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Journal articles on the topic "Nonlinear impact loads":
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Masoum, M. A. S., E. F. Fuchs, and D. J. Roesler. "Impact of nonlinear loads on anisotropic transformers." IEEE Transactions on Power Delivery 6, no. 4 (1991): 1781–88. http://dx.doi.org/10.1109/61.97721.
Schellin, Thomas E., and Ould el Moctar. "Numerical Prediction of Impact-Related Wave Loads on Ships." Journal of Offshore Mechanics and Arctic Engineering 129, no. 1 (November 8, 2006): 39–47. http://dx.doi.org/10.1115/1.2429695.
We present a numerical procedure to predict impact-related wave-induced (slamming) loads on ships. The procedure was applied to predict slamming loads on two ships that feature a flared bow with a pronounced bulb, hull shapes typical of modern offshore supply vessels. The procedure used a chain of seakeeping codes. First, a linear Green function panel code computed ship responses in unit amplitude regular waves. Ship speed, wave frequency, and wave heading were systematically varied to cover all possible combinations likely to cause slamming. Regular design waves were selected on the basis of maximum magnitudes of relative normal velocity between ship critical areas and wave, averaged over the critical areas. Second, a nonlinear strip theory seakeeping code determined ship motions under design wave conditions, thereby accounting for the nonlinear pressure distribution up to the wave contour and the frequency dependence of the radiation forces (memory effect). Third, these nonlinearly computed ship motions constituted part of the input for a Reynolds-averaged Navier–Stokes equations code that was used to obtain slamming loads. Favorable comparison with available model test data validated the procedure and demonstrated its capability to predict slamming loads suitable for design of ship structures.
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Ghorbani, M. Jawad, and Hossein Mokhtari. "Impact of Harmonics on Power Quality and Losses in Power Distribution Systems." International Journal of Electrical and Computer Engineering (IJECE) 5, no. 1 (February 1, 2015): 166. http://dx.doi.org/10.11591/ijece.v5i1.pp166-174.
This paper investigates the harmonic distortion and losses in power distribution systems due to the dramatic increase of nonlinear loads. This paper tries to determine the amount of the harmonics generated by nonlinear loads in residential, commercial and office loads in distribution feeders and estimates the energy losses due to these harmonics. Norton equivalent modeling technique has been used to model the nonlinear loads. The presented harmonic Norton equivalent models of the end user appliances are accurately obtained based on the experimental data taken from the laboratory measurements. A 20 kV/400V distribution feeder is simulated to analyze the impact of nonlinear loads on feeder harmonic distortion level and losses. The model follows a “bottom-up” approach, starting from end users appliances Norton equivalent model and then modeling residential, commercial and office loads. Two new indices are introduced by the authors to quantize the effect of each nonlinear appliance on the power quality of a distribution feeder and loads are ranked based on these new defined indices. The simulation results show that harmonic distortion in distribution systems can increase power losses up to 20%.
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Arsava, K. Sarp, and Yeesock Kim. "Modeling of Magnetorheological Dampers under Various Impact Loads." Shock and Vibration 2015 (2015): 1–20. http://dx.doi.org/10.1155/2015/905186.
Magnetorheological (MR) damper has received great attention from structural control engineering because it provides the best features of both passive and active control systems. However, many studies on the application of MR dampers to large civil structures have tended to center on the modeling of MR dampers under seismic excitations, while, to date, there has been minimal research regarding the MR damper model under impact loads. Hence, this paper investigates nonlinear models of MR dampers under a variety of impact loads and control signals. Two fuzzy models are proposed for modeling the nonlinear impact behavior of MR dampers. They are compared with mechanical models, the Bingham and Bouc-Wen models. Experimental studies are performed to generate sets of input and output data for training, validating, and testing the models: the deflection, acceleration, velocity, and current signals. It is demonstrated that the proposed fuzzy models are effective in predicting the complex nonlinear behavior of the MR damper subjected to a variety of impact loads and control signals. The proposed fuzzy model resulted in an accuracy of 99% to predict the impact forces of the MR damper.
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Lin, Jie, Chao Deng, and Jia Chu Xu. "Nonlinear Dynamic Buckling of FGM Shallow Conical Shells under Triangular Pulse Impact Loads." Advanced Materials Research 460 (February 2012): 119–26. http://dx.doi.org/10.4028/www.scientific.net/amr.460.119.
