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Artykuły w czasopismach na temat "Strength of Jointed Specimen"
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Qirui, Wang, Zhang Qihu, Yang Liyun, Kong Fuli, Ding Chenxi i Fan Junqi. "Study on Stress Evolution and Crushing Behavior of Jointed Rock Mass under Confining Pressure and Joint Materials". Geofluids 2023 (4.03.2023): 1–15. http://dx.doi.org/10.1155/2023/6954611.
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To study the effects of confining pressure and joint material properties on stress evolution and fracture behavior of jointed rock mass under SHPB impact load, the numerical software LS-DYNA and the indoor SHPB impact system are used to carry out experimental research on intact rock mass and jointed rock mass. The peak stress, reflection and transmission coefficient, and specimen failure state of rock specimens under different schemes are obtained. The effects of confining pressure level and joint material properties on the propagation and attenuation law of explosive stress waves are expounded. The test results show that when the confining pressure is within a specific range, the impact resistance of the limestone specimen can be increased, and the more difficult it is to be destroyed. Moreover, if the confining pressure continues to increase after rising to the peak value, the impact resistance of rock specimens will decline. In that case, the impact resistance of the specimen will decrease—the dynamic strength of jointed rock mass changes with a change in joint material. The dynamic strength of cement jointed rock is the highest, that of gypsum jointed rock is the second, and that of epoxy resin jointed rock is the lowest. The impact damage resistance of the jointed rock has the same law as the above.
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Chen, Qingzhi, Yuanming Liu i Shaoyun Pu. "Strength Characteristics of Nonpenetrating Joint Rock Mass under Different Shear Conditions". Advances in Civil Engineering 2020 (24.08.2020): 1–13. http://dx.doi.org/10.1155/2020/3579725.
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The mechanical property of jointed rock mass is an important factor to be considered in the analysis, evaluation, and design of actual rock engineering. The existence of joints threatens the stability and safety of underground engineering projects built in the rock mass. In order to study the change of mechanical properties and strength characteristics of nonpenetrating jointed rock mass under different test conditions, direct shear tests and triaxial tests were carried out. Direct shear tests under different normal stresses were carried out for nonpenetrating jointed rock mass to prepare specimens for triaxial tests. Then, triaxial tests were carried out to study the change of mechanical properties and strength characteristics of the nonpenetrating jointed rock mass. In the direct shear test part, the greater the normal stress is, the stronger the shear strength and the more serious the shear failure would be. The main conclusions are as follows: (1) the strength of rock mass would increase with the increase of confining pressure for those rock specimens with same degrees of shear after the direct shear test; (2) for rock specimens with different degrees of shear after the direct shear test, if the shearing degree of the rock specimen was greater, the strength of the rock specimen would be lower in the triaxial test; (3) for rock specimens with the same damage degree after direct shear test, the greater the normal stress in direct shear test is, the smaller the peak axial pressure would be in the triaxial test; (4) if the specimen was sheared under higher normal stress in direct shear test, the cohesion of it would be lower and the internal friction angle would be larger. For the specimens under the same normal stress, if the shear failure of one specimen was more serious, the cohesion of it would be smaller and the internal friction angle would be larger.
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Xiong, L. X., H. Y. Yuan, Y. Zhang, K. F. Zhang i J. B. Li. "Experimental and Numerical Study of the Uniaxial Compressive Stress-Strain Relationship of a Rock Mass with Two Parallel Joints". Archives of Civil Engineering 65, nr 2 (1.06.2019): 67–80. http://dx.doi.org/10.2478/ace-2019-0019.
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AbstractA “rock bridge”, defined as the closest distance between two joints in a rock mass, is an important feature affecting the jointed rock mass strength. Artificial jointed rock specimens with two parallel joint fractures were tested under uniaxial compression and numerical simulations were carried out to study the effects of the inclination of the rock bridge, the dip angle of the joint, rock bridge length, and the length of joints on the strength of the jointed rock mass. Research results show: (1) When the length of the joint fracture, the length of the rock bridge, and the inclination of the rock bridge stay unchanged, the uniaxial compressive strength of the specimen gradually increases as the inclination of the joint fracture increases from 0°to 90°. (2) When the length of the joint fracture, the length of the rock bridge, and the inclination of the joint fracture stay unchanged, the uniaxial compressive strength of the specimen shows variations in trends with the inclination of the rock bridge increasing from 30° to 150° (3). In the case when the joint is angled from the vertical loading direction, when the dip angle of the joint fracture, the inclination of the rock bridge, and the length of the rock bridge stay unchanged, the uniaxial compressive strength of the specimen gradually decreases with an increasing length of joint fracture. When the dip angle of the joint fracture, the inclination of the rock bridge, and the length of the joint fracture stay unchanged, the uniaxial compressive strength of the specimen does not show a clear trend with an increase of the length of the rock bridge.
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Cao, Rihong, Hua Dai, Rubing Yao, Hang Lin i Kaihui Li. "Failure Behaviour of Jointed Rock Masses with 3D Nonpenetrating Joints under Uniaxial Compression: Insights from Discrete Element Method Modelling". Applied Sciences 12, nr 21 (31.10.2022): 11027. http://dx.doi.org/10.3390/app122111027.
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It is well known that joints or fissures have an important effect on the failure mechanism of natural rocks. Previously, many numerical and experimental papers have been carried out to study the strength anisotropy and failure characteristics of jointed rocks. However, few studies have been carried out on the failure mechanism of nonpersistent jointed rock masses with different persistence, especially for nonpersistent joints in three dimensions. In the present study, the failure characteristics of a 3D nonpersistent jointed rock mass with different inclinations (θ) and persistence (K) are studied by numerical simulation. For the 3D digital elevation model (DEM), the linear parallel bond model (LPBM) and smooth-joint model (S-J) were used to model the rock-like material and joint interface, respectively. The connections between the geometric parameters of joints and peak strength are revealed. For the peak strength, the joint persistence only plays a minor role in specimens with inclinations of 0° and 90°, and its influence on strength is mainly reflected in the specimens with shear failure (θ = 45°, 60°, and 75°). Based on microcrack accumulation and evolution, four typical failure processes (shear failure, split failure, mixed failure, and intact failure) are analysed from the micro perspective. The shear stress evolution process on the 3D nonpersistent joint of the specimen with different inclinations under K1 = 0.42 was monitored by the measurement circle, and it was found that the distribution of shear stress inside the rock bridge is related to the failure mode of the specimen. For the specimens with θ = 0° and 90°, the shear stress had little change, indicating that there is slight shear slip behaviour on the joint surface. When the inclination is 45°, 60°, and 75°, the shear stress changes obviously during loading, indicating that the shear action is strong in this failure mode.
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D, Karunakaran, i Venkatachalapathy VSK. "Investigations of Microstructure and Mechanical Properties of Lap Jointed Dissimilar Metals by Friction Stir Spot Welding Process". Journal of Manufacturing Engineering 18, nr 1 (1.03.2023): 011–19. http://dx.doi.org/10.37255/jme.v18i1pp011-019.
