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Journal articles on the topic 'Eccentricity crank mechanism'
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1
Tuleshov, Amandyk, Recep Halicioglu, Azhar Shadymanova, and Moldir Kuatova. "Kinematic synthesis method and eccentricity effects of a Stephenson mechanism." Mechanical Sciences 12, no. 1 (January 11, 2021): 1–8. http://dx.doi.org/10.5194/ms-12-1-2021.
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Abstract. When implementing the technological process on crank presses, it is necessary to provide a predetermined working cycle of the slider motion: fast lifting, dwell, and slow lowering. The cycle cannot be realized without controlling the motor. In addition, using controllable motors increases the manufacturing cost. Due to the geometric and kinematic capabilities of the mechanism, changing the kinematics of the working link is the best choice. Thanks to the use of the Stephenson II mechanism, the slider skew is eliminated due to the parallel connecting rods and the increased area of slider contact. This study presents a numerical method for kinematic synthesis of the Stephenson mechanism that has kinematic advantages. The method is based on mean square deviation which is the minimizing of an objective function. Thanks to the proposed synthesis method, approximate dwell movement can be performed when the slider is on the bottom dead center. In this study, values of the crank length and parallel connecting rods' lengths, angular coordinates of the crank and connecting rods, and the eccentricity of the guide slider relative to the crank rotation axis were obtained. It is observed that eccentricity affects the lower forward and higher backward speed of the slider. The kinematic results of the slider movement are comparatively presented in this article.
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Long, Jiang Qi, Si Jia Zhou, and Ping Yu. "Experimental Investigation of Vibration and Noise Control of Reciprocating Compressors." Advanced Materials Research 443-444 (January 2012): 837–42. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.837.
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The reciprocating compressor contains crank-rod mechanism whose unbalanced inertia force mainly accounts for mechanical noise and vibration during the working process. Through the analysis of fit between the diameter of the compressor piston and the crank eccentricity, influence of imbalance force on the compressor vibration and noise is obtained under no change in other parts. The tests of vibration and noise are followed for the purpose of verification. The results show that the vibration and noise control will be better if a small piston diameter and a big crank eccentricity are utilized.
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Zhao, Man, Shurong Yu, Chao Li, and Yang Yu. "Effect of Mechanism Error on Input Torque of Scroll Compressor." International Journal of Rotating Machinery 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/438127.
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Based on the fundamental principle of plane four-bar mechanism, the force on the equivalent parallel four-bar mechanism was analyzed for scroll compressor with mini-crank antirotation, and the formula of input torque was proposed. The change of input torque caused by the mechanism size error was analyzed and verified with an example. The calculation results show that the mechanism size error will cause large fluctuation in input torque at the drive rod and connecting rod collinear and the fluctuation extreme value increases with rotational speed. Decreasing of the crankshaft eccentricity errors is helpful for reducing the effects of dimension error on input torque but will increase the friction loss of orbiting and fixed scroll wrap. The influence of size error should be considered in design in order to select suitable machining accuracy and reduce the adverse effect caused by size error.
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Sun, Tao, and Lu Fang Qin. "The Virtual Optimization Design on the Variable-Pitch Actuator of Wind Turbine." Advanced Materials Research 827 (October 2013): 302–8. http://dx.doi.org/10.4028/www.scientific.net/amr.827.302.
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According to the load calculation of blade, the required maximum torque of rotational blade is obtained. A mathematic analysis method can be used to deduce the following results: the thrust of hydraulic cylinder is related to crank length, the connecting rod length, the eccentricity, the installation angle, and the variable-pitch driving force. Finally, the optimal values of pitch-controlled actuator are obtained. Based on three-dimensional modeling, assembly and dynamic simulation analysis, the virtual design of variable blade pitch mechanism is completed by using the software Pro/E. By means of dynamic simulation analysis, the rationality of this design is verified, facilitating the further on development mechanism's optimized design.
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Chu, Zhi Bing, Qing Xue Huang, Zhi Yuan Zhang, and Dan Li. "Study of Structure and Properties of New Rolling-Cut Shear." Advanced Materials Research 146-147 (October 2010): 991–95. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.991.
