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Search Results: 1 - 10 of 3886 matches for " Bending Load "
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 World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.34019 Abstract: In present work, post-buckling behavior of imperfect (of eigen form) laminated composite cylindrical shells with different L/D and R/t ratios subjected to axial, bending and torsion loads has been investigated by using an equilibrium path approach in the finite element analysis. The Newton-Raphson approach as well as the arc-length approach is used to ensure the correctness of the equilibrium paths up to the limit point load. Post-buckling behavior of imperfect cylindrical shells with different L/D and R/t ratios of interest is obtained and the theoretical knock-down factors are reported for the considered cylindrical shells.
 Leonardo Electronic Journal of Practices and Technologies , 2011, Abstract: The force relations and dynamics of cutting knife in a vertical disc wood chipper were investigated. The tool geometry determined include: rake angle (20 deg C); Shear angle, (fi= 52.15 deg C); the mean frictional angle, (t = 5.71 deg C). The analysis and comparison of the cutting forces has shown that the chips separated from the wood are being formed by off cutting, since normal applied force N is compressive in nature, the magnitude of the forces used by the knife on the wood is expected to increase as the cutting edge of the knife goes deeper into the wood until the value of the resisting force acting against the cut wood Ff is reached and exceeded. The evaluated forces acting on the knife and the chip are: F = 3.63Nmm^-1; N = 34.7 Nmm^-1; Fs= 27.45Nmm^-1; Fn =31.92 Nmm^-1; Ft = -8.46Nmm^-1; Fc = 33.85Nmm^-1. The resultant force acting on the tool face, Pr = 34.89Nmm^-1. The specific cutting pressure, Pc and cutting force needed to cut the timber, Fc, are 1.79 × 10^6 N/m2 and 644.84N respectively. The energy consumed in removing a unit volume of material is 69.96kJ/mm^-3 and the maximum power developed in cutting the chip is 3591.77W (4.82hp). The chipper efficiency (86.6%) was evaluated by the highest percentage of accepted chip sizes.
 Journal of Engineering Science and Technology , 2008, Abstract: Replacement of wooden sleepers to prestressed concrete sleepers has marked as advancement in the railway sleepers industry in Malaysia. Despite superiority of these man-made composite sleepers, wooden sleepers still lead in terms of track performance qualities in particular on its natural elasticity. An initiative to investigate the degree of degradation of used wooden sleepers and the possibility of reusing them on low capacity railway track in Malaysia as a means of reducing the overall track rehabilitation cost was undertaken. Used wooden sleepers were tested according to Australian Standard, Railway Track Material, Prestressed Concrete Sleepers (AS 1085:14:2003) on Rail Seat Vertical Load Test and Centre Positive Bending Moment Test. Six wooden sleeper samples were tested under the static load until failure. Benchmarking was carried on high strength prestressed concrete sleeper, tested according to AS 1085:14:2003: Rail Seat - Positive Moment Test. The results obtained showed the maximum load that the used wooden sleepers can carry surpassed the design load of KTMB specifications and it is about 58% of high strength prestressed concrete sleeper.The maximum deflection produced by all used wooden sleepers is 20 mm showing that the sleepers maintained their elastic behaviour. Modulus of Elasticity ranging from 21 to 27 kN/mm2 of which within the standard value, indicating weathering process does not so much affect their stiffness. Most sleepers showed crack patterns propagated in the longitudinal direction. Toughness value is almost one half of the high strength prestressed concrete sleeper. This study indicates that there is a potential of reusing the wooden sleepers for light loading of the railway track. Hence, an extensive study is recommended to be carried out under fatigue loading condition.