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The joining of different materials is required for industrial application to utilize the hydride structures with attractive advantages such as superior strength to weight ratio, low cost, high tensile strength and less weight of the component. Specifically, Al-Cu composite material is widely used in foil conductors of a transformer, electrical connectors, foil windings in capacitors and tubes in heat exchangers. However, joining or spot welding the Al parts to Cu parts are significant challenge owing to variation in mechanical properties and chemical compositions of joining materials. In this present research work, the friction stir spot welded process (FSSWP) is carried out to join the Al and Cu materials. Further, microstructure and mechanical properties of friction stir spot welded specimens (FSSW) are studied at different tool rotational speeds likely from 1000rpm to 1500rpm. The microstructural study is carried out using scanning electron microscope images at the interface and overall welded region. The tensile strength of both single and double spot-welded specimens is analyzed using a universal tensile test machine. The output of this study states that the optimal tool rotational speed is 1500rpm for both single and double spot-welded specimens. Moreover, the double spot-welded specimen exhibits more tensile with a crack-free spot-welded surface than that of the single spot-welded specimen. The tensile strength double spot-welded specimen has a 6.8% higher strength than that of a single spot-welded specimen. Based on the present study, it is concluded that the double spot-welded specimen can be used for different industrial applications to replace Cu material with this Al-Cu material that gives added advantages to those components.
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Pan, Jiliang, Xu Wu, Qifeng Guo, Xun Xi i Meifeng Cai. "Uniaxial Experimental Study of the Deformation Behavior and Energy Evolution of Conjugate Jointed Rock Based on AE and DIC Methods". Advances in Civil Engineering 2020 (10.09.2020): 1–16. http://dx.doi.org/10.1155/2020/8850250.
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Conjugate joint is one of the most common joint forms in natural rock mass, which is produced by different tectonic movements. To better understand the preexisting flaws, it is necessary to investigate joint development and its effect on the deformation and strength of the rock. In this study, uniaxial compression tests of granite specimens with different conjugate joints distribution were performed using the GAW-2000 compression-testing machine system. The PCI-2 acoustic emission (AE) testing system was used to monitor the acoustic signal characteristics of the jointed specimens during the entire loading process. At the same time, a 3D digital image correlation (DIC) technique was used to study the evolution of stress field before the peak strength at different loading times. Based on the experimental results, the deformation and strength characteristics, AE parameters, damage evolution processes, and energy accumulation and dissipation properties of the conjugate jointed specimens were analyzed. It is considered that these changes were closely related to the angle between the primary and secondary joints. The results show that the AE counts can be used to characterize the damage and failure of the specimen during uniaxial compression. The local stress field evolution process obtained by the DIC can be used to analyze the crack initiation and propagation in the specimen. As the included angle increases from 0° to 90°, the elastic modulus first decreases and then increases, and the accumulative AE counts of the peak first increase and then decrease, while the peak strength does not change distinctly. The cumulative AE counts of the specimen with an included angle of 45° rise in a ladder-like manner, and the granite retains a certain degree of brittle failure characteristics under the axial loading. The total energy, elastic energy, and dissipation energy of the jointed specimens under uniaxial compression failure were significantly reduced. These findings can be regarded as a reference for future studies on the failure mechanism of granite with conjugate joints.
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Ping, Yang, i Shu Chen Li. "Triaxial Compression Experimental Study on Post-Peak Deformation Characteristics of Rock Masses with Persistent Joints". Advanced Materials Research 1030-1032 (wrzesień 2014): 1074–77. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.1074.
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Controlling the stability of surrounding rocks in underground excavations during in-depth resource development must be confronted with post-peak deformation and failure problems of jointed rock masses. This paper describes routine triaxial compression testing on standard cylinder specimen with persistent joints in different inclinations and under different confining pressures, and analyzes deformation characteristics of rock masses with persistent joints in different inclinations and under different confining pressures. Test results show that the peak strength, residual strength, and peak strain of the jointed specimen basically increase with increasing confining pressures but decrease with increasing joint inclinations. Test results well reflect that it is incorrect to evaluate deformation characteristics of jointed rock masses with continuum mechanics and research results provide a reference for the research on the stability of surrounding rocks in underground excavations.
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Wang, Qing Han, Shu Cai Li, Li Ping Li, Jing Wang i Qian Zhang. "Crack Propagation of Jointed Rock and Application". Applied Mechanics and Materials 651-653 (wrzesień 2014): 1143–46. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.1143.
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The excavation engineering in jointed rock masses, due to the changes in its original stress state, the preexisting fissures will expand and new fissures may emerge, which will degrade its mechanical and strength properties. This paper uses the DDARF method to preinstall fissures of different numbers and spacing in the rock block, then studies the crack initiation, expansion, transfixion and the destruction process by numerical modeling experiment, and finds the relevant stress strain curve. It also studies the influence of the numbers of fissures and different spacing and the influence of lateral compression on the test specimen to find the strength envelope of the test specimen. The parameters are applied in a case study. The differences in the failure behaviors of the intact and jointed rock masses after cavern excavation are analyzed and compared.
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Zhang, Zhiyu, Zhuo Li, Yonghui Huang i Haoshan Liu. "Influence of the Number of Parallel Joints on the Dynamic Mechanical Properties of Rock-Like Features". Geofluids 2022 (22.04.2022): 1–11. http://dx.doi.org/10.1155/2022/1564195.
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The number and distribution of joints in rock are closely related to their physical and mechanical properties. In this paper, given the propagation law of explosive stress waves in jointed rock during rock blasting and the influence of joints on dynamic mechanical properties and crushing energy dissipation of rock, parallel joints are simulated in the construction of concrete specimens using a mica sheet. The discrete Hopkinson test device is used to perform the impact test, which is based on the three-wave and fractal theory. Under dynamic load, the fluctuation characteristics, failure mode, fractal dimension, and energy dissipation transfer law of rock-like specimens with various parallel joints are studied in detail. The results show that the overall failure of the specimen becomes more severe with the increase of parallel joints, and the failure mode is changed from the conjugate shear failure of the complete specimen to the edge collapse failure with joints. Thus, as the number of joints increases, the static strength decreases, and the degree of reduction is positively related to the number of joints. With the number of joints, the changing trend of enhancement factor increases first and then slows down. Compared with nonjointed specimens, the transmission coefficient of 1-3 jointed specimens is decreased by 0.22, 0.05, and 0.17, respectively. The dimension of the specimen D f is positively correlated. Under the synonymous impact pressure of 0.35 MPa, the corresponding fractal dimension is increased from 2.27 to 2.42. The crushing energy consumption density, transmission coefficient, and dynamic compressive strength σ d of the specimen are significantly negatively correlated, and the crushing energy consumption density of the specimen decreased from 0.82 J/cm3 to 0.28 J/cm3.
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Abdennour, C. Seibi, i M. Al-Alawi. "Experimental Investigation and Failure Analysis of Fastened GRP under Bending Using Finite Element Method and Artificial Neural Networks". Sultan Qaboos University Journal for Science [SQUJS] 4 (1.12.1999): 71. http://dx.doi.org/10.24200/squjs.vol4iss0pp71-78.
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This paper presents a novel approach that predicts the strength and failure modes of jointed Glass Reinforced Polyester (GRP) samples under bending using Finite Element Method (FEM) and Artificial Neural Network (ANN). The mechanical behavior of fastened glass fiber reinforced plastics composites under bending have been experimentally investigated. Samples were obtained from Amiantit Oman, a manufacturing company operating in Russail Industrial Zone in the Sultanate of Oman. The experimental program involved the conduct of three point bending tests as well as bending tests of mechanically fastened joints under static loads. The experimental results showed that the dimensions of the specimen such as the bending span length, specimen width, and specimen pitch affect GRP strength and stiffness. FEM and ANN results predicted accurately the types of failure modes and their locations along the specimens and compared well with the experimental results.
Rozprawy doktorskie na temat "Strength of Jointed Specimen"
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Stewart, Scott William. "Rock mass strength and deformability of unweathered closely jointed New Zealand greywacke". Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/1224.