In this paper, nonlinear dynamic buckling of FGM shallow conical shells under the action of triangular pulse impact loads are investigated. The nonlinear dynamic governing equation of symmetrically FGM shallow conical shells is built. Using Galerkin method, the nonlinear dynamic governing equation is solved, and the nonlinear dynamic response equation of symmetrically FGM shallow conical shells is obtained. The Runge-Kutta method is introduced to numerically solve the nonlinear dynamic response equation and the impact response curve is achieved. Budiansky-Roth motion criterion expressed by the displacement of the peak of the shell is employed to determine the critical impact buckling load. The influences of geometric parameters and gradient constants on impact buckling are discussed as well.
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Du, Chang Long, Yu Liu, and Jian Ping Li. "Numerical Analysis on Impact Load of Elasto-Plastic Spherical Impact." Advanced Materials Research 189-193 (February 2011): 1840–43. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1840.
The spherical impact is a common phenomenon in mechanical engineering. The elasto-plastic impact is more complicate than the elastic impact. The elasto-plastic impact loads are investigated for the different contact stiffness and the different impact velocity by the nonlinear finite element method. The accuracy and reliability of the finite elements model are verified by comparing the numerical results of the elastic impact with the Hertz results. The elasto-plastic impact simulation shows that the impact loads have a negative exponential relation with the contact stiffness as well as a linear relation with the impact velocity. The contact time decrease with the increase of the contact stiffness and the impact velocity. The comparison between the influence of the contact stiffness and the impact velocity indicates that the impact velocity has a significant influence on the impact load and the contact stiffness has a big influence on the contact time.
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Manito, Allan, Ubiratan Bezerra, Maria Tostes, Edson Matos, Carminda Carvalho, and Thiago Soares. "Evaluating Harmonic Distortions on Grid Voltages Due to Multiple Nonlinear Loads Using Artificial Neural Networks." Energies 11, no. 12 (November 26, 2018): 3303. http://dx.doi.org/10.3390/en11123303.
This paper presents a procedure to estimate the impacts on voltage harmonic distortion at a point of interest due to multiple nonlinear loads in the electrical network. Despite artificial neural networks (ANN) being a widely used technique for the solution of a large amount and variety of issues in electric power systems, including harmonics modeling, its utilization to establish relationships among the harmonic voltage at a point of interest in the electric grid and the corresponding harmonic currents generated by nonlinear loads was not found in the literature, thus this innovative procedure is considered in this article. A simultaneous measurement campaign must be carried out in all nonlinear loads and at the point of interest for data acquisition to train and test the ANN model. A sensitivity analysis is proposed to establish the percent contribution of load currents on the observed voltage distortion, which constitutes an original definition presented in this paper. Initially, alternative transient program (ATP) simulations are used to calculate harmonic voltages at points of interest in an industrial test system due to nonlinear loads whose harmonic currents are known. The resulting impacts on voltage harmonic distortions obtained by the ATP simulations are taken as reference values to compare with those obtained by using the proposed procedure based on ANN. By comparing ATP results with those obtained by the ANN model, it is observed that the proposed methodology is able to classify correctly the impact degree of nonlinear load currents on voltage harmonic distortions at points of interest, as proposed in this paper.
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Sarp Arsava, Kemal, Yeesock Kim, Tahar El-Korchi, and Hyo Seon Park. "Nonlinear system identification of smart structures under high impact loads." Smart Materials and Structures 22, no. 5 (April 3, 2013): 055008. http://dx.doi.org/10.1088/0964-1726/22/5/055008.
Finn, Patrick J., Robert F. Beck, Armin W. Troesch, and Yung Sup Shin. "Nonlinear Impact Loading in an Oblique Seaway." Journal of Offshore Mechanics and Arctic Engineering 125, no. 3 (July 11, 2003): 190–97. http://dx.doi.org/10.1115/1.1578499.
