Articles de revues : « Forced Responce Analysis »

1

Nikolic, M., E. P. Petrov et D. J. Ewins. « Coriolis Forces in Forced Response Analysis of Mistuned Bladed Disks ». Journal of Turbomachinery 129, n^o 4 (15 août 2006) : 730–39. http://dx.doi.org/10.1115/1.2720866.

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The problem of estimating the mutual interaction of the effects of Coriolis forces and of blade mistuning on the vibration characteristics of bladed disks is addressed in this paper. The influence of different degrees of mistuning on forced response and amplification factors are studied in the presence of Coriolis forces and then compared to their non-Coriolis counterparts using a computationally inexpensive, yet representative, model of a bladed disk. The primary objective of the study reported in this paper is to establish whether current mistuned bladed disk analyses should incorporate Coriolis effects in order to represent accurately all the significant factors that affect the forced response levels.

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Setúbal, Fábio Antônio do Nascimento, Sérgio de Souza Custódio Filho, Newton Sure Soeiro, Alexandre Luiz Amarante Mesquita et Marcus Vinicius Alves Nunes. « Force Identification from Vibration Data by Response Surface and Random Forest Regression Algorithms ». Energies 15, n^o 10 (20 mai 2022) : 3786. http://dx.doi.org/10.3390/en15103786.

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Several dynamic projects and fault diagnosis of mechanical structures require the knowledge of the acting external forces. However, the measurement of such forces is often difficult or even impossible; in such cases, an inverse problem must be solved. This paper proposes a force identification method that uses the response surface methodology (RSM) based on central composite design (CCD) in conjunction with a random forest regression algorithm. The procedure initially required the finite element modal model of the forced structure. Harmonic analyses were then performed with varied parameters of forces, and RSM generated a dataset containing the values of amplitude, frequency, location of forces, and vibration acceleration at several points of the structure. The dataset was used for training and testing a random forest regression model for the prediction of any location, amplitude, and frequency of the force to be identified with information on only the vibration acquisition at certain points of the structure. Numerical results showed excellent accuracy in identifying the force applied to the structure.

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Saito, Akira, et Tatsuya Suzuki. « Forced response vibration analysis of induction motor stators induced by electromagnetic forces ». IFAC-PapersOnLine 55, n^o 27 (2022) : 155–59. http://dx.doi.org/10.1016/j.ifacol.2022.10.504.

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Mitra, Anirban, Prasanta Sahoo et Kashinath Saha. « Large Amplitude Forced Vibration Analysis of Stiffened Plates Under Harmonic Excitation ». International Journal of Manufacturing, Materials, and Mechanical Engineering 1, n^o 2 (avril 2011) : 62–98. http://dx.doi.org/10.4018/ijmmme.2011040105.

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Large amplitude forced vibration behaviour of stiffened plates under harmonic excitation is studied numerically incorporating the effect of geometric non-linearity. The forced vibration analysis is carried out in an indirect way in which the dynamic system is assumed to satisfy the force equilibrium condition at peak excitation amplitude. Large amplitude free vibration analysis of the same system is carried out separately to determine the backbone curves. The mathematical formulation is based on energy principles and the set of governing equations for both forced and free vibration problems derived using Hamilton’s principle. Appropriate sets of coordinate functions are formed by following the two dimensional Gram-Schmidt orthogonalization procedure to satisfy the corresponding boundary conditions of the plate. The problem is solved by employing an iterative direct substitution method with an appropriate relaxation technique and when the system becomes computationally stiff, Broyden’s method is used. The results are furnished as frequency response curves along with the backbone curve in the dimensionless amplitude-frequency plane. Three dimensional operational deflection shape (ODS) plots and contour plots are provided in a few cases.

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david Logan, J. « Forced response of a linear hyperbolic system ». Applicable Analysis 33, n^o 3-4 (janvier 1989) : 255–66. http://dx.doi.org/10.1080/00036818908839877.

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Ma, Yong Jie, Yi Du Zhang et Xiao Ci Zhao. « Cutting Force Model of Aluminum Alloy 2014 in Turning with ANOVA Analysis ». Applied Mechanics and Materials 42 (novembre 2010) : 242–45. http://dx.doi.org/10.4028/www.scientific.net/amm.42.242.

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In the present study, aluminum alloy 2014 was selected as workpiece material, cutting forces were measured under turning conditions. Cutting parameters, the depth of cut, feed rate, the cutting speed, were considered to arrange the test research. Mathematical model of turning force was solved through response surface methodology (RSM). The fitting of response surface model for the data was studied by analysis of variance (ANOVA). The quadratic model of RSM associated with response optimization technique and composite desirability was used to find optimum values of machining parameters with respect to cutting force values. The turning force coefficients in the model were calibrated with the test results, and the suggested models of cutting forces adequately map within the limits of the cutting parameters considered. Experimental results suggested that the most cutting force among three cutting forces was main cutting force. Main influencing factor on cutting forces was obtained through cutting force models and correlation analysis. Cutting force has a significant influence on the part quality. Based on the cutting force model, a few case studies could be presented to investigate the precision machining of aluminum alloy 2014 thin walled parts.

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Jahng, Junghoon, Eric O. Potma et Eun Seong Lee. « Nanoscale spectroscopic origins of photoinduced tip–sample force in the midinfrared ». Proceedings of the National Academy of Sciences 116, n^o 52 (11 décembre 2019) : 26359–66. http://dx.doi.org/10.1073/pnas.1913729116.

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When light illuminates the junction formed between a sharp metal tip and a sample, different mechanisms can contribute to the measured photoinduced force simultaneously. Of particular interest are the instantaneous force between the induced dipoles in the tip and in the sample, and the force related to thermal heating of the junction. A key difference between these 2 force mechanisms is their spectral behavior. The magnitude of the thermal response follows a dissipative (absorptive) Lorentzian line shape, which measures the heat exchange between light and matter, while the induced dipole response exhibits a dispersive spectrum and relates to the real part of the material polarizability. Because the 2 interactions are sometimes comparable in magnitude, the origin of the chemical selectivity in nanoscale spectroscopic imaging through force detection is often unclear. Here, we demonstrate theoretically and experimentally how the light illumination gives rise to the 2 kinds of photoinduced forces at the tip–sample junction in the midinfrared. We comprehensively address the origin of the spectroscopic forces by discussing cases where the 2 spectrally dependent forces are entwined. The analysis presented here provides a clear and quantitative interpretation of nanoscale chemical measurements of heterogeneous materials and sheds light on the nature of light–matter coupling in optomechanical force-based spectronanoscopy.

