Journal articles: 'Under-platform damper'

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Zhao, Da Hai, and Jing Lin Zhang. "Vibration Control of Offshore Platform Structure with Friction Dampers." Applied Mechanics and Materials 638-640 (September 2014): 318–21. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.318.

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The performance of friction dampers to mitigate waves and earthquakes in tower-type offshore platform is investigated in this paper. Taking the offshore platform of TOWER-1 as an example, the equation of motion of offshore platform structure under earthquake and wave loads was established. The response reductions of offshore platform structure by different peak earthquakes were analyzed. The results show that the responses of the tower-type offshore platform structure under wave and earthquake could be effectively reduced by friction damper, and the energy dissipation ability of the friction damper differs in the different floors. The friction dampers give good response reductions in different peak earthquakes, and the response reductions of displacement are better than those of acceleration.

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Mirzai, Nadia M., Reza Attarnejad, and Jong Wan Hu. "Analytical investigation of the behavior of a new smart recentering shear damper under cyclic loading." Journal of Intelligent Material Systems and Structures 31, no. 4 (December 19, 2019): 550–69. http://dx.doi.org/10.1177/1045389x19888786.

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Shear recentering polyurethane friction damper is a type of passive control device, including the shape memory alloy plates, polyurethane springs, and friction devices. This damper can be employed in the shear link of an inverted Y-shaped braced frame. As the failure mode is a shear failure, in this study, the shear recentering polyurethane friction damper is proposed to remove the residual deformation of the structure that remains after a strong earthquake and causes considerable damage to the structure. The shear recentering polyurethane friction damper can help the structure to return to the initial position. Furthermore, as compared to many other dampers, this new damper is of low cost, and its assembling requires a simple technology. In order to evaluate the performance of the damper, four different cases are considered. Furthermore, the effect of each component is investigated in each case, and a finite element analysis is performed under cyclic loading using the ABAQUS platform. In addition, for the sake of comparison, the shape memory alloy plates are replaced by steel ones, and a comparison for the results demonstrates that the recentering shear dampers can significantly decrease residual deformation, while there is a large amount of residual deformation in the steel damper. Due to using the polyurethane springs, the ultimate capacity of the shear shape memory alloy polyurethane friction damper is 500 kN; however, in the shear steel polyurethane friction damper, it is only about 300 kN. Furthermore, the energy dissipation by the shear shape memory alloy polyurethane friction damper is larger than the shear steel polyurethane friction damper. The results show that the steel plates cannot effectively increase energy dissipation.

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Botto, Daniele, and Muhammad Umer. "A novel test rig to investigate under-platform damper dynamics." Mechanical Systems and Signal Processing 100 (February 2018): 344–59. http://dx.doi.org/10.1016/j.ymssp.2017.07.046.

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Wu, Qiong, Xilu Zhao, Shuai He, Wenxian Tang, and Rencheng Zheng. "A Bufferable Tuned-Mass Damper of an Offshore Platform against Stroke and Response Delay Problems under Earthquake Loads." Shock and Vibration 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/9702152.

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A tuned-mass damper (TMD) is applied to ensure the safety and stability of an offshore platform in practice; however, damper stroke and response delay problems always result in intractable performances of vibration control while exposed to large earthquake loads. Therefore, this paper proposes a bufferable TMD, a passive TMD with buffers on both sides, to improve the performance of offshore platforms subjected to large seismic waves. A comprehensive simulation and experimental study was executed to investigate the dynamic performances of the bufferable TMD, by application of a 1 : 200-scale offshore platform prototype. It is verified that the bufferable TMD can be effective in absorbing the stroke energy, while the damper exceeds limitations of motion. Meanwhile, the bufferable TMD can maintain high-response characteristics. In conclusion, the experimental results indicate that the displacement, acceleration, and frequency performances of an offshore platform can be significantly decreased, and the evaluation indices show that the method is effective in reducing overall vibration levels and maximum peak values, with the application of the bufferable damper system.

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Yang, Jiajia, Erming He, and Yaqi Hu. "Vibration Mitigation of the Barge-Type Offshore Wind Turbine with a Tuned Mass Damper on Floating Platform." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 2 (April 2018): 238–45. http://dx.doi.org/10.1051/jnwpu/20183620238.

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This paper evaluates the application of a passive control technique with a tuned mass damper on platform for the barge-type offshore wind turbine. First of all, the three degrees of freedom mathematical model for the floating wind turbine is established based on Lagrange's equations, and the Levenberg-Marquardt algorithm is adopted to estimate the parameters of the wind turbine. Then, the method of frequency tuning which is utilized in engineering projects and genetic algorithm are employed respectively to simulate the optimum parameters of the tuned mass damper. The vibration mechanism about the phase-angle difference between tuned mass damper and floating platform is analyzed. Finally, the dynamic responses of floating wind turbine with/without tuned mass damper are calculated under five typical wind and wave load cases, and the vibration mitigation effects are researched in marine environment. Partial ballast is substituted by the equal mass of tuned mass damper due to the mass of floating platform with tuned mass damper would increase obviously, which would change the design of the wind turbine, and the vibration mitigation is also simulated in five typical load cases. The results show that the suppression rate of standard deviation of platform pitch is up to 47.95%, after substituting the partial mass of ballast, the suppression rate is 50%. Therefore, the dynamic responses of the barge-type floating wind turbine would be reduced significantly when the ballast is replaced by the equal mass of the tuned mass damper on floating platform.

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Liu, Yu Li, He Yang, and Tao Gao. "Effects of Friction on Precision Forging Process of Blade with a Damper Platform." Materials Science Forum 561-565 (October 2007): 831–34. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.831.

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A blade with a damper platform, with excellent anti-vibration characteristic and high efficiency, has become one of the most important types of blades being developed in the aeronautical engines. During the precision forging process of this blade, the friction between dies and workpiece has important effects on metal flow, deformation defects, load and energy etc. So researching the effects of friction conditions on the forging process of blade with a damper platform has been a crucial problem urgent to be resolved. In this paper, the precision forging process of titanium alloy blade with a damper platform under different friction conditions has been simulated and analyzed based on the DEFORM-3D software platform. The obtained results reveal the influence laws of friction on temperature field and load-stroke curves, and provide a significant basis for determining technological parameters of the blade forging process.

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Chandrasekaran, Srinivasan, Deepak Kumar, and Ranjani Ramanathan. "Dynamic response of tension leg platform with tuned mass dampers." Journal of Naval Architecture and Marine Engineering 10, no. 2 (December 27, 2013): 149–56. http://dx.doi.org/10.3329/jname.v10i2.16184.

