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Comparative study on three dynamic modulus of elasticity and static modulus of elasticity for Lodgepole pine lumber 被引量:5
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作者 梁善庆 傅峰 《Journal of Forestry Research》 SCIE CAS CSCD 2007年第4期309-312,共4页
The dynamic and static modulus of elasticity (MOE) between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing (NDT), Portable Ultras... The dynamic and static modulus of elasticity (MOE) between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing (NDT), Portable Ultrasonic Non-destructive Digital Indicating Testing (Pundit), Metriguard and Fast Fourier Transform (FFT) and the normal bending method. Results showed that the dynamic and static MOE of bluestained wood were higher than those of non-bluestained wood. The significant differences in dynamic MOE and static MOE were found between bulestained and non-bluestained wood, of which, the difference in each of three dynamic MOE (Ep. the ultrasonic wave modulus of elasticity, Ems, the stress wave modulus of elasticity and El, the longitudinal wave modulus of elasticity) between bulestained and non-bluestained wood arrived at the 0.01 significance level, whereas that in the static MOE at the 0.05 significance level. The differences in MOE between bulestained and non-bluestained wood were induced by the variation between sapwood and heartwood and the different densities of bulestained and non-bluestained wood. The correlation between dynamic MOE and static MOE was statistically significant at the 0.01 significance level. Although the dynamic MOE values of Ep, Em, Er were significantly different, there exists a close relationship between them (arriving at the 0.01 correlation level). Comparative analysis among the three techniques indicated that the accurateness of FFT was higher than that of Pundit and Metriguard. Effect of tree knots on MOE was also investigated. Result showed that the dynamic and static MOE gradually decreased with the increase of knot number, indicating that knot number had significant effect on MOE value. 展开更多
关键词 Lodgepole pine Non-destructive testing dynamic modulus of elasticity Static modulus of elasticity
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On dynamics of elastic rod based on exact Cosserat model 被引量:11
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作者 刘延柱 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第1期1-8,共8页
The analysis of kinematics and dynamics of an elastic rod with circular cross section is studied on the basis of exact Cosserat model under consideration of the tension and shear deformation of the rod. The dynamical ... The analysis of kinematics and dynamics of an elastic rod with circular cross section is studied on the basis of exact Cosserat model under consideration of the tension and shear deformation of the rod. The dynamical equations of a rod with arbitrary initial shape are established in general form. The dynamics of a straight rod under axial tension and torsion is discussed as an example. In discussion of static stability in the space domain the Greenhill criteria of stability and the Euler load are corrected by the influence of tension and shear strain. In analysis of dynamical stability in the time domain it is shown that the Lyapunov and Euler stability conditions of the rod in space domain are the necessary conditions of Lyapunov's stability in the time domain. The longitudinal, torsional and lateral vibrations of a straight rod based on exact model are discussed, and an exact formula of free frequency of lateral vibration is obtained. The free frequency formulas of various simplified models, such as the Rayleigh beam, the Kirchhoff rod, and the Timoshenko beam, can be seen as special cases of the exact formula under different conditions of simplification. 展开更多
关键词 dynamics of elastic rod exact Cosserat model lateral vibration of rod
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Noether symmetry and conserved quantities of the analytical dynamics of a Cosserat thin elastic rod 被引量:6
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作者 王鹏 薛纭 刘宇陆 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第10期46-51,共6页
In this paper, we investigate the Noether symmetry and Noether conservation law of elastic rod dynamics with two independent variables: time t and arc coordinate s. Starting from the Lagrange equations of Cosserat ro... In this paper, we investigate the Noether symmetry and Noether conservation law of elastic rod dynamics with two independent variables: time t and arc coordinate s. Starting from the Lagrange equations of Cosserat rod dynamics, the criterion of Noether symmetry with Lagrange style for rod dynamics is given and the Noether conserved quantity is obtained. Not only are the conservations of generalized moment and generalized energy obtained, but also some other integrals. 展开更多
关键词 analytical mechanics Noether symmetry conservation laws Cosserat elastic rod dynamics
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Theoretical Research and Experimental Validation of Elastic Dynamic Load Spectra on Bogie Frame of High-speed Train 被引量:13
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作者 ZHU Ning SUN Shouguang +1 位作者 LI Qiang ZOU Hua 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第3期498-506,共9页