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You, Tian Qing, Jia Zhong Zhang et Cong Wang. « Water Exit Dynamic Analysis of Underwater Vehicle ». Applied Mechanics and Materials 50-51 (février 2011) : 649–53. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.649.

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The cavity, formed at the nose part of underwater launched vehicle due to the high launching velocity, will collapse while crossing water free surface and has a great impact on the strength of vehicle structure. In order to study the effect of the cavity collapse to vehicle structure, water exit dynamic analysis has been conducted. Before that, the computational model has been established. The external load, caused by cavity collapse, is assumed to be concentrated pulse forces applied on the vehicle at different time. And the flight vehicle structure is simplified into a free-free Timoshenko beam. The Fluid Structure Interaction (FSI) effect is treated as added mass and hydrodynamic drag force varying with wet surface area, which decreases with the water exit of vehicle. The dynamic response, excited by the external load, is calculated. Result presents the necessary of taking account of FSI and the influence of time space between the two concentrated forces.

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Alligné, S., P. C. O. Silva, A. Béguin, B. Kawkabani, P. Allenbach, C. Nicolet et F. Avellan. « Forced response analysis of hydroelectric systems ». IOP Conference Series : Earth and Environmental Science 22, n^o 4 (1 mars 2014) : 042001. http://dx.doi.org/10.1088/1755-1315/22/4/042001.

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Zirkelback, Nicole, et Luis San Andre´s. « Finite Element Analysis of Herringbone Groove Journal Bearings : A Parametric Study ». Journal of Tribology 120, n^o 2 (1 avril 1998) : 234–40. http://dx.doi.org/10.1115/1.2834415.

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Currently, the herringbone groove journal bearing (HGJB) has important applications in miniature rotating machines such as those found in the computer information storage industry. Grooves scribed on either the rotating or stationary member of the bearing pump the lubricating fluid inward thus generating support stiffness and improving its dynamic stability when operating concentrically. The narrow groove theory (NGT), traditionally adopted to model the concentric operation of these bearings, is limited to bearings with a large number of grooves. A finite element analysis is introduced for prediction of the static and rotordynamic forced response in HGJBs with finite numbers of grooves. Results from this analysis are then compared to available experimental data as well as to estimates from the NGT. A bearing geometry parametric study is then conducted to determine optimum rotordynamic force coefficients. A discussion on the temporal variation of the bearing reaction forces and force coefficients for a rotating journal with a small number of grooves is also presented. These changes can be significant at high operating eccentricities, possibly inducing a parametric excitation in rotating systems employing this type of bearing.

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He, Jian, Yu Jiang, Qichao Xue, Chunwei Zhang et Jingcai Zhang. « Energy response analysis of adjacent structures with polymer bumpers under seismic loadings ». Advances in Mechanical Engineering 10, n^o 12 (décembre 2018) : 168781401880915. http://dx.doi.org/10.1177/1687814018809157.

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Insufficient gap between adjacent buildings may lead serious poundings under seismic loadings. Installing polymer bumpers may decrease the pounding forces between colliding buildings, which can prevent column yielding from overlarge shearing forces. This article focuses on the analysis on energy responses of adjacent structures equipped with polymer bumpers. Based on a novel pounding analysis method, systematic comparisons of structural pounding performance are conducted and specific results are obtained and discussed. First, time history responses for pounding force, displacements, and yielding shearing forces in selected floors are calculated. Then, energy response analysis considering viscoelasticity of bumpers is investigated. Afterward, under different seismic waves, input energy response, pounding force procedures, and story displacements are studied and discussed. And finally, parametric studies on energy responses, including gaps, sizes, and viscoelasticity parameters, are carried out to investigate influence sensitiveness of bumper parameters. The results show that the novel viscoelastic pounding force model is effective in simulating and calculating adjacent structural pounding with polymer bumpers. Although, in many cases, viscoelasticity has little effect on pounding forces and energy response time histories, it still has certain influences on maximum values. And, equipping with polymer bumpers on adjacent buildings can decrease maximum pounding forces under all types of seismic waves, but pounding times and maximum displacements of stories increase after being equipped with bumpers. By comparing cases under different seismic waves, energy responses show sensitive characteristics to different earthquake waves. Besides, gaps, sizes of bumpers also have significant influence on energy performance. They affect peak yielding energy and peak damping energy significantly.

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Cenedese, Mattia, et George Haller. « How do conservative backbone curves perturb into forced responses ? A Melnikov function analysis ». Proceedings of the Royal Society A : Mathematical, Physical and Engineering Sciences 476, n^o 2234 (février 2020) : 20190494. http://dx.doi.org/10.1098/rspa.2019.0494.

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Weakly damped mechanical systems under small periodic forcing tend to exhibit periodic response in a close vicinity of certain periodic orbits of their conservative limit. Specifically, amplitude-frequency plots for the conservative limit have often been noted, both numerically and experimentally, to serve as backbone curves for the near resonance peaks of the forced response. In other cases, such a relationship between the unforced and forced response was not observed. Here, we provide a systematic mathematical analysis that predicts which members of conservative periodic orbit families will serve as backbone curves for the forced–damped response. We also obtain mathematical conditions under which approximate numerical and experimental approaches, such as energy balance and force appropriation, are justifiable. Finally, we derive analytic criteria for the birth of isolated response branches (isolas) whose identification is otherwise challenging from numerical continuation.

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Yao, Donghui, Yongsheng Ren, Yuhuan Zhang et Bole Ma. « Nonlinear Dynamics of Cutting Process considering Higher-Order Deformation of Composite Cutting Tool ». Shock and Vibration 2021 (2 décembre 2021) : 1–23. http://dx.doi.org/10.1155/2021/8699218.

