Rami Faraj, M.Sc., Eng.

Department of Intelligent Technologies (ZTI)
position: doctoral student
telephone: (+48) 22 826 12 81 ext.: 432
room: 440
e-mail: rfaraj

Recent publications
1.Faraj R., Graczykowski C., Holnicki-Szulc J., Adaptable pneumatic shock absorber, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546318795532, pp.1-11, 2018
Abstract:

Recent progress in the field of sensors, actuators, and smart materials allows the construction of more and more efficient controllable pneumatic dampers for shock absorption. Typically, such devices apply online semi-active control techniques, which utilize electromagnetic, piezoelectric, or magnetostrictive valves. As a result, they are characterized by a high efficiency of impact absorption, but simultaneously by a complicated construction and a specialized electronic system. The alternative solutions are semi-passive absorbers that ensure a similar performance by using a much simpler, low-cost construction and a less complicated adaptation mechanism. This paper introduces an adaptable semi-passive single-chamber pneumatic shock absorber, SOFT-DROP, which provides the optimal impact absorption and energy dissipation after a single reconfiguration performed at the beginning of the process. The high effectiveness of the proposed concept is proved in numerical and experimental investigations of the device. Moreover, the proposed semi-passive damper is also compared against already known pneumatic absorbers that utilize semi-active control methods. Ultimately, the device might be used in an airdrop system for delivery of light packages.

Keywords:

adaptable, semi-passive, impact absorption, optimal design, pneumatic shock absorber

Affiliations:
Faraj R.-IPPT PAN
Graczykowski C.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
2.Faraj R., Holnicki-Szulc J., Knap L., Seńko J., Adaptive inertial shock-absorber, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/25/3/035031, Vol.25, pp.035031-1-9, 2016
Abstract:

This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

Keywords:

adaptive impact absorption, adaptive inerter, semi-active control, shock-absorber

Affiliations:
Faraj R.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
Knap L.-Warsaw University of Technology (PL)
Seńko J.-Warsaw University of Technology (PL)

Conference papers
1.Faraj R., High Performance Pneumatic Shock-absorbers for aeronautical applications, ICAS 2018, 31st Congress of the International Council of the Aeronautical Sciences, 2018-09-09/09-14, Belo Horizonte (BR), pp.1-10, 2018
Abstract:

The paper is aimed at development of high performance shock-absorbers for aeronautical applications. This contribution concerns pneumatic dampers because of their lightweight, technical simplicity and low manufacturing costs. The concept of semi-passive devices is introduced and single reconfiguration technique is discussed for both single- and double-chamber shock-absorber. Presented general approach to optimal design of the semi-passive devices can be applied for design of different types of fluid-based absorbers, e.g. hydraulic or oleo-pneumatic dampers. The absorbers can be used as a suspension of light airdrop system as well as a part of landing gear of small UAV.

Affiliations:
Faraj R.-IPPT PAN
2.Graczykowski C., Faraj R., Self-adaptive fluid-based absorbers for impact mitigation and vibration damping , ISMA 2018 / USD 2018, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2018-09-17/09-19, Leuven (BE), pp.217-228, 2018
Abstract:

The paper presents development of innovative, self-adaptive, fluid-based absorbers and investigation of
their application for mitigation of impacts and forced vibrations. The considered absorbers are composed
of two chambers filled with fluid and separated by a piston equipped with a controllable valve. The valve
enables control of the fluid flow between the chambers and adjustment of the actual value of force
generated by the absorber. The aim of the research is to develop the strategy of valve control providing
self-adaptive operation of the absorber ensuring dissipation of submitted energy by using minimal value of
generated force. The paper includes description of self-adaptive impact absorber, presentation of the
control system and numerical simulation of its effectiveness in the case of impact excitation and harmonic
loading. It is concluded that self-adaptive system provides optimal mitigation of impact excitation, but its
response in the case of harmonic loading is not always optimal and requires further improvement.