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Tension Leg Platform (TLP) is a taut-moored compliant offshore platform that deploys tethers under high initial pretension to counteract the excess buoyancy. TLPs show large amplitude responses under the encountered lateral forces, which challenges the serviceability of the platform in critical sea states. One of the passive control device i.e. Tuned Mass Damper (TMD) is attempted in the present study to control large amplitude motion of TLPs. In the present study, response control of TLP using single and multiple TMDs is compared. Optimized parameters of multiple tuned mass dampers (MTMD) are obtained using H2 optimization algorithm for the maximum control of the motion of the platform. Based on the studies conducted, it is seen that MTMD systems show better response control in comparison to the single TMD. Higher robustness of the MTMD system is also examined to highlight the use of MTMD over a wide range of excitation frequencies in extreme sea states.DOI: http://dx.doi.org/10.3329/jname.v10i2.16184

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Sun, Yu Hong, Qun Niu, Li Wu Nie, and Ji Gang Zhang. "Vibration Control of Offshore Platform Based on Outrigger Damping System." Applied Mechanics and Materials 351-352 (August 2013): 1112–16. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1112.

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Outrigger damping system is used in JZ20-2 north high wellhead platform, making simulation analysis to the whole structure subjected to pushing ice load by finite element software ANSYS, calculating displacement and acceleration response under different length of horizontal pole and different height of damper. The height of the damper has great influence on displacement and acceleration. The damping effect of horizontal bar length has an impact on the damping system, and the main influencing factor is the damper height, and when the height is H2 the damping effect is the most ideal.

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Peng, Y. B., Z. K. Zhang, J. G. Yang, and L. H. Wang. "Full-Scale Simulations of Magnetorheological Damper for Implementation of Semi-Actively Structural Control." Journal of Mechanics 35, no. 4 (August 2, 2018): 549–62. http://dx.doi.org/10.1017/jmech.2018.26.

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ABSTRACTFull-scale simulations of a (Magnetorheological) MR damper are carried out for revealing its hysteretic behaviors associated with implementation of semi-active control using the routine of computational fluid dynamics. By virtue of the structural symmetry of the MR damper, a two-dimensional configuration for finite element simulation is built up. Herschel-Bulkley model is employed to represent the property of the MR fluid, of which the control parameters and their relevances to the input current are addressed. Typical cases involving sinusoidal and irregular displacements, steady and transient currents loaded upon the MR damper are investigated. Numerical investigations reveal that the damper force has a positive correlation with input current, excitation amplitude and excitation frequency. The full-scale simulation is proved to exhibit a sound accuracy through the validation of experimental data. It provides a logical manner revealing the true performance of MR dampers under desirable operating modes in practice, and can be readily integrated with the gain design of the associated semi-actively controlled structure. This progress bypasses the technical challenge inherent in the traditional tests with low-frequency cyclic loadings due to the limitation of experimental setup. Besides, comparative study between two-dimensional and three-dimensional configuration simulations of the MR damper shows that former has a better applicability, which can be carried out on a low-cost platform.

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Gastaldi, Chiara, and Muzio M. Gola. "Estimation accuracy vs. engineering significance of contact parameters for solid dampers." Journal of the Global Power and Propulsion Society 1 (July 4, 2017): VLXC9F. http://dx.doi.org/10.22261/vlxc9f.

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AbstractAll numerical models of friction-damped bladed arrays require knowledge or information of contact-friction parameters. In the literature, these parameters are typically tuned so that the experimental Frequency Response Function (FRF) of a damped blade matches its numerical counterpart. It is well known that there exist multiple combinations of contact parameters capable of satisfying a given experimental-numerical FRF match. A better approach towards a finer tuning could be based on directly measuring contact forces transmitted between blade platforms through the damper: in this case friction coefficients are estimated through tangential over normal force components during those hysteresis segments which are safely identified as being in a slip condition. This has been applied by these authors to rigid bar (solid) dampers. Unfortunately, the four contact stiffness values (left and right damper-platform contact, normal and tangential) are more than the measurements available in the technique presented by these authors. Therefore, the problem is underdetermined. The purpose of this paper is twofold,i.e., to propose an alternative way to estimate contact stiffness values (i.e.thus solving the under-determinacy mentioned above) and to check the effective significance of such estimates from a practical engineering point of view. The contact parameter estimation technique proposed by these authors produces, for each contact parameter, a best-fit value and an uncertainty band. It will be shown that the uncertainty affecting each contact parameter results in an uncertainty on the equivalent damping and stiffness indicators at blade level which is lower than 5%.

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Ye, Hang, Yanrong Wang, Bin Liu, and Xianghua Jiang. "Experimental Study on the Damping Effect of Multi-Unit Particle Dampers Applied to Bracket Structure." Applied Sciences 9, no. 14 (July 20, 2019): 2912. http://dx.doi.org/10.3390/app9142912.

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Particle damping (PD) is a passive mean of vibration control in which small metallic or ceramic particles are placed inside a cavity that attached to the primary structure at the place of high vibration amplitudes. The kinetic energy of the primary structure is dissipated by non-elastic impact and friction between particles and walls. This paper represents a series of experimental investigations of the effects of multi-unit particle dampers (MUPD) attached to a bracket structure under harmonic excitation and random excitation. As a platform to investigate the particle damping characteristics under extreme acceleration environments, the bracket structure was featured by an extremely high response on the top, and its maximum acceleration exceeds 50 times gravity acceleration when the bracket structure was subjected to resonance. This broad range of acceleration conditions was far beyond the scope concerned in most previous work. The experimental results show that for a small weight penalty (no more than 8.8%), multi-unit particle damper can reduce the resonance of the primary structure by more than 50%, whether under sinusoidal excitation or random excitation. And the response of the primary structure depends on the type of cavities and filled coefficient. Layering the cavity in the direction of the main vibration can improve the damping capacity of the multi-unit particle damper. And the damper with small particle size and large number of features is suitable for vibration reduction under high acceleration conditions.

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12

Botto, D., C. Gastaldi, M. M. Gola, and M. Umer. "Experimental Study of under-platform Damper Kinematics in Presence of Blade Dynamics." IOP Conference Series: Materials Science and Engineering 302 (January 2018): 012016. http://dx.doi.org/10.1088/1757-899x/302/1/012016.

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13

Gola, M. M., and C. Gastaldi. "The Present State of “Solid” under-Platform Damper Mechanics at AERMEC - POLITO." IOP Conference Series: Materials Science and Engineering 302 (January 2018): 012017. http://dx.doi.org/10.1088/1757-899x/302/1/012017.

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Jin, S., L. Deng, J. Yang, S. Sun, D. Ning, Z. Li, H. Du, and W. H. Li. "A smart passive MR damper with a hybrid powering system for impact mitigation: An experimental study." Journal of Intelligent Material Systems and Structures 32, no. 13 (January 24, 2021): 1452–61. http://dx.doi.org/10.1177/1045389x20988085.