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In this paper, the nonlinear dynamic analysis of the cutting process of composite cutting tool is performed. The cutting tool is simplified to a nonplanar bending rotating shaft. The higher-order bending deformation, structural damping, and gyroscopic effect of cutting tool are considered. It is assumed that cutting tool is subjected to a regenerative two-dimensional cutting force containing the first and second harmonic components. Based on the Hamilton principle, the motion equation of nonlinear chatter of the cutting system is derived. The nonlinear ordinary differential equations in the generalized coordinates are obtained by Galerkin method. In order to analyze the nonlinear dynamic response of cutting process, the multiscale method is used to derive the analytical approximate solution of the forced response for the cutting system under periodic cutting forces. In the forced response analysis, four cases including primary resonance and superharmonic resonance, i.e., Ω ¯ = ω 1 , Ω ¯ = ω 2 , 2 Ω ¯ = ω 1 , and 2 Ω ¯ = ω 2 , are considered. The influences of ratio of length to diameter, structural damping, cutting force, and ply angle on primary resonance and superharmonic resonance are investigated. The results show that nonlinearity due to higher-order bending deformation significantly affects the dynamic behavior of the milling process and that the effective nonlinearity of the cutting system is of hard type. Multivalued resonance curves and jump phenomenon are presented. The influences of various factors, such as ratio of length to diameter, ply angle, structural damping, cutting force, and rotating speed, are thoroughly discussed.

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Wang, X. M., et M. L. Spaulding. « A Two-Dimensional Potential Flow Model of the Wave Field Generated by a Semisubmerged Body in Heaving Motion ». Journal of Ship Research 32, n^o 02 (1 juin 1988) : 83–91. http://dx.doi.org/10.5957/jsr.1988.32.2.83.

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A two-dimensional potential flow model is formulated to predict the wave field and forces generated by a sere!submerged body in forced heaving motion. The potential flow problem is solved on a boundary fitted coordinate system that deforms in response to the motion of the free surface and the heaving body. The full nonlinear kinematic and dynamic boundary conditions are used at the free surface. The governing equations and associated boundary conditions are solved by a second-order finite-difference technique based on the modified Euler method for the time domain and a successive overrelaxation (SOR) procedure for the spatial domain. A series of sensitivity studies of grid size and resolution, time step, free surface and body grid redistribution schemes, convergence criteria, and free surface body boundary condition specification was performed to investigate the computational characteristics of the model. The model was applied to predict the forces generated by the forced oscillation of a U-shaped cylinder. Numerical model predictions are generally in good agreement with the available second-order theories for the first-order pressure and force coefficients, but clearly show that the third-order terms are larger than the second-order terms when nonlinearity becomes important in the dimensionless frequency range 1≤ Fr≤ 2. The model results are in good agreement with the available experimental data and confirm the importance of the third order terms.

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Berthillier, M., C. Dupont, R. Mondal et J. J. Barrau. « Blades Forced Response Analysis With Friction Dampers ». Journal of Vibration and Acoustics 120, n^o 2 (1 avril 1998) : 468–74. http://dx.doi.org/10.1115/1.2893853.

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A multiharmonic frequency domain analysis combined with a Craig-Bampton component mode synthesis is presented to compute the dry friction damped forced response of blades. The accuracy of the analysis is established, for a cantilever beam with a dry friction damper attached, by comparison with experimental results and time domain analysis. The method has then been applied to a model fan blade damped by a blade to ground damper.

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Chiang, Hsiao-Wei D., et R. E. Kielb. « An Analysis System for Blade Forced Response ». Journal of Turbomachinery 115, n^o 4 (1 octobre 1993) : 762–70. http://dx.doi.org/10.1115/1.2929314.

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A frequent cause of turbomachinery blade failure is excessive resonant response. The most common excitation source is the nonuniform flow field generated by inlet distortion, wakes and/or pressure disturbances from adjacent blade rows. The standard method for dealing with this problem is to avoid resonant conditions using a Campbell diagram. Unfortunately, it is impossible to avoid all resonant conditions. Therefore, judgments based on past experience are used to determine the acceptability of the blade design. A new analysis system has been developed to predict blade forced response. The system provides a design tool, over and above the standard Campbell diagram approach, for predicting potential forced response problems. The incoming excitation sources are modeled using a semi-empirical rotor wake/vortex model for wake excitation, measured data for inlet distortion, and a quasi-three-dimensional Euler code for pressure disturbances. Using these aerodynamic stimuli, and the blade’s natural frequencies and mode shapes from a finite element model, the unsteady aerodynamic modal forces and the aerodynamic damping are calculated. A modal response solution is then performed. This system has been applied to current engine designs. A recent investigation involved fan blade response due to inlet distortion. An aero mechanical test had been run with two different distortion screens. The resulting distortion entering the fan was measured. With this as input data, the predicted response agreed almost exactly with the measured response. In another application, the response of the LPT blades of a counterrotating supersonic turbine was determined. In this case the blades were excited by both a wake and a shock wave. The shock response was predicted to be three times larger than that of the wake. Thus, the system identified a new forcing function mechanism for supersonic turbines. This paper provides a basic description of the system, which includes: (1) models for the wake excitation, inlet distortion, and pressure disturbance; (2) a kernel function solution technique for unsteady aerodynamics; and (3) a modal aeroelastic solution using strip theory. Also, results of the two applications are presented.

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HSUEH, W. J. « FORCED RESPONSE ANALYSIS FOR MULTI-LAYERED STRUCTURES ». Journal of Sound and Vibration 227, n^o 1 (octobre 1999) : 222–29. http://dx.doi.org/10.1006/jsvi.1999.2362.

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Vuksanović Herceg, Iva, Vukašin Kuč, Veljko M. Mijušković et Tomislav Herceg. « Challenges and Driving Forces for Industry 4.0 Implementation ». Sustainability 12, n^o 10 (21 mai 2020) : 4208. http://dx.doi.org/10.3390/su12104208.

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Industry 4.0 has been a major force framing the societal, economic and technological environment after 2010. Exposed to ongoing digital transformation, companies are able to exploit opportunities offered by Industry 4.0, and are forced to manage immanent risks and barriers. However, studies on opportunities and challenges relevant for the implementation of Industry 4.0 for companies are scarce. In response to this literature gap, the aim of this exploratory research is to provide a deeper analysis of the level of digital transformation of companies in Serbia based on a digital maturity model, and examine their managers’ opinions on the most important driving forces and implementation barriers. The paper uses exploratory research design based on a survey responded to by 122 high-level managers within the Serbian manufacturing sector. Findings show that, contrary to expectations, digitally transforming enterprises do not see human resources as a driving force, but rather as an obstacle to Industry 4.0 implementation, when they lack necessary competences and skills. Resistance to change caused by Industry 4.0 implementation is not seen as an important barrier. On the other hand, efficiency factors represent the main driving force, while the lack of competences and financial resources represent the greatest barriers to Industry 4.0 implementation.