There is an increasing interest in developing direct calculation methods and procedures for determining extreme wave loads on ship girders (e.g. ISSC, 2000 [1]). Ships experiencing bottom and bow flare slamming have heightened the need for computational tools suitable to accurately predict motion and structural responses. The associated nonlinear impact problem is complicated by the complex free surface and body boundary conditions. This paper examines a “blended” linear–nonlinear method by which extreme loads due to bottom impact and flare slamming can be determined. Using a high-speed container ship as an example, comparisons of motions, shear and bending moments, and pressures are made in head and oblique bow-quartering waves. The time-domain computer program used in the comparison is based upon partially nonlinear models. The program, NSHIPMO, is an blended strip theory method using “impact” stations over the forward part of the ship and partially nonlinear stations over the rest. Body exact hydrostatics and Froude-Krylov excitation are used over the entire hull. The impact theory of Troesch and Kang [2] is employed to estimate the sectional nonlinear impact forces acting upon the specified nonlinear sections, while the linear theory of Salvesen et al. (STF) [3] is used to blend the remainder of the hydrodynamic forces, that is the radiation and diffraction components. Results from the simulation are presented with discussions of accuracy and time of computation. Several issues associated with the blended nonlinear time-domain simulation are presented, including modeling issues related to directional yaw-sway control and a vertical plane dynamic instability in long waves that has not previously been recognized.
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Piatkowski, Tomasz, Janusz Sempruch, and Tomasz Tomaszewski. "DYNAMICS OF A SORTING PROCESS WITH A STREAM OF DISCRETE IMPACT LOADS." Transactions of the Canadian Society for Mechanical Engineering 38, no. 1 (March 2014): 139–54. http://dx.doi.org/10.1139/tcsme-2014-0009.
The sorting process applied to a stream of unit loads (cubiform objects, parcels) transported on conveyors is investigated. The sorting process is performed by means of an active fence (flexible arm) that makes a 1dof rotary motion. The manipulated loads are treated as bodies with nonlinear elastic-damping properties described by modified nonlinear Kelvin model. The equations of motion of the flexible fence, and those of the interacting object, are derived using the finite element method. The assessment of influence of constructional and operating parameters of the fence on the course of the sorting process and dynamic forces exerted on the loads handled is studied.
Dissertations / Theses on the topic "Nonlinear impact loads":
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Arsava, Kemal Sarp. "Modeling, Control and Monitoring of Smart Structures under High Impact Loads." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/105.
In recent years, response analysis of complex structures under impact loads has attracted a great deal of attention. For example, a collision or an accident that produces impact loads that exceed the design load can cause severe damage on the structural components. Although the AASHTO specification is used for impact-resistant bridge design, it has many limitations. The AASHTO specification does not incorporate complex and uncertain factors. Thus, a well-designed structure that can survive a collision under specific conditions in one region may be severely damaged if it were impacted by a different vessel, or if it were located elsewhere with different in-situ conditions. With these limitations in mind, we propose different solutions that use smart control technology to mitigate impact hazard on structures. However, it is challenging to develop an accurate mathematical model of the integrated structure-smart control systems. The reason is due to the complicated nonlinear behavior of the integrated nonlinear systems and uncertainties of high impact forces. In this context, novel algorithms are developed for identification, control and monitoring of nonlinear responses of smart structures under high impact forces. To evaluate the proposed approaches, a smart aluminum and two smart reinforced concrete beam structures were designed, manufactured, and tested in the High Impact Engineering Laboratory of Civil and Environmental Engineering at WPI. High-speed impact force and structural responses such as strain, deflection and acceleration were measured in the experimental tests. It has been demonstrated from the analytical and experimental study that: 1) the proposed system identification model predicts nonlinear behavior of smart structures under a variety of high impact forces, 2) the developed structural health monitoring algorithm is effective in identifying damage in time-varying nonlinear dynamic systems under ambient excitations, and 3) the proposed controller is effective in mitigating high impact responses of the smart structures.
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Abdolmaleki, Kourosh. "Modelling of wave impact on offshore structures." University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0055.
