Partner: Jacek Bajkowski

Warsaw University of Technology (PL)

Recent publications
1.Bajkowski J.M., Dyniewicz B., Bajer C.I., Semi-active damping strategy for beams system with pneumatically controlled granular structure, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2015.09.026, Vol.70-71, pp.387-396, 2016
Abstract:

The paper deals with a control method for semi-active damping of a double beam system with a smart granular structure placed in a thin silicone envelope. The damping properties of the system are controlled pneumatically, by subjecting the granular material to underpressure at particular moments. A mathematical model of the layered beam with a granular damping structure is represented by the two degrees of freedom, modified Kelvin–Voigt model of two masses, a spring with controllable stiffness, and a viscous damper with a variable damping coefficient. The optimal control problem is posed, using the concept of switching of the parameters to increase the efficiency of suppressing the displacement׳s amplitude. The resulting control strategy was verified experimentally for free vibrations of a cantilever system. The research proved that the appropriate, periodic switching of the properties of the considered structure enables reducing the vibration more effectively than if the material is treated passively.

Keywords:

Granular materials, Smart materials, Adaptive control, Vibration damping

Affiliations:
Bajkowski J.M.-Warsaw University of Technology (PL)
Dyniewicz B.-IPPT PAN
Bajer C.I.-IPPT PAN
2.Pisarski D., Bajer C.I., Dyniewicz B., Bajkowski J.M., Vibration control in smart coupled beams subjected to pulse excitations, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2016.05.050, Vol.380, pp.37-50, 2016
Abstract:

In this paper, a control method to stabilize the vibration of adjacent structures is presented. The control is realized by changes of the stiffness parameters of the structure׳s couplers. A pulse excitation applied to the coupled adjacent beams is imposed as the kinematic excitation. For such a representation, the designed control law provides the best rate of energy dissipation. By means of a stability analysis, the performance in different structural settings is studied. The efficiency of the proposed strategy is examined via numerical simulations. In terms of the assumed energy metric, the controlled structure outperforms its passively damped equivalent by over 50 percent. The functionality of the proposed control strategy should attract the attention of practising engineers who seek solutions to upgrade existing damping systems.

Keywords:

vibration, damping, smart materials, control, semi-active

Affiliations:
Pisarski D.-IPPT PAN
Bajer C.I.-IPPT PAN
Dyniewicz B.-IPPT PAN
Bajkowski J.M.-Warsaw University of Technology (PL)
3.Bajkowski J.M., Bajer C.I., Dyniewicz B., Pisarski D., Vibration control of adjacent beams with pneumatic granular coupler: an experimental study, Mechanics Research Communications, ISSN: 0093-6413, DOI: 10.1016/j.mechrescom.2016.10.005, Vol.78, pp.51-56, 2016
Abstract:

A novel type of pneumatic device filled with granular material is proposed in the implementation of a switched control strategy to stabilize the vibration of slender structures. The analytically obtained control law for the airtight, elastic, granular coupler is implemented in a test structure with a relay-type control logic. In the experiment, the deformable granular coupler semi-actively damps an initially deflected pair of adjacent, aluminum beams. Two cases of initial excitation are considered, showing an improvement of up to 33 percent in vibration abatement efficiency compared to the passive case. Although this semi-active device is conceptually simple, its ease of operation and low cost should attract the attention of engineers who seek solutions that can be used to build new structures and upgrade existing ones.

Affiliations:
Bajkowski J.M.-Warsaw University of Technology (PL)
Bajer C.I.-IPPT PAN
Dyniewicz B.-IPPT PAN
Pisarski D.-IPPT PAN
4.Pisarski D., Szmidt T., Bajer C.I., Dyniewicz B., Bajkowski J.M., Vibration Control of Double-Beam System with Multiple Smart Damping Members, SHOCK AND VIBRATION, ISSN: 1070-9622, DOI: 10.1155/2016/2438902, Vol.2016, pp.2438902-1-14, 2016
Abstract:

A control method to stabilize vibration of a double cantilever system with a set of smart damping blocks is designed and numerically evaluated. The externally controlled magnetorheological sheared elastomer damping block is considered, but other smart materials can be used as well. The robust bang-bang control law for stabilization the bilinear system is elaborated. The key feature of the closed loop controller is the efficiency for different types of initial excitement. By employing the finite element model, the performance of the controller is validated for strong wind blow load and concentrated impact excitement of the particular point of one of the beams. For each of the excitations, the closed loop control outperforms the optimal passive damping case by over 27% for the considered energy metric.

Affiliations:
Pisarski D.-IPPT PAN
Szmidt T.-IPPT PAN
Bajer C.I.-IPPT PAN
Dyniewicz B.-IPPT PAN
Bajkowski J.M.-Warsaw University of Technology (PL)
5.Dyniewicz B., Bajkowski J.M., Bajer C.I., Semi-active control of a sandwich beam partially filled with magnetorheological elastomer, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2015.01.032, Vol.60-61, pp.695-705, 2015
Abstract:

The paper deals with the semi-active control of vibrations of structural elements. Elastomer composites with ferromagnetic particles that act as magnetorheological fluids are used. The damping coefficient and the shear modulus of the elastomer increases when it is exposed to an electro-magnetic field. The control of this process in time allows us to reduce vibrations more effectively than if the elastomer is permanently exposed to a magnetic field.