 Hans Journal of Civil Engineering (HJCE) , 2014, DOI: 10.12677/HJCE.2014.33012 Abstract: 火灾下由于梁和柱间相互作用，构件一般会在弯矩和轴力的联合作用下破坏，此时，构件的承载力由轴力–弯矩相关曲线(P-M相关曲线)决定。规范中给出的计算P-M相关曲线是基于截面全截面均匀升温的假定。此假定针对梁柱四面受火的情况是可行的，但当梁柱1、2、3面受火时，截面上各点的温度不同，计算结果可能会偏于不安全。因此，本文针对箱形截面分析了不同的高宽比、宽厚比对P-M相关曲线形状的影响，结果表明截面的高宽比和宽厚比对P-M相关曲线形状的影响不大。并且，本文提出一种简化P-M相关曲线，用来考虑不均匀升温对P-M相关曲线形状的影响。最后，通过一个数值计算实例来验证所提出的简化P-M相关曲线的准确性，结果表明，简化P-M相关曲线能很好的预测三面受火的箱形梁柱构件的破坏时间，并且偏于保守。 The load carrying capacity of steel beam-columns subject to fire is determined through axial and moment capacity curves (P-M curves). A uniform temperature distribution through the depth of the section is assumed in Codes and standards. This assumption may be acceptable for some members, such as a column exposed to fire from four sides, but it may not be valid for columns or beams exposed to fire from 1, 2, or 3 sides since significant thermal gradients develop across the section. This study evaluates the effects of section depth, and plate thickness on the plastic P-M interaction diagram of box section. And the P-M interaction diagram is developed by adjusting the P-M interaction diagrams based on a uniform temperature. The applicability of the proposed method to a design situation is illustrated through a numerical example. It is indicated from the results that the simplified method can be applied to predict the load-bending capacity of beam- columns with temperature gradient in section under fire exactly.
 Remzi Y？ld？r？m Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.310114 Abstract: In this experimental study, the laser light was split and bended using a specially designed glass lenses at the same time. This process has been done at the atmospheric pressure and room temperature conditions. During the experiments, the semiconductor laser as a source of green and red laser diode is used. In addition, polari- zation, magnetic field, electric field or any other auxiliary materials and systems which affect laser light are not used to bend the laser light. Only transparent glass lenses that are designed specially are used in the experimental study.
 姜明,贾近,肖海英,张东兴 - , 2018, DOI: 10.11918/j.issn.0367-6234.201704087 Abstract: 为探究不同孔隙率碳纤维/环氧树脂层合板在仿超音速飞行的高低温湿热老化环境及外加载荷作用对弯曲力学性能的影响规律，基于材料服役期间的吸湿状态和内应力状态，对T700CF/3234EP进行模拟超音速飞机服役环境的高低温交变加速湿热循环试验.通过控制模压压力，制备3种孔隙率分别为0.04、0.08和0.11的层合板，将3种孔隙率的层合板进行加载，加载载荷为层合板最大弯曲载荷的0、30%、40%和60%，然后将其置于高低温环境模拟试验箱中，分别测量不同循环周期复合材料层合板的弯曲强度变化，并采用ABAQUS软件对其弯曲力学性能进行有限元模拟.试验结果表明：温湿场交变环境下，外加载荷和孔隙率加速层合板弯曲强度的下降，在高低温湿热循环4~6周期时，随着载荷的增大，二次固化现象越明显，层合板的弯曲强度变化比较平缓.使用ABAQUS软件建立有限元模型，计算得到的弯曲力学强度变化趋势与试验结果相一致，说明高低温湿热老化环境和外加载荷对复合材料弯曲性能的影响，对不同孔隙率的碳纤维/环氧树脂层合板弯曲性能进行较为准确的预测.In order to investigate the influence of different porosity carbon fiber/epoxy resin laminates on the bending mechanical properties at the high and low temperature and hygrothermal aging environment and subjected external load, the supersonic state and the internal stress state were simulated. High and low temperature accelerated hygrothermal cyclical tests for T700CF / 3234EP were employed to simulate supersonic aircraft service environment. Three laminates with porosity of 0.04, 0.08 and 0.11 were prepared by controlling the molding pressure. The loading of the laminates was loaded with 0, 30%, 40% and 60% of the maximum bending load of the laminates, respectively, and then placed in the high and low temperature environment test chamber. The bending strength of composite laminates under different temperature cycles is measured respectively, which were simulated based on ABAQUS software. The experimental results show that the external load and porosity increase the bending strength reduction of the laminates under the alternating temperature and humidity field.During the high and low temperature and hygrothermal cycle 4~6 periods, the secondary curing phenomenon becomes more obvious as the load increases andthe changes of the bending strength of the laminate is relatively gentle. The calculated trend of bending strength based on finite element model was consistent with the experimental results. The effects of high and low temperature, hygrothermal aging environment and external loading on the bending strength of composites were explained. The bending property of carbon fiber / epoxy resin laminates with different porosities were predicted accurately.