When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test... When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test evaluation standard and design criteria of bogie frames are all based on the quasi-static deformation hypothesis. Structural fatigue damage generated by structural elastic vibrations has not yet been included. In this paper, theoretical research and experimental validation are done on elastic dynamic load spectra on bogie frame of high-speed train. The construction of the load series that correspond to elastic dynamic deformation modes is studied. The simplified form of the load series is obtained. A theory of simplified dynamic load–time histories is then deduced. Measured data from the Beijing–Shanghai Dedicated Passenger Line are introduced to derive the simplified dynamic load–time histories. The simplified dynamic discrete load spectra of bogie frame are established. Based on the damage consistency criterion and a genetic algorithm, damage consistency calibration of the simplified dynamic load spectra is finally performed. The computed result proves that the simplified load series is reasonable. The calibrated damage that corresponds to the elastic dynamic discrete load spectra can cover the actual damage at the operating conditions. The calibrated damage satisfies the safety requirement of damage consistency criterion for bogie frame. This research is helpful for investigating the standardized load spectra of bogie frame of high-speed train. 展开更多
关键词 elastic dynamic load spectra finite element method modal deformation calibration bogie frame high-speed train
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ON SOME BASIC PRINCIPLES IN DYNAMIC THEORY OF ELASTIC MATERIALS WITH VOIDS 被引量:2
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作者 罗恩 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1993年第2期142-148,共7页
According to the basic idea of dual-complementarity,in a simple and unified way proposed by the author,some basic principles in dynamic theory of elastic materials with voids can be established sys- tematically.In thi... According to the basic idea of dual-complementarity,in a simple and unified way proposed by the author,some basic principles in dynamic theory of elastic materials with voids can be established sys- tematically.In this paper, an important integral relation in terms of convolutions is given,which can be con- sidered as the generalized principle of virtual work in mechanics.Based on this relation,it is possible not on- ly to obtain the principle of virtual work and the reciprocal theorem in dynamic theory of elastic materials with voids,but also to derive systematically the complementary functionals for the eight-field,six-field, four-field and two-field simplified Gurtin-type variational principles.Furthermore,with this approach,the in- trinsic relationship among various principles can be explained clearly. 展开更多
关键词 dynamic theory of elastic materials with voids principle of virtual work reciprocal theorem variational principle complementary relation
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Dynamic Elastic Modulus of Cement Paste at Early Age based on Nondestructive Test and Multiscale Prediction Model 被引量:1
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作者 赵海涛 黄冬辉 +1 位作者 WANG Xiaojun CHEN Xudong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第2期321-328,共8页
This paper introduced a nondestructive testing method to evaluate the dynamic elastic modulus of cement paste. Moreover, the effect of water-cement ratio and conventional admixtures on the dynamic elastic modulus of c... This paper introduced a nondestructive testing method to evaluate the dynamic elastic modulus of cement paste. Moreover, the effect of water-cement ratio and conventional admixtures on the dynamic elastic modulus of cement paste was investigated, in which three kinds of admixtures were taken into account including viscosity modifying admixture (VMA), silica.fume (SF), and shrinkage-reducing admixture (SRA). The experimental results indicate that the dynamic elastic modulus of cement paste increases with decreasing water-cement ratio. The addition of SF increases the dynamic elastic modulus, however, the overdosage of VMA causes its reduction. SRA reduces the dynamic elastic modulus at early age without affecting it in later period. Finally, a multiscale micromechanics approach coupled with a hydration model CEMHYD3D and percolation theory is utilized to predict the elastic modulus of cement paste, and the predictive results by the model are in accordance with the experimental data. 展开更多
关键词 dynamic elastic modulus nondestructive test viscosity modifying admixture silica fume shrinkage-reducing admixture multiscale model
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Static and dynamic snap-through behaviour of an elastic spherical shell 被引量:3
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作者 D. Karagiozova X.-W. Zhang T.-X. Yu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期695-710,共16页