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Based on rolling-cut shear simulation, using a kind of single-shaft and double eccentricity rolling-cut shear, which adopts a new structure of asymmetric feature and negative bias, as the calculating model by establishing motion path equation of spatial shear mechanism, comparing with the steel shear forces, link forces and horizontal link force components with or without asymmetric feature, the asymmetric formulation is deduced. Such asymmetric crank structure can decrease horizontal force component between the linkages during rolling-cut process, increase the effective drive force on links while it comes to the maximum shear force, and decrease the extrusion of blade arc on steel edge as well. Theoretical analysis and steel-shearing quality at site indicate that asymmetric and negative bias is an important and efficient way to prolong the lifetime of blade, decrease blade wear, improve shearing quality, and maintain the constant clearance between blades.
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Moskvichev, V. V., and E. A. Chaban. "Analysis of the fatigue cracks development in crane girders and assessment of their residual life." Industrial laboratory. Diagnostics of materials 84, no. 7 (August 8, 2018): 47–54. http://dx.doi.org/10.26896/1028-6861-2018-84-7-47-54.
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The results of analysis of the residual life of crane girders with operational defects based on numerical studies of the stress-strain state, equations of limiting states, and kinetic dependences of the fatigue crack development, based on the criteria of deformation and fracture mechanics are presented. High level of wear of the fixed capital assets of engineering constructions and metal structures as well as operation of the facilities in beyond-design-basis terms contribute to origination of the emergency situations caused by damage accumulation. Crane girders operated under emergency conditions due to the fatigue cracks of different lengths present in the most dangerous zones of the beam wall with an eccentric application of crane load are studied. The results of the numerical experiment revealed the lines of tension intensity impact at the crack tip appeared at the upper zone of the wall at different values of the loading eccentricity attributed to the rail shift from the vertical axis of the beam. The dependence of the length of the fatigue crack and stress intensity in the crack tip on the number of load cycles of the beam is determined. To assess the bearing capacity of crane girders operated in emergency conditions, it is suggested to use the effective values of the stress intensity factors calculated for the specific loading conditions, taking into account the structural features of the beams, size of the fatigue cracks and their location in the crane girders. Proceeding from the results of analysis the diagrams which provide of the remaining residual life of crane girders with a crack are constructed. Using traditional methods of structure calculation for cyclic fracture toughness we developed and implemented the calculation algorithm for individual lifetime of the crane girders which includes the obligatory analysis of the stress-strain state of the crane girders with a crack at the upper zone of the wall.
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Xiao, Chenglong, Renshu Yang, Chenxi Ding, Cheng Chen, Yong Zhao, Yiqiang Kang, and Guoli Shi. "Dynamic Fracture Experiment of Medium with Defects under Impact Loading." Shock and Vibration 2021 (February 16, 2021): 1–9. http://dx.doi.org/10.1155/2021/8860929.
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Defects have a significant effect on the dynamic fracture characteristics of the medium. In this paper, the dynamic fracture experiment of specimens with bias precracks is designed by utilizing the digital laser dynamic caustics system, and the effect of defect eccentricity on the dynamic fracture behavior is studied. Research shows that crack propagation can be divided into four stages: crack initiation stage, attraction stage, repulsion stage, and specimen fracture stage. The change of defect eccentricity has no obvious effect on the crack propagation behavior in the crack initiation stage and penetration stage but has a significant effect on the attraction stage and specimen fracture stage. In the process of the interaction between defect and crack, mode I stress intensity factor decreases at first and then increases. The decrease of mode I stress intensity factor reduces with the increase of defect eccentricity. The value of mode II stress intensity factor changes from negative to positive. With the increase of defect eccentricity, the symbol of mode II stress intensity factor no longer changes. The fractal dimension and the deflection angle of crack trajectory both decrease with the increase of defect eccentricity. In addition, a numerical simulation of the experiment is conducted by ABAQUS, which provides results that are in good agreement with the experimental results.
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ЧУРИЛОВ, Д. Г., И. С. АРАПОВ, А. В. СТАРУНСКИЙ, and С. Д. ПОЛИЩУК. "JUSTIFICATION OF APPLICATION MODES OF MACHINING ATTACHMENTS FOR PROCESSING PARTS BY THE METHOD OF PLASTIC DEFORMATION." VESTNIK RIAZANSKOGO GOSUDARSTVENNOGO AGROTEHNOLOGICHESKOGO UNIVERSITETA IM P A KOSTYCHEVA, no. 2(50) (June 30, 2021): 136–41. http://dx.doi.org/10.36508/rsatu.2021.50.2.019.
