Academic literature on the topic 'Nonlinear wave loading'
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Journal articles on the topic "Nonlinear wave loading"
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Mockutė, Agota, Enzo Marino, Claudio Lugni, and Claudio Borri. "Comparison of Nonlinear Wave-Loading Models on Rigid Cylinders in Regular Waves." Energies 12, no. 21 (October 23, 2019): 4022. http://dx.doi.org/10.3390/en12214022.
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Monopiles able to support very large offshore wind turbines are slender structures susceptible to nonlinear resonant phenomena. With the aim to better understand and model the wave-loading on these structures in very steep waves where ringing occurs and the numerical wave-loading models tend to lose validity, this study investigates the distinct influences of nonlinearities in the wave kinematics and in the hydrodynamic loading models. Six wave kinematics from linear to fully nonlinear are modelled in combination with four hydrodynamic loading models from three theories, assessing the effects of both types of nonlinearities and the wave conditions where each type has stronger influence. The main findings include that the nonlinearities in the wave kinematics have stronger influence in the intermediate water depth, while the choice of the hydrodynamic loading model has larger influence in deep water. Moreover, finite-depth FNV theory captures the loading in the widest range of wave and cylinder conditions. The areas of worst prediction by the numerical models were found to be the largest steepness and wave numbers for second harmonic, as well as the vicinity of the wave-breaking limit, especially for the third harmonic. The main cause is the non-monotonic growth of the experimental loading with increasing steepness due to flow separation, which leads to increasing numerical overpredictions since the numerical wave-loading models increase monotonically.
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Jamieson, Wayne W., Etienne P. D. Mansard, and Geoffrey R. Mogridge. "IRREGULAR WAVE LOADING ON A CONICAL STRUCTURE." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 167. http://dx.doi.org/10.9753/icce.v21.167.
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The horizontal forces, vertical forces and overturning moments exerted by waves on a fixed model of a 45" conical structure are presented. Irregular wave loading tests were conducted for a range of conditions described by base diameter on peak period wave length D/Lp from 0.31 to 1.76, water depth on peak period wave length h/Lp from 0.11 to 0.63, and significant wave height on peak period wave length Hm./Lp up to 0.07. Time series records, spectral densities and transfer functions for the irregular wave loading tests are used to illustrate the nonlinear nature of the measured wave loads. In most cases, similar trends in wave loading were observed for irregular and regular wave tests. For deep-water waves, the irregular and regular force measurements showed spectral peaks at the second harmonic of the wave frequency even though the waves themselves had relatively small second-order components. However, unlike the regular wave loading results, the fundamental spectral peak frequency for the irregular wave forces occurred at a frequency considerably lower than the peak frequency of the waves. Although linear diffraction theory provided a reasonable estimate of the wave forces for waves of low steepness, larger deviations were often present for higher wave steepness results. Comparison of theory and experiment for overturning moments was generally very poor for most wave conditions.
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Chen, L. F., J. Zang, P. H. Taylor, L. Sun, G. C. J. Morgan, J. Grice, J. Orszaghova, and M. Tello Ruiz. "An experimental decomposition of nonlinear forces on a surface-piercing column: Stokes-type expansions of the force harmonics." Journal of Fluid Mechanics 848 (June 1, 2018): 42–77. http://dx.doi.org/10.1017/jfm.2018.339.
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Wave loading on marine structures is the major external force to be considered in the design of such structures. The accurate prediction of the nonlinear high-order components of the wave loading has been an unresolved challenging problem. In this paper, the nonlinear harmonic components of hydrodynamic forces on a bottom-mounted vertical cylinder are investigated experimentally. A large number of experiments were conducted in the Danish Hydraulic Institute shallow water wave basin on the cylinder, both on a flat bed and a sloping bed, as part of a European collaborative research project. High-quality data sets for focused wave groups have been collected for a wide range of wave conditions. The high-order harmonic force components are separated by applying the ‘phase-inversion’ method to the measured force time histories for a crest focused wave group and the same wave group inverted. This separation method is found to work well even for locally violent nearly-breaking waves formed from bidirectional wave pairs. It is also found that the $n$th-harmonic force scales with the $n$th power of the envelope of both the linear undisturbed free-surface elevation and the linear force component in both time variation and amplitude. This allows estimation of the higher-order harmonic shapes and time histories from knowledge of the linear component alone. The experiments also show that the harmonic structure of the wave loading on the cylinder is virtually unaltered by the introduction of a sloping bed, depending only on the local wave properties at the cylinder. Furthermore, our new experimental results reveal that for certain wave cases the linear loading is actually less than 40 % of the total wave loading and the high-order harmonics contribute more than 60 % of the loading. The significance of this striking new result is that it reveals the importance of high-order nonlinear wave loading on offshore structures and means that such loading should be considered in their design.