The deformation and snap-through behaviour of a thin-walled elastic spherical shell statically compressed on a flat surface or impacted against a fiat surface are studied the- oretically and numerically in order to es... The deformation and snap-through behaviour of a thin-walled elastic spherical shell statically compressed on a flat surface or impacted against a fiat surface are studied the- oretically and numerically in order to estimate the influence of the dynamic effects on the response. A table tennis ball is considered as an example of a thin-walled elastic shell. It is shown that the increase of the impact velocity leads to a variation of the deformed shape thus resulting in larger de- formation energy. The increase of the contact force is caused by both the increased contribution of the inertia forces and contribution of the increased deformation energy. The contact force resulted from deformation/inertia of the ball and the shape of the deformed region are calcu- lated by the proposed theoretical models and compared with the results from both the finite element analysis and some previously obtained experimental data. Good agreement is demonstrated. 展开更多
关键词 Elastic spherical shell Snap-through buckling.Static dynamic
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Dynamic stress concentrations in thick plates with two holes based on refined theory 被引量:1
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作者 周传平 胡超 +1 位作者 F.MA 刘殿魁 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2014年第12期1591-1606,共16页
Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem ... Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese. 展开更多
关键词 refined vibration equation complex variable and conformal mappingmethod two holes elastic wave scattering and dynamic stress concentrations thick plate
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Dynamic analysis of new type elastic screen surface with multi degree of freedom and experimental validation 被引量:6
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作者 宋宝成 刘初升 +1 位作者 彭利平 李珺 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第4期1334-1341,共8页
A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were c... A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF. 展开更多
关键词 vibrating screen elastic screen surface multi degree of freedom dynamic analysis mesh stoppage prevention
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Dynamic Design of Thick Orthotropic Cantilever Plates with Consideration of Bimoments 被引量:2
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作者 Мakhamatali K. Usarov 《World Journal of Mechanics》 2016年第10期341-356,共17页
The paper is devoted to dynamic design of thick orthotropic cantilever plates by applying the bimoment theory of plates, which takes into account the forces, moments and bimoments;and the theory takes into account non... The paper is devoted to dynamic design of thick orthotropic cantilever plates by applying the bimoment theory of plates, which takes into account the forces, moments and bimoments;and the theory takes into account nonlinear law of displacements distribution in cross section of the plate. The methods for constructing bimoment theory are based on Hooke’s Law, three-dimensional equations of the theory of dynamic elasticity and the method of displacements expansion into Maclaurin series. The article gives the expressions to determine the forces, moments and bimoments. Bimoment theory of plates is described by two unrelated two-dimensional systems with nine equations in each. On each edge of the plate, depending on the type of fastening, nine boundary conditions are given. As an example, the solution of the problem of dynamic bending of thick isotropic and orthotropic plate under the influence of transverse dynamic loads in the form of the Heaviside function is given. The equations of motion of the plate are solved by numerical method of finite differences. The numerical results are obtained for isotropic and orthotropic plate. The graphs of changes of displacements and stresses of faces surfaces of the plate are presented. Maximum values of these displacements are found and analyzed. It is shown that by Timoshenko theory numerical values of stresses are much smaller compared to the ones obtained by bimoment theory of plates. Maximum numerical values of generalized displacements, forces, moments, and bimoments are obtained and presented in tabular form. The analysis of numerical results is done and the conclusions are drawn. 展开更多
关键词 Hooke’s Law Thick Plate dynamic Theory of elasticity Three-Dimensional Problem Bimoment Theory
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Low embankment dynamic response under vehicle traffic loads in arid-oasis areas
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作者 WAN Qi YANG Xiao-hua +1 位作者 YIN Pei-jie BAO Han 《Journal of Mountain Science》 SCIE CSCD 2020年第7期1776-1789,共14页
