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1.
The inerter has garnered much attention in the past two decades owing to its unique mechanical characteristics. As a substitution of the capacitance element based on the electrical-mechanical analogy, the inerter has outstanding advantages. Extensive investigations have been conducted for the development of inerter-based vibration isolation system. This paper provides a retrospective perspective and an update on the inerter's progress for vibration isolation in different fields. The advantages of inerter compared with mass element are analyzed and revealed. Some existing reviews and highly-cited papers are summarized to outline the inerter development progress. Thereafter, the inerter is reviewed in detail from the perspective of network analogy and synthesis, mechanical domain, and power flow transmission. The devices improvement and control approach are summarized. Finally, the significance of inerter research, the challenge in current studies, and promising inerter application fields are presented and discussed. This paper is closed by conclusions, which highlight the necessity of inerter research, current challenges, and future research directions.  相似文献   

2.
This paper investigates the benefits of the inerter in improving vibration suppression of milling machine tools. The traditional method for repressing the cutting vibration of milling machines includes applying passive mechanical networks that consist of masses, dampers, and springs. However, because the mass element is not a genuine two-terminal network element, the achievable performance of the passive mechanical networks might be restricted. The inerter was invented to substitute the mass element and has been successfully applied to many mechanical systems, such as vehicles and buildings. This paper extends the application of the inerter to a milling machine and discusses the resulting vibration suppression improvements. We first built a model of the milling machine via experiments, followed by applying three basic suspension layouts to the model and illustrating how the inerter can help reduce system vibration. Lastly, we conducted experiments to verify the effectiveness of the inerter in improving the manufacturing performance of the milling machine.  相似文献   

3.
Two types of passive devices, namely, negative stiffness damper (NSD) and inerter damper (ID), have been receiving growing interest in vibration isolation and suppression, because both can produce negative-slope force-displacement relationships that are similar to those associated with active control forces. Despite such a similarity, these two passive dampers possess obvious differences in their mechanical behaviors. This study aims to illustrate the similarity and difference between these two dampers in vibration isolation applications with respect to the H2 and H∞ performance. The comparative study indicates that both dampers can reduce the H∞ norm effectively; the negative stiffness devices can reduce the H2 norm as well, whereas the H2 norm cannot converge under the influence of inerter. This finding explains why a tuned-inerter damper, i.e., an inerter connected in series with a spring with proper frequency tuning, is more commonly adopted in vibration isolation. The pros and cons of both devices were further discussed.  相似文献   

4.
Vibration suppression capabilities of linear passive vibration absorbers, such as traditional tuned mass damper (TMD), and recently proposed inerter-based vibration absorbers, have been studied for multiple mechanical systems. In particular, significant performance advantages have been obtained with a specific device making use of both inerter and mass elements, namely the tuned mass damper inerter (TMDI). However, there are still countless mass-included inerter-based configurations that have not been studied, which can potentially provide more preferred dynamic properties. In this paper, an immittance-function-layout (IFL) is introduced, which can cover a large range of topological connection possibilities with both mass and inerter elements. With the recently proposed structural immittance format, a systematic approach is established to identify the most beneficial IFL type mass-included inerter-based configurations with pre-determined number of each element type. Vibration suppression performance with single-IFL type device and two parallel-connected IFLs (i.e. dual-IFL) type devices are investigated in this paper. Three optimal configurations are identified for mitigating the maximum inter-storey drift of an example 3-storey building model subjected to base excitation. With this 3-storey building model, results show that, for the optimum single-IFL configuration, the performance improvement is 7.3% compared with the optimum TMDI, and with identified beneficial dual-IFL configurations, up to 34.9% performance advantages are obtained. Furthermore, consistent performance gains are shown under real-life earthquake inputs and with a 10-storey building model using identified absorber configurations.  相似文献   