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Dudko, Olga V., and Alexandr A. Mantsybora. "Shock Loading of Heteromodular Elastic Materials under Plane-Strain Condition." Key Engineering Materials 887 (May 2021): 634–39. http://dx.doi.org/10.4028/www.scientific.net/kem.887.634.
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The paper discusses the results of mathematical modeling the two-dimensional nonlinear dynamics of heteromodular elastic materials. The resistance of these materials under tension and compression is various. The deformation properties of the heteromodular medium are described within the framework of the isotropic elasticity theory with stress-dependent elastic moduli. In the plane strain case, it is shown that only two types of the nonlinear deformation waves can appear in the heteromodular elastic materials: a plane-polarized quasi-longitudinal wave and a plane-polarized quasi-transverse wave. Basing on obtained properties of the plane shock waves, two plane self-similar boundary value problems are formulated and solved.
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Erofeev, Vladimir I., Sergey I. Gerasimov, and Alexey O. Malkhanov. "Nonlinear Spatial Localized Strain Waves." EPJ Web of Conferences 183 (2018): 02030. http://dx.doi.org/10.1051/epjconf/201818302030.
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A possible way of study of single waves in solids is discussed. The soliton is one of these waves without shape and parameters varying. Soliton deformation parameters are connected with the elastic moduli of the third order that allows defining values of these moduli by means of the measured solitondeformation parameters in various type waveguides made of the same material. The conditions under which a soliton can exist in a rod are analytically determined. For simultaneous excitation of loading in several wave guides two new energetic photosensitive structures (the mixtures are given) initiated by means of short light impulses of noncoherent light sources are proposed. Conditions of excitation of the waves on the basis of multipoint optical initiation loading impulses are described. As a technique for registration the shadowgraph visualization is proposed. It is discussed, how the problem connected to the use of energetic initiation structures consisting in the power background illumination can be solved. The shadow scheme with the use of a tiny dot explosive light source (Tbr ~41 kK) allows to carry out modelling experiments on research of slabbing actions, jet formations, fluffings, hydrodynamic instability during shock-wave loading of investigated samples, which makes it attractive for determination of parameters in equations-of-state for investigated materials, creation of numerical models and their validation. Some examples showing basic possibility of application of the declared techniques are included.
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Zhu, Bo, and Jaesun Lee. "A Study on Fatigue State Evaluation of Rail by the Use of Ultrasonic Nonlinearity." Materials 12, no. 17 (August 23, 2019): 2698. http://dx.doi.org/10.3390/ma12172698.
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Nonlinear ultrasonic testing has been accepted as a promising manner for evaluating material integrity in an early stage. Stress fatigue is the main threats to train safety, railways examinations for stress fatigue are more significant and necessary. A series of ultrasonic nonlinear wave experiments are conducted for rail specimens extracted from railhead with different degree of fatigue produced by three-point bent loading condition. The nonlinear parameter is the indicator of nonlinear waves for expressing the degree the fatigue. The experimental results show that the sensitivity of a third harmonic longitudinal wave is higher than second harmonic longitudinal wave testing. As the same time, collinear wave mixing shows strong relative with fatigue damages than a second longitudinal wave nondestructive testing (NDT) method and provides more reliable results than third harmonic longitudinal waves nonlinear testing method.
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Liaw, Chih Young, and Xiang Yuan Zheng. "Polynomial Approximations of Wave Loading and Superharmonic Responses of Fixed Structures." Journal of Offshore Mechanics and Arctic Engineering 125, no. 3 (July 11, 2003): 161–67. http://dx.doi.org/10.1115/1.1576818.