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This paper presents a smart passive MR damper with fast-responsive characteristics for impact mitigation. The hybrid powering system of the MR damper, composed of batteries and self-powering component, enables the damping of the MR damper to be negatively proportional to the impact velocity, which is called rate-dependent softening effect. This effect can keep the damping force as the maximum allowable constant force under different impact speed and thus improve the efficiency of the shock energy mitigation. The structure, prototype and working principle of the new MR damper are presented firstly. Then a vibration platform was used to characterize the dynamic property and the self-powering capability of the new MR damper. The impact mitigation performance of the new MR damper was evaluated using a drop hammer and compared with a passive damper. The comparison results demonstrate that the damping force generated by the new MR damper can be constant over a large range of impact velocity while the passive damper cannot. The special characteristics of the new MR damper can improve its energy dissipation efficiency over a wide range of impact speed and keep occupants and mechanical structures safe.

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Deng, Zhaoxue, Xinxin Wei, Xingquan Li, Shuen Zhao, and Sunke Zhu. "Design and multi-objective optimization of magnetorheological damper considering vehicle riding comfort and operation stability." Journal of Intelligent Material Systems and Structures 33, no. 9 (October 9, 2021): 1215–28. http://dx.doi.org/10.1177/1045389x211048223.

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Mostly, magnetorheological (MR) dampers were optimized based on individual performance, without considering the influence of structure parameters change on vehicle performance. Therefore, a multi-objective optimization scheme of MR damper based on vehicle dynamics model was proposed. The finite element method was used to analyze magnetic flux density distribution in tapered damping channel under different structure parameters. Furthermore, the damping force expression of the tapered flow mode MR damper was derived, and the damping force was introduced into the vehicle dynamics model. In order to improve the ride comfort and operation stability of the vehicle, a collaborative optimization platform combining magnetic circuit finite element analysis and vehicle dynamics model was established. Based on this platform, the optimal design variables were determined by comfort and stability sensitivity analysis. The time domain optimization objective and frequency domain optimization objective are proposed simultaneously to overcome the lack of time domain optimization objective. The results show that compared with the time domain optimization and the initial design, the suspension dynamic deflection, tire dynamic load and vehicle body vertical acceleration are decreased after the time-frequency optimization. At the same time, in the frequency domain, the amplitude of vibration acceleration in each working condition is significantly reduced.

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Hu, Hong Sheng, and Juan Wang. "Model Reference Adaptive Control for Magnetorheological Damper Subjected to High Impact Load." Advanced Materials Research 301-303 (July 2011): 436–41. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.436.

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Using the developed hardware-in-the-loop simulation platform for weapon system under impact load excitation and a novel large-scale single-ended MR damper without the accumulator, impact tests for the special designed long-stroke magnetorheological recoil damper were done and its dynamic performances under different impact loads and input current were examined in this paper. Model of damping force was established by using the model reference adaptive control method. Its dynamic performances of MR damper under model reference adaptive control strategies were analyzed by numerical simulations and tests. Experimental results show that the model reference adaptive control method could reduce its peak value of recoil damping force to 27.33% and its peak value of stroke to 48.75%, and its adjustability of damping force could be well applied for its impact resistance design of gun recoil mechanism.

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Janbazi Rokni, Hossein, and Mohammad Reza Tabeshpour. "Spectral fatigue analysis of jacket platform under wave load equipped with viscous damper." Journal of Marine Science and Technology 24, no. 3 (September 1, 2018): 855–70. http://dx.doi.org/10.1007/s00773-018-0592-9.

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He, Bingbing, Huajiang Ouyang, Shangwen He, and Xingmin Ren. "Stick–slip vibration of a friction damper for energy dissipation." Advances in Mechanical Engineering 9, no. 7 (July 2017): 168781401771392. http://dx.doi.org/10.1177/1687814017713921.

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This article studies energy dissipation of a friction damper (due to stick–slip vibration) in the context of harmonic excitation. There are numerous applications of such friction dampers in engineering. One particular example is a new kind of under-platform dry friction dampers for aero engines. The model consists of a clamped cross-like beam structure and two masses (friction dampers) in contact with the short beam of the cross. The two masses are allowed to slide along two extra short vertical clamped beams. They can exhibit three distinct dynamic regimes: pure slip, pure stick and a mixture of stick–slip relative to the short horizontal beam. The finite element method is used to obtain the numerical modes of the structure. The friction at the contact interface between the short horizontal beam and the friction dampers is assumed to follow the classical discontinuous Coulomb friction law in which the static coefficient of friction is greater than the kinetic coefficient. Modal superposition method is applied to solve the dynamic response of the structure with numerical modes. One major finding of this investigation is that there is an intermediate range of the normal contact forces (in stick–slip regime) that provides the best energy dissipation performance.

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Zhang, Yuan, Shuqing Wang, Hui Fang, Huawei Han, and Yihua Xu. "Design and Simulation of a Damper with Negative Stiffness for Vibration Mitigation from Drilling Equipment to a Semi-Submersible Platform." Shock and Vibration 2020 (July 10, 2020): 1–15. http://dx.doi.org/10.1155/2020/2605381.

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A negative-stiffness damper (NSD) that incorporates eccentric columns and high-stiffness springs is proposed for vibration mitigation from drilling equipment to a semi-submersible platform. Eccentric columns are considered as negative-stiffness elements, which can provide high static stiffness and achieve negative stiffness with hysteresis energy dissipation caused by buckling mode transition under dynamic conditions. With the assistance of high-stiffness springs, the damper possesses a hysteresis loop that can dissipate vibration energy and mitigate responses. Firstly, the hysteresis characteristics and negative stiffness of eccentric columns are analyzed. Then, the design principle of the NSD is derived, and several characteristics required for applications are investigated. In addition, an NSD system is designed for a target drilling mud pump based on measured data, and the mitigation performance is analyzed by comparing the vibration responses between cases of the proposed NSD system and the steel pedestal. The results demonstrate that the proposed system can effectively reduce the width of affected coverage and the magnitudes of vibration responses. The investigations performed in this paper not only provide the design principle of the new damper, but also prove the great potential of the proposed damper in vibration mitigation from drilling equipment to the hull of the platform.

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ZHANG, B. L., and Y. M. XU. "DELAYED FUZZY CONTROL OF OFFSHORE STEEL JACKET PLATFORMS." ANZIAM Journal 58, no. 3-4 (April 2017): 446–54. http://dx.doi.org/10.1017/s1446181117000128.

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We study a delayed fuzzy $H_{\infty }$ control problem for an offshore platform under external wave forces. First, by considering perturbations of the masses of the platform and an active mass damper, a Takagi–Sugeno fuzzy model is established. Then, by introducing time delays into the control channel, a delayed fuzzy state feedback $H_{\infty }$ controller is designed. Simulation results show that the delayed fuzzy state feedback $H_{\infty }$ controller can reduce vibration amplitudes of the offshore platform and can save control cost significantly.

