• Structural Engineering and Mechanics
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• 제89권4호
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• pp.383-397
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• 2024

To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.127-132
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• 2007

In this paper, to overcome local damages of structures, an uncertainty of structural model, installing sensors of structures, and economics of building system, decentralized semi-active magnetorheological(MR) damper using the displacement or velocity transferred to the response of floor installed damper is proposed. Relative magnitude between the control force of dampers and the story shear force is difined as design variables and the performance indices response spectra analysis through nonlinear time history analysis excited by seismic loads is performed according to this design variables. And the performance of this decentralized MR damper is compared with previous centralized LQR control algorithm using 3-stories benchmark building structure excited by El Centro (1940, N.S) in order to evaluate the application of building structures.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.861-866
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• 2002

A seat suspension system with a controlled MR(Magneto Rheological) fluid damper is introduced to improve the ride quality and prevent the health risk of a driver compared to fixed seats. The system is located between a seat cushion and the base, and is composed of a spring, MR fluid damper and controller. The MR fluid damper designed in valve mode is capable of producing a wide range of damping force according to applied currents. In experiments, a person was sitting on the controlled seat excited by a hydraulic system The skyhook control, continuous skyhook control and relative displacement control were applied and the continuous skyhook control improved the vibration suppression by 36.6%.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.111.6-111
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• 2001

A seat suspension system with a controlled MR(Magneto Rheological) fluid damper is introduced to improve the ride quality and prevent the health risk of a driver compared to conventional seats. The system locates between a seat cushion and base, and is composed of a spring, MR fluid damper and controller. The MR fluid damper designed in valve mode is capable of producing a wide range of damping force according to applied currents. In experiments, a person was sitting on the controlled seat excited by a hydraulic system. The skyhook control, continuous skyhook control and relative displacement control were applied and the continuous skyhook control improved the vibration suppression by 36.6%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.117-120
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• 1995

In this machining process, variation in cutting forces results in relative displacements between the tool and the workpiece leading to tool vibration. Also there is a demand to change the depth of cut very frequently. A soluion for both cases is to develop a system which has the ability to reposition a cutting tool to a very small level, i.e., micron. This ppaper presents the development of a micropositioning system (MPS) using a magnetostrictive material. The deveoped MPS is implemented to a lathe and subjected to static and machining test. The results show that the MPS has good potential for machining application

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.82-88
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• 2006

The objective of this paper is to get excitation forces of the engine. A powertrain geometry model is produced by CATIA and its FE model is made by MSC/Patran. A vibration mode analysis which makes us know the natural frequency and mode shape and a running mode analysis which measures the mode shape as a relative displacement about one reference point by measuring the acceleration of each bracket to take a place at the running vehicle are experimentally implemented. After getting a satisfied MAC value by doing a correlation about a measured mode analysis value and analyzed value through MSC/Nastran software, all components are assembled through MSC/ADAMS software which is a dynamic analysis tool. We can predict the vibration of brackets which is the last points to occur the force of the engine combustion by analyzing the combustion force produced by engine mechanism.

• 한국정밀공학회지
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• 제15권3호
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• pp.75-81
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• 1998

In the machining process, variation in cutting forces results in relative displacements between the tool and the workpiece leading to tool vibration. Also there is a demand to change the depth of cut very frequently. One solution for the both cases is to develop a system which has the ability to reposition a cutting tool to a very small level, i.e., micron. This paper presents the development of a micropositioner using a magnetostrictive material. The developed micropositioner is implemented to a lathe and subjected to various tests. The results show that the micropositioner with a magnetostrictive actuator has good potential for machining application.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2595-2609
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• 2024

This paper introduces a base isolation system-tuned mass damper inerter (BIS-TMDI) hybrid system to the AP1000 nuclear power plant (NPP), which reduces seismic damage potential of the NPP structure. The effects of fluid-structure interaction (FSI) caused by the passive containment cooling system water storage tank (PCCWST) on NPP's seismic performance are investigated. The FSI of water tank theoretical model is considered based on the Housner's model, and a series of time history analyses are performed to prove the rationality of the proposed model. Three single-objective optimization strategies are employed to minimize the relative displacement variance and absolute acceleration variance of the upper structure, as well as the filtered energy index (FEI). Furthermore, a multi-objective optimization strategy considering all these three indexes is proposed to obtain optimal parameters of vibration control. The influence of vibration control strategies on the relative deformation and acceleration of the upper structure is explored with various water level ratios. The analytical results indicate that the proposed BIS-TMDI strategy has significantly reduced the NPP structure's seismic response. The effectiveness of the vibration control strategy is influenced by the water level ratio, emphasizing the significance of designing an appropriate water level ratio to reduce NPP structure's seismic response.

• Earthquakes and Structures
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• 제26권4호
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• pp.285-297
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• 2024

Due to the imbalanced vibration of the adjacent buildings, the pounding phenomenon occurs as a result of an insufficient gap between them. Providing enough gap between adjacent structures is the most efficient approach to preventing the pounding effect. This paper calculated the required separation gaps between adjacent buildings, including two, four, eight, twelve and twenty stories steel moment-resisting frames, and investigated their related influencing parameters such as time periods, damping ratios, and the number of bays. The linear and nonlinear dynamic time-history analyses under real seismic event records were conducted to calculate the required separation gaps by obtaining relative displacement and velocity functions of two adjacent frames. The results showed that the required separation gap increased when the time periods of adjacent frames were not the same. The resulting separation gaps values of linear and nonlinear analyses were similar only for two and four stories frames. In other frames, the resulting separation gap values of linear analyses surpassed the corresponding nonlinear analyses. Although increasing the damping ratios in adjacent frames causes a decrease in the required separation gaps, the number of bays had no significant effect on them.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.453-475
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• 2009

The literature regarding the free vibration analysis of Bernoulli-Euler and Timoshenko beams on elastic soil is plenty, but the free vibration analysis of Reddy-Bickford beams on elastic soil with/without axial force effect using the Differential Transform Method (DTM) has not been investigated by any of the studies in open literature so far. In this study, the free vibration analysis of axially loaded Reddy-Bickford beam on elastic soil is carried out by using DTM. The model has six degrees of freedom at the two ends, one transverse displacement and two rotations, and the end forces are a shear force and two end moments in this study. The governing differential equations of motion of the rectangular beam in free vibration are derived using Hamilton's principle and considering rotatory inertia. Parameters for the relative stiffness, stiffness ratio and nondimensionalized multiplication factor for the axial compressive force are incorporated into the equations of motion in order to investigate their effects on the natural frequencies. At first, the terms are found directly from the analytical solutions of the differential equations that describe the deformations of the cross-section according to the high-order theory. After the analytical solution, an efficient and easy mathematical technique called DTM is used to solve the governing differential equations of the motion. The calculated natural frequencies of one end fixed and the other end simply supported Reddy-Bickford beam on elastic soil using DTM are tabulated in several tables and figures and are compared with the results of the analytical solution where a very good agreement is observed and the mode shapes are presented in graphs.