[Truncated abstract] The hydrodynamics of wave impact on offshore structures is not well understood. Wave impacts often involve large deformations of water free-surface. Therefore, a wave impact problem is usually combined with a free-surface problem. The complexity is expanded when the body exposed to a wave impact is allowed to move. The nonlinear interactions between a moving body and fluid is a complicated process that has been a dilemma in the engineering design of offshore and coastal structures for a long time. This thesis used experimental and numerical means to develop further understanding of the wave impact problems as well as to create a numerical tool suitable for simulation of such problems. The study included the consideration of moving boundaries in order to include the coupled interactions of the body and fluid. The thesis is organized into two experimental and numerical parts. There is a lack of benchmarking experimental data for studying fluid-structure interactions with moving boundaries. In the experimental part of this research, novel experiments were, therefore, designed and performed that were useful for validation of the numerical developments. By considering a dynamical system with only one degree of freedom, the complexity of the experiments performed was minimal. The setup included a plate that was attached to the bottom of a flume via a hinge and tethered by two springs from the top one at each side. The experiments modelled fluid-structure interactions in three subsets. The first subset studied a highly nonlinear decay test, which resembled a harsh wave impact (or slam) incident. The second subset included waves overtopping on the vertically restrained plate. In the third subset, the plate was free to oscillate and was excited by the same waves. The wave overtopping the plate resembled the physics of the green water on fixed and moving structures. An analytical solution based on linear potential theory was provided for comparison with experimental results. ... In simulation of the nonlinear decay test, the SPH results captured the frequency variation in plate oscillations, which indicated that the radiation forces (added mass and damping forces) were calculated satisfactorily. In simulation of the nonlinear waves, the waves progressed in the flume similar to the physical experiments and the total energy of the system was conserved with an error of 0.025% of the total initial energy. The wave-plate interactions were successfully modelled by SPH. The simulations included wave run-up and shipping of water for fixed and oscillating plate cases. The effects of the plate oscillations on the flow regime are also discussed in detail. The combination of experimental and numerical investigation provided further understanding of wave impact problems. The novel design of the experiments extended the study to moving boundaries in small scale. The use of SPH eliminated the difficulties of dealing with free-surface problems so that the focus of study could be placed on the impact forces on fixed and moving bodies.
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Barakati, Amir. "Dynamic interactions of electromagnetic and mechanical fields in electrically conductive anisotropic composites." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3562.
Recent advances in manufacturing of multifunctional materials have provided opportunities to develop structures that possess superior mechanical properties with other concurrent capabilities such as sensing, self-healing, electromagnetic and heat functionality. The idea is to fabricate components that can integrate multiple capabilities in order to develop lighter and more efficient structures. In this regard, due to their combined structural and electrical functionalities, electrically conductive carbon fiber reinforced polymer (CFRP) matrix composites have been used in a wide variety of applications in most of which they are exposed to unwanted impact-like mechanical loads. Experimental data have suggested that the application of an electromagnetic field at the moment of the impact can significantly reduce the damage in CFRP composites. However, the observations still need to be investigated carefully for practical applications. Furthermore, as the nature of the interactions between the electro-magneto-thermo-mechanical fields is very complicated, no analytical solutions can be found in the literature for the problem.
In the present thesis, the effects of coupling between the electromagnetic and mechanical fields in electrically conductive anisotropic composite plates are studied. In particular, carbon fiber polymer matrix (CFRP) composites subjected to an impact-like mechanical load, pulsed electric current, and immersed in the magnetic field of constant magnitude are considered. The analysis is based on simultaneous solving of the system of nonlinear partial differential equations, including equations of motion and Maxwell's equations. Physics-based hypotheses for electro-magneto-mechanical coupling in transversely isotropic composite plates and dimension reduction solution procedures for the nonlinear system of the governing equations have been used to reduce the three-dimensional system to a two-dimensional (2D) form. A numerical solution procedure for the resulting 2D nonlinear mixed system of hyperbolic and parabolic partial differential equations has been developed, which consists of a sequential application of time and spatial integrations and quasilinearization. Extensive computational analysis of the response of the CFRP composite plates subjected to concurrent applications of different electromagnetic and mechanical loads has been conducted. The results of this work verify the results of the previous experimental studies on the subject and yield some suggestions for the characteristics of the electromagnetic load to create an optimum impact response of the composite.
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ElMohandes, Fady. "Advanced Three-dimensional Nonlinear Analysis of Reinforced Concrete Structures Subjected to Fire and Extreme Loads." Thesis, 2013. http://hdl.handle.net/1807/43945.
With the rise in hazards that structures are potentially subjected to these days, ranging from pre-contemplated terror attacks to accidental and natural disasters, safeguarding structures against such hazards has increasingly become a common design requirement. The extreme loading conditions associated with these hazards renders the concept of imposing generalized codes and standards guidelines for structural design unfeasible. Therefore, a general shift towards performance-based design is starting to dominate the structural design field.