The use of low embankments is of significant concern for ecological protection in aridoasis areas.Based on the project of Sansha Expressway located in Kashgar City,Xinjiang,China,physical model tests were conducted in... The use of low embankments is of significant concern for ecological protection in aridoasis areas.Based on the project of Sansha Expressway located in Kashgar City,Xinjiang,China,physical model tests were conducted in this study to investigate the dynamic response of the low embankment as per the effects of road structure,load amplitude,load frequency,load cycle,and moisture content.The dynamic stress is shown to increase with load amplitude while the dynamic elastic modulus decreases with load amplitude under short-term loading.The load frequency slightly influences the soil’s dynamic behavior;higher frequencies can improve the dynamic elastic modulus of the subgrade soil.The moisture content has greater influence on the mechanical properties of the subsoil than that of subgrade layer.The subgrade bears the majority of the traffic load as the stress dissipates to 37%of the whole value on its surface.The number of load cycles has the greatest effect on the dynamic response among the influencing factors tested.The dynamic elastic modulus with the type of long-term dynamic loading is only 40%-52%of that with static loading across the entire depth range.The dynamic stress shows significant accumulation with load cycles over the long-term dynamic loading test and becomes stable after 8×10~4 cycles of loading.An equation is established to quantify the cumulative dynamic stress in the low embankment under long-term dynamic loading conditions. 展开更多
关键词 Low embankment dynamic response Model test Moisture content dynamic elastic modulus Cumulative dynamic stress
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Elastic Dynamic Stability of Big-Span Power Transmission Tower Subjected to Seismic Excitations
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作者 张行 李黎 +1 位作者 方秦汉 叶昆 《Journal of Southwest Jiaotong University(English Edition)》 2009年第1期65-71,共7页
By combining the time-history response analysis and the eigenvalue buckling analysis, this paper developed a computational procedure to study the elastic dynamic stability of a transmission tower by APDL language in A... By combining the time-history response analysis and the eigenvalue buckling analysis, this paper developed a computational procedure to study the elastic dynamic stability of a transmission tower by APDL language in ANSYS. The influences of different input directions of seismic excitations and damping ratio on the elastic dynamic stability of tower were discussed. The following conclusions were obtained: ( 1 ) Longitudinal direction of the transmission lines is the worst input direction of seismic excitation for the transmission tower. (2) Dead load has no significant effect on the critical load and the occurrence time of buckling. (3) Vertical input of seismic excitations has no great effect on the dynamic stability of the transmission tower. (4) Damping effect has an influence on the dynamic stability of the transmission tower; however, the inherent characteristics of dynamic buckling is not changed. 展开更多
关键词 Transmission tower Seismic excitation Elastic dynamic stability Big span
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Pressure Effect on Elastic and Lattice Dynamic Properties of Beryllium Selenide from First Principles
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作者 罗雰 GUO Zhicheng CAI Lingcang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第2期378-381,共4页
The lattice dynamic, elastic, and thermodynamic properties of Be Se were investigated with first principles calculations. The phase transition pressure from the zinc blende(B3) to the nickel arsenide(B8) structure... The lattice dynamic, elastic, and thermodynamic properties of Be Se were investigated with first principles calculations. The phase transition pressure from the zinc blende(B3) to the nickel arsenide(B8) structure of Be Se was determined. The elastic stability analysis suggests that the B3 structure Be Se is mechanically stable in the applied pressure range of 0-50 GPa. Our lattice dynamic calculations show that the B3 structure is lattice dynamically stable under high pressure. Within the quasiharmonic approximation, the thermodynamic properties including the constant volume heat capacity and constant pressure heat capacity are predicted. 展开更多
关键词 lattice dynamic elastic properties density functional theory
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Using Refined Theory to Studied Elastic Wave Scattering and Dynamic Stress Concentrations in Plates with Two Cutouts
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作者 Xujiao Yang Zihe Li Haoyu Liu 《Journal of Applied Mathematics and Physics》 2020年第12期2999-3018,共20页
In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied.... In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied. Applying the orthogonal function expansion method, the problem to be solved can be reduced into the solution of a set of infinite algebraic equations. According to free boundary conditions, numerical results of dynamic moment concentration factors in thick plates with two circular cutouts analyze that: there will be more complex interaction changes between two-cutout situation than single cutout situation. In the case of low frequency or high frequency and thin plate, the hole-spacing in the absence of coupling interactions was larger or smaller. The numerical results and method can be used to analyze the dynamics and strength of plate-like structures. 展开更多
关键词 Refined Vibration Equation of Plate Bending Complex Variable and Conformal Mapping Method Two Holes Elastic Wave Scattering and dynamic Stress Concentrations