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Closely jointed greywacke rock masses are widespread throughout both the North and South Islands of New Zealand and much of New Zealand's infrastructure is constructed upon greywacke rock masses. This thesis deals with determining the rock mass strength of unweathered closely jointed New Zealand greywacke rock masses. Currently, the estimation of rock mass strength and deformability is reasonably well predicted through the use of such empirical failure criteria as the Hoek-Brown failure criterion and empirical expressions to predict deformability. However, previous studies upon predicting the strength and deformability of unweathered closely jointed New Zealand greywacke rock masses has shown that existing empirical methods of determining strength and deformability are unsatisfactory. The problem with predicting rock mass strength and deformability moduli of New Zealand greywacke and the lack of adequate data to calibrate a failure criterion was the starting point for this work. The objective of this thesis was to increase the knowledge of intact and defect properties of closely jointed greywacke, develop reliable rock mass data with which to calibrate a failure criterion and improve the ability to estimate the rock mass strength of greywacke rock masses. A review of existing failure criteria for rock masses was conducted and of these criteria, the Hoek-Brown rock mass failure criteria was selected to calibrate to both the intact rock and rock mass failure data, because of its broad acceptance in the rock mechanics community. A database of greywacke properties was developed based on previous studies upon unweathered greywacke around New Zealand and is attached to the thesis as an Appendix. The database included descriptions of greywacke defect properties and mechanical properties of the intact rock and joints. From this database, inputs could be justified for numerical modelling and later analyses of failure criteria. Records from the construction archives of the Benmore and Aviemore hydroelectric power projects in the South Island of New Zealand were reviewed to obtain information and results from a series of shear tests carried out on unweathered closely jointed greywacke in the 1960s. Data on rock mass strength at failure and rock mass deformability were extracted from these records to assess the predictability of the failure criterion and deformability expressions. Problems experienced during the shear tests at the Aviemore dam site created doubt as to the actual rock mass strengths achieved at failure. The behaviour of these tests was studied using the finite difference code FLAC. The work was aimed at investigating the potential for transfer of shear force between the two concrete blocks sheared in each test and the impact shear force transfer had upon the likely normal stresses beneath each block at failure. The numerical modelling results indicated that a combination of preferential failure occurring in one direction, and doubt in the actual normal load applied to the concrete blocks during testing lead to premature failure in the blocks sheared upstream. The blocks sheared in the opposite direction failed at normal stresses that are reflective of the strength of an unweathered greywacke rock mass, but these results could be explained by failure occurring along defects therefore not satisfying the assumptions of homogeneity typically required of a rock mass failure criterion. The Hoek-Brown failure criterion for intact rock was investigated by fitting it to the largest intact greywacke datasets. For a full set of test data (i.e. including tensile data), the Mostyn & Douglas (2000) variant of the Hoek-Brown failure criterion gave the best fit for a full set of rock mass data. A multiple regression method was developed which improved the fitted curve to intact data in the tensile region and gave the best estimate of tensile strength if no existing lab results for tensile strength were available. These results suggest that the Hoek-Brown failure criterion is significantly limited in its applicability to intact NZ greywacke rock. Hoek-Brown input parameters different to those suggested by Hoek et al (2002) are recommended for using the Hoek-Brown failure criterion for intact NZ greywacke. For closely jointed NZ greywacke rock masses, the results from the shear tests at Aviemore and Benmore were separated into different GSI classes and Hoek-Brown envelopes fitted to the datasets by multiple regression. Revised expressions were proposed for each Hoek-Brown input parameter (mb, s, ab) as a function of the GSI. The resulting revised Hoek-Brown failure envelopes for NZ greywacke offer a significant improvement on the existing criterion used to predict the strength of NZ greywacke intact rock and rock masses. The differences in the behaviour of the reaction blocks that failed before the test blocks and the reduction in rock strength due to sliding along defects from that predicted could be reasoned from recorded observations and the behaviour of the concrete blocks during the shear tests. This study has clearly illustrated the need for continued research in this area. This includes (1) a means of assessing the role of defects upon the shear strength of closely jointed greywacke rock mass into a failure criterion, (2) further modelling of the in-situ shear tests by a discrete element procedure to expressly determine the role of the defect on failure, (3) more testing on rock masses to obtain more data to calibrate a rock mass failure criterion, and (4) more studies on predicting the strength of extremely disturbed rock masses.
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Betamar, Naeima Mohamed. "Influence of specimen designs on the microtensile bond strength to dentine". Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489353.
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Wang, Shuxin. "Fundamental studies of the deformability and strength of jointed rock masses at three dimensional level". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185923.
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The deformability and strength properties of jointed rock masses are two of the fundamental parameters needed for the design and performance estimation of rock structures. Due to the presence of complicated minor discontinuity patterns (joints, bedding planes etc.), jointed rock masses show anisotropic and scale (size) dependent mechanical properties. At present, satisfactory procedures are not available to estimate anisotropic, scale dependent mechanical properties of jointed rock. Because of the statistical nature of joint geometry networks in rock masses, the joint patterns should be characterized statistically. The available joint geometry modeling schemes are reviewed. One of these schemes is used in this dissertation to generate actual joints in rock blocks. Three dimensional distinct element code (3DEC), which is used to perform stress analyses on jointed rock blocks in this study, is introduced and its shortcoming is identified. To overcome the shortcoming of 3DEC, a new technique is developed by introducing fictitious joints into rock blocks. Concerning the introduced fictitious joints, their geometry positions are mathematically determined; the representative mechanical properties for them found at 2D level are reviewed and verified at 3D level. By using the new technique, the deformation and strength properties of the rock blocks with many different joint configurations are found. Then effects of joint geometry parameters on the mechanical properties of jointed rock blocks are investigated. It is found that the joint geometry patterns have significant influences on the mechanical properties of rock blocks. All the joint geometry parameters are then integrated into fracture tensor. The relationships between the mechanical properties of jointed rock blocks and the fracture tensor parameters (its first invariant and directional component) are investigated. The possibility of obtaining the equivalent continuum behavior (REV properties) of jointed rock blocks is explored by using the aforementioned relationships. Finally, based on the research results, a new 3D constitutive model for jointed rock masses is developed to describe their pre-failure behavior. The constitutive model includes the effects of joints in terms of fracture tensor components and it shows the anisotropic and scale dependent natures of jointed rock masses.
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Ucpirti, Hasan. "Joint geometry parameter effects on deformability and strength of jointed rock masses at the two dimensional level". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185975.
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In this study, the pre-failure behavior of a jointed rock block is modeled by an incrementally linear elastic anisotropic constitutive model (using an orthotropic model in 2D). In order to estimate the parameters in the constitutive model, a new technique was used in this dissertation. A 2D joint geometry generation code was used to generate finite size actual joint networks in 2D rock blocks. A 2D distinct element code (UDEC) was chosen as the stress analysis tool in this study. Fictitious joints were introduced into the rock blocks which contain finite size actual joints to discretize the problem domain into polygons. A number of stress analyses of rock blocks which contain only persistent joints were performed to estimate representative values for mechanical properties of fictitious joints to simulate the intact rock behavior. Finally, the rock blocks having different deterministic actual joint configurations with fictitious joints were subjected to 2D stress analysis under various stress paths using UDEC. Results of these stress analyses were used to estimate the deformational and strength properties of these rock blocks. Influence of joint geometry parameters on the mechanical properties of jointed rock blocks were found to be very significant. Plots are given to show how mechanical properties of rock blocks vary with joint intensity and joint size/block size for different joint orientations. These plots can also be used to estimate REV (Representative Elementary Volume) size and REV properties for rock masses. It is important to note that these REV property values depend on the chosen constitutive models for intact rock and joints. The concept of fracture tensor is reviewed at the 2D level. Relationships between the mechanical properties of jointed rock blocks and the fracture tensor parameters (its first invariant and components) are established. These relationships can be used to estimate the parameters of the chosen constitutive model for the rock block. This constitutive model has captured both scale dependent and anisotropic behaviors of rock masses. The possibility of obtaining the equivalent continuum properties (REV properties) of jointed rock blocks is explored by using the aforementioned relationships. (Abstract shortened by UMI.)