This study introduces a powerful structural analysis tool for reinforced concrete structures, possessing a high level of reliability in handling a wide range of typical and extreme loading conditions in a sophisticated structural framework. VecTor3, a finite element computer program previously developed at the University of Toronto for nonlinear analysis of three-dimensional reinforced concrete structures employing the well-established Modified Compression Field Theory (MCFT), has been further developed to serve as the desired tool.
VecTor3 is extended to include analysis capabilities for extreme loading conditions, advanced reinforced concrete mechanisms, and new material types. For extreme loading conditions, an advanced coupled heat and moisture transfer algorithm is implemented in VecTor3 for the analysis of reinforced concrete structures subjected to fire. This algorithm not only calculates the transient temperature through the depth of concrete members, but also calculates the elevated pore pressure in concrete, which enables the prediction of the occurrence of localized thermally-induced spalling. Dynamic loading conditions are also extended to include seismic loading, in addition to blast and impact loading.
Advancing the mechanisms considered, VecTor3 is developed to include the Disturbed Stress Field Model (DSFM), dowel action and buckling of steel reinforcement bars, geometric nonlinearity effects, strain rate effects for dynamic loading conditions, and the deterioration of mechanical properties at elevated temperatures for fire loading conditions. Finally, the newly-developed Simplified Diverse Embedment Model (SDEM) is implemented in VecTor3 to add analysis capability for steel fibre-reinforced concrete (SFRC).
Various analyses covering a wide range of different structural members and loading conditions are carried out using VecTor3, showing good agreement with experimental results available in the literature. These analyses verify the reliability of the models, mechanisms, and algorithms incorporated in VecTor3.
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Rylander, Matthew Robert 1981. "Single-phase nonlinear power electronic loads: modeling and impact on power system transient response and stability." Thesis, 2008. http://hdl.handle.net/2152/3939.
This dissertation examines single-phase nonlinear power electronic loads. The transient response of power electronic loads is unlike traditional linear loads. Therefore, a composite power electronic transient load model is developed. The load model dynamics are validated with actual utility voltage sag response data, laboratory controlled load response testing, and power electronic load dynamic simulations. The power electronic load model is applied in the University of Texas at Austin power system. The system transient response is unique and considerably different from what it would be with traditional linear loads. The power electronic load can be friendly or unfriendly to the system depending on the fault and system configuration. text
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Hrynyk, Trevor. "Behaviour and Modelling of Reinforced Concrete Slabs and Shells Under Static and Dynamic Loads." Thesis, 2013. http://hdl.handle.net/1807/35851.
A procedure for improved nonlinear analysis of reinforced concrete (RC) slab and shell structures is presented. The finite element program developed employs a layered thick-shell formulation which considers out-of-plane (through-thickness) shear forces, a feature which makes it notably different from most shell analysis programs. Previous versions were of limited use due to their inabilities to accurately capture out-of-plane shear failures, and because analyses were restricted to force-controlled monotonic loading conditions. The research comprising this thesis focuses on addressing these limitations, and implementing new analysis features extending the range of structures and loading conditions that can be considered.
Contributions toward the redevelopment of the program include: i) a new solution algorithm for out-of-plane shear, ii) modelling of cracked RC in accordance with the Disturbed Stress Field Model, iii) the addition of fibre-reinforced concrete (FRC) modelling capabilities, and iv) the addition of cyclic and dynamic analysis capabilities. The accuracy of the program was verified using test specimens presented in the literature spanning various member types and loading conditions. The new program features are shown to enhance modelling capabilities and provide accurate assessments of shear-critical structures.
An experimental program consisting of RC and FRC slab specimens under dynamic loading conditions was performed. Eight intermediate-scale slabs were constructed and tested to failure under sequential high-mass low-velocity impact. The data from the testing program were used to verify the dynamic and FRC modelling procedures developed, and to contribute to a research area which is currently limited in the database of literature: the global response of RC and FRC elements under impact. Test results showed that the FRC was effective in increasing capacity, reducing crack widths and spacings, and mitigating local damage under impact.
Analyses of the slabs showed that high accuracy estimates can be obtained for RC and FRC elements under impact using basic modelling techniques and simple finite element meshes.
Books on the topic "Nonlinear impact loads":
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Hayden, Griffin O., Johnson Eric R, and United States. National Aeronautics and Space Administration., eds. Static and dynamic large deflection flexural response of graphite-epoxy beams. Blacksburg, Va: Virginia Tech Center for Composite Materials and Structures, Virginia Polytechnic Institute and State University, 1987.
