• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.221-235
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• 2023

To calculate the vibrations of a tout cable subjected to axial support excitations, a nonlinear relationship of cable force and the support displacement under static situations are employed to depict the quasi-static vibration of the cable. The dynamic components of quasi-static vibration are inputted as "direct loads" to cause the parametric vibrations on the cable. Both the governing equations of motion and deformation compatibility for parametric vibrations are then derived, which indicates the high coupling of cable parametric force and deformation. Numerical solutions, based on the finite difference method, are put forward for the parametric vibrations, which is validated by the finite element method under periodic axial support excitations. For the quasi-static response, the shorter cables are more sensitive to support excitations than longer ones at small cable force. The quasi-static cable force makes the greatest contribution to the total cable force, but the parametric cable force is responsible for the occurrence of cable loosening at large excitation amplitudes. Moreover, this study also revealed that the traditional approach, assuming a linear relationship between quasi-static cable force and axial support displacement, would result in some great error of the cable parametric responses.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.129-136
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• 2009

The estimation of muscle force is important to understand the roles of the muscles. The static optimization method can be used to figure out the individual muscle forces. However, muscle forces during the movement including muscle co-contraction cannot be considered by the static optimization. In this study, a hybrid static optimization method was introduced to find the well-matched muscle forces with EMG signals under muscle co-contraction conditions. To validate the developed algorithm, the 3D motion analysis and its corresponding inverse dynamics using the musculoskeletal modeling software (SIMM) were performed on heel-rise movements. Results showed that the developed algorithm could estimate the acceptable muscle forces during heel-rise movement. These results imply that a hybrid numerical approach is very useful to obtain the reasonable muscle forces under muscle co-contraction conditions.

• Architectural research
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• v.10 no.2
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• pp.21-26
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• 2008

The number of measured degrees of freedom for detecting the damage of any structures is usually less than the number of model degrees of freedom. It is necessary to expand the measured data to full set of model degrees of freedom for updating modal data. This study presents the expansion methods to estimate all static displacements and dynamic modal data of finite element model from the measured data. The static and dynamic methods are derived by minimizing the variation of the potential energy and the Gauss's function, respectively. The applications illustrate the validity of the proposed methods. It is observed that the numerical results obtained by the static approach correspond with the Guyan condensation method and the derived static and dynamic approaches provide the fundamental idea for damage detection.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.282-284
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• 2006

In this paper, Static load models are developed using measurement based approach which is fundamental for on-line load modeling. The measurement data can be acquired from PMU(phasor measurement units). On the assumption that we have on-line measurement data, a scheme which is for Static load model capable to apply SCADA/EMS is developed. The Least Squares criterion is used for minimizing between measured and simulated data. In this manner, On-line Static load modeling algorithm can be developed. In this paper, a scheme that simple Static load model is applied for On-line load modeling is studied.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.231-238
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• 2002

The AASHTO seismic base isolation design approach has been reviewed and modified to fit the nonlinear static analysis procedure for reinforced concrete structures in a simpler way. Such an adaptation may be possible for the fact that the reinforced concrete under development of damage due to earthquake loading keeps softening to result in period shifting toward longer side. The validity of the proposed approach was verified by applying it to the examples presented in the current state-of-the-practice approach.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2009-2020
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• 2004

A parametric study of the factors controlling static and dynamic denting, as well as local stiffness, has been made on simplified panels of different sizes, curvatures, thicknesses and strengths. Analyses have been performed using the finite element method to predict dent resistance and panel stiffness. A parametric approach is used with finite element models of simplified panels. Two sizes of panels with square plan dimensions and a wide range of curvatures are analysed for several combinations of material thickness and strength, all representative of auto-motive closure panels. Analysis was performed using the implicit finite element code, LS-NIKE, and the explicit dynamic code, LS-DYNA for the static and dynamic cases, respectively. Panel dent resistance and stiffness behaviour are shown to be complex phenomena and strongly interrelated. Factors favouring improved dent resistance include increased yield strength and panel thickness. Panel stiffness also increases with thickness and with higher curvatures but decreases with size and very low curvatures. Conditions for best dynamic and static dent performance are shown to be inherently in conflict ; that is, panels with low stiffness tend to perform well under impact loading but demonstrate inferior static dent performance. Stiffer panels are prone to larger dynamic dents due to higher contact forces but exhibit good static performance through increased resistance to oil canning.