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Lu, Kai Bo, Min Qing Jing, Heng Liu et Chun Xiao Cong. « Dynamic Analysis of Slender Shaft in Twin-Spindle Turning ». Applied Mechanics and Materials 48-49 (février 2011) : 448–54. http://dx.doi.org/10.4028/www.scientific.net/amm.48-49.448.

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Machining slender workpiece is still a technical difficulty. This paper investigates the dynamic behavior of a slender shaft subject to constant feedrate moving cutting forces in twin-spindle turning process. The Euler-Bernoulli theory is used to model the rotating shaft. A dynamic cutting force model is formulated considering the flexibility of workpiece and rigid machine tool. The modal analysis method is employed to solve the dynamic response of the shaft. The parametric influence to the response and natural frequencies of shaft is discussed. Finally, the results are presented and compared between constant cutting forces and deflection-dependent force model introduced in this paper. It is found that there exists a stiffening effect due to the cutting process.

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Li, Jun Qiang, Yi Fan Li et Yong Peng. « Theoretical Analysis of Seismic Response for Marine Drilling Risers ». Applied Mechanics and Materials 423-426 (septembre 2013) : 1531–36. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.1531.

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With the continuous development of the marine oil industry, risers have become necessary equipment in offshore drilling engineering. On the basis of mode-superposition response spectrum method which is used commonly in anti-seismic design, the seismic responses of the marine drilling riser is analyzed on the theoretical and the related anti-seismic calculation formulas of the discrete system are promoted to the continuous system. The earthquake force and the resultant internal forces when the earthquake happening are analyzed and calculated. The calculation formulas of shear force and bending moment for each cross section of a riser under the earthquake action are deduced, which can offers some theoretical reference for riser engineering design when considering earthquake action.

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Trąbka, Arkadiusz. « Effect of Pulse Shape and Duration on Dynamic Response of a Forging System ». Acta Mechanica et Automatica 13, n^o 4 (1 décembre 2019) : 226–32. http://dx.doi.org/10.2478/ama-2019-0030.

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Abstract Forging hammers are machines whose operation causes negative effects both at the place of their foundation (the soil settlement) and in their surroundings (e.g., vibrations propagating to the other devices, noise, etc.). Knowledge of the parameters characterizing the time history of the force that arises as a result of impact of a ram on a shaped material is of fundamental importance for the correct analysis of both the structure of the hammer and its impact on the surroundings. In the paper, the effect of the shape and duration of a pulse load on the dynamic response of a hammer-foundation forging system was assessed. An analytical method of description of the forces that arise as a result of impact of the ram on the forged material, using different forms of pulses was presented. The forces defined in this way as loads in a mathematical model of three degrees of freedom forging system were used. The equations of motion derived from d’Alembert’s principle were solved numerically in the Matlab program. The analyses for eight forms of the pulse loads with the same pulse sizes but different durations were performed. The results in the graphs were presented. It was found, among other things, that a greater impact on the maximum displacement, velocity and acceleration of each component of the hammer-foundation system as well as on the maximum forces transmitted to the soil has the duration of a pulse than its shape.

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Petrov, E. P., et D. J. Ewins. « Advanced Modeling of Underplatform Friction Dampers for Analysis of Bladed Disk Vibration ». Journal of Turbomachinery 129, n^o 1 (1 février 2006) : 143–50. http://dx.doi.org/10.1115/1.2372775.

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Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. An approach for using the new damper models in the dynamic analysis of large-scale finite element models of bladed disks is proposed and realized. Numerical investigations of bladed disks are performed to demonstrate the capabilities of the new models and an analysis of the influence of the damper parameters on the forced response of bladed disks is made.

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Brown, Jeffrey M., et Ramana V. Grandhi. « Reduced-Order Model Development for Airfoil Forced Response ». International Journal of Rotating Machinery 2008 (2008) : 1–12. http://dx.doi.org/10.1155/2008/387828.

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Two new reduced-order models are developed to accurately and rapidly predict geometry deviation effects on airfoil forced response. Both models have significant application to improved mistuning analysis. The first developed model integrates a principal component analysis approach to reduce the number of defining geometric parameters, semianalytic eigensensitivity analysis, and first-order Taylor series approximation to allow rapid as-measured airfoil response analysis. A second developed model extends this approach and quantifies both random and bias errors between the reduced and full models. Adjusting for the bias significantly improves reduced-order model accuracy. The error model is developed from a regression analysis of the relationship between airfoil geometry parameters and reduced-order model error, leading to physics-based error quantification. Both models are demonstrated on an advanced fan airfoil's frequency, modal force, and forced response.

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Yildirim, Kenan, et Sertan Alkan. « Dynamic Response Analysis of a Forced Fractional Viscoelastic Beam ∗ ». Journal of Mathematics 2021 (15 décembre 2021) : 1–10. http://dx.doi.org/10.1155/2021/3920937.

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In this paper, dynamic response analysis of a forced fractional viscoelastic beam under moving external load is studied. The beauty of this study is that the effect of values of fractional order, the effect of internal damping, and the effect of intensity value of the moving force load on the dynamic response of the beam are analyzed. Constitutive equations for fractional order viscoelastic beam are constructed in the manner of Euler–Bernoulli beam theory. Solution of the fractional beam system is obtained by using Bernoulli collocation method. Obtained results are presented in the tables and graphical forms for two different beam systems, which are polybutadiene beam and butyl B252 beam.

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Wang, Haifei, et Junjie Gong. « Dynamic analysis of coupling misalignment and unbalance coupled faults ». Journal of Low Frequency Noise, Vibration and Active Control 38, n^o 2 (8 janvier 2019) : 363–76. http://dx.doi.org/10.1177/1461348418821582.