5.
In this paper a novel type of frictionless mechanical inerter device is presented, where instead of gears, motion of the flywheel is achieved using living-hinges. The design is a type of pivoted flywheel inerter inspired in part by the Dynamic Anti-resonant Vibration Isolator (DAVI) concept, which was first developed in the 1960s. Unlike the DAVI, it will be shown that the pivoted flywheel inerter has the advantage of producing balanced forces. Furthermore the use of living-hinges eliminates the need for gears or other frictional elements in the inerter mechanism. To demonstrate the utility of the new concept, a bench-top experiment was performed using a small-scale living-hinge inerter manufactured using polypropylene hinges. By estimating the experimental system parameters, the transmissibility results from the experiment could be compared to a mathematical model. These results showed that the living-hinge inerter provided an isolation effect of at least three orders of magnitude in terms of the maximum amplitude reduction from the uncontrolled system compared to that with the inerter added. Although friction was eliminated, the living-hinges did introduce additional damping, and this was found to correspond to an increase in the equivalent damping ratio for the uncontrolled system of 1.2%. It is shown that the living-hinge inerter developed in this paper fits all of the essential conditions required to be a practical inerter device. Furthermore, as it operates without mechanical friction, or fluid flow, it represents a new paradigm in experimental inerter technology.  相似文献   

6.
This work studies the advantageous features of the fluid inerter device for optimised structural control of buildings. Experimental data are first presented to characterise the fluid inerter dynamics, and validate the simplified analytical formulations. Building on these observations, the device is modelled as an inerter in parallel with a nonlinear dashpot representing a power law damping term. The latter dissipative effects are mainly induced by the pressure drops occurring in helical channels due to the fluid viscosity and density. Then, novel passive vibration control schemes are implemented for the earthquake protection of base-isolated buildings by combining the fluid inerter with a tuned mass damper system. To account for the uncertain nature of the earthquake input, the base acceleration is modelled as a Kanai–Tajimi filtered stationary random process. The optimal fluid inerter parameters, namely inertance and damping, are identified numerically by minimising stochastic performance indices relevant to displacement, acceleration, and energy-based measures of the structural response. The nonlinear damping behaviour of the fluid inerter is fully incorporated in the optimal design procedure via the statistical linearisation technique. Nonlinear response history analysis under an ensemble of 44 natural earthquake ground motions is carried out to assess the seismic performance of the system. Since inertance and damping are coupled characteristics in a real fluid inerter, design guidelines are finally outlined to determine the actual geometrical and mechanical properties of the device to achieve targeted parameters resulting from the optimisation procedure.  相似文献   

7.
This study introduces a novel particle inerter system (PIS) designed for vibration mitigation of structures. The new system comprises an inerter subsystem, a spring, and a tuned particle element, where the spring is used for tuning the particle element and the inerter subsystem is set for energy absorption and dissipation. The structural performance and the vibration mitigation effect of the PIS are assessed in terms of displacement and acceleration responses. An optimal design method is developed for a PIS under a performance-oriented design framework. Following the criterion of lightweight control, the added mass of the PIS is minimized under the constraints of target displacement and acceleration responses. A parametric analysis is performed and the robustness of the PIS for seismic response mitigation is verified. Design cases are carried out for the illustration of the proposed design method. The results show that the structural displacement and acceleration responses can be reduced significantly with the help of a PIS. Compared with the particle tuned mass damper with the same parameters, both the energy absorption and dissipation effects of the PIS are increased and the relative displacement response of the container in the PIS is reduced by the inerter subsystem. Under the same performance target, the required physical mass of the container and particles in the PIS is minimized and is significantly smaller than that of the conventional particle tuned mass damper.  相似文献   