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Проблема и цель. Установлено, что функциональное действие машин в значительной мере определяется параметрами качества их поверхностного слоя. Цель работы – обеспечение качества поверхностного слоя деталей одним из наиболее эффективных способов, обеспечивающих управление в широком диапазоне показателями качества обработки деталей поверхностным пластическим деформированием (ОУО ППД). Одни и те же параметры качества поверхностного слоя можно получить, используя различные методы и режимы ОУО ППД. Для их оценки необходимо определение трудоемкости операции. Следовательно, имеет место совокупность научно-технических задач, решение которых позволяет разработать методологию, алгоритм и программу выбора оптимального метода и условий ОУО ППД, обеспечивающих требуемые параметры качества поверхности при минимальной технологической себестоимости, что дает значительный экономический эффект. Методология. Одним из способов обработки деталей при восстановлении служит алмазное выглаживание после процесса шлифования. Выглаживатель – кристаллический алмаз – перераспределят металл поверхностного слоя, при этом меняется микрорельеф. После алмазного выглаживания увеличивается надежность, долговечность деталей, износостойкость. Для достижения цели предлагается использование двухзвенных оправок, которые позволяют исключить биение обрабатываемой поверхности. Структурный эквивалент механизма близок к кривошипно-шатунному механизму, в отличие от которого радиус обрабатываемой детали распределяется по дуге. Изменения силы выглаживания устанавливают связь между статической силой и силой инерции. Статическую силу сглаживания можно определить, зная основные технологические параметры и процессы. Сила инерции зависит от массы подвижного звена оправки. Результаты. Результаты настоящего исследования показали: к числу задаваемых параметров относятся масса подвижного звена оправки, диаметр детали, скорость скольжения, эксцентриситет, постоянная механизма и сила инерции. Найдены разрешенные частоты вращения в зависимости от диаметра детали. Заключение. Данная методика может быть применена для восстановления рабочих поверхностей поршневых пальцев автотракторных дизельных двигателей сельскохозяйственного назначения и позволяет снизить уровень шероховатости поверхности обрабатываемых деталей. Problem and purpose. Problem and purpose. It has been established that the functional action of machines is largely determined by the quality parameters of their surface layer. The purpose of the work is to ensure the quality of the surface layer of parts by one of the most effective methods that provides control over a wide range of quality indicators for processing parts by surface plastic deformation (SPD). The same parameters of the quality of the surface layer can be obtained using different methods and modes of SPD. To assess them, it is necessary to determine the complexity of the operation. Consequently, there is a set of scientific and technical problems, the solution of which makes it possible to develop a methodology, an algorithm and a program for choosing the optimal method and conditions for SPD, which provide the required surface quality parameters at a minimum technological cost, that gives a significant economic effect. Methodology. One of the methods of processing parts during restoration is diamond burnishing after the grinding process. The smoother or the crystal diamond will redistribute the metal of the surface layer, thus changing the microrelief. After diamond burnishing, reliability, durability of parts, and wear resistance increase. To achieve the goal, it is proposed to use two-link mandrels, which allow to exclude the beating of the treated surface. The structural equivalent of the mechanism is close to the crank gear, in contrast to which the radius of the workpiece is distributed along the arc. Changes in the smoothing force establish a relationship between static force and inertial force. The static smoothing force can be determined by knowing the basic technological parameters and processes. The force of inertia depends on the mass of the moving link of the mandrel. Results. The results of this study showed that the parameters set included the mass of the movable link of the mandrel, the diameter of the part, the sliding speed, the eccentricity, the constant of the mechanism and the force of inertia. The permitted speeds were found depending on the diameter of the part. Conclusion. This technique can be used to restore the working surfaces of the piston pins of automotive diesel engines for agricultural purposes and can reduce the level of surface roughness of the processed parts
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Malíková, Lucie, Petr Miarka, and Hana Šimonová. "Propagation conditions of an eccentric crack in a semi-circular disk loaded in I+II mixed mode." MATEC Web of Conferences 310 (2020): 00017. http://dx.doi.org/10.1051/matecconf/202031000017.
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Multi-parameter fracture mechanics concept is applied to investigate crack propagation conditions during a three-point bending (3PB) test performed on an asymmetrical semi-circular disk under I+II mixedmode loading. The asymmetry is represented by an eccentricity of the angled crack as well as by different distances of both supports during the 3PB test from the middle of the specimen. The Williams series expansion is used for the crack-tip stress field approximation and fracture response of the crack is assessed by means of the combination of the numerical and analytical solution. Comparison between the individual configurations is carried out and discussion on the importance of the higher-order terms considered in the Williams expansion for various cases of asymmetry is presented.