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Singh, Tanuja, Megha Kalra, and Anil Kumar Misra. "Simplified probabilistic seismic assessment of dampers in tall and braced structures in buildings." Journal of Engineering, Design and Technology 18, no. 5 (January 2, 2020): 1037–52. http://dx.doi.org/10.1108/jedt-09-2019-0234.

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Purpose The paper aims to focus on adjacent buildings response, equipped with damper, to analyze the vibration reduction in the nearby buildings. The nearby buildings were also equipped with dampers. The occurrence of adjacent buildings with adequate or inadequate space in between is a common phenomenon. However, many a times not much attention is paid to provide or check gap adequacy or to connect the two buildings suitably to avoid pounding of two structures on each other. This study emphasizes the utility of providing a damper in between two adjacent buildings for better performance. Design/methodology/approach The two steel structures taken for study are prototype of two structures normally found in industrial structure such as power plant, where in one of boiler structure is often tall and braced and short structure of turbine building which is moment resistant, modeled in SAP. There could be similar such structures which are often connected to a platform or a walkway with a sliding end, so as not to transfer horizontal force to other structures. If the advantage of stiffness of tall braced structure is taken into account, shorter structure can be suitably connected to braced structure to transfer forces during seismic cases under nonlinear conditions, thereby avoiding pounding (incase gap is too less), reducing response and thus optimizing the section sizes. The structures were subjected to El Centro earthquake, to simulate MCE (which could be the other site TH scaled up as desired for real site PGA), and damper location and parameters were varied to find optimum value which offers reduced base shear, reduced top floor displacement and minimum inter story drift and highest energy absorption by fluid viscous dampers. Findings The findings show that taller structures, which are braced, have more stiffness; the effect of damper is more pronounced in reducing displacement of shorter moment resistant structure to the tune of 60%, with suitably defined Cd value which is found to be 600 KNs/m for the present study. Thus, advantage of stiffener structure is taken to leverage and reduce the displacement of shorter moment resistant structure in reducing its displacement under nonlinear conditions of seismic case. Originality/value This work shows the original findings, of the adjacent buildings response, equipped with damper, to analyze the vibration reduction on other buildings which were planned to be constructed nearby.

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Gola, Muzio M., and Tong Liu. "A direct experimental–numerical method for investigations of a laboratory under-platform damper behavior." International Journal of Solids and Structures 51, no. 25-26 (December 2014): 4245–59. http://dx.doi.org/10.1016/j.ijsolstr.2014.08.011.

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Sun, Haoding, Qing Cao, Haoxiang He, and Daxing Zhou. "Control Performance of Tuned Liquid Dampers for Construction Platform and Super Tall-Rise Building." Journal of Physics: Conference Series 2437, no. 1 (January 1, 2023): 012094. http://dx.doi.org/10.1088/1742-6596/2437/1/012094.

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Abstract To meet the engineering demand for vibration control of a super-tall integral jacking platform moulding system, a tuned liquid damper (TLD) is used for the tuned control device of the construction steel platform. An experimental method for isolating the substructure is proposed, and the effectiveness of the TLD for vibration damping control of the steel platform is verified by shaking table tests. The test results show that the dynamic response of the construction steel platform and the main body of the structure under earthquake can be suppressed simultaneously by controlling the mass ratio of TLD to the construction platform within 5%, and the displacement damping effect is good.

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Adam, Malik. "Wave-induced Force Dynamics Analysis of Tension Leg Platform." Hyperscience International Journals 2, no. 1 (March 2022): 14–25. http://dx.doi.org/10.55672/hij2022pp14-25.

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This work analyses the dynamic response of Tension Leg Platform, TLP under sea wave induced forces with the aid of fluid dynamics modified Morison equation, single degree of freedom mass spring damper theory, and the Runge-Kutta ode45. Specifically, we employ the modified Morison equation to calculate the sea wave forces acting on a cylinder hull of the TLP. Two types of sea wave characteristics are analysed including sea waves in the South China Sea to compute the waves loading on the hull. Evaluated results are incorporated into the equation of motion of the platform, modeled as a single degree of freedom mass-spring-damper system to obtain the platform displacement at x-axis direction. The results showed that the dynamic response of the platform under the influence of sea wave A exhibits a displacement of 0.02 m in the direction of wave propagation parallel to the x-axis of the platform. Meanwhile, sea wave B manifests a magnitude at least twenty times larger compared to sea wave A, resulting in 0.5 m displacement in the same axis direction. We further examine the consequence of velocity profile of sea waves on displacement and time taken for a complete vibrational cycle. A parameter-fed CFD simulation with Star-CCM+ shows clear dynamic response of the TLP when acted upon by sea wave A. Obtained results indicate the importance of materials selection for construction of the hull tendons based on the motion of the hull and gives a fair estimate for cyclic loading on the tendons throughout the life cycle of the platform.

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He, Shangwen, Wenzhen Jia, Zhaorui Yang, Bingbing He, and Jun Zhao. "Dynamics of a Turbine Blade with an Under-Platform Damper Considering the Bladed Disc’s Rotation." Applied Sciences 9, no. 19 (October 7, 2019): 4181. http://dx.doi.org/10.3390/app9194181.

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Hu, Shijie, Houxin She, Guang Yang, Chaoping Zang, and Chaofeng Li. "The Influence of Interface Roughness on the Vibration Reduction Characteristics of an Under-Platform Damper." Applied Sciences 13, no. 4 (February 7, 2023): 2128. http://dx.doi.org/10.3390/app13042128.

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Analysis of the vibration reduction characteristics of shock absorbers is crucial for engines. In this study, the fractal theory was applied to the contact surface of an under-platform damper (UPD), and the influence of the excitation force in the same and opposite directions on the roughness of the contact surface was studied. First, based on fractal geometry theory (FGT), the roughness characterization method of a UPD contact surface was proposed. Then, the friction mechanical model of the rough contact surface was established by combining it with a 3D contact mechanical model. Furthermore, a finite element dynamic model of a blade with a UPD structure was set up. Next, the harmonic balance method was used to calculate the nonlinear response characteristics of a blade under different levels of contact surface roughness. Finally, the influence of the contact surface roughness on the vibration reduction ability of a UPD under different excitation modes was analyzed. According to the simulation results, as the contact surface became rougher, the vibration suppression ability of the UPD on the blade became stronger and stronger. With the change in the centrifugal force of the UPD and the amplitude of the same/reverse excitation force, the influencing law of the contact surface roughness on the vibration suppression ability of the UPD remained unchanged, indicating that the rougher the contact surface roughness, the better the vibration suppression effect.