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Besides the commonly considered drag force, inundation due to variable water surface is another important nonlinear effect of wave loading. Quadratic and quartic approximations of the inundation drag force are derived using the least squares method. Other nonlinear effects, including the second-order wave kinematics and nonlinear inertia wave forces, are also considered. Superharmonic forces and the corresponding structural responses due to different nonlinear effects are compared using a single mode representation of the fixed offshore structural system. The appropriate expressions that can serve as the basis for the Volterra series representation of the nonlinear wave forces are presented.
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Nekouzadeh, Ali, Guy M. Genin, Philip V. Bayly, and Elliot L. Elson. "Wave motion in relaxation-testing of nonlinear elastic media." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2058 (April 26, 2005): 1599–626. http://dx.doi.org/10.1098/rspa.2004.1437.
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Relaxation testing is a fundamental tool for mechanical characterization of viscoelastic materials. Inertial effects are usually neglected when analysing these tests. However, relaxation tests involve sudden stretching of specimens, which causes propagation of waves whose effects may be significant. We study wave motion in a nonlinear elastic model specimen and derive expressions for the conditions under which loading may be considered to be quasi-static. Additionally, we derive expressions for wave properties such as wave speed and the time needed to reach a steady-state wave pattern. These expressions can be used to deduce nonlinear elastic material properties from dynamic experiments.
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Li, Fu Cai, Zheng Hao Sun, Hong Guang Li, and Li Min Zhou. "A Nonlinear Ultrasound Method for Fatigue Evaluation of Marine Structures." Materials Science Forum 813 (March 2015): 116–23. http://dx.doi.org/10.4028/www.scientific.net/msf.813.116.
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Fatigue is a major cause of failure in marine structures resulting from random wave and wind loading. A nonlinear ultrasound method for fatigue evaluation which uses interaction of two non-collinear nonlinear ultrasonic waves with quadratic nonlinearity is investigated in this paper. A hyperbolic system of conservation laws is applied here and a semi-discrete central scheme is used to solve the numerical problem. The numerical results prove that a resonant wave can be generated by two primary waves with certain resonant conditions. Features of the resonant wave are analyzed both in the time and frequency domains, and several regularities are found on intensity distribution of the resonant wave in two-dimensional domain.
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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.
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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.
Dissertations / Theses on the topic "Nonlinear wave loading"
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Rodriguez, Marcos. "The nonlinear wave loading and dynamic response of a freely-floating two-dimensional box." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/31524.
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This thesis concerns the nonlinear loading and dynamic response of a rectangular box in two dimensions. A fully-nonlinear potential flow model and a series of experimental procedures are employed to describe the nonlinearities governing the floating-body behaviour. Adopting this twin-track approach, nonlinear forcing components are found to make major contributions to both the excitation problem and the motion response. Two main sources of nonlinearity are established: a first associated with higher-order wave-structure interactions, and a second associated with viscous dissipation. The main advance of the present work lies in the quantification of the relative influence of these two sources. The first source, prevalent in steep wave conditions, is particularly significant in the diffraction regime and leads to significant excitation force amplifications. In deep water, these nonlinearities are primarily driven by interactions between the incident and the reflected wave components. The second source, due to viscosity, plays a minor role in the excitation problem, but has a major influence on the motion response. Viscous effects are critically important when the structure exhibits large motions, particularly at resonance. The relative importance of both types of nonlinearity is discussed in regular waves, focused wave groups and random seas. The first two cases are included to gain a clear physical description of the problem, whilst the random sea states are chosen to relate to practical ocean conditions. Experimental data is provided for sea states comprising in excess of 150,000 individual waves, presenting one of the most substantial data sets of this kind to date. In considering this random sea data, the two sources of nonlinearity are found to approximately balance in heave, with a load amplification due to wave-structure interactions and a motion reduction due to viscous dissipation. In roll, viscous dissipation dominates the overall response. Setting the work into its wider context, practical engineering approaches are also offered. A time-domain simulation, building upon a linear hydrodynamic description and a quadratic Morison's type drag term, is generally found to lead to a good agreement with the experimental data. An approach of this type is computationally very efficient, and hence suitable to day-to-day engineering practice.