Hayden, Griffin O., Johnson Eric R, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., eds. Static and dynamic large deflection flexural response of graphite-epoxy beams. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.
Book chapters on the topic "Nonlinear impact loads":
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Zhang, Jinghua, Shuai Chen, and Like Chen. "Dynamic Buckling of FGM Cylindrical Shells Under Torsional Impact Loads." In New Trends in Nonlinear Dynamics, 109–17. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34724-6_12.
Ibrahimbegovic, Adnan, and Naida Ademovicć. "The dynamics of extreme impact loads in an airplane crash." In Nonlinear Dynamics of Structures Under Extreme Transient Loads, 145–64. First edition. | Boca Raton, FL : CRC Press/Taylor & Francis Group, [2019]: CRC Press, 2019. http://dx.doi.org/10.1201/9781351052504-6.
Liu, Yu, Andrew J. Dick, Jacob Dodson, and Jason Foley. "Nonlinear High Fidelity Modeling of Impact Load Response in a Rod." In Topics in Modal Analysis II, Volume 8, 129–34. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04774-4_12.
Gorripotu, Tulasichandra Sekhar, Ahmad Taher Azar, Ramana Pilla, and Nashwa Ahmad Kamal. "Impact of Ultra Capacitor on Automatic Load Frequency Control of Nonlinear Power System." In Lecture Notes in Electrical Engineering, 333–41. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-8439-8_27.
Awrejcewicz, Jan, and Vadim Anatolevich Krysko. "Nonlinear Vibrations of the Euler-Bernoulli Beam Subjected to Transversal Load and Impact Actions." In Understanding Complex Systems, 357–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-77676-5_16.
Guo, Baoquan, Shilin Xie, and Xinong Zhang. "The Nonlinear Vibration of Axially Moving Beam Impacted by High-Speed Moving Load." In Computational Mechanics, 402. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75999-7_202.
Zhou, Shibo, and Wenjun Zhang. "Nonlinear Finite-Element Analysis of Offshore Platform Impact Load Based on Two-Stage PLS-RBF Neural Network." In Communications in Computer and Information Science, 508–17. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2826-8_44.
Khan, Shoaib. "Impact of Nonlinear Loads on Power System and Equipment." In Industrial Power Systems, 429–46. CRC Press, 2018. http://dx.doi.org/10.1201/9781420015393-16.
"Impact of Nonlinear Loads on Power System and Equipment." In Industrial Power Systems, 429–46. CRC Press, 2007. http://dx.doi.org/10.1201/9781420015393.ch16.
Oyguc, Evrim, Abdul Hayır, and Resat Oyguc. "Structural Modeling and Dynamic Analysis of a Nuclear Reactor Building." In Structural Integrity and Failure [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94956.
Increasing energy demand urge the developing countries to consider different types of energy sources. Owing the fact that the energy production capacity of renewable energy sources is lower than a nuclear power plant, developed countries like US, France, Japan, Russia and China lead to construct nuclear power plants. These countries compensate 80% of their energy need from nuclear power plants. Further, they periodically conduct tests in order to assess the safety of the existing nuclear power plants by applying impact type loads to the structures. In this study, a sample third-generation nuclear reactor building has been selected to assess its seismic behavior and to observe the crack propagations of the prestressed outer containment. First, a 3D model has been set up using ABAQUS finite element program. Afterwards, modal analysis is conducted to determine the mode shapes. Nonlinear dynamic time history analyses are then followed using an artificial strong ground motion which is compatible with the mean design spectrum of the previously selected ground motions that are scaled to Eurocode 8 Soil type B design spectrum. Results of the conducted nonlinear dynamic analyses are considered in terms of stress distributions and crack propagations.
Conference papers on the topic "Nonlinear impact loads":
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Peng, Zhong, Tim Raaijmakers, and Peter Wellens. "Nonlinear Wave Group Impact on a Cylindrical Monopile." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10838.