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Zhao, Xin, and Ai Qi. "Slotted Beam-Column Energy Dissipating Connections: Applicability and Seismic Behavior." Advances in Civil Engineering 2021 (May 20, 2021): 1–16. http://dx.doi.org/10.1155/2021/5530083.

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Energy dissipating joint can effectively strengthen the connection of prefabricated buildings. In the present study, a new slotted mild steel damper was installed at the beam end of the prefabricated structure to form as the energy-dissipating joint of the beam-column. By using ABAQUS software, a finite element (FE) analysis was conducted for the single-story-and-span of the single-frame structure with a slotted damper as energy-dissipating joint. The result shows that the damper was the first to yield in the structure and performed well in energy dissipation, indicating its reasonable design of structure and connection. The energy dissipation mainly occurred at the flange of the variable cross sections, between which beam-ribbed webs ensured the required bearing capacity and stiffness and provided a reliable connection. The hysteretic curves were obtained by analyzing the mechanical properties of the slotted damper under pure bending and pure shearing. In the OpenSees platform, the Steel02 Material model and the twoNodeLink element were used to fit the hysteretic curves; this method was employed for the parametric simulation of the slotted energy dissipation. The dynamic characteristics and seismic response of the controlled structure with slotted energy dissipating joint were also analyzed and compared with those of the uncontrolled structure in the OpenSees platform. The results show that the period of the controlled structure was prolonged and the top story acceleration decreased, indicating its effect in reducing seismic response. The shear-dependent seismic reduction ratio was about 35%, while the drift-dependent seismic reduction ratio was about 10%. The seismic performance of bottom story was better than that of the top story, and the damper has good energy dissipation performance in the bending direction. Some detailed design criteria are put forward and consequences for design on the basis of the performed simulations are shown.

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Wu, Qiong, Xilu Zhao, Rencheng Zheng, and Keisuke Minagawa. "High Response Performance of a Tuned-Mass Damper for Vibration Suppression of Offshore Platform under Earthquake Loads." Shock and Vibration 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/7383679.

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Currently, tuned-mass dampers (TMDs) are widely applied to maintain the stability of offshore platforms in hostile environments; however, the stability system of offshore platforms faces considerable challenges under critical earthquake loads of the initial period. Therefore, this study concentrated on the high response performance of a simple passive TMD system, and numerical and experimental investigations were performed using a 1 : 200-scale prototype. The obtained results indicated that the displacement, acceleration, and their power spectral density all decreased significantly for the offshore platform with the TMD system. By further analyses of its high response characteristics, it was validated that the TMD reactions can commence within the first 3 s of earthquake excitation, while the fundamental natural frequency was consistently tuned for the TMD system dependent on the dynamic magnification factor. The evaluation indices also confirmed that this method is effective in reducing the overall vibration level and the maximum peak values of the offshore platform exposed to earthquake excitations, mainly because of its high response characteristics.

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Mahmoodi, Aram, and Hamid Ahmadian. "Forced Response Vibration Analysis of the Turbine Blade with Coupling between the Normal and Tangential Direction." Shock and Vibration 2022 (February 4, 2022): 1–11. http://dx.doi.org/10.1155/2022/2413022.

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This paper is about the nonlinear dynamic of turbine blades due to the friction between blades. This paper investigates the coupling effect in an experimental turbine blade model. In this contact model, coupling between friction in tangential and normal directions and energy dissipation in the lateral direction are considered simultaneously, which has not been considered elsewhere in the contact model of the turbine blade. The mathematical model of the blade under-platform damper model is derived, and to solve nonlinear equations, the multi-harmonic balance method is used. The contact force is calculated by the alternative frequency time-domain method in this solution method. To solve nonlinear derived algebraic equations, a continuation algorithm is applied. It is shown that considering the coupling phenomenon causes the results to be different from the situation in which this physical phenomenon is ignored. To validate the algorithm of the solution, numerical results of previous references in the turbine-blade field are regenerated. Experimental analysis on the under-platform damper and turbine blade model is done to investigate the coupling effect. It is shown that the contact model with consideration with coupling effect between tangential and normal direction can predict experimental results (amplitude and frequency of resonance) most of the other contact models used in the turbine field. To accurately determine the amplitude and frequency of resonance, it is necessary to consider the coupling effect.

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Janusz, Wojciech, Roman Czyba, Grzegorz Szafrański, and Michał Niezabitowski. "Extended Modeling of Vertical Axis Motion Dynamics of VTOL Vehicle." Applied Mechanics and Materials 789-790 (September 2015): 883–88. http://dx.doi.org/10.4028/www.scientific.net/amm.789-790.883.

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Development of a reliable high-performance multirotor unmanned aerial vehicle (UAV) requires an accurate and practical model of the vehicle dynamics. This paper describes the process and results of the dynamic modeling of an unmanned aerial platform known as quadrotor. To model a vehicle dynamics, elementary physical and aerodynamical principles has been employed. Parameter estimations, from a UAV design have been obtained through direct and indirect measurements. In addition to standard configuration of VTOL (Vertical Take-Off and Landing) platform, the amortized landing gear, modeled as spring-damper system, has been added. The resulting model has been implemented in a simulation environment under MATLABs toolbox, SIMULINK. Some numerical results are presented to illustrate response of the open loop system to specific commands.

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Zhang, Jigang, Zhehao Ma, Feifei Liu, Chunwei Zhang, Pezhman Sharafi, and Maria Rashidi. "Seismic Performance and Ice-Induced Vibration Control of Offshore Platform Structures Based on the ISO-PFD-SMA Brace System." Advances in Materials Science and Engineering 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/3596094.

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Pall-typed frictional damper (PFD) has higher capacity of energy dissipation, whereas shape memory alloy (SMA) has excellent superelastic performance. Therefore, combining PFD and SMA together as a brace system has a great prospect in vibration control of structures. This paper investigates the performance of offshore platform with three structural configurations including the SMA brace system, the ISO-SMA (where ISO stands for isolation) brace system, and the ISO-PFD-SMA brace system, which are subjected to seismic and ice-induced excitations. In this study, PFD-SMA brace system is installed on the isolation layer of jacket platform, which is under earthquake excitations and ice loading. Then, the reduction of vibration is evaluated by using ANSYS program. The results show that the PFD-SMA brace system is useful in reducing the seismic response and ice-induced response of offshore platform structures; meanwhile, it also demonstrates excellent energy dissipation and hysteretic behavior.

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Mousavi, Seyed Amin, Seyed Mehdi Zahrai, and Khosrow Bargi. "Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation." Earthquake Engineering and Engineering Vibration 11, no. 4 (December 2012): 579–92. http://dx.doi.org/10.1007/s11803-012-0143-z.