8.
In recent years different inerter-based vibration absorbers (IVAs) emerged for the earthquake protection of building structures coupling viscous and tuned-mass dampers with an inerter device. In the three most popular IVAs the inerter is functioning either as a motion amplifier [tuned-viscous-mass-damper (TVMD) configuration], mass amplifier [tuned-mass-damper-inerter (TMDI) configuration], or mass substitute [tuned-inerter-damper (TID) configuration]. Previous work has shown that through proper tuning, IVAs achieve enhanced earthquake-induced vibration suppression and/or weight reduction compared to conventional dampers/absorbers, but at the expense of increased control forces exerted from the IVA to the host building structure. These potentially large forces are typically not accounted for by current IVA tuning approaches. In this regard, a multi-objective IVA design approach is herein developed to identify the compromise between the competing objectives of (i) suppressing earthquake-induced vibrations in buildings, and (ii) avoiding development of excessive IVA (control) forces, while, simultaneously, assessing the appropriateness of different modeling assumptions for practical design of IVAs for earthquake engineering applications. The potential of the approach to pinpoint Pareto optimal IVA designs against the above objectives is illustrated for different IVA placements along the height of a benchmark 9-storey steel frame structure. Objective (i) is quantified according to current performance-based seismic design trends using first-passage reliability criteria associated with the probability of exceeding pre-specified thresholds of storey drifts and/or floor accelerations being the engineering demand parameters (EDPs) of interest. A variant, simpler, formulation is also considered using as performance quantification the sum of EDP variances in accordance to traditional tuning methods for dynamic vibration absorbers. Objective (ii) is quantified through the variance of the IVA force. It is found that reduction of IVA control force of up to 3 times can be achieved with insignificant deterioration of building performance compared to the extreme Pareto optimal IVA design targeting maximum vibration suppression, while TID and TMDI achieve practically the same building performance and significantly outperform the TVMD. Moreover, it is shown that the simpler variant formulation may provide significantly suboptimal reliability performance. Lastly, it is verified that the efficacy of optimal IVA designs for stationary conditions is maintained for non-stationary stochastic excitation model capturing typical evolutionary features of earthquake excitations.  相似文献   

9.
The paper presents an explicit two-step calibration procedure for tuned inerter based vibration absorbers on flexible structures. It makes use of a local approximate representation of the structural response to the device force, in which the contribution of the non-resonant modes is represented approximately around the resonance frequency by a background flexibility and a background inertia term. The calibration procedure then consists of two steps. The first step calibrates an equivalent vibration absorber including the background terms, and the second step subsequently evaluates the parameters of the actual device by extracting the background flexibility and inertia parameters. The first step represents the classic idealized single degree of freedom representation of the structure, whereas the second step leads to an increase of stiffness, inertia and damping parameters of the actual device due to background flexibility of the structure. The procedure is illustrated in detail for three inerter based vibration absorbers: parallel coupling of damper and stiffness, parallel coupling of damper and inerter, and finally a device with two dampers in parallel with stiffness and inerter elements, respectively. Explicit expressions for the calibration are obtained for each device, and it is demonstrated that the procedure leads to a balanced plateau of amplification around the resonance frequency of the magnitude assumed as the basis for the device parameter calibration.  相似文献   

10.
This paper develops a unified approach for modeling and controlling mechanical systems that are constrained with general holonomic and nonholonomic constraints. The approach conceptually distinguishes and separates constraints that are imposed on the mechanical system for developing its physical structure between constraints that may be used for control purposes. This gives way to a general class of nonlinear control systems for constrained mechanical systems in which the control inputs are viewed as the permissible control forces. In light of this view, a new and simple technique for designing nonlinear state feedback controllers for constrained mechanical systems is presented. The general applicability of the approach is demonstrated by considering the nonlinear control of an underactuated system.  相似文献   

11.
A procedure is developed which uses bond graph modeling and a digital computer to determine if semi-active control can provide a suitable performance in an application where totally active control is considered. The application areas principally addressed are those in which the disturbance inputs to the system are of zero mean, i.e. shock and vibration control.The procedure is developed through examples and then generalized to systems of high order and large complexity. The procedure consists basically of designing a control strategy suitable for totally active control and then enforcing a passivity constraint on the actuating device. Experience has shown that semi-active control approaches that of totally active control in most vibration isolation applications.  相似文献   

12.
This paper investigates an application of a ball-screw inerter for mitigation of impact loadings. The problem of impact absorption is to provide a minimum reaction force that optimally decelerates and eventually stops an impacting object within the available absorber stroke. It significantly differs from vibration mitigation problems which are typical application of inerters. The paper demonstrates that the optimum absorption can be achieved by fully passive means. For known values of the object mass and inerter parameters, the obtained solution is independent of the impact velocity. The optimum passive absorption is achieved by employing a variable thread lead. As a result, two force components emerge, the typical inertance-related force and a damping-like term, and sum up to provide the optimum constant deceleration force. This result is relatively unique: conventional absorbers do not provide a constant force even with complex active control systems. Finally, an optimization problem is formulated to reduce the influence of process uncertainties (range of possible mass values, unknown friction). The results are verified and analyzed in a numerical example.  相似文献   