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Chun, Sangeon. "Nonlinear Fluid-Structure Interaction in a Flexible Shelter under Blast Loading." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29849.
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Recently, numerous flexible structures have been employed in various fields of industry. Loading conditions sustained by these flexible structures are often not described well enough for engineering analyses even though these conditions are important. Here, a flexible tent with an interior Collective Protection System, which is subjected to an explosion, is analyzed. The tent protects personnel from biological and chemical agents with a pressurized liner inside the tent as an environmental barrier. Field tests showed unexpected damage to the liner, and most of the damage occurred on tent's leeward side.
To solve this problem, various tests and analyses have been performed, involving material characteristics of the liner, canvas, and zip seals, modeling of the blast loading over the tent and inside the tent, and structural response of the tent to the blast loading as collaborative research works with others. It was found that the blast loading and the structural response can not be analyzed separately due to the interaction between the flexible structure and the dynamic pressure loading. In this dissertation, the dynamic loadings imposed on both the interior and the exterior sides of the tent structure due to the airblasts and the resulting dynamic responses were studied. First, the blast loadings were obtained by a newly proposed theoretical method of analytical/empirical models which was developed into a FORTRAN program. Then, a numerical method of an iterative Fluid-Structure Interaction using Computational Fluid Dynamics and Computational Structural Dynamics was employed to simulate the blast wave propagation inside and outside the flexible structure and to calculate the dynamic loads on it.
All the results were compared with the field test data conducted by the Air Force Research Laboratory. The experimental pressure data were gathered from pressure gauges attached to the tent surfaces at different locations. The comparison showed that the proposed methods can be a good design tool to analyze the loading conditions for rigid or flexible structures under explosive loads. In particular, the causes of the failure of the liner on the leeward were explained. Also, the results showed that the effect of fluid-structure interaction should be considered in the pressure load calculation on the structure where the structural deflection rate can influence the solution of the flow field surrounding the structure.Ph. D.
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Azarhoushang, Azin. "Dynamic response of fixed offshore platforms to environmental loads." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/135.
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In this thesis a simplified method for dynamic response of jacket type offshore structures to extreme environmental load is investigated using existing experience and the procedures available within the industry. Fixed Jacket type offshore platforms may, under extreme wave loading conditions, exhibit significant nonlinear behavior. This must be accounted for in the design of such platforms, in order to ensure satisfactory structural safety. The complicated and nonlinear dynamic platform behavior implies that a wide number of significant uncertainties are introduced to the design process through the included mathematical models, analysis methods and the practical use of these methods. The major sources of nonlinear behavior are the wave loading, the damping mechanisms and the soil structure interaction. The inclusion of nonlinear dynamic platform behavior in the design process implies that nonlinear stochastic dynamic response based on time domain simulation methods must be applied. Time domain stochastic dynamic response analysis is an analysis method which will be a central element of the procedure. However, it seems not to be clear so far how this method should be integrated in a practical design procedure. Initially an overview of the different sources of nonlinear platform behavior is clarified with the underlying mechanism. Furthermore, it is outlined how those nonlinear effects may be accounted for with a special focus on estimation of extreme response and dynamic amplification factors. The discussion and outlines are illustrated by an example of fixed offshore platform. Finally the practical use of the method in the design of fixed jacket type offshore platforms is recommended.
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Carbol, Ladislav. "Měření akustických vlastností stavebních materiálů pomocí pseudonáhodné sekvence." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355599.