Affiliations:
Graczykowski C.-IPPT PAN
Faraj R.-IPPT PAN
3.Wołejsza Z., Holnicki-Szulc J., Graczykowski C., Hinc K., Faraj R., Kowalski T., Mikułowski G., Kaźmierczak K., Wiszowaty R., Pawłowski P., Dynamics and control of adaptive airbags for UAV impact protection, ISMA 2018 / USD 2018, International Conference on Noise and Vibration Engineering / International Conference on Uncertainty in Structural Dynamics, 2018-09-17/09-19, Leuven (BE), pp.3661-3670, 2018
Abstract:

Small drones with total mass of a few kilograms are becoming more and more popular in many
applications increasing the probability of occurrence of emergency situations caused by an equipment
failure or a human error. In case of a fall from a high altitude very often it is possible to use parachute
rescue systems, which however require relatively long time for deployment and development of braking
forces. The touchdown velocity may be large enough to exceed limit accelerations for UAV equipment.
The paper presents the concept of deployable airbag systems, in particular with adaptive flow control,
which provides a possible solution to the above-mentioned problems. The paper discusses the overall
control and adaptation strategy. Simplified methods for mathematical modeling are proposed and
formulated for an example on a cylindrical airbag. The conceptual part is concluded with the presentation
of the methodology of experimental verification and results of initial tests of the integrated airbag system.

Affiliations:
Wołejsza Z.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
Graczykowski C.-IPPT PAN
Hinc K.-other affiliation
Faraj R.-IPPT PAN
Kowalski T.-Adaptronica Sp. z o.o. (PL)
Mikułowski G.-IPPT PAN
Kaźmierczak K.-IPPT PAN
Wiszowaty R.-IPPT PAN
Pawłowski P.-IPPT PAN
4.Faraj R., Graczykowski C., Mikułowski G., Wiszowaty R., Holnicki-Szulc J., Control techniques for adaptive absorbers, WCSCM, 7th World Conference on Structural Control and Monitoring, 2018-07-22/07-25, Qingdao (CN), pp.1-9, 2018
Abstract:

The paper is aimed at discussion of various control techniques developed for adaptive impact-absorbers protecting structures and machines. Different approaches to the problem of optimal damper design are presented and systems comparison is provided with the example of pneu-matic shock-absorber. The influences of selected control strategy on the absorber characteris-tics, its efficiency and adaptation capabilities are shown. The contribution includes both numerical and experimental examples. The authors highlight the fact that the final design of the device should be elaborated simultaneously with the development of dedicated control system. In some cases properly assumed architecture of the control system enables significant simplifi-cation of the absorber. The paper covers analyses of semi-passive devices with single reconfig-uration to identified excitation conditions and semi-active absorbers capable of adaptation to unknown impact loading. Adaptation mechanisms of such devices and their robustness are com-pared in reference to volatility of system parameters and variety of loading conditions. Limita-tions of smart devices (e.g. piezo-electric valve in pneumatic absorbers) used in practice for absorbers’ control are described in relevant mathematical models. Technological challenges in the design and manufacturing of absorbers are identified and methods of their overcoming are proposed.

Keywords:

Adaptive Impact Absorption, adaptive control, adaptable system, damper

Affiliations:
Faraj R.-IPPT PAN
Graczykowski C.-IPPT PAN
Mikułowski G.-IPPT PAN
Wiszowaty R.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
5.Faraj R., Popławski B., Suwała G., Jankowski Ł., Holnicki-Szulc J., Mitigation of dynamic response in frame structures by means of smart joints, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.138-144, 2017
Abstract:

This paper discusses passive and semi-active techniques of structural control by means of smart joints, and then it proposes a specific smart joints system for frame structures and tests its capability in mitigation of free vibrations. Basically, the proposed solution modifies frame beams by addition of truss-type hinges, and its effectiveness relies on the softening effect that occurs in compression due to geometric nonlinearities and which triggers the highly-damped high-frequency response modes of the structure. First, the finite element (FE) model of the specific frame structure with geometrical nonlinearities is derived, and the proposed passive joints are described and incorporated into the model. Then, their principle of operation and effectiveness is examined numerically for the first two natural modes of vibrations with various initial displacement amplitudes. An objective function is proposed to assess joints placement, based on the efficiency in mitigation of the excited vibrations.