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Gupta, Kiriti. "Effect of specimen geometry on creep crack growth rate behavior in 1 Cr-1Mo-25V steel". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20217.
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Lindstam, Gustaf. "Effect of relative humidity and temperature on the strength properties of finger-jointed furniture components from solid scots pine". Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-75368.
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Mechanical strength in wood has always been compromised due to the complex behaviours of the material when interfered with moisture and heat. These factors has always limited the use of the material. However, the will of using more sustainable materials such as wood has contributed to a wider use of the material and several new ways that lead to improvement. Several of these methods emphasizes the joining of two wood components together endwise, where finger-joints are the most commonly used method. Several studies regarding how well finger-joints can withstand external load has been made over the years. However, many of these studies focuses on geometrical properties or strength varying in different species. This study focuses on how relative humidity and temperature affects mechanical strength in finger-jointed wood products. There were beliefs before the research started that increasing temperature would affect mechanical strength greatly. However, it turned out to only affect the mechanical strength marginally, and that relative humidity was the largest contributor to decreasing tolerance levels. It is important to notify that mechanical strength seemed to be directly affected to moisture content (MC), which is a result of an interactive relationship with both temperature and RH. It was particularly MC-levels above 9.2% that showed a decrease in mechanical strength. This research also focused on estimating the relative MOR per cross-section in varying conditions. This method could be used to better understand to which degree hygroscopic factors affects mechanical strength relative to the glued-surface area between finger-joints. Even though the findings in this study indicates that there seems to be possible to estimate strength in regards to relative MOR per cross-section, the results were not sufficient to be viewed as scientifically proof. The findings could however be used as ground for future studies.
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Chhabra, Nitin. "FINITE ELEMENT ANALYSIS OF A TEST SPECIMEN FOR STRENGTH OF A CO-POLYMER LAYER AT A BONE-IMPLANT INTERFACE". Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4427.
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The aim of this work is to evaluate the mechanical strength of a co-polymer of 2-hydroxyethylmethacrylate (HEMA) and methylmethacrylate (MMA), so that it can be applied as an interfacial layer between bone cement and steel implants to improve their performance and life. Finite element (FE) analysis techniques are used to assess the behavior of the interface layer under static and dynamic loading conditions. The material property of the co-polymer is a function of its composition and water saturation. The factors affecting the strength of the bone-implant interface are many. Implant interfacial fracture can lead to decreased stability. Fatigue life is a very important process in failure. The results obtained from static and dynamic analyses show that increasing the percentage of HEMA improves the strength of the interface by reducing the stiffness of the implant, absorbing more energy and by reducing the interfacial stress peaks and making the stress distribution more nearly uniform.M.S.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical, Materials and Aerospace Engineering
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Vrazel, Matthew Eric. "The effects of species, adhesive type, and cure temperature on the strength and durability of a structural finger joint". Thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-05152002-122630.
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Elmo, Davide. "Evaluation of a hybrid FEM/DEM approach for determination of rock mass strength using a combination of discontinuity mapping and fracture mechanics modelling, with particular emphasis on modelling of jointed pillars". Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439831.
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Tichý, Aleš. "Vliv velikosti a tvaru zkušebního tělesa na modul pružnosti lehkých betonů". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391974.
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The diploma thesis deals with the determination of the influence of size, shape and type of test specimen on values of modulus of elasticity of light-weight concrete. A lot of different specimens were prepared from two concrete’s mixtures for the experiment. Tests for measurement of static modulus of elasticity and dynamic modulus of elasticity by ultrasonic impulse velocity method were made. The results were assessed and summarized in tabular and graphical form.
Książki na temat "Strength of Jointed Specimen"
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India. Central Board of Irrigation and Power. i India. Ministry of Water Resources., red. Strength, deformation modulus, and classification of jointed rocks. New Delhi: Central Board of Irrigation and Power, 1996.
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Kevin, O'Brien T., i Langley Research Center, red. Influence of specimen preparation and specimen size on composite transverse tensile strength and scatter. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 2001.
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Terrell, J. B. Fatigue strength of smooth and notched specimens of ASME SA 106-B steel in PWR environments. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1988.
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Hanhijarvi, Antti. Computational optimisation of test specimen for planar shear strength tests of wood based panels. Espoo, Finland: VTT, Technical Research Centre of Finland, 1998.
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United States. National Aeronautics and Space Administration., red. An evaluation of the Iosipescu specimen for composite materials shear property measurement. Blacksburg, Va: Virginia Polytechnic Institute and State University, 1991.
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Joyce, J. A. Comparison of J[subscript I][subscript c] and J-R curves for short crack and tensilely loaded specimen geometries of a high strength structural steel. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1992.
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An interlaminar tension strength specimen. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1992.
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National Aeronautics and Space Administration (NASA) Staff. Influence of Specimen Preparation and Specimen Size on Composite Transverse Tensile Strength and Scatter. Independently Published, 2018.
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Tamin, Mohd Nasir. Elasto-plastic finite element program and numerical study of a compact specimen. 1987.
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Krieger, Nancy. Ecosocial Theory, Embodied Truths, and the People's Health. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197510728.001.0001.
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This book employs the ecosocial theory of disease distribution to combine critical political and economic analysis with a deep engagement with biology, in societal, ecological, and historical context. It illuminates what embodying (in)justice entails and the embodied truths revealed by population patterns of health. Chapter 1 explains ecosocial theory and its focus on multilevel spatiotemporal processes of embodying (in)justice, across the lifecourse and historical generations, as shaped by the political economy and political ecology of the societies in which people live. The counter is to dominant narratives that attribute primary causal agency to people’s allegedly innate biology and their allegedly individual (and decontextualized) health behaviors. Chapter 2 discusses application of ecosocial theory to analyze: the health impacts of Jim Crow and its legal abolition; racialized and economic breast cancer inequities; the joint health impacts of physical and social hazards at work (including racism, sexism, and heterosexism) and relationship hazards (involving unsafe sex and violence); and measures of structural injustice. Chapter 3 explores embodied truths and health justice, in relation to: police violence; climate change; fossil fuel extraction and sexually transmitted infectious disease: health benefits of organic food—for whom? ; public monuments, symbols, and the people’s health; and light, vision, and the health of people and other species. The objective is to inform critical and practical research, actions, and alliances to advance health equity—and to strengthen the people’s health—in a deeply troubled world on a threatened planet.
Części książek na temat "Strength of Jointed Specimen"
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Kim, Hanlim, Gyeongjo Min, Gyeonggyu Kim, Chanhwi Shin, Pureun Jeon, Jusuk Yang, Kyungjae Yun i Sangho Cho. "New approach for determining dynamic shear strength of jointed rock specimen using long-bar drop impact apparatus". W Rock Dynamics: Progress and Prospect, Volume 1, 384–88. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003359142-64.