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Misalignment is a common fault occurring in the rotor system. However, the response characteristics have not been understood comprehensively, especially the relation between forces or torques and displacements, accelerations, or moments. First, misalignment modeling is investigated in this paper. Two coupled rotor system is modeled by six degrees of freedom. Misalignment effects are considered at coupling location using nodal force vectors and moment vectors. Second, Newmark- β method is used to solve the nonlinear equations. Acceleration, displacement, and force or moment response characteristics are discussed. Some results are obtained as follows: (1) 2× will appear in the parallel misalignment forces spectrum, and 0× will appear in the vertical force spectrum; 2×, 4×, 6× will appear in the angular misalignment moment spectrum. (2) In parallel misalignment simulation, it is found that multifrequency components are more obvious, static components are showed in vertical forces and displacements, 1× is dominated and 2× is weak in the displacement spectrum, and 2× is obvious in the force spectrum; acceleration is periodic impulse signal and 1× and 2× are dominated in its spectrum; vertical displacement is truncated and its values are positive, the orbit looks like an inverted triangle. (3) In angular misalignment simulation, it is found that multifrequency components of response are more obvious, 2× is obvious in the vertical displacement spectrum, and 2× is dominated in the moment spectrum; acceleration is periodic impulse signal, horizontal and vertical displacements are periodic, the orbit looks like a moon or an eight shape, and 2× is obvious in the moment spectrum.

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Goel, Rakesh K., et Anil K. Chopra. « Extension of Modal Pushover Analysis to Compute Member Forces ». Earthquake Spectra 21, n^o 1 (février 2005) : 125–39. http://dx.doi.org/10.1193/1.1851545.

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This paper extends the modal pushover analysis (MPA) procedure for estimating seismic deformation demands for buildings to compute member forces. Seismic demands are computed for six buildings, each analyzed for 20 ground motions. A comparison of seismic demands computed by the MPA and nonlinear response history analysis (RHA) demonstrates that the MPA procedure provides good estimates of the member forces. The bias (or error) in forces is generally less than that noted in earlier investigations of story drifts and is comparable to the error in the standard response spectrum analysis (RSA) for elastic buildings. The four FEMA-356 force distributions, on the other hand, provide estimates of member forces that may be one-half to one-fourth of the value from nonlinear RHA.

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Petrov, E. P. « Method for Direct Parametric Analysis of Nonlinear Forced Response of Bladed Disks With Friction Contact Interfaces ». Journal of Turbomachinery 126, n^o 4 (1 octobre 2004) : 654–62. http://dx.doi.org/10.1115/1.1776588.

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An effective method for direct parametric analysis of periodic nonlinear forced response of bladed disks with friction contact interfaces has been developed. The method allows, forced response levels to be calculated directly as a function of contact interface parameters such as the friction coefficient, contact surface stiffness (normal and tangential coefficients), clearances, interferences, and the normal stresses at the contact interfaces. The method is based on exact expressions for sensitivities of the multiharmonic interaction forces with respect to variation of all parameters of the friction contact interfaces. These novel expressions are derived in the paper for a friction contact model, accounting for the normal load variation and the possibility of separation-contact transitions. Numerical analysis of effects of the contact parameters on forced response levels has been performed using large-scale finite element models of a practical bladed turbine disk with underplatform dampers and with shroud contacts.

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Kubur, M., A. Kahraman, D. M. Zini et K. Kienzle. « Dynamic Analysis of a Multi-Shaft Helical Gear Transmission by Finite Elements : Model and Experiment ». Journal of Vibration and Acoustics 126, n^o 3 (1 juillet 2004) : 398–406. http://dx.doi.org/10.1115/1.1760561.

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A dynamic model of a multi-shaft helical gear reduction unit formed by N flexible shafts is proposed in this study. The model consists of a finite element model of shaft structures combined with a three-dimensional discrete model of helical gear pairs. Bearing and housing flexibilities are included in the model as well. Eigenvalue solution and the Modal Summation Technique are used to predict the free and forced vibrations of the system. Results of experimental study on a helical gear-shaft-bearing system are also presented for validation of the model. It is demonstrated that the predictions match well with the experimental data in terms of excited modes and the forced response given in the form of the dynamic transmission error. Forced vibrations of an example system formed by three shafts are also studied to demonstrate the influence of some of the key system parameters.

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Li, Qi Zhen, Hong Quan Li et Zhi Qian Zhang. « Response Analysis of Bridge across Seismic Fault Zone ». Applied Mechanics and Materials 178-181 (mai 2012) : 2224–27. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2224.

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Through simulating the happening location of the fault zone, the structure model is duly simplified, analysing the forced deformation law of the bridge surface with different fault zone position. Because of statically indeterminate structure, continuous beam shall be produced larger additional moment, shear force and torque as a result of displacement in bridge pier, additional stress will be increased with the the increasement of fault zone displacement, especially for the top surface parts of bridge pier. Hence, the corresponding position of the structure and construction measures for reinforcement should strengthened, the overall rigidity of the structure should be improved, and based on the study of the bridge across the fault zone is a simplified, and the actual stress process may be more complex, the investigation on geological condition must be clear, and avoid the bridge structure crossing fault zone.

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Calleja, Renato C., Alessandra Celletti, Livia Corsi et Rafael de la Llave. « Response Solutions for Quasi-Periodically Forced, Dissipative Wave Equations ». SIAM Journal on Mathematical Analysis 49, n^o 4 (janvier 2017) : 3161–207. http://dx.doi.org/10.1137/151005397.

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Wang, Jing, Huijuan Wei et Xindong Xu. « Response solutions for quasi-periodically forced harmonic oscillators in Gevrey class ». Journal of Differential Equations 355 (mai 2023) : 296–333. http://dx.doi.org/10.1016/j.jde.2023.01.034.

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Ryu, Bong Jo, Hee Jung Kim et Young Shik Kim. « Dynamic Response and Vibration of a Cantilevered Beam under an Accelerated Moving Mass ». Advanced Materials Research 711 (juin 2013) : 305–11. http://dx.doi.org/10.4028/www.scientific.net/amr.711.305.

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In this research we investigate dynamic responses and vibration of a cantilevered beam subjected to a moving mass with variable speeds. Governing equations of motion under a moving mass are derived by Galerkin's mode summation method considering the effects of all forces acting on the beam (gravity force, Coriolis force, inertia force caused by a slope of the beam, and transverse inertia of the beam). A Runge-Kutta integration method is then applied to calculate dynamic responses of the beam. The effects of the speed, acceleration and the magnitude of the moving mass on the response of the beam are investigated in these numerical analyses. Furthermore, experimental tests are conducted to validate our analysis.