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Wu, Qiong, Wei Zhao, Weiguo Zhu, Rencheng Zheng, and Xilu Zhao. "A Tuned Mass Damper with Nonlinear Magnetic Force for Vibration Suppression with Wide Frequency Range of Offshore Platform under Earthquake Loads." Shock and Vibration 2018 (August 16, 2018): 1–18. http://dx.doi.org/10.1155/2018/1505061.

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Tuned mass dampers (TMDs) are applied to ensure the safety and stability of offshore platforms; however, linear dampers are effective for a single resonance frequency, providing vibration suppression only within a narrow frequency band. Therefore, this paper proposed a magnetic TMD with two pairs of permanent magnets on both sides of the structures, which can generate a nonlinearly repulsive force, making the magnetic TMD reliable and robust in damping the oscillations of structures with wide frequency range under seismic excitations. A comprehensively numerical and experimental study was processed to investigate the dynamic performances of the proposed magnetic TMD, by application of a 1 : 200-scale prototype of the offshore platform. The results verified that the performance of the magnetic TMD can be significantly improved than that of the linear TMD, meanwhile maintaining high-speed response characteristics. The experimental results indicated that the displacement, acceleration, and frequency responses of the offshore platform can be significantly reduced; furthermore, the evaluation indices showed that the magnetic TMD system is credible in reducing the overall vibration levels and maximum peak values.

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Zhao, Tianji, and Hongjuan Chen. "Design and research on impact resistance characteristics of vector hydrophone application platform." MATEC Web of Conferences 283 (2019): 09001. http://dx.doi.org/10.1051/matecconf/201928309001.

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On the basis of the analysis of the impact resistance of the application platform of the vector hydrophone is analysed , this paper designed single-stage and two-stage vibration isolation system based on rubber damper by using its characteristics of large viscous damping coefficient, low mass and easy installation and disassembly. By comparing the output signal of vector hydrophones in the state of rigid connection and with single-stage vibration isolation system, it can be seen that under different connection conditions, the signal amplitude of the impact response of the hydrophone are also different. The results of the experiment verified the effect of vibration isolation system on impact signal and the accuracy of theoretical analysis results.

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Nur’Amirah Busu, Norasikin Mat Isa, Azian Hariri, and Mohamed Hussein. "The Comparison of P, PI and PID Strategy Performance as Temperature Controller in Active Iris Damper for Centralized Air Conditioning System." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 102, no. 2 (February 27, 2023): 143–54. http://dx.doi.org/10.37934/arfmts.102.2.143154.

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The topic of maintaining thermal comfort efficiency in the heating, ventilation and air conditioning (HVAC) sector has always been tricky due to numerous challenges. The study focused on the challenge of under-actuated zones in non – residential and commercial buildings. The active iris damper with the integration of thermal controller is proposed to control the indoor temperature. Besides, integration of PID control strategy will be a tempting control system in enhancing the thermal performance of the building. Again, the PID controller has proven good compatibility as a primary closed-loop mechanism to maintain a comfortable room temperature. The development of the control system is done through the Arduino platform with LabVIEW as the front panel and data logging platform. The Heuristic tuning method was employed to obtain optimal gains for P, PI and PID controllers. The performance of each controller was tested by observing their ability to maintain steadily at the desired temperature set point. These tests conveyed that the best controller for this application is the PID controller. It reached the desired temperature set point and maintained it even with a temperature disruption. This study indicates that an active iris damper can effectively maintain the thermal comfort performance of indoor environment with the implementation of PID strategy, thus remedying some of the problems faced by centralized air-conditioning systems.

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Lei, Zhenbo, Jingchao Wang, Tian Peng, Huili An, Lang Shen, and Tao Wang. "Vibration Control of Steel Wind Turbine Tower Using a Novel Tuned Mass Damper Refitted via Inner Platform." Shock and Vibration 2023 (March 3, 2023): 1–15. http://dx.doi.org/10.1155/2023/9119331.

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Steel large-megawatts wind turbines have the light-damping and long-period properties, resulting in the adverse vibrations under the wind loads. In this paper, a novel tuned mass damper refitted via inner platform (IP-TMD) is proposed to control the excessive vibration of steel wind turbine tower (WTT). Firstly, the dynamic equation of steel WTT controlled by the IP-TMD system is established according to the principle of virtual work, and its dynamic coefficient and frequency ratio at corresponding fixed points are deduced. Then, the optimal frequency ratio and optimal stiffness and damping coefficients are obtained by the system optimization. Furthermore, a numerical simulation research is employed to analyze the frequency-response curves and resonance mitigation effect of IP-TMD under harmonic excitation. Finally, the vibration control efficiency of IP-TMD is calculated using the Wilson-θ method under the wind loadings; the results indicated that IP-TMD is able to reduce the dynamic response of steel WTT over 45% compared with the uncontrolled WTT cases.

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Tabeshpour, Mohammad Reza, and Ebrahim Malayjerdi. "Surge Motion Passive Control of TLP with Double Horizontal Tuned Mass Dampers." International Journal of Acoustics and Vibration 26, no. 1 (March 30, 2021): 4–8. http://dx.doi.org/10.20855/ijav.2020.25.11273.

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The tension leg platform (TLP) is comprised of a buoyant hull that holds the platform's topside. A group of tendons under the columns connect the TLP to the foundation. The TLP is displaced in six degrees of freedom due to environmental loads. Tendons moor the TLP in vertical direction (heave and pitch). Surge amplitude (horizontal displacement) of TLP is greater than other degrees of freedom. Also heave motion is coupled with surge one. Therefore, it is important to introduce and implement a method to control and reduce displacement of the TLP in horizontal direction. In this paper, a passive control system (double horizontal tuned mass damper (TMD)) is used to mitigate the surge motion of TLP that is under regular waves. Also the efficiency and performance of double horizontal TMD and single horizontal TMD in reduction of surge response is compared.

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Afzal, Mohammad, Leif Kari, and Ines Lopez Arteaga. "Adaptive control of normal load at the friction interface of bladed disks using giant magnetostrictive material." Journal of Intelligent Material Systems and Structures 31, no. 8 (March 13, 2020): 1111–25. http://dx.doi.org/10.1177/1045389x20910269.