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The thesis deals with research of pulse compression of the acoustic signal in terms of applications in civil engineering. Based on the study and analysis of these methods, automated measuring equipment for non-destructive testing with pseudorandom sequence of maximum length and automated signal analysis, have been designed and implemented. In a single test cycle are obtained three parameters that characterize the linear and nonlinear behavior of the sample. A nonlinear parameter, Time of Flight of ultrasonic wave in the sample is further in the work compared with the conventional pulse measuring, and spectral analysis is compared with the method impact-echo. Functionality and optimization of the testing method was performed on a total of three sets of test pieces made of various building materials. The experiments proved simple result interpretation, and high sensitivity to structural damage associated with temperature loading. The results were correlated with conventional nondestructive methods and by destructive testing was measured change in compressive strength and flexural strength. This work also includes continual measurement of fundamental frequency influenced by moisture on a mortar sample. Use of pulse compression signal is in the civil engineering quite unusual. Only in recent years this topic is discussed in scientific articles with increasing frequency. Great potential lies in the association of three test methods into a single. Beneficial is high test speed and measurement reproducibility, but also theoretical possibility of testing massive test elements.
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Mockute, Agota. "Suitability of wave loading models for offshore wind turbine monopiles in rough seas." Doctoral thesis, 2019. http://hdl.handle.net/2158/1178434.
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This thesis discusses the suitability of numerical wave loading models for monopile-supported offshore wind turbines in rough seas, where models tend to lose validity and dangerous nonlinear phenomena occur.
Books on the topic "Nonlinear wave loading"
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S, Kim Michael, Holcomb Franklin H, and Construction Engineering Research Laboratories (U.S.), eds. Effects of harmonics on EMI/RFI filters operating under nonlinear loading conditions. [Champaign, IL]: US Army Corps of Engineers, Construction Engineering Research Laboratories, 1993.
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Conner, Mark P. Shear wave measurements to determine the nonlinear elastic response of fused silica under shock loading. 1988.
Find full textBook chapters on the topic "Nonlinear wave loading"
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Han, Seon Mi, and Haym Benaroya. "Environmental Loading-Waves and Currents." In Nonlinear and Stochastic Dynamics of Compliant Offshore Structures, 95–110. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-015-9912-2_4.
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West, Bruce J. "LEVY STATISTICS OF WATER WAVE LOADING ON SHIPS AND PLATFORMS." In Stochastically Excited Nonlinear Ocean Structures, 252–65. WORLD SCIENTIFIC, 1998. http://dx.doi.org/10.1142/9789812816504_0010.
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Zhang, Chuang, Longlong He, Suzhen Liu, and Qingxin Yang. "Simulation and Experimental Study of Closed Crack Detection by Ultrasonic Nonlinearity Under Electromagnetic Loading." In Studies in Applied Electromagnetics and Mechanics. IOS Press, 2020. http://dx.doi.org/10.3233/saem200017.
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The reliability of micro-damage detection of metal materials plays a crucial role in the safe and reliable operation of large equipment. In recent years, nonlinear ultrasonic nondestructive testing technology has achieved good development in closed cracks detection, but the problem of nonlinear ultrasonic detection of closed cracks is weak response signal and vulnerable to external interference. This paper realizes the modulation of the ultrasonic wave by electromagnetic loading at the closed cracks, which can effectively enrich the frequency components of nonlinear ultrasonic and magnify the amplitude. This lays a foundation for further research on nonlinear ultrasonic detection of closed cracks under electromagnetic loading.
Conference papers on the topic "Nonlinear wave loading"
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Ma, Rujian, Guixi Li, and Dong Zhao. "Spectral Analysis of Nonlinear Random Wave Loadings." In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67287.
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The spectral analysis of nonlinear random wave loadings on circular cylinders is performed in this paper by means of nonlinear spectral analysis. The study is carried out by expressing the wave profile and velocities of water particles as a nonlinear composition of the first order wave profile. Under the assumption of the first order wave profile being a zero-mean Gaussian process, the random wave spectra of finite amplitude waves are given. In order to solve the loading spectra of the finite amplitude random waves, the drag force is extended into power series of velocity. The loadings of the finite amplitude random waves are then expressed as nonlinear compositions of the first order wave profile and its derivatives. These techniques made it easier to compute the spectral densities of the finite amplitude random wave loadings.
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Spidsoe, N., H. P. Brathaug, and O. Skjåstad. "Nonlinear Random Wave Loading on Fixed Offshore Platforms." In Offshore Technology Conference. Offshore Technology Conference, 1986. http://dx.doi.org/10.4043/5101-ms.
