Wyniki wyszukiwania - BazTech

1

Mapowanie wiedzy na temat współdziałania różnorodnych przyczyn katastroficznego rozwoju pęknięć w samolotach jako sposób na poprawę jakości ich projektowania, wykonania i niezawodności eksploatacyjne

Dzidowski E., Dzidowski A.

Rudy i Metale Nieżelazne Recykling

|

2017

|

R. 62, nr 12

24--35

PL

Wiedza na dany temat oznacza m.in. rozumienie zasad działania mechanizmu określonego zjawiska oraz umiejętność odpowiadania na pytanie - dlaczego? W rozważanym tu przypadku idzie o wiedzę na temat przyczyn katastrof lotniczych, spowodowanych rozwojem pęknięć zmęczeniowych w materiałach stosowanych na poszycie samolotów. Wiele wskazuje na to, że związane z tym problemy wynikały głównie ze stosowania nieodpowiedniej lub nieaktualnej filozofii projektowania samolotów. Ostatnia z tych filozofii nie uwzględniała np. wielomiejscowego rozwoju krótkich pęknięć zmęczeniowych i ich nagłego łączenia się z pęknięciem dominującym, uważanym powszechnie za najbardziej istotne. Taki stan rzeczy sprawiał, że samoloty ulegały katastroficznemu zniszczeniu dużo wcześniej niż zakładał projekt. Rozwiązanie tego problemu wymaga zarówno głębszego zrozumienia złożoności przyczyn przyśpieszonego rozwoju pęknięć zmęczeniowych, jak też szerszej popularyzacji wiedzy na ten temat. Dlatego też zasadniczym celem niniejszego opracowania jest wskazanie narzędzi, które ułatwiają takie rozumienie oraz popularyzację i innowacyjne stosowanie wiedzy na powyższy temat. Narzędziami tymi są: mapowanie wiedzy oraz mapy mechanizmów pękania. Przedstawiono wyniki mapowania wiedzy na temat dotychczasowych filozofii projektowania samolotów oraz omówiono możliwości likwidacji aktualnej luki pomiędzy teorią i praktyką. Wskazano przy tym na potrzebę i znaczenie nowych kryteriów oceny i przewidywania wytrzymałości blach cienkich, osłabionych otworami pod nity. Ponadto, wykazano korzyści wynikające ze stosowania map określających obszary przyśpieszonego zarodkowania pęknięć wskutek frettingu oraz mapy zarodkowania i rozwoju pęknięć wskutek frettingu połączonego ze zmęczeniem. Znajomość takich map umożliwia bowiem opóźnianie rozwoju wielomiejscowych pęknięć zmęczeniowych, stanowiących aktualny problem lotnictwa, a w szczególności problem związany z bezpieczeństwem samolotów długo używanych. Zwrócono również uwagę na potrzebę interdyscyplinarnego podejścia do niezawodności samolotów, zarówno w fazie ich projektowania, wytwarzania, jak i eksploatacji.

EN

Knowledge about a certain subject means the ability to understand operating principles (e.g. the mechanism of a specific phenomenon), and to answer the question: why? In the case considered here, it stands for knowledge about nucleation and the catastrophic development of multi-site fatigue cracks. The issue lies in the fact that the classical fatigue crack theory has been applied too frequently in an idealistic manner. In other words, the presence of post-production cracks, as well as the presence of short (and allegedly safe) multi-site operational cracks has been disregarded or omitted in principle. Consequently, the basic objective of this paper is to indicate a tool which facilitates removal of the gaps between theory and practice, and enables knowledge to be applied in order to improve airplanes’ resistance to the catastrophic development of multi-site fatigue cracks. The tool mentioned above is knowledge mapping which makes it possible to identify the gaps between theory and practice. The development of airplane design philosophy serves as an example showing how fruitful finding such gaps, evaluating their consequences, and – subsequently – removing those consequences can be. As regards aviation, the current gap results from the lack of theory for multi-site development of short (and allegedly safe) cracks and the lack of theory for those cracks linking up with the lead crack which so far has been considered to be fully controllable. Unfortunately, those allegedly safe (as they are short) multi-site cracks may rapidly link up with the lead crack which results in a catastrophic damage to the airplane fuselage before expiry of the expected deadline for its safe operation. The paper presents a test to fill the gap specified above by means of Feddersen’s engineering method which allows for determining the residual strength of panels containing multi-site fatigue cracks and by means of the intuitive Swift’s criterion, specifying the conditions for multi-site cracks linking up with the lead crack. This is followed by an important role of fretting and corrosion as factors expediting nucleation and the development of multi-site fatigue cracks. Simultaneously, the utility of fretting maps and maps showing the interaction between fretting and fatigue has been proven, as these maps offer an opportunity to understand both the specific character and the mutual connections among those phenomena, and make it possible to determine the directions of the activities delaying the development of multi-site fatigue cracks.