 - , 2015, DOI: 10.3969/j.issn.1000-0844.2015.01.0094 Abstract: 假定软土地区海底沉管隧道地基土为Kelvin模型,车辆荷载是随时间变化的波动荷载形式,引入黏弹性地基梁模型,利用模态叠加法给出三种情况下沉管隧道的竖向位移、弯矩和地基反力的解答。结合天津海河沉管隧道工程实例,分析车辆速度、地基土模量对沉管隧道竖向位移及弯矩的影响。研究结果表明:车辆荷载引起的管段中点振动振幅达5 mm左右,振动周期为0.25 s;引起的管段中点弯矩为15 500 kN·m左右,且车速越大,管段振动一个周期所需时间越短,振动越剧烈,但对振动幅度及弯矩影响不大;地基土模量越大,振动幅度和弯矩越小,但对周期影响不大。As unique underground structures, submerged tube tunnels have been subject to vehicle loads for long periods of time.As the loads change, the underwater tunnel will show cyclical changes in displacement, bending moment, and ground reaction force.These periodic changes represent a significant potential threat to the integrity of tunnel structures.The purpose of this study was to assess the impacts of vehicle load on those tunnels.The modal superposition method was used to analyze three characteristics of vertical displacement, bending moment, and ground reaction force in underwater tunnels.In this method, two conditions were assumed:(1)the underwater tunnel in soft soil areas is the foundation of the Kelvin model, and (2)vehicle loading is the fluctuation of load form changing with time.The impact of vehicle speed and the foundation soil modulus on the tunnel's vertical displacement and bending moment was analyzed.Using the Beam-On-Elastic-Foundation (BOEF) model, combined with data from the Tianjin Haihe River tunnel engineering, the results of the analysis showed that:(1)the midpoint pipe vibration amplitude induced by vehicle loads was up to 5 mm, the midpoint pipe bending moment was approximately 15 500 kN·m, and the vibration cycle was 0.25 s;(2)the higher the vehicle speed, the shorter the pipe vibration cycle time, the more intense the vibration, and the lower the effect on amplitude;and, (3)the greater the modulus of foundation soils, the smaller the amplitude of vibration and bending moment, and the lower the effect on the cycle.
 陈旭,兰孟飞,刘庆,李郭瑞,鲁毅,曹广富 - , 2016, DOI: 10.11835/j.issn.1000-582X.2016.03.016 Abstract: 为了对G324牵引车的车架进行强度分析及改进,根据牵引车的实际工况,选择对车架影响较大的弯扭工况进行分析,利用HyperMesh有限元软件建立了某牵引车车架结构有限元分析计算模型。通过计算得出该车架在这两种工况下的应力分布云图,对车架进行改进并分析增加L板和将鞍座瓦轮板改为平板以及取消加强板3种模型的实际情况,得出满足车架强度要求的具体模型,为牵引车车架的设计及改进提供参考依据。In order to analysis and improve the strength of G324 tractor frame, according to the actual condition of the tractor, we analyzed the bending and the torsional conditions which have great impact on the frame and established a finite element calculation model of the G324 tractor vehicle frame using the HyperMesh finite element analysis software. Through calculating the stress distribution of the frame in the two kinds of working conditions, we improved the frame and analyzed the stress distributions of adding L plate, changing the saddle tile wheel plate to plane plate and canceling reinforcing plate, respectively. At last, we figured out the specific model of the frame to meet strength requirements, and the results could provide references for the design and improvement of tractor frame
 International Journal of Geosciences (IJG) , 2015, DOI: 10.4236/ijg.2015.68075 Abstract: Major seismic activity in the Northern Apennines concentrates in few zones, distributed in a peculiar way. It is argued that such context may be plausibly explained as an effect of belt-parallel？shortening, which has caused oroclinal bending of the longitudinal ridges formed during the Late Miocene to Lower Pliocene evolutionary phase. The main effects of this process, developed since the upper Pliocene, have mainly affected the outer sectors of the belt. The major seismic sources have generated in the zones where different oroclinal bendings of adjacent ridges have produced extensional/transtensional deformation. In the inner side of the Northern Apennines, belt parallel shortening has occurred at a lower rate. The main effects have resulted from the shortening of the？Albano-Chianti-Rapolano-Cetona ridge. In particular, the proposed tectonic setting may account？for the moderate seismic activity that occurs in the Firenze, Elsa, Pesa, Siena and Radicofani basins.
 力学学报 , 1992, Abstract: In the present paper, the point-load normal to the middle surface,located at a arbitrary place on a plate, is taken as a point source and expressed as the 6-fun-ction. In the paper is derived the non-homogeneous solution in closed form and homogeneous solution in series form of the differential equation for the bending of the circular plate under single load, thus obtaining the uniform displacement expression valid for the whole plate.
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