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Ding, Yue, Xi Bin Wang, Li Jing Xie et Hao Yang. « Modeling and Analysis of Cutting Forces in Hard Turning T250 Steel Using CBN Tools ». Advanced Materials Research 154-155 (octobre 2010) : 694–700. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.694.

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The objective of this paper is to study the cutting forces in hard turning T250 steel with CBN tools. Experiments based on the Box-Behnken design were conducted to develop the cutting forces models by response surface methodology (RSM). Significance tests of the model are performed by the analysis of variance (ANOVA). It is also discussed the effects of cutting parameters (cutting speed, feed rate and depth of cut) on the cutting force components. The results show that the models can fit experimental data via analysis of variance. The most important cutting parameter is depth of cut, followed by feed rate, while the effect of cutting speed can be neglected. Compared to cutting force and feed force, thrust force is the largest. In addition, the cutting forces generated by the uncoated tool are smaller than by the coated one due to tool wear.

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Zhang, Ningyuan, Bin Luo, Haixia Liu et Minquan Zhang. « Prestress Self-Equilibrium Force-Finding Method for Cable-Supported Grid Structures Considering Zero-Stress State Form-Finding and the Construction Process ». Buildings 12, n^o 6 (31 mai 2022) : 749. http://dx.doi.org/10.3390/buildings12060749.

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The cable-supported grid structure (CSGS) is a hybrid structure combined with rigidity and flexibility. Its formed state is closely related to the zero-stress state, construction process, and prestress distribution. The prestress self-equilibrium force-finding method is proposed in this paper to continuously conduct zero-stress state form-finding, the construction process, and prestress state force-finding analysis. As the first engineering project adapting CSGS with an internal compression ring, Shanghai Pudong Football Stadium was taken as the analysis object. The structural finite element model was established in ANSYS, structural components were divided into prestress and ordinary components to form a prestress self-equilibrium system, and the equivalent temperature difference was applied to the prestress components as prestress. The Newton–Raphson method was used for geometric nonlinear analysis. The analysis results show that the internal forces and displacements of the formed structure are consistent with the design state, which proves the validity of the method and provides significant guidance for the actual construction. The method proposed in this paper can effectively and accurately obtain the zero-stress state configuration, structural response during construction, and the prestress distribution after forming in a single analysis, without analyzing the above three separately, which improves the analysis efficiency.

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Petrov, E. P., et D. J. Ewins. « Effects of Damping and Varying Contact Area at Blade-Disk Joints in Forced Response Analysis of Bladed Disk Assemblies ». Journal of Turbomachinery 128, n^o 2 (28 septembre 2005) : 403–10. http://dx.doi.org/10.1115/1.2181998.

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An approach is developed to analyze the multiharmonic forced response of large-scale finite element models of bladed disks taking account of the nonlinear forces acting at the contact interfaces of blade roots. Area contact interaction is modeled by area friction contact elements which allow for friction stresses under variable normal load, unilateral contacts, clearances, and interferences. Examples of application of the new approach to the analysis of root damping and forced response levels are given and numerical investigations of effects of contact conditions at root joints and excitation levels are explored for practical bladed disks.

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Troesch, Armin W., et Jeffrey M. Falzarano. « Modern Nonlinear Dynamical Analysis of Vertical Plane Motion of Planing Hulls ». Journal of Ship Research 37, n^o 03 (1 septembre 1993) : 189–99. http://dx.doi.org/10.5957/jsr.1993.37.3.189.

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When operating in a seaway, high-speed planing hulls exhibit strong nonlinearities. This paper investigates the vertical plane dynamic stability and response associated with such craft. Explicit expressions for the hydrodynamic forces are developed and modern methods of dynamical systems analysis are applied. An illustrative example is given in which the forced and unforced motions are examined. Parameter studies relating to the following topics are made: the onset of porpoising, the magnitude of motions while porpoising, and forced motions due to regular waves. It is found that while nonlinear effects can reduce the response over that predicted by linear theory, these same effects can also be responsible for sudden extreme behavior. The method described here is another tool that designers and operators can use to provide a more comfortable and safer vessel performance.

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Zhao, Dong Xiao, Jun Jie Wang et Jun Sheng Su. « Seismic Response Analysis of Deep Water Bridges with Pile Group Foundations ». Applied Mechanics and Materials 580-583 (juillet 2014) : 1494–98. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.1494.

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In this paper, we intended to replace the fluid-structure interaction of deep water bridge piers with acceleration-dependent forces during an earthquake. The hydrodynamic pressure on bridge pier groups under seismic excitation is studied using the finite volume method. Different seismic waves with various spectrum components are selected in order to cover frequently encountered cases. The calculated forces of these cylinders are fitted into the Morison equation, and by calculation, the drag force term is negligible, thus the effect of fluid is converted into one added mass term. The paper further calculated the dynamic response of a continuous beam bridge with pier groups in water to check the validity of our proposed method.

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Chiang, Hsiao-Wei D., et Sanford Fleeter. « Analysis of forced response of detuned blade rows ». Journal de Physique III 2, n^o 4 (avril 1992) : 527–44. http://dx.doi.org/10.1051/jp3:1992146.

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Gill, M. B. « The non-consequentialist moral force of promises : a response to Sinnott-Armstrong ». Analysis 72, n^o 3 (30 mai 2012) : 506–13. http://dx.doi.org/10.1093/analys/ans072.

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Katrín Hákonardóttir, Guðlaug, Pablo López-Ceballos, Alejandra Donají Herrera-Reyes, Raibatak Das, Daniel Coombs et Guy Tanentzapf. « In vivo quantitative analysis of Talin turnover in response to force ». Molecular Biology of the Cell 26, n^o 22 (5 novembre 2015) : 4149–62. http://dx.doi.org/10.1091/mbc.e15-05-0304.

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Cell adhesion to the extracellular matrix (ECM) allows cells to form and maintain three-dimensional tissue architecture. Cell–ECM adhesions are stabilized upon exposure to mechanical force. In this study, we used quantitative imaging and mathematical modeling to gain mechanistic insight into how integrin-based adhesions respond to increased and decreased mechanical forces. A critical means of regulating integrin-based adhesion is provided by modulating the turnover of integrin and its adhesion complex (integrin adhesion complex [IAC]). The turnover of the IAC component Talin, a known mechanosensor, was analyzed using fluorescence recovery after photobleaching. Experiments were carried out in live, intact flies in genetic backgrounds that increased or decreased the force applied on sites of adhesion. This analysis showed that when force is elevated, the rate of assembly of new adhesions increases such that cell–ECM adhesion is stabilized. Moreover, under conditions of decreased force, the overall rate of turnover, but not the proportion of adhesion complex components undergoing turnover, increases. Using point mutations, we identify the key functional domains of Talin that mediate its response to force. Finally, by fitting a mathematical model to the data, we uncover the mechanisms that mediate the stabilization of ECM-based adhesion during development.