2

Designing process of landing gear in 3D CAD program

Grygorcewicz P.

Journal of KONES

|

2016

|

Vol. 23, No. 3

165--170

EN

This article presents selected issues related to the design methodology of the landing gear during the construction process. The 3D modelling of the landing gear nowadays is very popular method, which simplifies the process and reduces the costs of the prototype. The author used the designing program Solid Edge ST 7. The concepts and phases of designing will be shown in this elaboration. Readers can see the problems resolved by designers and this is showing the scale of designing challenges. The landing gear consist of many parts and every of this parts needs to be design to meet the requirements of construction. Only experienced designers can effort to design landing gear because they have to acquire specific knowledge. The aim of the paper is to discuss design process from the very beginning first steps to the final version of the landing gear. All of different factors like weight, durability, resistance of the weather are taken into account when designing a prototype of the landing gear as well as economical factor of the design. It is also necessary to verify the design during its creation using experimental and laboratory test data from other similar designs. The article also subscribes some methods, which help designer to find the proper solution. The presented landing gear was designed by Landing Gear Laboratory team Institute of Aviation.

3

Analysis of electric - drive applicability in mechanical brake for the commuter class airplane

Grygorcewicz P.

Journal of KONES

|

2013

|

Vol. 20, No. 2

143--148

EN

This article presents selected issues related to the design methodology of the electric brakes during the construction process as well as other factors which are important in the design process. It is a very important issue due to affect on the airplane and automotive brake design. Nowadays when new solution of brakes is being designed there is a need to take into account various factors influencing the design such as: weight, compatibility and flexibility of use in various aircraft, reliability and durability, ease of installation and maintenance, low-cost operation and low cost components, braking efficiency, short braking distance. All of these factors are taken into account when designing a prototype of the electric brake as well as economical factor of the design. It is also necessary to verify the design during its creation using experimental and laboratory test data from other similar designs. The aim of the paper is to discuss design process from the very beginning (i.e. by comparing features of the electric brakes with other types of brakes in order to show advantages and disadvantages of chosen solution) to the creation of a working demonstrator in future. Author of the paper in his electric brake design bases on the experience of the Warsaw’s Institute of Aviation Landing Gear Department.

4

Maximization of flight time for airplane with an electrical power plant

Serokhvostov S.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

|

2001

|

nr 12

131-134

EN

Considered herein is the problem of flight time maximization for an airplane with an electrical power plant. Energy is supplied by the on-board batteries during the flight at a stationary altitude with the specified initial and final speeds. The rational control laws are searched using the Pontryagin principle of maximum. On the basis of this solution some recommendations for the power plant arrangement have been drawn up.

5

Some pecularities of the aeroelastic influence on the aerodynamic characteristics of the airplane with high aspect ratio wing

Kabin S., Nushtaev P.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

|

1999

|

nr 9

27-30

EN

It is well known, that elastic deformations could significantly influence on the aerodynamic characteristics of the modem airplane, especially on the characteristics of the airplane with high aspect ratio swept wing. If we try to obtain the maximum of economical benefit and try to diminish the weight of the construction of the airplane, the stiffness of the main elements (wing, fuselage , tail) must be diminished too, and it leads to the increase of elastic deformations and corresponding aeroelastic effects. This problem has many aspects, one of them is the follows: how to take into account the aeroelastic effects in flight dynamics modelling.