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Singh, Mahendra. "Shear Strength Behaviour of Jointed Rock Masses". W Landslides: Theory, Practice and Modelling, 41–60. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77377-3_3.
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Zhang, Zhi Gang, C. S. Qiao i X. Li. "Study on the Strength of Jointed Rock Mass". W Key Engineering Materials, 381–84. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.381.
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Zhang, Qiang Yong, Wei Shen Zhu, Shu Cai Li i W. Xiang. "Fracture Strength Model for Jointed Rockmass and Its Application to Engineering". W Fracture and Strength of Solids VI, 1379–84. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-989-x.1379.
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Shao, Peng, Yong Zhang, Wen Ming Gao i Yong Qiang Liu. "Dynamic Response of Intermittent Jointed Rock Mass Subjected to Blast Waves". W Fracture and Strength of Solids VI, 1415–20. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-989-x.1415.
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Metcalfe, M. P., N. Tzelepi i D. Wilde. "Effect of Test Specimen Size on Graphite Strength". W Graphite Testing for Nuclear Applications: The Significance of Test Specimen Volume and Geometry and the Statistical Significance of Test Specimen Population, 1–29. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2014. http://dx.doi.org/10.1520/stp157820130123.
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Zhang, Ke. "Empirical Methods for Estimating Strength Parameters of Jointed Rock Masses". W Failure Mechanism and Stability Analysis of Rock Slope, 69–74. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5743-9_4.
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Lee, Hyun Woo, i Se-Jong Oh. "Fatigue Crack Growth of Notched Tubular Specimen under Biaxial Loading Conditions". W Fracture and Strength of Solids VI, 139–44. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-989-x.139.
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Zhu, Wei Shen, Shu Cai Li, Q. Zhang i X. Qiu. "Model of Damage Fracture and Damage Rheology for Jointed Rock Mass and Its Engineering Application". W Fracture and Strength of Solids VI, 1385–90. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-989-x.1385.
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Zhou, Hao, Yang Song, Qimin Wang, Weishen Zhu i Yanqing Men. "Experiment on the Failure Process of Jointed Rock Specimen Under Compression and Numerical Test". W Proceedings of GeoShanghai 2018 International Conference: Rock Mechanics and Rock Engineering, 158–65. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0113-1_18.
Pełny tekst źródłaStreszczenia konferencji na temat "Strength of Jointed Specimen"
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Koguchi, Hideo, i Naoki Kimura. "Evaluation of Strength in Joints of Silicon and Sapphire Coating Silicon". W ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipack2013-73113.
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Recent electronic device packaging, for instance, Chip size package (CSP) has a bonded structure of IC chip and polymers, and delamination occurs frequently at the interface between IC and a resin. Furthermore, thermal stresses which are caused by a temperature variation in the bonding process of CSP and heat cycles for environment temperature will influence on the strength of interface. In the present paper, the delamination test for specimens with different bonding areas and geometries is carried out to investigate the strength of multi-layered joints. In particular, a silicon wafer is joined with a silicon-on-sapphire (SOS) plate by a resin. The SOS is composed of silicon film, SiO2 film and sapphire plate. The thicknesses of silicon film, SiO2 film and sapphire plate are 0.45μm, 0.2μm, 600μm, respectively. The joining strength in silicon, resin and SOS joints with triangular and rectangular bonding area is investigated. The triangular and rectangular shape bonding areas are 3mm2 and 12mm2, respectively. The bonded specimens are prepared under different cooling rate. Load is applied to the specimen so as to delaminate at the interfaces of SiO2 film and sapphire. From the delamination test, it is found that residual thermal stress and the geometry of bonding area affect the strength of interface. In the case of the triangular area specimen, delamination occurs at the interface between SiO2 film and sapphire plate in the silicon-resin-SOS specimen. The nominal stress for delamination is about 1.99MPa. In the case of rectangular bonding area specimen, delamination occurs at the interface between SiO2 film and sapphire plate in the silicon-resin-SOS specimen. Nominal stress for delamination is about 2.23MPa. From a comparison of the strength of joint for rapid and slow cooling conditions, it is found that the residual stress reduces the strength of joint.
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West, I. G., G. Walton, M. A. Gonzalez-Fernandez i L. R. Alejano. "Strain Localization in Jointed Rockmass Analog Laboratory Specimens Under Compression". W 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0073.
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ABSTRACT Field-scale rock formations (i.e. rockmasses) are composed of sections of intact rock separated by a preexisting joint network. As rockmass deforms, strain accumulates within the intact rock and slip occurs along the preexisting joints. However, the magnitude of strain within the intact rock sections are not necessarily equal everywhere throughout the rockmass due to the presence of the discontinuities. In general, testing representative rockmass specimens in the laboratory is difficult because of the required size. As an alternative, small-scale rockmass analog laboratory specimens can be used to investigate trends in rockmass behavior. This research evaluates the mechanical behavior of rockmass analog specimens of Carrara marble containing two orthogonal sets of smooth joints. Both intact and the jointed specimens were tested under triaxial compression with 1 and 12 MPa of confinement. Axial and radial deformation within each section of intact rock in the specimens were recorded with separate strain gages, and strain gages in these same positions were also attached to intact specimens for comparison. Notable radial strain heterogeneity was observed in the jointed specimens and this heterogeneity was suppressed under higher confinement levels. Strain was also found to localize in intact rock blocks with higher surface area to volume ratios. INTRODUCTION Field-scale rock formations are commonly referred to as rockmasses, which are composed of sections of intact rock separated by a network of preexisting discontinuities (Mendes et al., 1966). Such discontinuities can include joints (i.e. fractures), shear zones, faults, and other structural planes (Cui et al., 2020), which are formed from varying stress fields throughout the rockmass's tectonic history (Mandl, 2005). The presence of discontinuities reduces the strength of the rock and affects other aspects of its mechanical behavior (Hoek and Brown, 1997). Rockmasses are more difficult to test in the laboratory compared to intact rock because representative rockmass specimens are typically on the scale of meters. Large triaxial testing apparati are uncommon and typically allow for a maximum specimen diameter of 1 meter, which is not sufficient for many rockmasses with joint spacing of multiple meters (Muschler and Natau, 1991; Natau, 1977; Singh and Huck, 1972; Vergara et al., 2015).
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Gianetto, J. A., J. T. Bowker, R. Bouchard, D. V. Dorling i D. Horsley. "Tensile and Toughness Properties of Pipeline Girth Welds". W 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10399.
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The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.
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Ogata, Takashi. "Creep Strength Evaluation of a New and a Used Grade 91 Welded Joints by Using a Miniature Specimen". W ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84010.
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Grade 91 is widely used for steam pipes and tubes in high temperature boilers of ultra-super critical power plants in Japan. It was reported that creep damage may initiate at the fine grain region within the heat affected zone (HAZ) in welded joints prior to the base metal, so called “Type IV” damage, which causes steam leakage in existing power plants. Therefore, development of creep damage assessment methods is not only an important but also an urgent subject to maintain operation reliability. In order to evaluate creep damage of welded joints based on finite element analyses, creep deformation properties of a base metal, a weld metal and a HAZ have to be obtained from creep tests. However, it is difficult to cut a standard size creep specimen from the HAZ region. Only a miniature size specimen is available from the narrow HAZ region. Therefore, development of creep testing and evaluation technique for miniature size specimens is highly expected. In this study, a miniature tensile type solid bar specimen with 1mm diameter was machined from a base metal, a weld metal and a HAZ of a new and a used Grade 91 welded joints, and creep tests of these miniature specimens were conducted by using a special developed creep testing machine. It was found that creep deformation property is almost identical between the base metal and weld metal, and creep strain rate of the HAZ is much faster than that of these metals in the new welded joint. Relationships between stress and creep strain rates of the base metal and the HAZ in the used welded joint are within scatter bands of those in the new material. On the other hand, creep strain rate of the weld metal in the used welded joint became much faster than that in the new one. Then both the standard size and the miniature size cross weld specimens were machined from the new and the used welded joints and were tested under the same temperature and stress conditions. Rupture time of the miniature cross weld specimen is much shorter than that of the standard size cross weld specimen. The finite element creep analysis of the specimens indicates that higher triaxiality stress yields within the HAZ of the standard size specimen than that of the miniature specimen causing faster creep strain rate in the HAZ of the miniature cross weld specimen.
