Wyniki wyszukiwania - Biblioteka Nauki

1

Efficiency and Fatigue/Endurance Laboratory Tests of Aviation Friction Brakes

100%

Skorupka Z.

Fatigue of Aircraft Structures

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2022

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tom Iss. 14

104--113

EN

Brakes are one of the most important safety systems in moving vehicles and machines. In vehicles such as cars or motorcycles brakes are used for stopping, controlling speed, and sometimes changing direction of travel. In aircraft, the main function of brakes is to reduce landing speed. As landing is one of the most dangerous maneuvers in aircraft operation, brakes must be efficient and reliable in order to ensure safety of the crew, passengers, and cargo. The most efficient brakes nowadays are friction brakes where velocity is controlled by friction of a pair of specially designed materials, which ensure stable and high friction coefficient over the course of the required braking process. The process itself is the dissipation of energy during aircraft movement which generates very high temperatures in friction materials during the time of the braking process. The materials and the whole brakes have to be temperature resistant, and we must ensure braking parameters are stable during the whole process. The same principle relates to the endurance/fatigue of the brake assemblies which must be durable enough to survive as high number of braking cycles as possible without any failure, which can result in fatal consequences. Every friction pair and every newly designed brake assembly must be laboratory tested for efficiency and endurance/fatigue in order to be used in an aircraft or vehicle. In this paper, we present the basic set of laboratory tests in the scope of friction materials and brake assemblies. Results of the tests are used as confirmations/proofs of proper and safe operation of the brakes for use in vehicles, especially in aircraft but also in land-based vehicles.

2

Dynamic Testing and Fatigue Analysis of the I-31P Nose Landing Gear

100%

Skorupka Z.

Fatigue of Aircraft Structures

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2023

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tom Iss.15

133--145

EN

The landing gear is a critical safety component of any aircraft, playing a key role in managing the significant loads experienced during landing and ground maneuvers. In the case of the I-31P aircraft, a redesign of the I-23 landing gear system, required comprehensive testing to validate its performance, after change of landing gear parts manufacturer and minor updates to materials and technologies. This study focuses on the dynamic testing of the I-31P nose landing gear (NLG), particularly to assess its energy dissipation and fatigue resistance under operational conditions. Dynamic tests, performed in accordance with CS-23 standards, utilized strain gauges to monitor potential stress concentrations, especially on the half-fork design. Results demonstrated that the I-31P nose landing gear meets the required safety standards, with key performance metrics such as deflection and load factors within acceptable limits. The findings also highlighted the importance of continued monitoring for potential fatigue issues, offering valuable insights for future design enhancements.

3

Lift Force Measurement in Landing Gears Dynamic Tests

100%

Skorupka Z.

Fatigue of Aircraft Structures

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2021

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tom Iss. 13

8--16

EN

As one of the key components of the aircraft in terms of both operation and safety landing gears are of special interest of the aviation regulations. During the touch down landing gears need to dissipate as much of the energy as possible maintaining the lowest volume and weight as required by the aviation design restrictions. According to the aviation regulations landing gears have to be tested in order to prove the dissipation of the calculated landing energy and to evaluate actual loads acting on the fuselage via the mounting nodes of the landing gears. The tests need to replicate the real landing conditions as closely as possible - including the lift force (or lift) acting on the aircraft during landing. The lift force during landing is not sufficient to maintain the aircraft in flight but acts as the relief force to the aircraft weight resulting in lowering loads applied to the fuselage and decreasing landing energy needed to be dissipated. The lift force or lift has to be taken into account during laboratory tests of landing gears. The lift force needs to be simulated in all of the landing gears dynamic tests: performance optimization, proof of the operation for the certification, and the fatigue evaluation. There are two main methods of applying the lift during the tests: equivalent/effective mass or direct lift application. The latter is used at the Landing Gear Laboratory of the Lukasiewicz Research Network - Institute of Aviation (where author works on daily basis). The lift is applied by the pneumatic cylinders built in the test stand. Until recently the control of the lift force value was performed indirectly by the measurement of the pressure inside the pneumatic system. Recently the experimental direct measurement system using force transducers was introduced in order to directly measure the lift force during every test. In the presented paper, the author gives an overview of the lift force measurement system including its design and the results of the preliminary use evaluation.

4

Health monitoring in landing gears

63%

Skorupka Z. , Tywoniuk A.

Journal of KONES

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2019

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tom Vol. 26, No. 1

167--174

EN

Every mechanical construction loses its properties in time due to the usage wear that leads to malfunctions and, in the end, to failure. Widely used method of failure time prediction base on extended laboratory tests where a device is tested against fatigue and wear. This method is well established but is expensive, time-consuming, and costly. Another way of failure prediction is to calculate it using advanced algorithms what is faster and cheaper but less accurate than actual tests. Furthermore, both methods are not optimal due to the principle of operation based on simplified assumptions. In such cases, it is common to make the lifespan of the safety wise devices for example landing gears much less than real in case of fatal failure not covered by the predictions. This can lead to much higher price and maintenance costs of the landing gear. Nowadays the worldwide trend is to monitor the behaviour of the devices in real time and predict failure using actual state. There are several methods of health monitoring, most of them including sensors, acquisition systems and computer software for analysis. In this article, authors describe possible landing gears health monitoring methods based on authors’ laboratory experience in sensor appliance and test data analysis. The authors also present their idea of adding health monitoring to existing landing gears where no dedicated infrastructure was initially designed.