13.
There exist mixed deadzone-saturation input nonlinearities and output constraint in the practical implementation environment for flexible mechanical systems, and they have crucial influences on the performance of flexible systems. In this paper, two class of flexible structures are investigated and analyzed by designing the active boundary vibration control with auxiliary systems. Based on the infinite dimensional dynamic model of flexible mechanical systems, the barrier logarithmic terms are brought into the Lyapunov function and boundary vibration control laws for maintaining the output signals within the constrained region. Besides, the auxiliary terms are designed in the control laws to compensate for mixed nonlinear inputs which integrate the deadzone and saturation characteristics. With the simulation results, the theoretical analysis for the flexible mechanical systems is verified to be correct and the designed control laws are effective.  相似文献   

14.
In this paper, a novel semi-active variable admittance (VA) concept is proposed, and a seat suspension prototype with a magnetorheological fluid damper based rotary VA device is designed, manufactured, and experimentally validated. The conventional inerter with a single flywheel has a constant inertance, which can effectively improve the suspension performance by being integrated into a mechanical network with springs and dampers. The proposed rotary VA device comprises a gear reducer, two flywheels and a variable damping (VD) device which is used to connect the two flywheels. With carefully designing, the rotary VA device is compacted and is similar with a VD device in size. The rotary VA device is installed in the centre of a seat suspension's scissors structure to form a VA seat suspension. According to the test results, the equivalent inertance of the seat suspension can vary from 11.3 Kg–76.6 Kg with a 3 Hz frequency and 5 mm amplitude sinusoidal movement by changing the current from 0 A–1 A. By analysing the system characteristics, a hybrid controller with two acceleration feedbacks is proposed. Thereafter, the seat suspension and controller are validated in experiments by comparing the performance with a conventional passive seat suspension. The random vibration test shows the excellent performance of the proposed seat suspension; the frequency weighted root mean square acceleration of the seat is reduced by 43.6%, which indicates a great improvement of the ride comfort. The VA device shows great prospect in the suspension application.  相似文献   

15.
In this paper we investigate an inerter equipped with a prototype continuously variable transmission (CVT) designed for the novel tuned mass damper. Inerter enables stepless changes of inertance via varying transmission ratio of the CVT. The main difference from classical inerter is addition of CVT, hence we present its design and properties in details. Motion of the proposed CVT is oscillatory and we test it for the actual working conditions. We derive the mathematical model of the system that include dissipation via dry friction. We analyse the actual transmission ratio, internal motion resistances and identify the inertia of CVT components using energy conservation method and validate further. Finally, we apply actual working conditions and compare the experimental and numerical exciting torques of the CVT. We obtain good agreement between them, hence the proposed model is robust and gives reliable results.  相似文献   

16.
High-throughput size-based rare cell enrichment using microscale vortices   总被引：2，自引：0，他引：2  
Cell isolation in designated regions or from heterogeneous samples is often required for many microfluidic cell-based assays. However, current techniques have either limited throughput or are incapable of viable off-chip collection. We present an innovative approach, allowing high-throughput and label-free cell isolation and enrichment from heterogeneous solution using cell size as a biomarker. The approach utilizes the irreversible migration of particles into microscale vortices, developed in parallel expansion-contraction trapping reservoirs, as the cell isolation mechanism. We empirically determined the critical particle∕cell diameter D(crt) and the operational flow rate above which trapping of cells∕particles in microvortices is initiated. Using this approach we successfully separated larger cancer cells spiked in blood from the smaller blood cells with processing rates as high as 7.5×10(6) cells∕s. Viable long-term culture was established using cells collected off-chip, suggesting that the proposed technique would be useful for clinical and research applications in which in vitro culture is often desired. The presented technology improves on current technology by enriching cells based on size without clogging mechanical filters, employing only a simple single-layered microfluidic device and processing cell solutions at the ml∕min scale.  相似文献   