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Detection of Frost-Resistance Property of Large-Size Concrete Based on Impact-Echo Method
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作者 Qi Feng Zhengyue Ren Dan Wang 《Structural Durability & Health Monitoring》 EI 2023年第1期71-88,共18页
The dynamic elasticity modulus(Ed)is the most commonly used indexes for nondestructive testing to represent the internal damage of hydraulic concrete.Samples with a specific size is required when the transverse resona... The dynamic elasticity modulus(Ed)is the most commonly used indexes for nondestructive testing to represent the internal damage of hydraulic concrete.Samples with a specific size is required when the transverse resonance method was used to detect the Ed,resulting in a limitation for field tests.The impact-echo method can make up defects of traditional detection methods for frost-resistance testing,such as the evaluation via the loss of mass or strength.The feasibility of the impact-echo method to obtain the relative Ed is explored to detect the frost-resistance property of large-volume hydraulic concretes on site.Results show that the impact-echo method can replace the traditional resonance frequency method to evaluate the frost resistance of concrete,and has advantages of high accuracy,easy to operate,and not affecting by the aggregate size and size effect of samples.The dynamic elastic modulus of concrete detected by the impact-echo method has little difference with that obtained by the traditional resonance method.The one-dimensional elastic wave velocity of concrete has a good linear correlation with the transverse resonance frequency.The freeze-thaw damage occurred from the surface to the inner layer,and the surface is expected to be the most vulnerable part for the freeze-thaw damage.It is expected to monitor and track the degradation of the frost resistance of an actual structure by frequently detecting the P-wave velocity on site,which avoids coring again. 展开更多
关键词 Impact-echo method frost-resistance property dynamic elastic modulus ED elastic wave velocity transverse resonance frequency
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Assessment of flexural properties of different grade dimension lumber by ultrasonic technique 被引量:2
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作者 江京辉 吕建雄 +2 位作者 任海青 龙超 骆秀琴 《Journal of Forestry Research》 SCIE CAS CSCD 2007年第4期305-308,共4页
The dimension lumber (45mm×90mm×3700mm) of plantation Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) was graded to four different classes as SS, No. 1, No.2 and No.3, according to national lumber ... The dimension lumber (45mm×90mm×3700mm) of plantation Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) was graded to four different classes as SS, No. 1, No.2 and No.3, according to national lumber grades authority (NLGA) for structure light framing and structure joists and planks. The properties of apparent density was determined at 15% moisture content, bending strength and stiffness were tested according to American Society for Testing and Materials (ASTM) D198-99, and dynamic modulus of elasticity (Eusw) was measured by ultrasonic technique, for predicting the flexural properties of different grade lumbers. The results showed that Eosw was larger than the static MOE. The relationship between Eusw and static MOE was significant at 0.01 level, and the determination coefficients (R2) of the four grade lumbers followed the sequence as R^2No.2 (0.616)〉 R^2ss (0.567)〉 R^2No1 (0.366)〉 R^2No.3 (0.137). The R^2 of Fusw and MOR were lower than that of the Etru and MOR for each grade. The Eusw of all the grade lumbers, except No.3-grade, had significant correlation with the static MOE and MOR, thus the bending strengthof those grade lumbers can be estimated by the E The Etru valuesof four grade lumbers followed a sequence as No.2-grade (10.701 GPa) 〉 SS-grade (10.359 GPa) 〉 No.l-grade (9.840 GPa) 〉 No.3-grade (9.554 GPa). For the same grade dimension lumber, its Eusw value was larger than static MOE. Mean values of MOR for four grade lumbers follow a sequence as No.2-grade (48.67 MPa) 〉 SS-grade (48.16 MPa) 〉 No.3-grade (46.55 MPa) 〉 No. 1-grade (43.39MPa). 展开更多
关键词 Dimension lumber Lumber grade Ultrasonic technique dynamic modulus of elasticity Static modulus of elasticity Modulus of rupture
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Effect of Li addition on mechanical properties and ageing precipitation behavior of extruded Al-3.0 Mg-0.5 Si alloy 被引量:3
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作者 YANG Xiao-kun XIONG Bai-qing +6 位作者 LI Xi-wu YAN Li-zhen LI Zhi-hui ZHANG Yong-an LI Ya-nan WEN Kai LIU Hong-wei 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第9期2636-2646,共11页