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Yoshida, Mikihito, i Yasushi Nishimura. "IMPROVEMENT OF BEARING FAILURE BEHAVIOR OF T-SHAPED S BEAM – RC COLUMN JOINTS USING PERFOBOND PLATE CONNECTORS". W 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.7007.
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For the joints composed of steel beams and reinforced concrete columns, shear failure and bearing failure are the key failure modes. The shear failure indicates stable hysteresis loop without the strength degradation. On the other hand, the bearing failure mode indicates large pinching and strength degration after the attainment of the maximum load.Accordingly, bearing failure in the joints should not be caused in RCS system.To improve the bearing failure behavior of S beam - RC column joint, joint details using perfobond plate connectors were proposed. Perfobond plate connectors were attached on the upper and bottom flanges at right angles to the steel flange. The objective of this study is to clarify the effectiveness of proposed joints details experimentally and theoretically.Six specimens were tested. All specimens were T-shaped planar beam - column joints with 350mm square RC column and S beams with the width of 125mm and the depth of 300mm. The beams were all continuous through the column.Perfobond plate connectors were attached on the bottom flanges at right angles to the steel flange.Three holes were set up in the perfobond plate connectors. The experimental variable was the transverse reinforcement ratio of the joints. The transverse reinforcement ratio of the joints was 0.181% and 0.815%. For each transverse reinforcement ratio of the joints, specimen without the perfobond plate connectors, specimen with the perfobond plate connectors and specimen with the reinforcing bar inserted the hole of perfobond plate connectors were planned.For all specimens, the hysteresis loop showed the reversed S-shape. However, energy dissipation for specimens for specimens with perfobond plate connectors was larger than of specimen without perfobond plate connectors. Bearing strength of specimens with perfobond plate connectors was larger than that of specimen without perfobond plate connectors. From the test results, shear strength of concrete connector a hole was 0.7 times compression strength of concrete.On the other hand, shear strength of inserted reinforcing bar was 1.25 times shear strength of reinforcing bar.Based on the stress transferring mechanism and resistance mechanism of joints proposed by authors, the design formulae of joints with perfobond plate connectors were proposed.The predictions were shown to be in good agreement with the test results.
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Arul, Senthil, Grant H. Kruger, Scott F. Miller, Tsung-Yu Pan i Albert J. Shih. "Spot Friction Weld Strength Improvement Through In-Process Metal Matrix Formation". W ASME 2008 International Manufacturing Science and Engineering Conference collocated with the 3rd JSME/ASME International Conference on Materials and Processing. ASMEDC, 2008. http://dx.doi.org/10.1115/msec_icmp2008-72502.
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The effects of metal matrix composite (MMC) on the joint strength of Spot Friction Welded (SFW) specimens made of Al 1100 and Al 6111 alloys are studied. The MMC-SFW joints were created by sandwiching metal reinforcing powder (<75μm mesh) between the upper (1.3mm thick) and lower (1.5mm thick) Al coupons, at the center of the SFW joint. To maximize the heat input into the specimen, a Zirconium (ZrO2) ceramic anvil was used. Depth of penetration of the tool played an important role in determining the distribution of the reinforcing material within the MMC during plastic mixing in the SFW joint, and hence its influence on the joint strength. At a lower depth of penetration, 2.1 mm, the results showed that the MMC-SFW reinforced with Ancorsteel 1000, copper or Al12Si powders did not increase the joint strength since they did not spread uniformly in the stir zone. However, at a higher depth of penetration, 2.5 mm, the MMC-SFW joint reinforced with Ancorsteel 1000, copper, or Al12Si did increase the joint strength compared to that of the base SFW specimens. Using steel powder as the reinforcement material, the MMC showed the maximum increase in the lap shear joint strength. For example, at 2.5 mm depth of penetration, the SFW joint strength increased by 19% and 24% compared to that of the base SFW specimen made of Al 1100 and Al 6111 alloys respectively.
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Goglio, Luca, i Massimo Rossetto. "Strength of Adhesive Joints Under Impact Stress Conditions". W ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95306.
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The paper reports an experimental study on the bonded joints, carried out by means of an instrumented impact pendulum, equipped to load overlap specimens in tensile shear. Such testing configuration is the most adequate and natural to study the possible modifications of the behavior of the joint, changing from static to dynamic loading condition, keeping the same specimen type. The specimens were steel strips bonded by an epoxy adhesive (Hysol 3425). Several values of lap length, adhesive and adherends thickness were adopted, to achieve rupture under different stress combinations. The stress state at rupture has been calculated by means of a structural solution. The results show that it is possible to represent the failure condition on a chart having as axes the peel and shear structural stress, in a way similar to that found for static cases. Furthermore, in spite of the concerns associated with the impact condition, the strength of the adhesive does not decrease with respect to the case of static loading.
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Koguchi, Hideo, i Naoki Kimura. "Evaluation of the Strength of Interface for Multi-Layered Materials in Photonic Devices". W ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48105.
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Recent electronic device packaging, for instance, CSP has a bonded structure of IC chip and polymers, and delamination occurs frequently at the interface between IC and a resin. Furthermore, thermal stresses which are caused by a temperature variation in the bonding process of CSP and heat cycles for environment temperature will influence on the strength of interface. In the present paper, the delamination test for specimens with different thicknesses of an interlayer is carried out to investigate the strength of multi-layered joints, and the critical value for the intensity of singularity at delamination of interface is determined through a numerical analysis using a boundary element analysis. In experiment, a silicon wafer is joined with a silicon-on-sapphire (SOS) plate by a resin. The SOS is composed of silicon film and sapphire plate. The joining strength in silicon, resin and SOS joints with a rectangular bonding area is investigated. The bonded specimens are prepared under different cooling rate. Load is applied to the specimen so as to delaminate at the interfaces of silicon film and sapphire. Delamination occurs at the interface between silicon film and sapphire plate in the specimen. Nominal stress for delamination is about 2.23–3.59 MPa. From a comparison of the strength of joint for rapid and slow cooling conditions, it is found that the residual stress reduces the strength of joint. In the numerical analysis, the intensity of singularity at the corner of interface for a unit load is determined. The intensity of singularity at the corner of the interface is related to the intensities of singularity in the radial direction and on the angle from the side free surface. The critical intensity of singularity for delamination of the interface is obtained by multiplying the force at delamination. Then, the critical intensity of singularity is determined as 168 MPa•mm0.18 regardless of the thickness of silicon film.
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Tomosawa, Fuminori, Shigeo Tsujikawa, Teruyuki Nakatsuji, Keisuke Yonemaru, Koji Saka i Hiroyasu Kawaguchi. "Research on Applicability of New Materials to Marine Structures in Tropical Climates: Specimens Exposed for 1 Year". W ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28184.