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Spagnuolo, Roberto. "Out-of-plane local mechanism analysis with finite element method." Curved and Layered Structures 8, no. 1 (January 1, 2021): 130–36. http://dx.doi.org/10.1515/cls-2021-0012.
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Abstract The stability check of masonry structures is a debated problem in Italy that poses serious problems for its extensive use. Indeed, the danger of out of plane collapse of masonry walls, which is one of the more challenging to evaluate, is traditionally addressed not using finite element models (FEM). The power of FEM is not properly used and some simplified method are preferred. In this paper the use of the thrust surface is suggested. This concept allows to to evaluate the eccentricity of the membrane stresses using the FEM method. For this purpose a sophisticated, layered, finite element with a no-tension material is used. To model a no-tension material we used the smeared crack method as it is not mesh-dependent and it is well known since the early ’80 in an ASCE Report [1]. The described element has been implemented by the author in the program Nòlian by Softing.
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Deng, Haishun, Qingchun Wang, Haifeng Wang, and Chuanli Wang. "Relative motion relation in the external return spherical bearing pair of a balanced double-row axial piston pump." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 11 (October 9, 2018): 3858–72. http://dx.doi.org/10.1177/0954406218805114.
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Based on the external compaction return mechanism of a balanced double-row axial piston pump and the vector coordinate transformation principle, a mathematical model of the relative motion relation within the external return spherical bearing pair was built. The influence of slant inclination of the external swash plate and of pump shaft rotating speed and eccentricity on the relative motion trail, movement speed and acceleration was analysed. The relative motion velocity and acceleration between external retainer plate and external spherical hinge, at top and bottom dead centres, were discussed. By increasing the slant inclination of the external swash plate, the relative motion trail increased correspondingly, leading to a larger size of the pump integral structure. The relative speed and acceleration increased with the pump shaft speed and the slant inclination of the external swash plate, leading to a larger fluctuation of the slipper pair oil film. The increase of eccentricity slightly influenced the relative velocity and acceleration along the x-axis, without significantly increasing the fluctuation of the slipper pair oil film. Increasing the pump shaft speed, the external swash plate slant inclination and the eccentricity all caused fluctuations in the relative velocity and acceleration along the y- and z-axes, deepening the grinding crack on the compaction surface of the external retainer plate. In case of eccentricity and a 0° rotation angle of the principal axis, the related acceleration of the radial friction surface of the retainer plate showed the largest fluctuation amplitude, and a scratch could easily occur.
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Li, Hongxi, Chusheng Liu, Ling Shen, and Lala Zhao. "Vibration Characteristics of an Industrial-Scale Flip-Flow Screen with Crank-Link Structure and Parameters Optimization." Shock and Vibration 2021 (September 27, 2021): 1–16. http://dx.doi.org/10.1155/2021/2612634.
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Flip-flow screens are increasingly used in the processing of fine wet coal. In this work, the vibration characteristics of an industrial-scale flip-flow screen with crank-link structure (FFSCLS) were investigated theoretically and experimentally. An improved kinematic model of FFSCLS was proposed and experiments are carried out to verify the reasonability. The effects of the key parameters of the eccentricity of the crankshaft, the rotational speed of the crankshaft, and the tension length of the screen surface on the vibration characteristics of the screen were investigated parametrically. The results show that the kinematic model can describe the vibration characteristics of screen perfectly with the maximum error between the theoretical and experimental results being within 6.96%. Moreover, the key parameters of the eccentricity of the crankshaft, the rotational speed of the crankshaft, and the tension length of the screen surface have significant effects on the vibrations of the screen body and screen surface. These parameters should be optimized to achieve maximum screening performance of the FFSCLS. This work should be useful for optimal design and efficient operation of the flip-flow screen.
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Xu, Ge Ning, Guang Heng Gao, and Zeng Cai Guo. "Analysis on Nonlinear Buckling Failure Influence Factors of Telescopic Boom System Based on Arc-Length and FEM Method." Applied Mechanics and Materials 532 (February 2014): 291–96. http://dx.doi.org/10.4028/www.scientific.net/amm.532.291.