First the analytical solution for the vibrations of a sandwich beam filled with an elastomer is given. Then the control problem is defined and applied to the analytical formula. The numerical solution of the minimization problem results in a periodic, perfectly rectangular control function if free vibrations are considered. Such a temporarily acting magnetic field is more efficient than a constantly acting one. The surplus reaches 20–50% or more, depending on the filling ratio of the elastomer. The resulting control was verified experimentally in the vibrations of a cantilever sandwich beam.

The proposed semi-active control can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.

Keywords:

Semi-active control, Beam vibration, Magnetorheological elastomer, Sandwich beam, Damping

Affiliations:
Dyniewicz B.-IPPT PAN
Bajkowski J.M.-Warsaw University of Technology (PL)
Bajer C.I.-IPPT PAN
6.Bajkowski J.M., Dyniewicz B., Bajer C.I., Damping properties of a beam with vacuum-packed granular damper, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2014.12.036, Vol.341, pp.74-85, 2015
Abstract:

An experimental study of the properties of a layered beam partially treated with a damping element based on a granular material is presented. The beam structure comprises two aluminium face strips connected at the tip by a hermetic, elastic envelope, filled with bulk granules. Changing the underpressure value inside the airtight envelope allows variation of the mechanical properties of such a complex system, like stiffness or damping coefficients. Four types of granules, different in size, shape, and material, were examined to find the most promising one. A detailed discussion of the experimental amplitude, frequency, and damping capacity of the cantilever is given. The Zener, Kelvin–Voigt, and classic Maxwell models were employed for modelling and parameter identification. The range of applicability and limitations of the proposed solution has been given, as well as the benefits from the application.

Keywords:

Granular materials, smart materials, vibrations

Affiliations:
Bajkowski J.M.-Warsaw University of Technology (PL)
Dyniewicz B.-IPPT PAN
Bajer C.I.-IPPT PAN
7.Bajkowski J.M., Rezonanse wewnętrzne w nieliniowych układach drgających. Część I, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.15, pp.1-21, 1984
8.Bajkowski J.M., Szemplińska-Stupnicka W., Rezonanse wewnętrzne w nieliniowych układach drgających. Część II, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.23, pp.1-23, 1984
9.Bajkowski J.M., Szemplińska-Stupnicka W., Zagadnienie rezonansów wewnętrznych w nieliniowych układach drgających, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.19, pp.1-44, 1982
10.Szemplińska-Stupnicka W., Bajkowski J.M., Multi-harmonic Response in the Regions of instability on Harmonic Solution in Multi-degree-of-freedom Nonlinear Systems, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.15, pp.1-24, 1979
11.Bajkowski J.M., Program analogowy i układ pomiarowo-rejestrujący do automatycznego wyznaczania obszarów niestateczności układów dynamicznych, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.3, pp.1-31, 1978
12.Bajkowski J.M., Niezgodzki Paweł, Nowaczek W., Model analogowy silnika asynchronicznego, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.35, pp.1-28, 1978
13.Bajkowski J.M., Obszary przyciągania rezonansów pobocznych w nieliniowych układach drgających (Praca doktorska), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.6, pp.1-140, 1977
14.Bajkowski J.M., Orkan-Łęcki K., Wyznaczanie obszarów niestateczności dynamicznej za pomocą maszyn analogowych i automatycznego układu pomiarowo-rejestrującego, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.42, pp.1-22, 1977
15.Szemplińska-Stupnicka W., Bajkowski J.M., Obszary przyciągania nieliniowych rezonansów prawie, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.53, pp.1-75, 1974

List of recent monographs
1.
372
Bajer C.I., Dyniewicz B., Pisarski D., Bajkowski J.M., Vibration control with smart materials, IPPT PAN, pp.1-240, 2015

Conference papers
1.Dyniewicz B., Bajkowski J.M., Bajer C.I., Smart control in vibrations of structures, 6WCSCM, 6th World Conference on Structural Control and Monitoring, 2014-07-15/07-17, Barcelona (ES), pp.2227-2241, 2014
Abstract:

A semi-active control of structural vibrations is presented as an efficient method of damping. We consider structures subjected to a load applied in stationary points or to a moving load. We claim that the periodically switched magnetorheological actuators, controlled dampers, or elastic envelopes filled with granular materials subjected to controlled underpressure, give a more efficient vibration reduction than a permanently activated ones. In our work we show the efficiency of such a control strategy applied to a beams under moving inertial load, cantilevers and rotating shaft. The mathematical analysis allowed as to propose the particular control strategy. The finite element simulation, together with the solution for the control problem, proved that the damping devices should act only for a short period of each cycle of vibration. The control function depends on the type of the structure, excitation and the type of vibrations. The efficiency of the concept was proved in the experimental tests. The considered structures exhibit the reduction of amplitudes at the range 10-40% in the periodically controlled case, in comparison to the constant damping.

Keywords:

Mechanical vibrations, semi-active control, smart materials

Affiliations:
Dyniewicz B.-IPPT PAN
Bajkowski J.M.-Warsaw University of Technology (PL)
Bajer C.I.-IPPT PAN

Conference abstracts
1.Bajkowski J.M., Dyniewicz B., Bajer C.I., Smart materials in semi-active controlled structures, ETAMM, Emerging Trends in Applied Mathematics and Mechanics, 2016-05-30/06-03, Perpignan (FR), pp.84, 2016
2.Dyniewicz B., Bajer C.I., Bajkowski J.M., Vibration abatement using layered structures with smart core, XXIV Francusko-Polskie Seminarium Mechaniki, 2016-10-17/10-18, Warszawa (PL), pp.20-21, 2016