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Yue, Jingxia, Lihua Peng, Wengang Mao, Chi Zhang, Wei Dong, and Zhentao Zhu. "Research on Ship Structural Fatigue Damage Under Nonlinear Wave Bending Moment." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62328.
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Loads acting on ship structures are complex and randomly over time and the nonlinear effect caused by wave loading is one of the research focus. The linear and nonlinear vertical wave bending moment (VBM) in different speeds and sea states and their effects on ship structural fatigue strength were investigated for a flat container with high ratio of width to depth. The VBM under the linear regular waves and irregular waves were calculated based on the three dimension (3D) potential theory. The considered nonlinear wave loading was caused by sea pressure near the mean free surface as well as the geometric nonlinearity. Hydrodynamic calculations in regular wave were presented to figure out the frequency response function (FRF) of VBM in the mid-ship section. Irregular waves were verified to obtain the VBM history in 4 sea states. What’s more, VBMs from a segmented elastic model test were obtained to investigate the influence of nonlinearity. On the basis of the wave loadings obtained from simulation and test, the hotspot stress histories under irregular waves were deduced in time domain by using the beam theory. Fatigue cumulative damage per hour under several random sea states were obtained on the basis of the rain-flow counting and S-N curve. Based on the fatigue damage from the numerical analysis and model test, it is believed that speeds and significant wave height have a positive correlation with the fatigue damage of ship structures. A good agreement was obtained between the numerical analysis values and the low frequency part of the test and the nonlinear analysis in the simulation could offer reasonable prediction for the fatigue damage caused by the wave frequency response. Also shown as the test result, fully nonlinearities have a great contribution to the fatigue damage.
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Laksari, Kaveh, Mehdi Shafieian, Kurosh Darvish, and Keyanoush Sadeghipour. "Shock Wave Propagation as a Mechanism of Injury in Nonlinear Viscoelastic Soft Tissues." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64717.
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This study investigates the propagation of shock waves and self-preserving waves in soft tissues such as brain as a mechanism of injury in high rate loading conditions as seen in blast-induced neurotrauma (BINT). The derived mathematical models indicate that whereas linear viscoelastic models predict only decaying waves, instances of such phenomena as shock can be achieved in nonlinear media. In this study, a nonlinear viscoelastic material model for brain tissue was developed in compression. Furthermore, nonlinear viscoelastic wave propagation in brain tissue was studied and a criterion for the development of shock waves was formulated. It was shown that discontinuities in the acceleration that happen in blast loading conditions may evolve to shock waves, resulting in large discontinuities in strain and stress at the wave front leading to tissue injuries.
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Abbasi, M., and A. R. M. Gharabaghi. "Study the Effect of Wave Directionality on Dynamic Nonlinear Behavior of Jack-Up Subjected to Wave and Earthquake Loading." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29350.
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Sea waves are random in nature as they propagate with different frequencies and in different directions. In literature, there are several studies about dynamic behavior of marine structures under random waves in frequency domain, but little or nothing has been done about wave directionality. In this paper, the behavior of a typical jack-up platform operating in Caspian Sea is studied. In order to model the interaction between spudcan and surrounding soil, it was modeled separately by PLAXIS software. The applied soil properties are based on the field measurements. The results from plastic analyses show that they can differ up to 18 percent compared with those obtained based on the recommendations of API. A 3D model of Iran-Khazar Jack-up was studied using ANSYS software. All elements of triangular legs were modeled by PIPE59 elements and the results obtained from previous step were used to model nonlinear interaction of spudcan footings. The wave and current characteristics are based on the field data. The time-history records of earthquake used in this research are based on Manjil earthquake related to the same area. Nonlinear dynamic analyses including large deflection and material non-linearity was performed. The temporal variation of displacement at deck level was compared under solely wave or earthquake loading and simultaneously acting wave and earthquake loading assuming to be in the same direction and in different directions. It is found that when earthquake loading is applied simultaneously with wave loading in the same direction, displacements are less than wave loading alone. However, when they are applied in different directions, especially when the direction of applied earthquake differs about 30 or 90 degrees with respect to wave direction, displacements become larger. In addition, the effect of wave directionality on the maximum displacement of structure was considered.