Keywords:

Vibration Damping, Structure Response, Smart Structure, Structural Control

Affiliations:
Faraj R.-IPPT PAN
Popławski B.-IPPT PAN
Suwała G.-IPPT PAN
Jankowski Ł.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
6.Faraj R., Graczykowski C., Holnicki-Szulc J., Knap L., Seńko J., Adaptable pneumatic shock-absorber, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.1-8, 2017
Abstract:

Pneumatic dampers are still an attractive subject of research in both modelling and experimental testing. Progress in the field of sensors and actuators allows to construct more and more efficient absorbers and dampers based on active or semi-active control algorithms. However, passive and semi-passive solutions are also developed because of their lower costs and simplicity. This paper presents adaptable pneumatic shock-absorber that allows to obtain optimal impact absorption and energy dissipation by a single reconfiguration performed at the beginning of the process. The absorber is composed of two cylinders including at least one narrow rectangular slot and adequate number of outflow vents precisely shaped for certain impact scenarios. During operation of the device the air is released through overlapping slots and selected vents, which provides constant value of the generated force. As a result, the shock-absorber works as a passive device but provides minimal value of the reaction force in similar manner as semi-active system equipped with fully controllable mechanical valve. The paper presents the results of numerical simulations of adaptable shock-absorber operation and attempts of demonstrator construction aimed at conducting experimental verification of the concept.

Keywords:

Adaptable, Semi-passive, Impact Absorption, Pneumatic Shock-absorber

Affiliations:
Faraj R.-IPPT PAN
Graczykowski C.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
Knap L.-Warsaw University of Technology (PL)
Seńko J.-Warsaw University of Technology (PL)
7.Jankowski Ł., Graczykowski C., Pawłowski P., Mikułowski G., Ostrowski M., Popławski B., Faraj R., Suwała G., Holnicki-Szulc J., Adaptive Self-Protection against Shock and Vibration, Advances in Science and Technology, ISSN: 1662-0356, DOI: 10.4028/www.scientific.net/AST.101.133, Vol.101, pp.133-142, 2017
Abstract:

This contribution reviews the challenges in adaptive self-protection of structures. A proper semi-active control strategy can significantly increase structural ability to absorb impact-type loads and damp the resulting vibrations. Discussed systems constitute a new class of smart structures capable of a real-time identification of loads and vibration patterns, followed by a low-cost optimum absorption of the energy by structural adaptation. Given the always surging quest for safety, such systems have a great potential for practical applications (in landing gears, road barriers, space structures, etc.). Compared to passive systems, their better performance can be attributed to the paradigm of self-adaptivity, which is ubiquitous in nature, but still sparsely applied in structural engineering. Being in the early stages of development, their ultimate success depends on a concerted effort in facing a number of challenges. This contribution discusses some of the important problems, including these of a conceptual, technological, methodological and software engineering nature.

Keywords:

adaptive impact absorption, smart structures, semi-active control, safety engineering

Affiliations:
Jankowski Ł.-IPPT PAN
Graczykowski C.-IPPT PAN
Pawłowski P.-IPPT PAN
Mikułowski G.-IPPT PAN
Ostrowski M.-IPPT PAN
Popławski B.-IPPT PAN
Faraj R.-IPPT PAN
Suwała G.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN