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Saatcioglu, Murat, et JagMohan Humar. « Dynamic analysis of buildings for earthquake-resistant design ». Canadian Journal of Civil Engineering 30, n^o 2 (1 avril 2003) : 338–59. http://dx.doi.org/10.1139/l02-108.

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The proposed 2005 edition of the National Building Code of Canada specifies dynamic analysis as the preferred method for computing seismic design forces and deflections, while maintaining the equivalent static force method for areas of low seismicity and for buildings with certain height limitations. Dynamic analysis procedures are categorized as either linear (elastic) dynamic analysis, consisting of the elastic modal response spectrum method or the numerical integration linear time history method, or nonlinear (inelastic) response history analysis. While both linear and nonlinear analyses require careful analytical modelling, the latter requires additional considerations for proper simulation of hysteretic response and necessitates a special study that involves detailed review of design and supporting analyses by an independent team of engineers. The paper provides an overview of dynamic analysis procedures for use in seismic design, with discussions on mathematical modelling of structures, structural elements, and hysteretic response. A discussion of the determination of structural period to be used in association with the equivalent static force method is presented.Key words: dynamic analysis, earthquake engineering, elastic analysis, fundamental period, hysteretic modelling, inelastic analysis, National Building Code of Canada, seismic design, structural analysis, structural design.

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Fujii. « Prediction of the Maximum Seismic Member Force in a Superstructure of a Base-Isolated Frame Building by using Pushover Analysis ». Buildings 9, n^o 9 (5 septembre 2019) : 201. http://dx.doi.org/10.3390/buildings9090201.

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It is essential for the seismic design of a base-isolated building that the seismic response of the superstructure remains within the elastic range. The evaluation of the maximum seismic member force in a superstructure is thus an important issue. The present study predicts the maximum seismic member force of five- and fourteen-story reinforced concrete base-isolated frame buildings adopting pushover analysis. In the first stage of the study, the nonlinear dynamic (time-history) analysis of the base-isolated frame buildings is carried out, and the nonlinear modal responses of the first and second modes are calculated from pushover analysis results. In the second stage, a set of pushover analyses is proposed considering the combination of the first and second modal responses, and predicted maximum member forces are compared with the nonlinear time-history analysis results. Results show that the maximum member forces predicted in the proposed set of pushover analyses are satisfactorily accurate, while the results predicted considering only the first mode are inaccurate.

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Liao, C. L., et J. S. Tsai. « Dynamic Response Analysis in End Milling Using Pretwisted Beam Finite Element ». Journal of Vibration and Acoustics 117, n^o 1 (1 janvier 1995) : 1–10. http://dx.doi.org/10.1115/1.2873862.

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This paper develops an analytical model to estimate the dynamic responses in end milling, i.e., dynamic milling cutter deflections and cutting forces, by using the finite element method along with an adequate end milling cutting force model. The whole cutting system includes spindle, bearings and cutter. The spindle is structurally modeled with the Timoshenko-beam element, the milling cutter with the pretwisted Timoshenko-beam element due to its special geometry, and the bearings with lumped springs and dampers. Because the damping matrix in the resulting finite element equation of motion for the whole cutting system is not of proportional damping due to the presence of bearing damping, we use state-vector approach and convolution integral to find the solution of equations of motion. To assure the accuracy of dynamic response predication, the associated cutting force model should be sufficiently precise. Since the dynamic cutting force is proportional to the chip thickness, a quite accurate algorithm for the calculation of chip thickness variation due to tool geometry, runout and spindle-tool vibration is developed. A number of dynamic cutting forces and tool deflections obtained from the present model for various cutting conditions are compared with the experimental and analytical results available in the literature, and good agreement is demonstrated for these comparisons. Therefore the present model is useful for the prediction of end milling instability. Also, the tool deflections obtained by using the pretwisted beam element are found smaller than those by straight beam elements without pretwist angle. Hence, neglecting the pretwist angle in the structural model of milling cutter may overestimate the tool deflections.

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Jana, Tamonash, Anirban Mitra et Prasanta Sahoo. « Dynamic analysis of elastically and plastically graded spherical and cylindrical contact ». Proceedings of the Institution of Mechanical Engineers, Part J : Journal of Engineering Tribology 233, n^o 11 (3 avril 2019) : 1712–28. http://dx.doi.org/10.1177/1350650119841756.

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A dynamic analysis of a hemispherical and cylindrical contact, material properties of which are graded elastically and plastically along the radius, is presented. The static force–displacement behavior of a hemisphere and a semi-cylinder in contact with a rigid flat is obtained using finite element software. The force–displacement is used in a further dynamic analysis for undamped-free as well as for forced-damped vibration of the contact interface. For the undamped free vibration, variation of natural frequency w.r.t. initial displacement is furnished for different values of elastic and plastic gradation parameter. In addition, variation of maximum initial displacement for contact loss is also demonstrated. The forced-damped vibration characteristics of the spherical and cylindrical contact interfaces are presented in the form of frequency response curves with jump up and jump down frequencies. Spherical and cylindrical contact interfaces are found to exhibit softening and hardening type nonlinearity, respectively.

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Vlahopoulos, Nickolas, Yury Kalish et S. T. Raveendra. « Development of an Equivalent Force Method and an Application in Simulating the Radiated Noise from an Operating Diesel Engine ». Shock and Vibration 6, n^o 3 (1999) : 113–23. http://dx.doi.org/10.1155/1999/323427.

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In this paper a new methodology is presented for applying measured accelerations and forces as excitation on a structural finite element model in order to perform a forced frequency response analysis. The computed vibration constitutes the excitation for an acoustic boundary element analysis. The new developments presented in this paper are associated with: the equivalent force method that can prescribe the acceleration at certain parts of the structure; the integration within a single process of test data that define the excitation, with the vibration analysis, and the acoustic prediction; the utilization of the new technology in simulating the noise radiated from a running engine and determining the effects of design changes. Numerical results for noise radiated from a running engine are compared to test data for a baseline design. The effect of two structural design modifications on the radiated noise is computed, and conclusions are deduced.