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Telescopic jib is the key load-bearing component for both truck crane and all-terrain crane,seriously affect hoisting capacity of crane. Different stress feature or structural feature produce different affects on the hoisting capacity of telescopic jib. In order to study the mechanism and levels of different factors,multiple telescopic jib models with different factors are built based on nonlinear finite element method. Adopting Arc-length method to analysis structural nonlinear deformation in the whole course,the impact degree for hoisting performance of material yield strength, load eccentricity, lap length of telescopic jib and the support position of lifting hydraulic cylinder are acquired respectively. The results shows: A finite element method combined with arc-length method can be used to analysis the buckling problem of nonlinear deformation of telescopic jib. All the above four factors have affect on the hoisting performance of telescopic jib, but the levels are different. By analyzing change law of impact factors, corresponding measure are adopted in practical deign to reduce its impact and to strengthen the capacity of resisting local buckling of the telescopic jib.
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Papadopoulos, G. A., and G. C. Papanicolaou. "The effect of eccentricity on dynamic crack propagation behaviour of rubber-modified PMMA models." Journal of Materials Science 25, no. 9 (September 1990): 4066–74. http://dx.doi.org/10.1007/bf00582483.
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Duong, C. N., and C. H. Wang. "On the Characterization of Fatigue Crack Growth in a Plate With a Single-Sided Repair." Journal of Engineering Materials and Technology 126, no. 2 (March 18, 2004): 192–98. http://dx.doi.org/10.1115/1.1647129.
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An unsupported cracked plate repaired with a reinforcement bonded on one side may experience considerable out-of-plane bending due to the load-path eccentricity. This out-of-plane bending causes the stress intensity factor at the crack tip to vary significantly through the plate’s thickness with a maximum value attained at the un-patched side of the crack. Even though significant analytical work has been done in the past to evaluate these thickness-varying stress intensity factors, however, to the authors’ knowledge, little work has been done to characterize the fatigue crack growth in a plate with a single-sided repair. The purposes of the present work are to (i) assess the accuracy of the available analytical methods for predicting the stress intensity factors of the panels with a single-sided repair and more importantly, and (ii) characterize the fatigue crack growth in these panels, using test results generated recently under the Composite Repair of Aircraft Structures (CRAS) program.
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Niu, Qian, and Shi-xi Yang. "Study on Fatigue Degradation Behavior of a Cracked Rotor Subjected to Lateral Vibration." Shock and Vibration 2018 (August 29, 2018): 1–21. http://dx.doi.org/10.1155/2018/3239523.
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Fatigue crack in a rotary shaft is a common failure observed in rotor systems. Since vibration of the shaft causes alternating fatigue loads, the crack propagates slowly. Meanwhile, the propagating crack may cause nonlinear or unstable vibration of the rotor system. In fact, growth of the crack and vibration of the shaft are coupled with each other. Hence, it is necessary to study the fatigue degradation behavior of the cracked rotor accounting for this coupling effect. In this paper, a coupling model of rotor vibration and crack growth is established through dynamic theory and fracture mechanics, and a sequential iterative procedure is proposed to solve the coupling model. Then, the competing degradation failure mode of the cracked rotor is analyzed with regard to the rapid crack growth failure and the unstable vibration failure. And degradation measures are proposed based on the competing degradation failure criterion. At last, degradation behaviors with the coupling effect of nonlinear vibration behavior and multiple parameters including rotation speed, unbalance eccentricity and orientation angle, and damping are investigated by numerical simulation. The results indicate that nonlinear vibration behavior and multiple parameters have considerable influence on the degradation behaviors, which present complex regularity. The findings are of significance to guide the safety design of the rotor system for long time operation and help to the further research on prognostics and lifetime prediction.
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Yuen, Terry Y. P., and J. S. Kuang. "Seismic Performance and Lateral Stability of RC Frames with Vertical Irregular Infill Arrangements." International Journal of Structural Stability and Dynamics 17, no. 02 (March 2017): 1750025. http://dx.doi.org/10.1142/s0219455417500250.
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In this paper, the effects of vertical irregularity of masonry-infill wall arrangements on the seismic performance and lateral stability of reinforced concrete (RC) frames have been investigated using nonlinear response history analysis. Discrete finite element models, which are endowed with a damage-based cohesive crack modeling, were developed for six prototype structures with different arrangements of infill panels. The analysis of failure modes and lateral force transfer mechanisms of infilled frames shows that the arrangement of infill panels can critically affect the dynamic properties and structural stability under seismic excitations. Diagonal continuity, infill ratios, and eccentricity of infill walls play essential roles in the lateral-load and displacement capacities of the structures. The hysteresis behavior, failure modes, and force transfer mechanisms of RC frames with concentric and eccentric arrangements of infill panels are compared and their implications on the seismic resistant design are discussed.