17.
The evaluation of exploratory search relies on the ongoing paradigm shift from focusing on the search algorithm to focusing on the interactive process. This paper proposes a model-driven formative evaluation approach, in which the goal is not the evaluation of a specific system, per se, but the exploration of new design possibilities. This paper gives an example of this approach where a model of sensemaking was used to inform the evaluation of a basic exploratory search system(s) in the context of a sensemaking task. The model suggested that, rather than just looking at simple search performance measures, we should examine closely the interwoven, interactive processes of both representation construction and information seeking. Participants were asked to make sense of an unfamiliar topic using an augmented query-based search system. The processes of representation construction and information seeking were captured and analyzed using data from experiment notes, interviews, and a system log. The data analysis revealed users’ sources of ideas for structuring representations and a tightly coupled relationship between search and representation construction in their exploratory searches. For example, users strategically used search to find useful structure ideas instead of just accumulating information facts. Implications for improving current search systems and designing new systems are discussed.  相似文献   

18.
In data fusion, the linear combination method is a very flexible method since different weights can be assigned to different systems. However, it remains an open question which weighting schema should be used. In some previous investigations and experiments, a simple weighting schema was used: for a system, its weight is assigned as its average performance over a group of training queries. However, it is not clear if this weighting schema is good or not. In some other investigations, different numerical optimisation methods were used to search for appropriate weights for the component systems. One major problem with those numerical optimisation methods is their low efficiency. It might not be feasible to use them in some situations, for example in some dynamic environments, system weights need to be updated from time to time for reasonably good performance. In this paper, we investigate the weighting issue by extensive experiments. The key point is to try to find the relation between performances of component systems and their corresponding weights which can lead to good fusion performance. We demonstrate that a series of power functions of average performance, which can be implemented as efficiently as the simple weighting schema, is more effective than the simple weighting schema for the linear data fusion method. Some other features of the power function weighting schema and the linear combination method are also investigated. The observations obtained from this study can be used directly in fusion applications of component retrieval results. The observations are also very useful for optimisation methods to choose better starting points and therefore to obtain more effective weights more quickly.  相似文献   

19.
We used two simple control laws based on linear velocity and cubic velocity feedback to suppress the high-amplitude vibrations of a structural dynamic model of the twin-tail assembly of an F-15 fighter when subjected to primary resonance excitations. We developed the nonlinear differential equations of motion and obtained an approximate solution using the method of multiple scales. Then, we conducted bifurcation analyses for the open- and closed-loop responses of the system and investigated theoretically the performance of the control strategies. The theoretical findings indicate that the control laws lead to effective vibration suppression and bifurcation control. Furthermore, we conducted experiments to verify the theoretical analysis. We built a digital control system that consists of a SIMULINK modeling software and a dSPACE controller installed in a personal computer. Actuators made of piezoelectric ceramic material were used. The results show that both laws are effective at suppressing the vibrations. To compare the performance of both techniques, we calculated the power requirements for a simple system.  相似文献   

20.
The advent of new information technology has radically changed the end-user computing environment over the past decade. To enhance their management decision-making capability, many organizations have made significant investments in business intelligence (BI) systems. The realization of business benefits from BI investments depends on supporting effective use of BI systems and satisfying their end user requirements. Even though a lot of attention has been paid to the decision-making benefits of BI systems in practice, there is still a limited amount of empirical research that explores the nature of end-user satisfaction with BI systems. End-user satisfaction and system usage have been recognized by many researchers as critical determinants of the success of information systems (IS). As an increasing number of companies have adopted BI systems, there is a need to understand their impact on an individual end-user's performance. In recent years, researchers have considered assessing individual performance effects from IS use as a key area of concern. Therefore, this study aims to empirically test a framework identifying the relationships between end-user computing satisfaction (EUCS), system usage, and individual performance. Data gathered from 330 end users of BI systems in the Taiwanese electronics industry were used to test the relationships proposed in the framework using the structural equation modeling approach. The results provide strong support for our model. Our results indicate that higher levels of EUCS can lead to increased BI system usage and improved individual performance, and that higher levels of BI system usage will lead to higher levels of individual performance. In addition, this study's findings, consistent with DeLone and McLean's IS success model, confirm that there exists a significant positive relationship between EUCS and system usage. Theoretical and practical implications of the findings are discussed.  相似文献   

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