The effect of Li(2.0 wt%)addition on mechanical properties and ageing precipitation behavior of Al-3.0 Mg 0.5 Si was investigated by tensile test,dynamic elasticity modulus test,scanning electron microscopy(SEM),trans... The effect of Li(2.0 wt%)addition on mechanical properties and ageing precipitation behavior of Al-3.0 Mg 0.5 Si was investigated by tensile test,dynamic elasticity modulus test,scanning electron microscopy(SEM),transmission electron microscopy(TEM)and high-resolution transmission electron microscopy(HRTEM)images.The results show that the tensile strength of the Li-containing alloy can be significantly improved;however,the ductility is sharply decreased and the fracture mechanism changes from ductile fracture to intergranular fracture.The elasticity modulus of the Li-containing alloy increases by 11.6%compared with the base alloy.The microstructure observation shows that the Li addition can absolutely change the precipitation behavior of the base alloy,andδ′-Al_(3)Li phase becomes the main precipitates.Besides,β′′-Mg_(2)Si andδ′-Al_(3)Li dual phases precipitation can be visibly observed at 170℃ ageing for 100 h,although the quantity ofδ′-Al_(3)Li phase is more thanβ′′-Mg_(2)Si phase.The width of the precipitate-free zone(PFZ)of the Li-containing alloy is much wider at the over-ageing state than the base alloy,which has a negative impact on the ductile and results in the decrease of elongation. 展开更多
关键词 Al-3.0 Mg-0.5 Si alloy Li addition microstructure ageing behavior mechanical properties dynamic elasticity modulus
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BEHAVIOR OF AIR-ENTRAINED CONCRETE AFTER FREEZE-THAW CYCLES 被引量:11
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作者 Huaishuai Shang Yupu Song Jinping Ou 《Acta Mechanica Solida Sinica》 SCIE EI 2009年第3期261-266,共6页
The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive streng... The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in northern cold regions. 展开更多
关键词 air-entrained concrete freeze-thaw cycles mechanical properties the dynamic mod-ulus of elasticity weight loss
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Brine-freeze-thaw Durability and Crack Density Model of Concrete in Salt Lake Region 被引量:5
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作者 GONG Wei YU Hongfa +1 位作者 MA Haiyan HAN Wenliang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2020年第3期561-570,共10页
The brine-freeze-thaw durability (defined as the durability under freeze-thaw cycles in Qinghai salt lake brine) of concrete (ordinary Portland cement concrete (OPC), high performance concrete (HPC-a), high performanc... The brine-freeze-thaw durability (defined as the durability under freeze-thaw cycles in Qinghai salt lake brine) of concrete (ordinary Portland cement concrete (OPC), high performance concrete (HPC-a), high performance concrete with steel fiber (HPC-b), and high performance concrete with high Young's modulus polyethylene fiber (HPC-c)) was systematically investigated by the relative dynamic elastic modulus, the relative mass, the appearance, the scanning electron microscopy, and the X-ray diffraction. In addition, the low-temperature physical and chemical corrosion mechanism and a crack density model after the modified relative dynamic elastic modulus being taken into consideration were proposed. The results show that the deterioration of OPC is the severest, followed by HPC-a, HPC-c and HPC-b. The admixture or the fiber is mixed into concrete, which can improve the brine-freeze-thaw durability of concrete. The critical mass growth of the failure of concrete is 3.7%. The cause of the deterioration of concrete under the brine-freeze-thaw cycles is physical and chemical corrosion, not freezing and thawing. The crack density model can effectively describe the deterioration evolution of concrete. 展开更多
关键词 brine-freeze-thaw durability relative dynamic elastic modulus relative mass micro-analysis modeling
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Correlations between ultrasonic pulse wave velocities and rock properties of quartz-mica schist 被引量:5
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作者 Bharti Chawre 《Journal of Rock Mechanics and Geotechnical Engineering》 CSCD 2018年第3期594-602,共9页
Physico-mechanical properties are critically important parameters for rocks. This study aims to examine some of the rock properties of quartz-mica schist(QMS) rocks in a cost-effective manner by establishing correla... Physico-mechanical properties are critically important parameters for rocks. This study aims to examine some of the rock properties of quartz-mica schist(QMS) rocks in a cost-effective manner by establishing correlations between non-destructive and destructive tests. Using simple regression analysis, good correlations were obtained between the pulse wave velocities and the properties of QMS rocks. The results were further improved by using multiple regression analysis as compared to those obtained by the simple linear regression analysis. The results were also compared to the ones obtained by other empirical equations available. The general equations encompassing all types of rocks did not give reliable results of rock properties and showed large relative errors, ranging from 23% to 1146%. It is suggested that empirical correlations must be investigated separately for different types of rocks. The general empirical equations should not be used for the design and planning purposes before they are verified at least on one rock sample from the project site, as they may contain large unacceptable errors. 展开更多
关键词 Pulse wave velocity Physico-mechanical properties Quartz-mica schist (QMS) rocks Non-destructive methods Static elastic constants dynamic elastic constants
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