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Julien, D., T. Bui-Quoc, M. Bernard, N. R. Saad, and H. Luan Nguyen. "Low-Cycle Fatigue Behavior of a Nickel-Based Alloy Under Combined Bending/Tension Loading." Journal of Pressure Vessel Technology 121, no. 1 (February 1, 1999): 109–15. http://dx.doi.org/10.1115/1.2883657.
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In this paper, the effect of a combined bending/tension loading on the fatigue resistance and on the fatigue crack growth characteristics of a nickel-based alloy at room temperature is studied. For this purpose, a device was specifically designed so that it can be mounted onto a servohydraulic push-pull testing machine. With the device, a simultaneous displacement and rotation of the specimen extremities generate a combined bending/axial stress; the ratio between the bending stress and the axial stress may be specified by adjusting the eccentricity between the specimen axis and the load axis. Stress-controlled fatigue tests were carried out on plate specimens under bending/tension loading with a surface stress ratio of −0.52 (ratio between the maximum cyclic stress on the back face and that on the front face of the specimen). During each test, the fatigue crack length was monitored using two traveling video-cameras. The experimental results obtained under bending/tension loading have been analyzed in connection with the data obtained under pure tension loading. In particular, the fatigue crack propagation rate expressed in terms of the stress intensity factor of a crack under combined loading was examined.
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Tan, Choon-Lai, Anthony P. Parker, and Chantz W. V. Cassell. "Stress Intensity Factors for a Curved-Front Internal Crack in an Autofrettaged Tube With Bauschinger Effect." Journal of Pressure Vessel Technology 126, no. 2 (May 1, 2004): 229–33. http://dx.doi.org/10.1115/1.1689358.
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Pressure vessel steels exhibit the Bauschinger effect that significantly reduces post-autofrettage residual compressive hoop stresses in the near-bore region in comparison with ‘ideal’ (elastic-perfectly plastic) behavior. These reduced hoop stress profiles were calculated using Von Mises’ criterion via a nonlinear analysis for the case of open-end (engineering plane strain) autofrettage. These profiles were then used to obtain stress intensity factor solutions via the Boundary Integral Equation (BIE) method, commonly known as the Boundary Element Method (BEM). Results are presented for tubes of diameter ratio 2 and 2.5 with an internal semi-elliptical surface crack having a maximum depth/surface length ratio of 0.4 (i.e., an eccentricity of 0.8). Crack depths range from 20% to 80% of wall thickness and results are presented for seven locations on the crack front from maximum depth to free surface. For crack depths up to 20% of wall thickness there is a significant reduction in magnitude of autofrettage stress intensity factor due to Bauschinger effect. For typical overstrain levels this reduction is approximately 30% of “ideal” values. Such a reduction may, in turn, cause an order of magnitude reduction in the fatigue lifetime of the vessel.
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Kitey, R., and H. V. Tippur. "Dynamic Crack Growth Past a Stiff Inclusion: Optical Investigation of Inclusion Eccentricity and Inclusion-matrix Adhesion Strength." Experimental Mechanics 48, no. 1 (April 26, 2007): 37–53. http://dx.doi.org/10.1007/s11340-007-9050-z.
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Rout, Mrutyunjay, Tanmoy Bandyopadhyay, and Amit Karmakar. "Free vibration analysis of pretwisted delaminated composite stiffened shallow shells: A finite element approach." Journal of Reinforced Plastics and Composites 36, no. 8 (January 19, 2017): 619–36. http://dx.doi.org/10.1177/0731684416689726.
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This paper presents the effect of stiffeners on the free vibration response of delaminated composite shallow cylindrical shells employing the finite element method. An eight-noded isoparametric shell element based on the first-order shear deformation theory is combined with a three-noded isoparametric curved beam element in the present formulation. The stiffeners follow the nodal lines of the shell wherein the stiffness and mass of the stiffeners are lumped at the corresponding nodal points of the shell elements considering curvature and eccentricity. The generalized dynamic equilibrium equation is derived from Lagrange’s equation of motion, wherein Coriolis effect for moderate rotational speeds is neglected. The multi-point constraint algorithm has been used to model delamination at the desired locations wherein the compatibility of deformation and equilibrium of stress resultants are ensured at the delamination crack front. Numerical results are presented for cantilevered long, intermediate and short cylindrical shells as defined by Aas-Jakobsen’s parameters, and the influence of important parameters like location of delamination, twist angle, rotational speed, number of layers and eccentricity of the stiffeners is studied. The mode shapes for a typical composite un-stiffened and stiffened long cylindrical shell at different rotational speeds and twist angles are also presented.
