A new cutting tool is always well-defined and sharp at the onset of the metal cutting process and gradually losses these properties as the machining process advances. Similarly, at the beginning of the machining process, amplitude of tool vibrations is considerably low and it increases gradually and peaks at the end of the service period of the cutting tool while machining. It is significant to provide a corresponding real-time varying damping to control this chatter, which directly influences accuracy and quality of productivity. This paper aims to review the literature related to the application of smart fluid to control vibration in metal cutting and also focused on the challenges involved in the implementation of active control system during machining process.,Smart dampers, which are used as semi-active and active dampers in metal cutting, were reviewed and the research studies carried out in the field of the magnetorheological (MR) damper were concentrated. In smart materials, MR fluids possess some disadvantages because of their sedimentation of iron particles, leakage and slow response time. To overcome these drawbacks, new MR materials such as MR foam, MR elastomers, MR gels and MR plastomers have been recommended and suggested. This review intents to throw light into available literature which exclusively deals with controlling chatter in metal cutting with the help of MR damping methods.,Using an MR damper popularly known for its semi-active damping characteristics is very adaptable and flexible in controlling chatter by providing damping to real-time amplitudes of tool vibration. In the past, many researchers have attempted to implement MR damper in metal cutting to control vibration and were successful. Various methods with the help of MR fluid are illustrated.,A new cutting tool is always well-defined and sharp at the onset of metal cutting process and gradually losses these properties as the machining process advances. Similarly, at the beginning of the machining process, amplitude of tool vibrations is considerably low and it increases gradually and peaks at the end of service period of cutting tool while machining. Application of MR damper along with the working methodology in metal cutting is presented, challenges met are analyzed and a scope for development is reviewed.,This study provides corresponding real-time varying damping to control tool vibration which directly influences accuracy and quality of productivity. Using an MR damper popularly known for its semi-active damping characteristics is very adaptable and flexible in controlling chatter by providing damping to real-time amplitudes of tool vibration.,This study attempts to implement smart damper in metal cutting to control vibrations.,It is significant to provide corresponding real-time varying damping to control tool vibration which directly influences accuracy and quality of productivity.

Application of smart fluid to control vibration in metal cutting: a review

A Smith predictor-Taylor series-based LQG (STLQG) control to compensate time delay of a semiactive suspension system is newly presented. This control consists of a Taylor series-based LQG (TLQG) control and a Smith predictor based on the TLQG. The TLQG control compensates one half of time delay to decrease magnification from whole time delay compensation. The Smith predictor based on the TLQG compensates the other half to decrease horizontal shift from whole time delay compensation using the Smith predictor-based LQG. Finally, a practical case illustrates advantages of the STLQG control.

/pdf/smith-predictor-taylor-series-based-lqg-control-for-time-109osr9j6p.pdf

Smith Predictor-Taylor Series-Based LQG Control for Time Delay Compensation of Vehicle Semiactive Suspension

The high heat induced by fire can substantially decrease the load-bearing capacity, which is more critical in unprotected steel structures than concrete reinforced structures. One of the conventional steel structures is a steel-plate shear wall (SPSW) in which thin infill steel plates are used to resist against the lateral loads. Due to the small thickness of infill plates, high heat seems to dramatically influence the lateral load-bearing capacity of this type of structures. Therefore, this study aims to provide an investigation into the performance of SPSW with reduced beam section at high temperature.,In the present paper, to examine the seismic performance of SPSW at high temperature, 48 single-span single-story steel frames equipped with steel plates with the thicknesses of 2.64 mm, 5 mm and 7 mm and yield stresses of 85 MPa, 165 MPa, 256 MPa and 300 MPa were numerically modeled. Furthermore, their behavioral indices, namely, strength, stiffness, ductility and hysteresis behavior, were studied at the temperatures of 20, 458, 642 and 917? The simulated models in the present paper are based on the experimental specimen presented by Vian and Bruneau (2004).,The obtained results revealed that the high heat harshly diminishes the seismic performance of SPSW so that the lateral strength is reduced even by 95% at substantially high temperatures. Therefore, SPSW starts losing its strength and stiffness at high temperature such that it completely loses its capacity of strength, stiffness and energy dissipation at the temperature of 917? Moreover, it was proved that by separating the percentage of their participations variations of the infill plate in SPSW, their behavior and the bare frame can be examined even at high temperatures.,To the best of the authors’ knowledge, the seismic performance of SPSW at different temperatures has not been evaluated and compared yet.

Performance of steel-plate shear wall at high temperature

Seismic reliability research of continuous girder bridge considering fault-tolerant semi-active control

Taking a twelve-layer RCF-SW structure as an example, the three-dimensional calculation model program of uncontrolled and MRD controlled RCF-SW structure was developed by MATLAB software. The simulation results of the model program are compared with those of the finite element model established by ANSYS software. The results show that the three-dimensional calculation model program of uncontrolled and MRD controlled RCF-SW structure can simulate the dynamic response and damping effect of the structure well. The displacement response of the RCF-SW structure controlled by MRD is smaller than those of the uncontrolled structure at the corresponding time, except for individual time periods.

Research on vibration reduction of high-rise RC frame-shear wall structure controlled by magnetorheological dampers

Time-delay of magnetorheological elastomer bearing (MRB) can bring structural response menace to bridges. This paper investigates a bridge pier-bearing semi-active-coupling control method based on model predictive control (MPC). The presented strategy takes the structure prediction model to predict the state responses of the controlled plant in a period of future time. Then, the control law can be determined by solving a finite horizon optimization problem. The peak shearing force of pier top, the displacement and the acceleration of beam are chosen as control goals, and the vibration isolation rate is applied to characterize the vibration isolation effect. It is noted that MPC method naturally takes the time-delay and uncertain interference into consideration, and significantly improves the control performance of the system. Finally, the numerical example is described and the seismic response of isolated bridge based on MRB is analyzed. The simulation results show that predictive control can be used to control the time-delay of bridge system in different degrees. The best control performance is at 0.4 s. Even if the time-delay reaches 2 s, it is still good. Therefore, the control method significantly reduces the adverse effects of time-delay on the system, and has a good vibration isolation performance.

WU Mengjuan (吴孟娟)

Papers

Semi-Active Predictive Control of Isolated Bridge Based on Magnetorheological Elastomer Bearing