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A novel application of magnetostrictive actuators in underplatform dampers of bladed disks is proposed for adaptive control of the normal load at the friction interface to achieve the desired friction damping in the structure. Friction damping in a bladed disk depends on operating parameters, such as rotational speed, engine excitation order, nodal diameter normal contact load, and contact interface parameters, such as contact stiffness and friction coefficient. The operating parameters have a fixed value, whereas the contact interface parameters vary in an unpredictable way at an operating point. However, the ability to vary some of these parameters such as the normal contact load in a controlled manner is desirable to attain an optimum damping in the bladed disk at different operating conditions. Under the influence of an external magnetic field, magnetostrictive materials develop an internal strain that can be exploited to vary the normal contact load at the friction interface, which makes them a potentially good candidate for this application. A commercially available magnetostrictive alloy, Terfenol-D is considered in this analysis that is capable of providing magnetostrain up to 2 × 10-3 under prestress and a blocked force over 1500 N. A linearized model of the magnetostrictive material, which is accurate enough for a direct current application, is employed to compute the output force of the actuator. A nonlinear finite element contact analysis is performed to compute the normal contact load between the blade platform and the underplatform damper as a result of magnetostrictive actuation. The nonlinear contact analysis is performed for different actuator mounting configurations and the obtained results are discussed. The proposed solution is potentially applicable to adaptively control vibratory stresses in bladed disks and consequently to reduce failure due to high-cycle fatigue. Finally, the practical challenges in employing magnetostrictive actuators in underplatform dampers are discussed.

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Yu, Yang, Lixin Xu, and Liang Zhang. "Experimental Study on Variation Rules of Damping with Influential Factors of Tuned Liquid Column Damper." Shock and Vibration 2017 (2017): 1–17. http://dx.doi.org/10.1155/2017/6209205.

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A tuned liquid column damper (TLCD) is a more effective form of passive control for structural vibration suppression and may be promising for floating platform applications. To achieve good damping effects for a TLCD under actual working conditions, factors that influence the damping characteristics need to be identified. In this study, the relationships between head loss coefficients and other factors such as the total length of the liquid column, opening ratio, Reynolds number, Kc number, and horizontal length of the liquid column were experimentally investigated. By using a hydraulic vibration table, a vibration test system with large-amplitude motion simulation, low-frequency performance, and large stroke force (displacement) control is devised with a simple operation and at low cost. Based on the experimental method of uniform design, a series of experimental studies were conducted to determine the quantitative relationships between the head loss coefficient and other factors. In addition, regression analyses indicated the importance of each factor affecting the head loss coefficient. A rapid design strategy of TLCD head loss coefficient is proposed. This strategy can help people conveniently and efficiently adjust the head loss coefficient to a specified value to effectively suppress vibration.

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Sun, Yue-Ting, Yan-Dong Zhao, Bao-Lin Zhang, Wei Zhang, and Hao Su. "Recoil Control of Deepwater-Drilling Riser with Optimal Guaranteed Cost H∞ Control." Applied Sciences 12, no. 8 (April 13, 2022): 3945. http://dx.doi.org/10.3390/app12083945.

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In deepwater-drilling engineering, it is necessary to disconnect the bottom equipment of the lower marine-riser package from the blowout preventer when encountering multi-hazard environmental factors. In order to reduce the impact of recoil on the drilling platform after the sudden disconnection of the riser, in this paper, an optimal guaranteed cost H∞ recoil control problem is considered for the drilling riser. First, a three-element mass-damper-spring deepwater-drilling riser model subject to fluid discharge and heave motion of offshore platform is given. Then, an optimal guaranteed cost H∞ controller (OGCHC) is designed to suppress the recoil response of the drilling riser, and the sufficient conditions for the asymptotic stability of the closed-loop system are derived. Third, it is found through simulation results that the designed OGCHC can reduce the recoil response effectively. In order to further analyze the advantages of the OGCHC, the performance indices of the riser without active-recoil control and with optimal control (OC) and OGCHC are compared. It is shown that the average response amplitudes of three mass blocks of the riser are almost the same, while the control cost by the OGCHC is less than that by the OC. Further, under the designed recoil control, no riser compression occurs, thereby ensuring the safety of the riser system.

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Qi, Guang Xia, Rui Bin Mei, and Na Cao. "Study on Microstructure Evolution in GH4169 Alloy Blade during Finish Forging." Applied Mechanics and Materials 217-219 (November 2012): 1671–75. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1671.

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Constitutive equations and dynamic recrystallization (DRX) model of GH4169 alloy were investigated using compression tests with temperature 940(°C)-1060(°C) and strain rate 0.001(s-1)-0.1(s-1). A coupled numerical simulation between thermal-mechanical and microstructure evolution was realized through embedding the developed user subroutines into the FEM software DEFORM-3D system. The simulated results show that higher speed of upper die is useful to the DRX but much higher and lower speed of upper die go against improving the finer and uniform of grain size in the blade. Furthermore, the grains are finer and uniform in the blade body compared with those of blade rabbet and damper platform. The experimental results of microstructure under the same forging condition were studied and the average grain degrees in the blade are over 9. The calculated results of microstructure have a good agreement with the measured value from experimental data and the prediction error is less than 7.0%. Therefore, the DRX model and developed program is reliable to optimize and improve the parameters in the blade finish forging.

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Manca, Raffaele, Marco Puliti, Salvatore Circosta, Renato Galluzzi, Sergio Salvatore, and Nicola Amati. "Design and Optimization of an Active Leveling System Actuator for Lunar Lander Application." Actuators 11, no. 9 (September 13, 2022): 263. http://dx.doi.org/10.3390/act11090263.

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This work proposes a systematic methodology for designing an active leveling system (ALS) actuator for lunar landing application. The ALS actuator is integrated into an inverted tripod leg layout, exploiting a honeycomb crushable damper as a shock absorber. The proposed ALS actuator is fitted within the leg’s primary strut and features a custom permanent-magnet synchronous machine rigidly coupled with a lead screw. The actuator aims to both provide proper leg deployment functioning and compensate for the different shock absorber deformations during landing. The leg dynamic behavior is simulated through a parameterized multi-body model to investigate different landing scenarios. First, a parametric sensitivity approach is used to optimize the transmission system and the electric machine characteristics. Then, the electric motor model is numerically validated and optimized through electromagnetic finite element analysis. To validate the proposed ALS design methodology, a virtual test bench is used to assess the ALS performances under different load scenarios. It is found that the proposed methodology is able to yield a compact, well-sized actuator which is numerically validated with the EL3 platform as a case study.

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Jiang, Luo, Jie Ji, Yue Ren, Hong Wang, and Yanjun Huang. "Risk Modeling and Quantification of a Platoon in Mixed Traffic Based on the Mass-Spring-Damper Model." Journal of Advanced Transportation 2020 (July 8, 2020): 1–12. http://dx.doi.org/10.1155/2020/7475682.