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Fitriani, Intan, Sukamta Sukamta, and Ilham Nurhuda. "Studi Eksperimental Kekuatan dan Perilaku Sambungan Kolom pada Struktur DfD (Design for Disassembly)." MEDIA KOMUNIKASI TEKNIK SIPIL 21, no. 2 (June 8, 2016): 113. http://dx.doi.org/10.14710/mkts.v21i2.11237.
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DfD building system is a new approach in construction. Using DfD building system can reduce construction waste and reuse building components. This research examines the strength and behaviour of DfD column connections. Two types column connections were studied.The first connection employed H shaped steel elements bolted to the column while the second connection was bolt and plate connection. The behavior of columns with connections was compared to that of without connection. This study was carried out to investigate the strength, crack patterns, and failure mechanisms of precast concrete with dry joint on DfD column structure. All specimens were subject to normal force applied with an eccentricity of 67 mm. The test results indicate that both columns with connections were able to withstand design loads. This study also confirmed that the shear strength calculation of corbel based on SNI 03-2847-2002 section 13.9 was conservative to use as the value was still smaller than that obtained from this experiment.
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Ouinas, Djamel. "Strength of aluminum single-lap bonded joints in various disbond size at circular and semi-circular notches." Journal of Sandwich Structures & Materials 14, no. 6 (September 19, 2012): 753–68. http://dx.doi.org/10.1177/1099636212460039.
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Applications of assembly bonded technique have been extended currently to various industrial fields. Adhesively bonded joints are widely used in the aeronautics and astronautics industry as a result of their high strength and convenience in using the single-lap joint. The geometry of bonded single-lap joint is nonlinear and causes the eccentricity due to the non-collinear applied load, which conducts to a significant stress concentration at the extremities of overlap area, where the cracks may initiate. In this article, the finite element (FE) method is used to analyze the behavior of a bonded lap joint of aluminum adherend. The comparison of stress concentration factor and stress intensity factor of crack emanating from the circular and semi-circular notches are investigated. The single-lap bonded joints were analyzed to study the combined effect of the notch and the disbond as they pertain to joint strength and failure conditions. The results show that the stress concentration factor and stress intensity factor are affected by the negative disbond effect and their values are strongly proportional to its size.
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Jiménez-Rabiela, Homero, Benjamín Vazquéz-González, José Luis Ramírez-Cruz, and Pedro García-Segura. "Mecanismo Diseñado y Simulado Virtualmente." Revista de Simulación y Laboratorio, December 31, 2019, 1–11. http://dx.doi.org/10.35429/jsl.2019.21.6.1.11.
Full textAbstract:
Objectives: To show a process to synthesize and analyze a crank mechanism oscillator function generator. Simulate it in a virtual reality environment, without losing its physical characteristic. Evaluate deviations between analytically desired and virtually obtained. Methodology: Using the analytical method described by Hartenberg and Denavit, a graphic package and an electronic spreadsheet; knowing the angle of rotation of the crank, the angular reference position of the crank, the displacement of the oscillator, the extreme values of the independent variable and the function; precision positions, link lengths, eccentricity and oscillator reference position were determined. The links were generated, the mechanism was assembled, analyzing fifteen of its positions. Of the infinite number of existing solutions, five were synthesized. For each solution that justify it, the deviation of the generated function was evaluated with respect to the desired one. Contribution: The friendly, fast, safe, accurate and parametric process was demonstrated; modifying the inputs and checking the update of the outputs, therefore it is a contribution to the scientific progress of the area.
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Flores, Paulo, Margarida Machado, Eurico Seabra, and Miguel Tavares da Silva. "A Parametric Study on the Baumgarte Stabilization Method for Forward Dynamics of Constrained Multibody Systems." Journal of Computational and Nonlinear Dynamics 6, no. 1 (October 13, 2010). http://dx.doi.org/10.1115/1.4002338.