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This study aims to investigate the applicability of newly developed structural materials, which are lightweight and highly durable, to marine structures from the aspect of reducing their life-cycle cost. Since corrosion is primarily the determining factor of the service life of marine structures, exposure tests have been conducted in this study with the focus on corrosion resistance of new structural materials. Twenty-one new materials have been exposed to the environment at three sites: the tropical island Okinotori-shima and subtropical island Miyako-jima, both in Japan, and a hygro-thermostatic room in a laboratory. These experiments started in 1999 as five-year exposure tests. The authors have reported on the selection of potential new structural materials for marine structures (six nonferrous metals, eight steels, four composite materials, and three rope materials), outline of exposure tests, and results of initial performance tests on these materials. As of October 2001, specimens at an age of 2 years were retrieved and are now being examined. This paper reports on the findings obtained after the publication of the previous paper, including the observation and test results of specimens retrieved in 2000 at an age of 1 year. After publishing the previous paper on the ongoing tests, tension tests on unjointed and jointed specimens and SEM observation of corrosion specimens were conducted. Some of the steels exhibited severe corrosion, as well as significant strength losses. Specimens other than those began to exhibit tendencies towards strength changes depending on the material type and specimen type (unjointed/jointed), though not very evident. SEM observation of corroded specimens revealed differences in the state of corrosion among materials.
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Nishi, H., M. Enoeda, T. Hirose, D. Tsuru i H. Tanigawa. "Evaluation of Strength on Dissimilar Metal Joints for ITER First Wall Components". W ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-26008.
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The first wall (FW) of ITER blanket includes beryllium (Be) armor tiles joined to CuCrZr heat sink with stainless steel cooling tube and backing plate in order to improve plasma performance and reduce thermal stress. Therefore dissimilar materials joints are indispensable for fabricating the high heat flux components. Since these joints must withstand thermal and mechanical loads caused by the plasma and electromagnetic force, it is important to evaluate the strength and thermal fatigue life of dissimilar materials joints. When the dissimilar materials joints are subjected by external force and thermal loading, the stress of the joint may indicate singularity at the interface edge. Since the stress singularity may lower the strength of joints, the singularity is evaluated numerically for the various materials combinations and joint configuration to be used in high heat flux components of fusion reactors in this investigation. Moreover, tensile test and elasto-plastic FEM analysis are performed to investigate the fracture behavior of Be/Cu alloy and stainless steel/ Cu alloy obtained the FW mock-up. The results reveal two singular solutions of type rpj−1 for a half-plane bonded to a quarter-plane joint and the singularity is larger than that of a bonded quarter-planes joint. From the viewpoint of stress singularity, the configuration of bonded quarter-planes joint is better than the half-plane bonded to a quarter-plane joint. The singularity for W/Cu alloy combination is large compared to other combination of materials. Especially the singularity of stainless steel/ Cu alloy is very small. Tensile specimen of Be/CuCrZr joint fractured at the bonding interface due to the stress singularity. For the stainless steel/ Cu alloy, however, the specimens fractured at the Cu alloy region apart from the interface.
Raporty organizacyjne na temat "Strength of Jointed Specimen"
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Begg, Darren. PR-214-124506-R02 Toughness and Strength of Sub-Arc Double Jointed High Strength Pipe. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), sierpień 2017. http://dx.doi.org/10.55274/r0011418.
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Current design of pipelines calls for overmatching weld metal tensile strength, forcing deformation to occur in the base material and not in the weld. If straining of the weld metal were to occur, higher levels of weld metal toughness would be required to prevent fracture initiation from pre-existing defects. There are three known issues related to the Submerged Arc Welding (SAW) double jointing of pipeline steels: - Consistently achieving weld metal strength and toughness requirements. - Heat affected zone (HAZ) softening of the base material. - Lack of an accepted test protocol for the entire range of pipe grades. The results herein will help improve the quality and efficiency of SAW welding in double jointing for all pipeline steels, and enhance industry's ability to complete double jointing and standardize its acceptance, and will improve construction efficiency, pipeline reliability and safety by addressing this important research gap in transmission pipeline welding.
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Horie, T. Face compression yield strength of the copper-Inconel composite specimen. Office of Scientific and Technical Information (OSTI), maj 1987. http://dx.doi.org/10.2172/5687566.
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Oakes, Jr, R E. Specimen type and size effects on lithium hydride tensile strength distributions. Office of Scientific and Technical Information (OSTI), grudzień 1991. http://dx.doi.org/10.2172/5930848.
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Doyle, Jesse D., Nolan R. Hoffman i M. Kelvin Taylor. Aircraft Arrestor System Panel Joint Improvement. U.S. Army Engineer Research and Development Center, sierpień 2021. http://dx.doi.org/10.21079/11681/41342.
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Aircraft Arresting Systems (AAS) for military applications utilize sacrificial panels made of Ultra-High Molecular Weight polyethylene (UHMWPE) that are embedded into the pavement beneath the AAS cable to protect the pavement from cable damage. Problems have been observed with the materials and practices used to seal the UHMWPE panel joints from water and debris. Data obtained from laboratory and field studies were used make improvements to current practice for sealing UHMWPE panel joints. The study evaluated four joint-sealant materials, eight alternative surface treatment and preparation techniques to promote adhesion to UHMWPE, and seven joint-edge geometries. Bond-strength testing of joint-sealant specimens was conducted in the laboratory, followed by field evaluation of construction techniques. Field performance of the joint systems was monitored for 24 months after installation. Additionally, a thermal response model was developed to refine the joint design dimensions. Results confirmed that the best material to use was self-leveling silicone joint sealant. It was recommended that a dovetail groove be cut into the edge of UHMW panels to provide positive mechanical interlock and to reduce adhesive failures of the sealant. It was also recommended that the panel-to-panel joint-sealant reservoir be widened to prevent sealant compression damage.
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Brosnahan i DeVries. PR-317-10702-R01 Testing for the Dilation Strength of Salt. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), grudzień 2011. http://dx.doi.org/10.55274/r0010026.
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A laboratory testing program on rock salt specimens was performed using test conditions that are consistent with the stresses that are experienced near the surfaces of salt caverns during storage operation. The proposed work effort focuses on improving the methodology for defining the onset of dilation for rock salt. Geomechanical studies use dilation criteria to assess the potential for salt damage that can lead to spalling in the cavern roof and/or walls and subsequent damage to the cavern or hanging string. This constraint is often the one that limits the minimum gas pressure in a natural gas storage cavern. This report documents the PRCI funded follow-on activities to the recently completed Gas Storage Technology Consortium project [DeVries, 2010]. The work activities completed include the following: Laboratory dilation strength testing of eight specimens having preconditioning durations longer than 10 days. Numerical modeling to identify and optimize an appropriate specimen shape for dilation testing in triaxial extension states of stress. Laboratory constant mean stress extension testing on the optimized specimen shape. DeVries [2010] documented the effects of the preconditioning durations on the dilation strength of salt specimens. Preconditioning of specimens is the process whereby specimens are subject to a relatively high hydrostatic stress for a specified period of time. It is believed that preconditioning mitigates some of the damage to the specimens induced by coring, transporting, and specimen preparation. The study documented by DeVries [2010] suggests that increasing the preconditioning duration increases the dilation strength of salt, with the maximum precondition duration limited to 10 days. This project expands upon these findings through additional testing to determine if preconditioning durations longer than 10 days has any additional benefit. In addition to the preconditioning task, this study will also investigate the variability issues observed during dilation strength tests performed under triaxial extension states of stress. It is hypothesized that the high variability seen in extensional test results might be attributed to end effects caused by (1) the friction at the specimen-platen interface and (2) specimens breaking outside the range measured by gages. To help reduce frictional effects and breakage location issues, numerical models of alternate specimen shapes were created to provide a basis for testing a new specimen geometry. Laboratory tests were performed on the new specimen geometry to validate any of its possible benefits.