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Lan, Jian, Zhen Liu, and Chensong Xianyu. "Experimental Study on Wave and Wave-Current Loads on Vertical Surface-Piercing Column Structures." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41278.
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Interactions between steep waves and a vertical surface-piercing cylinder as well as two cylinders in tandem arrangement with different spacings are investigated experimentally in this study. The focus of this study is on nonlinear wave and wave-current loads on structures. It is further aimed at investigating the higher harmonic loads and secondary loading cycle. The influence of non-dimensional parameters Kc, kA and Fr on the wave forces exerted on the structures is examined. The effect of spacing between two columns on the wave and wave-current loads is analyzed in depth. It is found that wave steepness plays an important role in the development of nonlinear wave force. It is also pointed out that the spacing effect on the nonlinear loading is rather pronounced.
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Najafian, G., and N. I. Mohd Zaki. "Finite-Memory Nonlinear System Modelling of Offshore Structures." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57755.
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Offshore structures are exposed to random wave loading in the ocean environment, and hence the probability distribution of the extreme values of their response to wave loading is of great value in the design of these structures. Due to nonlinearity of the drag component of Morison wave loading and also due to intermittency of wave loading on members in the splash zone, the response is often non-Gaussian; therefore, simple techniques for derivation of their extreme response probability distributions are not available. However, according to a recent paper, in the absence of current, the response of an offshore structure exposed to Morison wave loading, can be approximated by the response of an equivalent finite-memory nonlinear system (FMNS). These models can then be used, with great efficiency, to determine the probability distribution of response extreme values. In this paper, the progress made so far in extending these FMNS models to account for the effect of current on response is discussed.
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Syvertsen, K., K. A. Farnes, D. N. Karunakaran, and T. Overvik. "Extreme Response And Fatigue Damage In A Deepwater Platform Exposed To Nonlinear Wave Loading." In Offshore Technology Conference. Offshore Technology Conference, 1986. http://dx.doi.org/10.4043/5334-ms.
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Rabie, Oruba, and Yahia M. Al-Smadi. "Dynamic Response of RC Structures Subjected to Blast Wave Shock Loading." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88658.
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The collapse of significant structures caused by terrorist attacks in the past decades has motivated engineers to study the stability of current structural systems and their susceptibility to collapse. This collapse usually occurs due to blast waves generated by the high explosive bursts in the air that hit the structural components of the buildings leading to catastrophic damages which unfortunately happen before the evacuation. In an effort to find a safety criterion for buildings subjected to blasting; this study uses the nonlinear FEA explicit software LS-DYNA to highlight the effect of blast wave propagation on reinforced concrete column taking into account the standoff distance and charge weight variations. The effects of these two variables have been quantified through the comparison of resulted pressures, displacement and impulses.
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Mirzadehniasar, Jalal, Mehrdad Kimiaei, and Mark J. Cassidy. "Nonlinear Dynamic Analysis of Jack-Up Platforms Exposed to Extreme Random Waves." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83786.
Full textAbstract:
Deterministic waves with uniquely specified parameters remains widely used in the analysis of offshore platforms, even though the random nature of the sea-state is one of the main uncertainties in loading. The response of dynamically sensitive and highly redundant structures is significantly changed when random wave loading is considered. Therefore, to more confidently simulate wave loads, all of the randomness of water surface should be taken into account. Load history also plays an important role in the nonlinear dynamic response of structures. Accordingly, an appropriate way to consider these effects is dynamic analysis of offshore platforms using random time-domain generation of the sea surface over a long period of time. However, in general, this method is very complex and time consuming. Constrained NewWave theory is an alternative method that can effectively simulate many hours of random time domain simulation for wave loading but in a more computationally efficient manner. It takes a NewWave — a deterministic wave of predetermined height that accounts for the spectral composition of the sea — and constrains it within a random background. In this paper, both the singular NewWave and multiple constrained NewWaves are employed to simulate random sea-states in order to investigate the nonlinear dynamic response and collapse mechanisms of a jack-up platform subjected to extreme waves. Different assumptions of the behavior of the jack-up spudcan-soil interaction are considered.