Full textAbstract:
This paper presents and discusses the results obtained from a parametric study on the Baumgarte stabilization method for forward dynamics of constrained multibody systems. The main purpose of this work is to analyze the influence of the variables that affect the violation of constraints, chiefly the values of the Baumgarte parameters, the integration method, the time step, and the quality of the initial conditions for the positions. In the sequel of this process, the formulation of the rigid multibody systems is reviewed. The generalized Cartesian coordinates are selected as the variables to describe the bodies’ degrees of freedom. The formulation of the equations of motion uses the Newton–Euler approach, augmented with the constraint equations that lead to a set of differential algebraic equations. Furthermore, the main issues related to the stabilization of the violation of constraints based on the Baumgarte approach are revised. Special attention is also given to some techniques that help in the selection process of the values of the Baumgarte parameters, namely, those based on the Taylor’s series and the Laplace transform technique. Finally, a slider-crank mechanism with eccentricity is considered as an example of application in order to illustrate how the violation of constraints can be affected by different factors.
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Zamorano, Marta, María Jesus Gómez Garcia, and Cristina Castejón. "Selection of a mother wavelet as identification pattern for the detection of cracks in shafts." Journal of Vibration and Control, June 14, 2021, 107754632110260. http://dx.doi.org/10.1177/10775463211026033.
Full textAbstract:
Nowadays, there are many methods to detect and diagnose defects in mechanical components during operation. The newest methods that can be found in the literature are based on intelligent classification systems and evaluation of patterns to obtain a diagnosis; however, there is not any standard method to assess features. Wavelet packet transform allows to obtain interesting patterns for evaluating the condition of rotating elements. To perform this calculation, it is necessary to select a series of parameters that affect the resulting pattern. These parameters are the decomposition level and the mother wavelet function. A detailed methodology for the selection of the mother wavelet is proposed, which is the aim of this work, to obtain the most suitable patterns in the diagnostic task. This proposed methodology is applied to data obtained from a rotating shaft with a crack located at the change of section. These signals were measured at low rotation frequency (below the critical rotation frequency) and without eccentricity, where detection becomes more complex.
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EL-Bagory, Tarek M. A. A., and Maher Y. A. Younan. "Crack Growth Behavior of Pipes Made From Polyvinyl Chloride Pipe Material1." Journal of Pressure Vessel Technology 139, no. 1 (August 5, 2016). http://dx.doi.org/10.1115/1.4033124.
Full textAbstract:
The behavior of crack growth of polymeric materials is affected by several operating conditions such as crosshead speed, specimen thickness, load line, and specimen configurations, which reverse the behavior of crack from stable to unstable crack growth behavior. The main objective of the present paper is the determination of plane strain fracture toughness (KIC) for polyvinyl chloride (PVC) used in piping water transmission systems. The dimensions of the PVC pipe are outside diameter, Do = 315 mm, standard dimensions ratio, SDR = 13.23, ratio between outside to inside radii Ro/Ri = 1.179, and pipe thickness, t = 24 mm. Curved specimens are prepared from a pipe by cutting 12 mm thickness ring segments. The curved specimens are divided into two specimen configurations, namely, curved three-point bend (CTPB) and C-shaped tension (CST) specimens. All specimens are provided artificially with a precrack. CTPB specimen is further cut into five 72 deg sectors with each being centrally notched to a depth approximately a = 0.479 of the wall thickness. CST specimen configuration is characterized by the eccentricity X = 0, and 0.5 W, of the loading holes from the bore surface. The linear elastic fracture mechanics theory (LEFM) is used to predict the plane strain fracture. The tests are carried out at room temperature, Ta equal 20 °C, and different crosshead speeds of (10–500 mm/min). The numerical analysis carried out within the frame of the present work is done using the finite element program Cosmos 2.6. Finite element method (FEM) is used to compute the stress intensity factor KQ surrounding the crack tip. The computed stress intensity factor can then be compared with that obtained by theoretical equation. The experimental fracture test results reveal that the crosshead speed has been proven to affect the mode of failure and mode of fracture. At lower crosshead speeds, the mode of failure is ductile, while at higher crosshead speeds, it is brittle. The specimen configuration also affects the fracture toughness. CST specimens show higher fracture toughness in the case of pin loading location X = 0.5W than X = 0 by about (12%). The transitional crosshead speed is affected by specimen geometry. CST specimens (CST) at X = 0 and 0.5W have higher transitional crosshead speed compared with the CTPB specimen configuration.