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Aseel Mohammed Ali Hussein. « MECHANICAL ANALYSIS OF ORTHODONTIC WIRES ». Diyala Journal of Engineering Sciences 5, n^o 1 (1 juin 2012) : 172–80. http://dx.doi.org/10.24237/djes.2012.05114.

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Orthodontic tooth movement is a physiologic response to externally applied forces; the motive forces are primarily mechanical. The optimal application of orthodontic force enables maximum movement of teeth with minimal irreversible damage of the periodontal ligament (PDL), alveolar bone, and teeth. Since arch wires are the main force system in orthodontics, it is important in clinical practice that they deliver appropriate, predictable and repeatable forces during treatment. These specialized wires even promise shape memory properties and the possibility of super elastic behavior, which significantly impacts clinical practices. Since, standard stainless steel and titanium arch wires are still the materials of choice in many stages of treatment. They provide an attractive combination of stiffness, resilience and formability. However, clinical practitioners have commented on the variability of arch wire behavior for years. Inconsistent arch wire properties can contribute to unpredictable treatment duration and results. This paper examines the mechanical and physical characteristics of stainless steel and titanium wires to quantify their variability in engineering terms. From the results for both types of wires, the testing method provides the information required by designers wishing to improve the arch wire properties and provide valuable information to clinicians for their practice.

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Park, Min Su, Young Taek Kim, Sangki Park et Jiyoung Min. « Time Response Analysis of Caissons by Installing New Caisson on Existing Caisson Breakwater in Irregular Wave Condition ». Journal of Korean Society of Coastal and Ocean Engineers 34, n^o 6 (27 décembre 2022) : 233–46. http://dx.doi.org/10.9765/kscoe.2022.34.6.233.

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The design and the construction were carried out by installing new caissons on the back or the front of existing caissons to increase the structural stability of caisson breakwaters. In this study, we used the ANSYS AQWA program to analyze the wave forces acting on individual caissons according to the effects of wave-structure interaction when new caissons were additionally installed on existing caisson breakwaters. The wave force characteristics acting on the individual caisson were analyzed according to the distance among caissons in frequency domain analysis. In addition, the dynamic wave force characteristics were closely examined on the basis of the frequency at which the unusual distribution of wave forces occurs in irregular wave conditions using time domain analysis.

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Zhang, Zheng Mei, Bao Liang Xing, Jing Wang, Hui Ying Cao et Shao Hua Li. « Fractal Characterization Analysis in CNC Milling Aluminium Alloy ». Key Engineering Materials 748 (août 2017) : 212–17. http://dx.doi.org/10.4028/www.scientific.net/kem.748.212.

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Based on the experiment of milling aluminium alloy (7075-T651), the relations between the fractal dimensions of cutting forces with machining parameters are studied. Cutting speed, feed speed and cutting depth are considered as the process parameters. The cutting force in milling aluminium alloy operation are measured and the fractal dimension are calculated using the algorithm of correlation dimension. From main effect plots the fractal dimensions of three directions of cutting forces are reduced with the increase of cutting speed and increased with the increase of feed speed and cutting depth. The mathematic models of fractal dimension of cutting force are developed using response surface methodology (RSM). The results of the ANOVA show that feed speed and cutting depth have remarkable influence to fractal dimension Dx and Dy, cutting speed and feed speed for Dz.

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Maslen, E. H., C. K. Sortore, J. A. Va´zquez et C. R. Knospe. « Synchronous Response Estimation in Rotating Machinery ». Journal of Engineering for Gas Turbines and Power 124, n^o 2 (26 mars 2002) : 357–62. http://dx.doi.org/10.1115/1.1417482.

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Synchronous response estimation attempts to determine the forced response (displacement) of a rotor at critical points which cannot be measured directly. This type of prediction, if accurate and reliable, has broad potential use in the rotating machinery industry. Many machines have close clearance points on their shafts, such as seals, which can easily be damaged by excess vibration. Accurate estimates of the actual level of vibration at these points could usefully assist machine operators in troubleshooting and in protecting the equipment from expensive damage. This type of response information can be used both to generate less conservative alarm limits and, if magnetic bearings are available, to directly guide the bearing controllers in restricting the rotor motion at these critical points. It is assumed that the disturbance forces acting upon the rotor are predominantly synchronous. The response estimate is constructed using the measurable response in conjunction with an estimator gain matrix derived from a model of the transmissibilities of the rotor system. A fundamental performance bound is established based on the single-speed set of measurements by bounding the response to the unmeasurable component of the disturbance force. Acknowledging that some model uncertainty will always exist, a robust performance analysis is developed using structured singular value (μ) analysis techniques. Assuming some reasonable levels of uncertainty for the model parameters (natural frequencies, modal dampings, mode shapes, bearing stiffnesses, and dampings) the results of the estimator construction and analysis establish feasibility of the proposed estimation. Two reference rotor models that are representative of industrially sized machines are used to demonstrate and evaluate the estimation. The unmeasurable response estimation errors consistently lie below 25 μm for the examples examined.

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Huang, Dishan, et Hexi Shao. « Computation Method for Forced Vibration Response of a Multiple DOF Parametric System ». International Journal of Structural Stability and Dynamics 20, n^o 11 (octobre 2020) : 2050126. http://dx.doi.org/10.1142/s0219455420501266.

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In this paper, a mathematical approach is presented for the forced vibration analysis of a multiple DOF system that is governed by ordinary differential equations with both time-periodic stiffness and external force that have different periods. Based on an equivalent dynamic system, a closed-form solution, i.e. a special trigonometric series, is presented for the forced vibration response of the system. Computation is realized by applying the harmonic balance operation, and the parametric vibration equation is converted into a set of infinite-order linear algebraic equations. Based on the physical property of the forced vibration response, all the coefficient vectors of the forced response are solved by the use of inverse matrix. The present approach can be used to predict the forced vibration response and its spectrum with better computation performance. It can help reveal some nonlinear phenomena in the parametric system. Therefore, it proves to be a useful tool for future research and engineering applications of parametric systems.

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