Wyniki wyszukiwania - BazTech

1

Opis propagacji pęknięć zmęczeniowych w materiale łopat śmigłowców wycofanych z eksploatacji

Kłysz S., Lisiecki J., Klimaszewski S., Leski A., Gmurczyk G., Bochenek D., Bąkowski T.

Prace Naukowe Instytutu Technicznego Wojsk Lotniczych

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2013

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nr 32

75--91

PL

Przedstawiono wyniki badań i opisu analitycznego prędkości rozwoju pęknięć zmęczeniowych w materiale próbek pobranych z dźwigarów łopat wirników nośnych śmigłowców Mi-2 i Mi-8 pozyskanych z łopat wycofanych z eksploatacji. Analizę rozwoju pęknięć przeprowadzono z wykorzystaniem równania NASGRO da/dN = f(K).

2

Introduction of Fatigue Markers in Full Scale Fatigue Test of an Aircraft Structure

Leski A., Kłysz S., Lisiecki J., Gmurczyk G., Reymer P., Bochenek D., Zasada D.

Fatigue of Aircraft Structures

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2012

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Iss. 4

29--37

EN

Air Force Institute of Technology participates in the service life assessment programme SEWST. The aim of this programme, funded by the Polish Ministry of Defense, is to modify the operation system of PZL-130 "Orlik" TC-II turbo propelled trainer aircraft. The structural part of the programme is focused on the Full Scale Fatigue Test of the whole airframe to be conducted at the VZLU in the Czech Republic. The load spectrum for the test was developed by the AFIT based on the flight test results. The basic load block represents 200 simulated flight hours and consists of 194 flights showing different levels of severity. At the end of the Full Scale Fatigue Test a teardown inspection is planned during which it would be most beneficial to be able to determine crack propagation rate by means of a crack surface inspection. Markers are usually visible on most fatigue crack surfaces, however they occur randomly therefore it is almost impossible to conclude anything about the crack history. Since the preliminary load block consisted of separate flights (flight loads together with landing and taxing loads) showing significantly different levels of severity, the easiest way to modify the load block was to change the order of flights within the block. Hence a pilot programme was started at the AFIT which was focused on the determination of the influence of flight sequence on crack appearance. Several load blocks were determined using various techniques of rearranging the order of flights within the preliminary load spectrum. This approach ensured the preservation of the initial severity of the load block and simultaneously enabled a significant increase in the probability of the markers occurrence introducing neither artificial underloads nor overloads that would most probably affect the crack propagation rate. Fatigue crack surfaces were inspected using Scanning Electron Microscope. As a result of the investigations a series of images were obtained showing the specimen microstructure with visible markers arranged in the desired sequences. Based on the obtained pictures the most promising load block arrangements were chosen for the Full Scale Fatigue Test.

3

Wytworzenie i badanie elastycznej pianki poliuretanowej o ujemnym współczynniku Poissona

Lisiecki J., Błażejewicz T., Kłysz S., Gmurczyk G.

Modelowanie Inżynierskie

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2011

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T. 11, nr 42

241-248

PL

Modyfikując strukturę komórkową pianki poliuretanowej, można osiągnąć budowę auksetyczną. Odmienne właściwości użytkowe takich materiałów wynikają z ich podstawowej właściwości fizycznej, jaką jest ujemny współczynnik Poissona. Ze względu na planowane zastosowanie pianek auksetycznych na elementy siedzeń śmigłowców wojskowych, do oceny materiału na siedziska i oparcia niezbędna jest znajomość ich charakterystyk materiałowych. W Instytucie Technicznym Wojsk Lotniczych przeprowadzono próbę otrzymywania pianek auksetycznych z pianek o komórkach otwartych, a także przeprowadzono wstępne testy.

EN

By modifying the cellular structure of foam, auxetic structure can be achieved. The difference in properties are due to their basic physical property, which is a negative Poisson's ratio. Due to the planned use of auxetic foam on the seat elements of military helicopters, it is necessary to know the characteristics of those materials. Therefore, the Air Force Institute of Technology performed preparation of open cells, auxetic foams, and necessary, preliminary tests. The article describes the program, its aims and stages of implementation.

4

Global FEM model of combat helicopter

Gmurczyk G., Reymer P., Kurdelski M.

Journal of KONES

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2011

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Vol. 18, No. 2

137-144

EN

Air structures like Mi-24 were designed in last decades of the XX century, when computer aided design was not available. Philosophy of the exploitation so-called "safe life" postulate exploitation is defined by the manufacturer time. Such attitude turned out very uneconomical because of the various profiles of the use of aircrafts. Extending the initial period of exploitation is a quite common way to extend an aircrafts' life. Such solutions are accepted in the majority of countries, even the richest. In order to obtain detailed geometry of the real structure reversed engineering techniques were used. The geometry was obtained using two methods: digital photogrammetry and optical scanning using ATOS scanner from GOM Company. Geometric model, which was used for numerical Finite Element Method model, was developed based on the data from measurements, available technical documentation and detailed inspection of the structure. Global FEM model is being used for finding critical elements of aircraft's structure. Structure elements such as stringers, ribs or frames were modelled using bar and beam elements with specially defined properties and cross sections. Structure elements which didn't take part in transferring the loads, but with significant mass were made in a simplified manner so that their weight in the model correspond to actual or were modelled as concentrated masses.

5

ZL-130TCII Fracture Markers Solution for Full-Scale Fatigue Test

Kłysz S., Lisiecki J., Zasada D., Gmurczyk G., Leski A.

Fatigue of Aircraft Structures

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2011

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Iss. 3

22--27

EN

In the context of PZL-130TC-II full-scale fatigue test, several strategies of fatigue loadings that create fracture surface markings were considered. One block of spectrum is made of 200 flights. By reordering those flights, a block which should create a fracture marker, was developed. It was very important that reordering the load spectrum or adding overloads or underloads did not change spectrum severity. Pilot tests of aluminium alloys specimens were carried out to finalise appropriate marker intervals before commencing full-scale tests. The experiment was conducted with the MTS machine with 810.23 system. The results and conclusions are presented within this paper.

6

Investigations of Some Properties of Material Samples Taken from the Aircraft Withdrawn from Service

Klysz S., Gmurczyk G., Lisiecki J.

Fatigue of Aircraft Structures

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2010

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Iss. 2

52--58

EN

Materials used in aircraft structures have (should have) certificates confirming their quality. Nowadays, in majority of cases, the symbols of materials used in construction of aircraft give detailed information about their mechanical properties. This general material data is gathered in the widely available engineering material data bases. In the case of materials used in Polish aviation several decades ago, there is no reliable material data crucial for crack propagation estimation or fatigue life estimation among others. Examinations conducted in many different research institutes are not systematized and are not gathered in a remotely accessible data base. As aging aircraft are concerned, the influence of service time (often exceeding thirty years) on the overall material properties is a very important factor. It may be too crude estimation to use standard material properties when it comes to aging aircraft fleet. Some experimental works concerning this topic are published from time to time and they are always very welcome. In the Air Force Institute of Technology experimental tests were carried out to determine some specific properties of the materials used in the PZL-130 Orlik aircraft structure. The samples were obtained from aircraft withdrawn from service. This enabled estimating the difference in material properties over time. The following tests were conducted during the experiments: - fatigue tests (crack propagation examination) - static tests. The analyzed material was taken from the central upper part of the aircraft wing. The experiment was conducted with the MTS machine with the 810.23 system.