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Connected and automated vehicle (CAV) technologies have great potential to improve road safety. However, an emerging type of mixed traffic flow with human-driven vehicles (HDVs) and CAVs has also arisen in recent years. To improve the overall safety of this mixed traffic flow, a novel car-following model is proposed to control the driving behaviors of the above two types of vehicles in a platoon from the perspective of a mechanical system, mass-spring-damper (MSD) system. Furthermore, a quantitative index is proposed by incorporating the psychological field theory into the MSD model. The errors of spacing and speed in the car-following processes can be expressed as the accumulation of the virtual total energy, and the magnitude of the energy is used to reflect the danger level of vehicles in the mixed platoon. At the same time, the optimization model of minimum total energy is solved under the constraints of vehicle dynamics and the mechanical characteristics of the MSD system, and the optimal solutions are used as the parameters of the MSD car-following model. Finally, a mixed platoon composed of 3 CAVs and 2 HDVs without performing lane changing is tested using the driver-in-the-loop test platform. The test results show that, in the mixed platoon, CAVs can optimally adjust the intervehicle spacing by making full use of the braking distance, which also provides sufficient reaction time for the driver of HDV to avoid rear-end collisions. Furthermore, in the early stage of the emergency braking, the spacing error is the dominant factor influencing the car-following behaviors, but in the later stage of emergency braking, the speed error becomes the decisive factor of the car-following behaviors. These results indicate that the proposed car-following model and quantitative index are of great significance for improving the overall safety of the mixed traffic flow with CAVs and HDVs.

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Umer, Muhammad, and Daniele Botto. "Measurement of contact parameters on under-platform dampers coupled with blade dynamics." International Journal of Mechanical Sciences 159 (August 2019): 450–58. http://dx.doi.org/10.1016/j.ijmecsci.2019.06.010.

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Gastaldi, Chiara, and Muzio M. Gola. "On the relevance of a microslip contact model for under-platform dampers." International Journal of Mechanical Sciences 115-116 (September 2016): 145–56. http://dx.doi.org/10.1016/j.ijmecsci.2016.06.015.

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Zhang, Feng, Li Zhang, Yanshuang Xie, Zhiyuan Wang, and Shaoping Shang. "Smoothed Particle Hydrodynamics Simulation of a Mariculture Platform under Waves." Water 13, no. 20 (October 13, 2021): 2847. http://dx.doi.org/10.3390/w13202847.

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This work investigates the dynamic behaviors of floating structures with moorings using open-source software for smoothed particle hydrodynamics. DualSPHysics permits us to use graphics processing units to recreate designs that include complex calculations at high resolution with reasonable computational time. A free damped oscillation was simulated, and its results were compared with theoretical data to validate the numerical model developed. The simulated three degrees of freedom (3-DoF) (surge, heave, and pitch) of a rectangular floating box have excellent consistency with experimental data. MoorDyn was coupled with DualSPHysics to include a mooring simulation. Finally, we modelled and simulated a real mariculture platform on the coast of China. We simulated the 3-DoF of this mariculture platform under a typical annual wave and a Typhoon Dujuan wave. The motion was light and gentle under the typical annual wave but vigorous under the Typhoon Dujuan wave. Experiments at different tidal water levels revealed an earlier motion response and smaller motion range during the high tide. The results reveal that DualSPHysics combined with MoorDyn is an adaptive scheme to simulate a coupled fluid–solid–mooring system. This work provides support to disaster warning, emergency evacuation, and proper engineering design.

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Zhang, Feng, Li Zhang, Yanshuang Xie, Zhiyuan Wang, and Shaoping Shang. "Smoothed Particle Hydrodynamics Simulation of a Mariculture Platform under Waves." Water 13, no. 20 (October 13, 2021): 2847. http://dx.doi.org/10.3390/w13202847.

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This work investigates the dynamic behaviors of floating structures with moorings using open-source software for smoothed particle hydrodynamics. DualSPHysics permits us to use graphics processing units to recreate designs that include complex calculations at high resolution with reasonable computational time. A free damped oscillation was simulated, and its results were compared with theoretical data to validate the numerical model developed. The simulated three degrees of freedom (3-DoF) (surge, heave, and pitch) of a rectangular floating box have excellent consistency with experimental data. MoorDyn was coupled with DualSPHysics to include a mooring simulation. Finally, we modelled and simulated a real mariculture platform on the coast of China. We simulated the 3-DoF of this mariculture platform under a typical annual wave and a Typhoon Dujuan wave. The motion was light and gentle under the typical annual wave but vigorous under the Typhoon Dujuan wave. Experiments at different tidal water levels revealed an earlier motion response and smaller motion range during the high tide. The results reveal that DualSPHysics combined with MoorDyn is an adaptive scheme to simulate a coupled fluid–solid–mooring system. This work provides support to disaster warning, emergency evacuation, and proper engineering design.

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Tabeshpour, Mohammad Reza, and Younes Komachi. "Rehabilitation of jacket offshore platforms using friction damper device and buckling restrained braces under extreme loads." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, no. 1 (September 28, 2017): 209–17. http://dx.doi.org/10.1177/1475090217730944.

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Some existing platforms may have some problems with probable extreme future loads such as earthquake. From economic point of view, it is preferable to retrofit and continue using of existing jackets in many cases, in comparison to a new installation. Two efficient rehabilitation methods of friction damper device and buckling restrained braces are presented and investigated numerically for seismic loads from far-fault and near-fault earthquakes. As an example, an existing four-leg service platform placed in the Persian Gulf (Ressalat) is considered and the results are presented. Because of low redundancy in jacket platforms (after buckling of compression members), it is important to investigate the effect of friction damper device on the structural behavior. Buckling restrained braces solves the law redundancy because of no buckling and no decrease in strength. The results show the high efficiency of both methods in reducing structural responses and increasing seismic performance level. Such studies are very useful for many existing jacket platforms that their lifetime is to be extended.

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Yoo, Hyeongrok, Dohyun Kim, Jeonghyun Sohn, Kyungchang Lee, and Changwon Kim. "Development of a Worker-Following Robot System: Worker Position Estimation and Motion Control under Measurement Uncertainty." Machines 11, no. 3 (March 8, 2023): 366. http://dx.doi.org/10.3390/machines11030366.

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This study proposes a sensor data process and motion control method for a mobile platform essential for transporting finished products or subsidiary materials in a smart factory. We developed a system that recognizes a fiducial marker printed on the work clothes worn by a worker, estimates the worker’s location, and follows the worker using the estimated location. To overcome the limitations of simulation-based research, gait data on a two-dimensional plane were derived through a human gait model and an error model according to the distance between the image sensor and the reference marker. The derived gait data were defined as the localization result for the worker, and a Kalman filter was used to robustly address the uncertainty of the localization result. A virtual spring-damper system was applied to follow the Mecanum wheel-based mobile platform workers. The performance of the proposed algorithm was demonstrated through comparative simulations with existing methods.

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Qu, Zhen, Dianyin Hu, and Zhiying Chen. "Contact nonlinear analysis for the under-platform dampers of blade based on a frictional energy dissipation model." Structures 30 (April 2021): 146–55. http://dx.doi.org/10.1016/j.istruc.2021.01.011.

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Journal articles on the topic 'Under-platform damper'

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