomb structure had the highest compressive modulus and yield strength,which produced the highest strain absorption energy,anti-deformation performance and energy absorption.When exposed to a dynamic load at a high strain rate,the concave honeycomb also exhibited the highest dynamic compression modulus,the best impact resistance and best energy absorption among the three structures.In summary,the concave honeycomb structure was more resistant to deformation and had higher impact resistance than the regular hexagonal and regular quadrilateral honeycombs,and exhibited better energy absorption,which makes it a good candidate for application as a personal safety protection material.

关键词： negative poisson’s ratio effect quasi-static dynamic analysis energy absorption

Interpretation of s-Wave Data from Fanshi-Taipusiqi Dss Profile and Analysis of Correlation between Deep structural Characteristics and seismicity

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Earthquake Research in China 1998年第1期12卷 27-36页

作者： Zhou Xuesong,song songyan,Zhang Xiankang,Qiu shuyan,Gong Yi,and song JianliResearch Center of Exploration Geophysics,ssB,Zhengzhou 450003,China

By processing s-wave data from the Fanshi-Huai’an-Taipusiqi Dss profile,which is a three-component,wide-angle reflection/refraction profile,and in the light of the results from P-wave interpretation,two-dimensional(2-D)structures of the crust and upper mantle are presented,including s-wave velocity Vs and the physical parameter of medium-poisson’s ratio a.Taking other geological and geophysical information into account,and with reference to the results from petrophysical experiments at home and abroad,we carried out interpretation and inference with respect to deep crustal structure,tectonics,and lithologic characters.It has been concluded that in the upper and middle crust,a values are mostly not greater than 0.25,and rocks,which generally assume brittle,are mainly composed of granite; the rocks in the lower layer of the upper crust between Yangyuan-Huai’an containing inorganic CO2 itself releases carbon; for the rocks in the lower crust and crust-mantle transitional zone,which are comparatively

关键词： s-wave velocity poisson’s ratio lithologic character ultra-crustal fault earthquakes.

Examination of Minimum Time step, from Modified Heisenberg Uncertainty Principle, Inflaton Physics and Black Hole Physics

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Journal of High Energy Physics, Gravitation and Cosmology 2017年第1期3卷 39-45页

作者： Andrew Walcott Beckwith Physics Department College of Physics Chongqing University Huxi Campus Chongqing China

First, we calculate the minimum length for the creation of a 1045 Hz relic Gravitational wave. Next, we look Padamababhan’s inflaton physics, and work done by the author for a modified Heisenberg Uncertainty principle for constraints on a minimum time step. sciama’s work in “Black hole explosions” (1982) gives us a linkage between a decay rate for black holes, in terms of a life time, and the mass, M of the black hole, which when combined with a simple exposition from susskind and Hrabovsky (2013) for the most basic evolution the time change in energy E(t), which is how we form a first order treatment of the square of a minimum time step . We then reference what was done by Ng (2008) as far as infinite quantum statistics, for entropy as a particle count, and from first principle get constraints upon entropy production, as a function of boundaries on minimum time step. We assume massive Gravity, and obtain a peak 1036 Giga Hertz frequency range (1045 Hertz) for relic Gravitational waves, and Gravitons.

关键词： Massive Gravity Inflaton Physics Infinite Quantum statistics Modified poisson’s Equation

A poisson solver Based on Iterations on a sylvester system

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Applied Mathematics 2018年第6期9卷 749-763页

作者： Michael B. Franklin Ali Nadim Institute of Mathematical sciences Claremont Graduate University Claremont CA USA

We present an iterative scheme for solving poisson’s equation in 2D. Using finite differences, we discretize the equation into a sylvester system, AU +UB = F, involving tridiagonal matrices A and B. The iterations occur on this sylvester system directly after introducing a deflation-type parameter that enables optimized convergence. Analytical bounds are obtained on the spectral radii of the iteration matrices. Our method is comparable to successive Over-Relaxation (sOR) and amenable to compact programming via vector/array operations. It can also be implemented within a multigrid framework with considerable improvement in performance as shown herein.

关键词： poisson’s Equation sylvester system Multigrid

Using of an Auxetic structure as Reinforcement of a Bending Reinforced Concrete Beam

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Journal of Mechanics Engineering and Automation 2019年第1期9卷 1-16页

作者： Tarik Baran Department of Civil Engineering Osmaniye Korkut Ata UniversityOsmaniye 80000Turkey

Materials which have negative poisson’s ratio are entitled as auxetics.Auxetics can be designed as micro-to macro-sized structures.The use of auxetics in civil engineering structures has been studied only to a limited extent.In this study,a re-entrant medium-size auxetic structure is employed as reinforcement of a reinforced concrete beam.The beam is subjected to static and dynamic loading conditions and then investigated by means of maximum vertical displacements of the beam.Besides,normal stresses and shear stresses of the concrete are also assessed.To interpret the performance of the auxetic reinforcement,obtained results are compared with the results of another beam which has non-auxetic reinforcement.The results show that these structures behave with bending compatibility as expected and due to the negative poisson’s ratio,they led to shear strength increase.Auxetic structures can be employed as reinforcement in a beam.Besides,they can be employed without concrete to increase the shear strength in the case of high shear and impact strength if it is needed.

关键词： Auxetic re-entrant cell structure negative poisson’s ratio auxetic reinforcement indentation resistance

study of Rock Mechanic Property and Mineralogy Relationship of the Huai Hin Lat Formation, sap Phlu Basin, Northeastern Thailand: Implications for Understanding of shale Gas Reservoir Rock

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Open Journal of Geology 2019年第10期9卷 718-721页

作者： Boonnarong Arsairai Nawarak Ruenmai Qinglai Feng Chongpan Chonglakmani school of Geotechnology Institute of Engineering Suranaree University of Technology Nakhon Ratchasima Thailand state Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China

Thailand is lacked of gas that more information of probable (P2) and possible (P3) reserve data including shale gas can be acceptable to prove (P1) reserve data for new gas field. This research had implicated for understanding of unconventional reservoir rock by rock mechanical, micro-CT, and geochemistry analysis of the Huai Hin Lat Formation. The rock mechanical analysis is composed of average young’s modulus, poisson’s ratio, and compressive strength of 1933.79 MPa, 0.1472, and 52.56 MPa. The average porosity of 6.89% consists of 5.41% and 1.48% of closed and open porosities. The average mineralogical results consist mainly of 57.60% and 42.40% of brittle and ductile minerals indicating more elasticity except Bed 6. The Bed 6 is significantly higher quartz (15%) and brittle minerals (64%) indicating to easier fracture are, therefore, lower compressive strength (25.93 MPa), young’s modulus (1729.10 MPa) and poisson’s ratio (0.0705). The Beds 3B is slightly higher clay containing slightly higher closed porosity (5.46%) but the Bed 14 is slightly higher brittle mineral indicating to slightly higher open porosity.

关键词： Compressive strength Young’s Modulus poisson’s Ratio Brittle Mineral Porosity