The ComFLOW wave model has been employed to study the impact of nonlinear wave groups on cylindrical monopiles. Four nonlinear wave groups are selected from fully nonlinear waves generated by a 2D ComFLOW model, representing wave groups with the largest or the second largest crest heights, the largest wave height and a wave group consisting of consecutive large waves. These four wave groups are used to investigate the wave loads on the foundation and the platform in a 3D ComFLOW model. Model results show that the maximum wave loads on the foundation and the platform by nonlinear wave groups are determined by their individual wave crest height. This study presents a relationship between platform level and wave impact on the platform, as the vertical force on the platform is the combination of buoyancy force (if inundated) and wave impact force due to wave run-up. Results also show that wave loads on the foundation and wave impact on the platform decrease as the wave period increases from 13s to 16s (typical wave period at German Bight). A wave group can cause a larger wave load on the foundation and the platform than regular waves, considering a regular wave height equal to the maximum wave height, regardless of the associated wave period (period of individual wave or peak period).
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Abdel-Mooty, M., and S. Shaaban. "Nonlinear dynamic response of RC building façade panels to impact loads." In SUSI 2012. Southampton, UK: WIT Press, 2012. http://dx.doi.org/10.2495/su120251.
Schellin, Thomas E., and Ould El Moctar. "Numerical Prediction of Impact-Related Wave Loads on Ships." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92133.
We present a numerical procedure to predict impact-related wave-induced (slamming) loads on ships. The procedure was applied to predict slamming loads on two ships that feature a flared bow with a pronounced bulb, hull shapes typical of modern offshore supply vessels. The procedure used a chain of seakeeping codes. First, a linear Green function panel code computed ship responses in unit amplitude regular waves. Wave frequency and wave heading were systematically varied to cover all possible combinations likely to cause slamming. Regular design waves were selected on the basis of maximum magnitudes of relative normal velocity between ship critical areas and wave, averaged over the critical areas. Second, a nonlinear strip theory seakeeping code determined ship motions under design wave conditions, thereby accounting for the ship’s forward speed, the swell-up of water in finite amplitude waves, as well as the ship’s wake that influences the wave elevation around the ship. Third, these nonlinearly computed ship motions constituted part of the input for a Reynolds-averaged Navier-Stokes equations (RANSE) code that was used to obtain slamming loads. Favourable comparison with available model test data validated the procedure and demonstrated its capability to predict slamming loads suitable for design of ship structures.
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Maheswaran, D., A. Kalyanasundaram, and S. Kameshwaran. "Power quality issues in a distribution network impact of neutral current due to nonlinear loads." In 2006 India International Conference on Power Electronics (IICPE 2006). IEEE, 2006. http://dx.doi.org/10.1109/iicpe.2006.4685358.
da Silveira, Lucas C., Daniel P. Bernardon, and Caroline Raduns. "Elaboration of an impact study on the medium voltage electrical system caused by nonlinear loads." In 2018 Simposio Brasileiro de Sistemas Eletricos (SBSE) [VII Brazilian Electrical Systems Symposium (SBSE)]. IEEE, 2018. http://dx.doi.org/10.1109/sbse.2018.8395617.
Liu, Zhenhui, Ragnar Igland, Sindre Bruaseth, and Luca Ercoli-Malacari. "Dynamic Analysis of a Subsea Spool Under Dropped Container Impact Loads." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18578.
Abstract A rigid subsea spool is used to connect the riser of a jacket platform to oil export pipeline in Johan Sverdrup oil field. The location is within the lifting zones of the platform. Consequently, the dropped object hazard has potential high risk and needs to be checked. This paper presents a numerical model on accessing the structural dynamics of subsea spool under the dropped container impact loads by using de-coupled local and global model. The impact impulse was obtained from local impact analysis by Abaqus Explicit solver, in which deformations from container and pipeline are both captured. The global model was built by using inhouse program utilizing ANSYS APDL macros. A simple input file is only needed for end users. The nonlinear pipe and soil interaction is included in a simplified manner. The model comprises of static and dynamic analysis parts. The static analysis captures the in-place configuration and the functional loads. The dynamic analysis is a restart with inherited stress state from static analysis. The impact impulse was applied by point loads in a certain time range. The nonlinear soil stiffness was approached by spring elements (compression only). The dynamic analysis was done in a longer time, ensuring to capture any dynamic effects. The interface loads at the riser stick-out and riser anchor are both extracted and discussed. Concluding remarks have been made accordingly.
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Birknes-Berg, Jørn, and Thomas Berge Johannessen. "Methods for Establishing Governing Deck Impact Loads in Irregular Waves." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-42236.