Conference abstracts
1.Kowalski T., Faraj R., Graczykowski C., Hinc K., Mikułowski G., Pawłowski P., Wołejsza Z., Development of adaptive airbags for emergency landing of small uav, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.1-2, 2018
2.Faraj R., Graczykowski C., Holnicki-Szulc J., Investigations on shock-absorbers for small airdrop systems, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.1-2, 2018
3.Faraj R., Graczykowski C., Holnicki-Szulc J., Investigations on adaptable and adaptive impact absorption, ICAST2017, The 28th International Conference on Adaptive Structures and Technologies, 2017-10-08/10-11, Kraków (PL), pp.1, 2017
4.Faraj R., Graczykowski C., Holnicki-Szulc J., Knap L., Seńko J., Adaptable pneumatic shock-absorber, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.1, 2017
Abstract:

Pneumatic dampers are still an attractive subject of research in both modelling and experimental testing. Progress in the field of sensors and actuators allows to construct more and more efficient absorbers and dampers based on active or semi-active control algorithms. However, passive and semi-passive solutions are also developed because of their lower costs and simplicity. This paper presents adaptable pneumatic shock-absorber that allows to obtain optimal impact absorption and energy dissipation by a single reconfiguration performed at the beginning of the process. The absorber is composed of two cylinders including at least one narrow rectangular slot and adequate number of outflow vents precisely shaped for certain impact scenarios. During operation of the device the air is released through overlapping slots and selected vents, which provides constant value of the generated force. As a result, the shock-absorber works as a passive device but provides minimal value of the reaction force in similar manner as semi-active system equipped with fully controllable mechanical valve. The paper presents the results of numerical simulations of adaptable shock-absorber operation and attempts of demonstrator construction aimed at conducting experimental verification of the concept.

Keywords:

Adaptable, Semi-passive, Impact Absorption, Pneumatic Shock-absorber.

Affiliations:
Faraj R.-IPPT PAN
Graczykowski C.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
Knap L.-Warsaw University of Technology (PL)
Seńko J.-Warsaw University of Technology (PL)
5.Faraj R., Holnicki-Szulc J., Knap L., Seńko J., Mitigation of the structure response based on inertial shock-absorber, EACS2016, 6th European Conference on Structural Control, 2016-07-11/07-13, Sheffield (GB), pp.1, 2016
Abstract:

The goal of this paper is to present further development of the inertial shock-absorber called SPINMAN. Application of the device in mitigation of structures response is investigated and selected case study is discussed. The specific construction and operation of the device is introduced and explained. In reference to the impact absorption problems, the SPIN-MAN is a concept of adaptive inerter device with two phases of operation. The first of them includes energy absorption and accumulation. External energy of the load is converted to kinetic energy of rotational motion of the mass. During the second phase, accumulated energy is dissipated by inverse spinning of the second mass powered by the remaining part of the impact energy. To obtain this type of operation, special switchable actuators are used. Applicability of the device in mitigation of impact-born structure response, especially in case of space systems, is investigated. General concept of the device construction and operation is adjusted to meet the requirements for space systems. This results in a fluidless, passive-like solution but adaptable to the load conditions. Tuning of the shock-absorber may be realized by manual or easily automated mechanical adjustments. Effectiveness of the solution is based on the specific on/off type of control, which is responsible for the optimal energy flow in the system and efficient dissipation of impact energy inside the SPIN-MAN. Results of numerical simulations confirmed quick and effective operation of this device.

Keywords:

structure response mitigation, adaptive impact absorption, adaptive inerter, semi-active control, shock-absorber

Affiliations:
Faraj R.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
Knap L.-Warsaw University of Technology (PL)
Seńko J.-Warsaw University of Technology (PL)
6.Faraj R., Holnicki-Szulc J., Adaptive inertial shock-absorber for vibration damping, ICoEV-2015, ICoEV 2015 : IFTOMM International Conference on Engineering Vibration 2015, 2015-09-07/09-10, Ljubljana (SI), pp.1, 2015
Keywords:

Adaptive Impact Absorption, shock-absorber, vibration damping

Affiliations:
Faraj R.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
7.Holnicki-Szulc J., Faraj R., Graczykowski C., Jankowski Ł., Mikułowski G., Mróz A., Ostrowski M., Pawłowski P., Wiszowaty R., Adaptive impact absorption - potential applications for safety engineering, SMART 2015, 7th ECCOMAS Thematic Conference on Smart Structures and Materials, 2015-06-03/06-05, Ponta Delgada (PT), pp.1-2, 2015
Keywords:

Smart And Adaptive Structures, Adaptive Impact Absorption, Safety Engineering

Affiliations:
Holnicki-Szulc J.-IPPT PAN
Faraj R.-IPPT PAN
Graczykowski C.-IPPT PAN
Jankowski Ł.-IPPT PAN
Mikułowski G.-IPPT PAN
Mróz A.-IPPT PAN
Ostrowski M.-IPPT PAN
Pawłowski P.-IPPT PAN
Wiszowaty R.-IPPT PAN

Patents
Numer/data zgłoszenia patentowego
Ogłoszenie o zgłoszeniu patentowym
Twórca / twórcy
Tytuł
Kraj i Nazwa uprawnionego z patentu
Numer patentu
Ogłoszenie o udzieleniu patentu
pdf
420831
2017-03-13
BUP 21/18
2018-10-08
Faraj R., Wołejsza Z.
Konstrukcja mechanizmu do pre-rotacji wirnika nośnego oraz sposób wprawiania wirnika nośnego w stan wstępnej rotacji z zastosowaniem mechanizmu z kołem zamachowym, zwłaszcza do kapsuł zrzutowych
PL, Instytut Podstawowych Problemów Techniki PAN
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419786
2016-12-13
BUP 13/18
2018-06-18
Holnicki-Szulc J., Faraj R., Pawłowski P., Wołejsza Z., Kaźmierczak K., Hinc K.
Rozkładana konstrukcja sterowca stratosferycznego i sposób zmiany objętości, zwłaszcza rozkładanej konstrukcji sterowca stratosferycznego
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
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419285
2016-10-28
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Faraj R., Graczykowski C., Holnicki-Szulc J.
Absorber pneumatyczny o adaptowalnej charakterystyce odpowiedzi, wypełniony powietrzem atmosferycznym, zwłaszcza do łagodzenia przyziemienia zrzucanych ładunków
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
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415131
2015-12-04
BUP 12/17
2017-06-05
Holnicki-Szulc J., Knap L., Faraj R., Seńko J.
Amortyzator śrubowy
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
229926
WUP 9/18
2018-09-28



414970
2015-11-26
BUP 12/17
2017-06-05
Holnicki-Szulc J., Knap L., Faraj R., Seńko J.
Amortyzator śrubowo-rotacyjny
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
230102
WUP 9/18
2018-09-28



414367
2015-10-14
BUP 09/17
2017-04-24
Holnicki-Szulc J., Knap L., Seńko J., Faraj R.
Urządzenie do tłumienia udaru i sposób tłumienia udaru
PL, Instytut Podstawowych Problemów techniki PAN, Adaptronica Sp z o.o.
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411237
2015-02-11
BUP 17/16
2016-08-16
Holnicki-Szulc J., Mróz A., Faraj R.
Tłumik bezwładnościowy drgań
PL, Instytut Podstawowych Problemów techniki PAN, Adaptronica Sp z o.o.
227058
WUP 10/17
2017-10-31



410275
2014-11-27
BUP 12/16
2016-06-06
Holnicki-Szulc J., Faraj R., Mróz A.
Opakowanie amortyzujące uderzenia
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
225398
WUP 04/17
2016-10-21



409600
2014-09-25
BUP 07/16
2016-03-29
Holnicki-Szulc J., Mróz A., Faraj R.
Lądownik do bezpiecznych zrzutów z powietrza
PL, Instytut Podstawowych Problemów Techniki PAN, Adaptronica Sp. z o.o.
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