• Tribology and Lubricants
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• v.19 no.4
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• pp.230-236
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• 2003

In applications such as MEMS and NEMS devices, the adhesion force and contact load may be of the same order of magnitude and the static friction coefficient can be very large. Such large coefficient may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. To obtain the static friction coefficient of contacting real surfaces without the assumption of an empirical coefficient value, numerical simulations of the contact load, tangential force, and adhesion force are preformed. The surfaces in dry contact are statistically modeled by a collection of spherical asperities with Gaussian height distribution. The asperity micro-contact model utilized in calculation (the ZMC model), considers the transition from elastic deformation to fully plastic flow of the contacting asperity. The force approach of the modified DMT model using the Lennard-Jones attractive potential is applied to characterize the intermolecular forces. The effect of the surface topography on the static friction coefficient is investigated for cases rough, intermediate, smooth, and very smooth, respectively. Results of the static friction coefficient versus the external force are presented for a wide range of plasticity index and surface energy, respectively. Compared with those obtained by the GW and CEB models, the ZMC model is more complete in calculating the static friction coefficient of rough surfaces.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.230-237
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• 2020

In this part, an implicit time dependent solution is presented for the Boltzmann transport equation discretized by the analytic coarse mesh finite difference method (ACMFD) over the spatial domain as well as the simplified P₃ (SP₃) for the angular variable. In the first part of this work we proposed a SP₃-ACMFD approach to solve the static eigenvalue equations which provide the initial conditions for temp dependent equations. Having solved the 3D multi-group SP₃-ACMFD static equations, an implicit approach is resorted to ensure stability of time steps. An exponential behavior is assumed in transverse integrated equations to establish a relationship between flux moments and currents. Also, analytic integration is benefited for the time-dependent solution of precursor concentration equations. Finally, a multi-channel one-phase thermal hydraulic model is coupled to the proposed methodology. Transient equations are then solved at each step using the GMRES technique. To show the sufficiency of proposed transient SP₃-ACMFD approximation for a full core analysis, a comparison is made using transport peers as the reference. To further demonstrate superiority, results are compared with a 3D multi-group transient diffusion solver developed as a byproduct of this work. Outcomes confirm that the idea can be considered as an economic interim approach which is superior to the diffusion approximation, and comparable with transport in results.

• Earthquakes and Structures
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• v.15 no.6
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• pp.687-699
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• 2018

This paper investigates the pseudo-static analysis of reinforced slopes with geosynthetics under the influence of the uniform surcharge to evaluate the maximum tensile force of reinforcements. The analytical approach has basically been used to develop the new practical procedure to estimate both tensile force and its distribution in the height of the slope. The base of developed relationships has been adapted from the conventional horizontal slice method. The limit equilibrium framework and the assumptions of log-spiral failure surface have directly been used for proposed analytical approach. A new analytical approach considering a single layer of non-cohesion soil and the influence of uniform surcharge has been extracted from the 5n equation and 5n unknown parameters. Results of the proposed method illustrated that the location of the surcharge, amount of internal friction and the seismic coefficient have the remarkable effect on the tensile force of reinforcement and might be 2 times increasing on it. Furthermore, outcomes show that the amount of tensile force has directly until 2 times related to the amount of slope angle and its height range. Likewise, it is observed that the highest value of the tensile force in case of slope degree more than 60-degree is observed on the lower layers. While in case of less degree the highest amount of tensile force has been reported on the middle layers and extremely depended to the seismic coefficient. Hence, it has been shown that the tensile force has increased more than 6 times compared with the static condition. The obtained results of the developed procedure were compared with the outcomes of the previous research. A good agreement has been illustrated between the amount results of developed relationships and outcomes of previous research. Maximum 20 and 25 percent difference have been reported in cases of static and seismic condition respectively.

• Journal of Ocean Engineering and Technology
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• v.29 no.5
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• pp.342-350
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• 2015

A seismic reliability analysis of the jacket-type support structure for an offshore wind turbine was performed. When defining the limit state function using the dynamic response of the support structure, numerous dynamic calculations should be performedin an approach like the FORM (first-order reliability method). This causes a substantial increase in the analysis cost. Therefore, in this paper, a new reliability analysis approach using the static response is used. The dynamic effect of the response is considered by introducing a new parameter called the peak response factor (PRF). The probability distribution of the PRF could be estimated using the peak value of the dynamic response. The probability distribution of the PRF was obtained for a set of ground motions. A numerical example is considered to compare the proposed approach with the conventional static-response-based approach.