As offshore reservoirs are depleted, the seabed may subside. Bottom fixed installations which previously have had sufficient clearance between the deck and the surface may be in a situation where wave impact with the deck must be considered at relevant probability levels. The accurate calculation of deck impact loads with a prescribed probability of occurrence taking into account the relevant properties of the incident waves, presents a considerable challenge. The ShorTCrest JIP has addressed both the distribution of the crest height in extreme sea states, the properties of the largest crests and the deck impact loading on a closed deck. It has been concluded that the largest waves in the sea may be in the process of breaking and thus have properties which deviate significantly from estimates found from weakly nonlinear irregular or regular wave theory /5/. The present paper investigates a simple method to calculate deck impact loads in irregular waves which take into account the irregularity of the sea state and the possibility of wave breaking. The method is a two-step approach. Firstly, a long duration simulation of surface elevation is carried out using second-order theory in order to identify possible deck impact events. The individual wave events which are capable of impacting the deck is then reproduced using a CFD method and the distribution of the deck impact loads is established. The calculations are compared with model test results for wave impact with a large volume deck box in a single steep sea state and with CFD calculations of deck impact with regular waves.
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Mansour, Alaa M., Edward W. Huang, and John W. Chianis. "Submergence and Wave Impact Loads During Dry Transportation of an Offshore Structure." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51517.
In this paper, the submergence and wave impact loads acting on an offshore structure when transported on a heavy lift vessel has been experimentally studied. The nonlinear global system response under the effect of direct wave loads on the cargo has been investigated. An approach is developed to derive the global direct wave loads time history acting on the cargo in three-dimensions and correlate them to the submergence event. Numerical results are presented to illustrate this approach. Seafastening loads time history are also presented and correlated to the submergence event. Cargo Stability requirements against uplift and overturning on the vessel have been examined and reported.
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Mortazavi, Maryam, and YeongAe Heo. "Dynamic Constitutive Model Application and Validation for Offshore Structures Under Dropped Object Impact Loads." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78048.
It is critical to incorporate an appropriate constitutive model into a finite element analysis model to evaluate the nonlinear and dynamic effects on offshore structures subjected to dropped object impact loads. This paper demonstrates the high sensitivity of a dynamic constitutive model to mechanical properties of a specific offshore structural steel and its effect on nonlinear transient finite element analysis results for a steel plate system subjected to dropped object impact loads. Available stress-strain data obtained from dynamic tensile tests are used to validate the numerical results. The dynamic constitutive model recommended by Det Norske Veritas (DNV) was examined at both constitutive level and structural level. This paper proposes constitutive model parameters to improve the DNV’s recommendation.
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Shah, S. J., and B. Brenneman. "Fuel Assembly Nonlinear Dynamic Model." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22269.
Fuel assembly finite-element dynamic models are developed to perform the core seismic analysis. The fuel assembly is modeld by a single vertical beam, which represents the cross-sectional inertias of the fuel rods, guide thimbles and instrument thimble, and a series of rotational springs. The rotational springs are located at the intermediate spacer grid locations. Benchmarking to fuel assembly natural frequencies determined by testing is accomplished by adjusting the moment of inertia and the grid rotational stiffness to find their effective values. Most often these models are linear and are appropriate for the small amplitude stiffness representation of the fuel assembly. Large deflection problems are approximated by choosing a fuel assebly stiffness value appropriate to the average deflection range. Some loss of accuracy will naturally result from this approach. This paper presents a nonlinear model to approximate the hysterisis and free vibration response for large amplitudes fuel assembly motion. The force required to impose the initial displacement (pluck) and the free vibration responses are used to compare the nonlinear model’s behavior with the test data. This model correctly predicts fuel assembly deflection shapes as a function of axial position for various lateral loads for several fuel assembly designs. Displacement hysterisis is primarily due to fuel assembly to grid slippage, which is a strong function of grid preload. “Tight” and “relaxed” prototypes were tested to account for grid preload effect. The model correctly analyzes the grid preload effect. A nonlinear fuel assembly model provides better matching of grid impact loads determined by fuel assembly lateral impact testing and also prvides better matching of all of the initial conditions (initial deflection, initial force, initial energy and impact velocity). In this test, the fuel assembly impacts a test wall to determine grid internal stiffness. This value is used in the core model for seismic analyses.