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Roberson, Madeleine, Kathleen Inman, Ashley Carey, Isaac Howard i Jameson Shannon. Probabilistic neural networks that predict compressive strength of high strength concrete in mass placements using thermal history. Engineer Research and Development Center (U.S.), czerwiec 2022. http://dx.doi.org/10.21079/11681/44483.
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This study explored the use of artificial neural networks to predict UHPC compressive strengths given thermal history and key mix components. The model developed herein employs Bayesian variational inference using Monte Carlo dropout to convey prediction uncertainty using 735 datapoints on seven UHPC mixtures collected using a variety of techniques. Datapoints contained a measured compressive strength along with three curing inputs (specimen maturity, maximum temperature experienced during curing, time of maximum temperature) and five mixture inputs to distinguish each UHPC mixture (cement type, silicon dioxide content, mix type, water to cementitious material ratio, and admixture dosage rate). Input analysis concluded that predictions were more sensitive to curing inputs than mixture inputs. On average, 8.2% of experimental results in the final model fell outside of the predicted range with 67.9%of these cases conservatively underpredicting. The results support that this model methodology is able to make sufficient probabilistic predictions within the scope of the provided dataset but is not for extrapolating beyond the training data. In addition, the model was vetted using various datasets obtained from literature to assess its versatility. Overall this model is a promising advancement towards predicting mechanical properties of high strength concrete with known uncertainties.
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Graville, B. A. PR-225-9516-R01 Hydrogen Cracking in the HAZ of High Strength Steels - Development of a Test Method. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), styczeń 1996. http://dx.doi.org/10.55274/r0011702.
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Cracking tests for evaluating the susceptibility of the heat affected zone (HAZ) to hydrogen cracking during welding often give ambiguous results because cracks occur in the weld metal rather than the HAZ. To solve this problem, a simple bend test was developed in which a Charpy V-notch was cut in the HAZ after welding the specimen thus ensuring cracks occurred in the desired location when the specimen was subsequently loaded in three-point bending. The test was shown to effectively respond to changes in hydrogen content and base metal composition. The test provides a quantitative measure of susceptibility and it was demonstrated that this could be used to predict crackling behavior in more complex welds.
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Francini i Quade. PR-218-08702-R01 Additional Validation the Remaining Strength of Corroded Casing to Additional Cases. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), wrzesień 2010. http://dx.doi.org/10.55274/r0010715.
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This project is a follow up to the project titled "Effects of Tensile Loading on Remaining Strength of Corroded Casing." The objective is to test additional samples of corroded casing that will fail at typical storage well operating pressures and transfer the developed technology to MFL vendors for use in storage fields. A test matrix of 13 specimens was developed and tested. The test specimens consisted of natural corrosion and machined defects. Prior to testing: � the specimen material was characterized with tensile, Charpy V-notch, hardness, and chemical tests and � the test specimens were shipped to 2 MFL vendors for logging. The results of the testing and MFL characterization are summarized in this report.
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Graville. L51764 Hydrogen Cracking in the Heat-Affected Zone of High-Strength Steels-Year 2. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), marzec 1997. http://dx.doi.org/10.55274/r0010170.
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During year 1 of this project a test to evaluate the sensitivity of the heat affected zone (HAZ) to hydrogen cracking was developed. This was in response to a need for a test which provided unambiguous results in contrast to existing test methods which often led to difficulties in interpretation. For example, WIC tests usually cracked in the weld metal rather than the HAZ and therefore did not produce a clear indication of the sensistivity of the HAZ. The new test involves a machined notch which can be placed in the HAZ thus forcing crack initiation to occur in the desired region. A further advantage of the new test is that it is quantitative with each test specimen providing a measure of the sensitivity of the HAZ in that test. Existing tests are usually of the crack/no-crack type requiring a series of tests at different preheats to be carried out in order to establish a critical value. This is an expensive, time-consuming approach. The new test measures the deflection to first load drop (normally the onset of significant cracking) when the welded specimen is loaded in bending. It was also shown during the first year of the project that the simple geometry of the test lends itself to easy analysis enabling the stress/strain distribution to be calculated by finite element analysis. The quantitative measurement of susceptibility in the test enabled the cracking of more complex welds to be predicted on the basis of a local critical hydrogen model. The objective of the work was to extend the notched bend test to the evaluation of weld metal sensitivity to hydrogen cracking. The experiments were designed to determine whether the test could discriminate between two different weld metals and to study the effects of reducing hydrogen content. In addition, finite element analysis of the weld metal test was carried out and finite difference analysis used to predict the local hydrogen concentration. This work modifies the notched bend test, developed for evaluating the sensitivity of the heat affected zone (HAZ), to allow the evaluation of weld metal. The results showed that weld metal could readily be evaluated, with the test discriminating among weld metals of different composition and hydrogen contact. Finite element analysis was undertaken and showed that for the two weld metals tested, cracking occurred at the same local stress when the hydrogen content was the same, despite differences in strength. A finite model was used to calculate the distribution of hydrogen as a function of aging time. Although the general trends were confirmed by the experimental measurements of hydrogen content, there was considerable scatter attributed to the small hydrogen volumes measured.
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Shen, Gianetto i Tyson. L52342 Development of Procedure for Low-Constraint Toughness Testing Using a Single-Specimen Technique. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), grudzień 2011. http://dx.doi.org/10.55274/r0010687.
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Pipelines from remote frontier regions are increasingly required to have adequate resistance to large deformations such as that caused by ground movement. In response to this, �strain-based design"� has been developed to enable assessment of imperfections at applied strains beyond yield. In addition, it is proposed to take advantage of the increased apparent toughness of pipe under low constraint, such as girth weld imperfections under axial tension, compared with the high-constraint toughness measured in conventional tests such as ASTM E1290 [1]. Application of low-constraint testing has been dvantageously applied in assessment of toughness for offshore pipeline projects. Also in the pipeline industry, demands on new pipeline projects include low design temperatures as well as high strain capacity. At the same time, increased strength is specified, which increases the level of required toughness. These factors make it increasingly important to assure weldment toughness, in particular to ensure that the failure mode remains ductile. It is well known that brittle cleavage is especially sensitive to constraint, and the availability of a toughness test that would reproduce field conditions would enable more rational development and acceptance of candidate welds and, in particular, enable more appropriate testing of weld heat-affected zones. This work was performed for specific application to surface circumferential cracks in pipe under strain-based design, for which the best constraint matching has been found to occur for clamped single-edge tension (SE(T)) specimens with H/W=10. For this geometry, a test procedure similar to that of ASTM E1820-06 for single-edge bend (SE(B)) and compact tension (C(T)) specimens was developed for J-resistance tests using a single-specimen technique. All the equations used in the procedure, including those for evaluation of J-integrals from the area under load/plastic crack mouth opening displacement (CMOD) curves, and evaluation of crack length from unloading compliance including rotation correction, were developed using finite element analysis (FEA) with a range of crack depths, focusing on a/W= 0.2 to 0.5 which is of most practical interest. The present procedure is compared with that of E1820 for SE(B) testing regarding evaluation of J-integral with crack growth correction, crack length evaluation, and correction of compliance for rotation.