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Health monitoring in landing gears

Skorupka Zbigniew, Tywoniuk Andrzej

Journal of KONES

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2019

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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.

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Laboratory investigations on landing gear ground reactions (load) measurement

Skorupka Z.

Journal of KONES

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2017

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Vol. 24, No. 2

225--230

EN

Ground reaction measurement in landing gear laboratory tests is used in order to gain knowledge about loads transferred to the aircraft structure. Ground reaction level is defined during aircraft design phase and it is required not to exceed limit value in real construction. Load from landing affect directly strength of aircraft structure especially mounting points what translates both strength of aircraft structure especially mounting points what translates both on safety and weight of the final design. Meeting the safety requirements is crucial in aviation regulations conformity. Landing gear ground reactions evaluation is performed during laboratory tests in order to meet the compliance with the ground load requirements assumed in design phase. Proper test method is crucial to prove the actual load. One of the methods is landing gear dynamic drop test where landing forces are measured. Force measurement is made in several ways according to test stand construction and test object specifics. In this article, three methods are described due to author’s experience in landing gear tests. Proposed techniques cover two direct and one indirect force measurements. Direct approach is based on strain gauge measurement principle. One is a strain gauge plate fixed to the ground while the second one is based on strain gauges attached to landing gear mounting nodes. Indirect approach is based on the acceleration of the tested object, which by definition is correlated with the force applied to the structure. Obtained test results allow determining the kinetic energy absorbed by landing gear during drop test. In this article author also presented numerical integration of the time history data and compared them with simulation results in order to show equivalence of all three of the test methods and to prove correctness of the test initial conditions determination.

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Landing gear dynamic tests with strain gages

Sobieszek A., Paprzycki I., Tywoniuk A.

Journal of KONES

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2015

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Vol. 22, No. 3

221--227

EN

Strain gage sensing is widely used method for measurements conducted during dynamic tests. This article describes electrical resistance strain gages performing force measurement during the tests of main and nose landing gear of medium-lift civil aircraft. It is the most common method used for measuring mechanical properties like force, pressure, stress, strain, etc. Strain gages were installed in selected areas of the Drop Test Stand. The paper presents advantages of strain gage measuring method in regards to commercially available, ready-made force sensors. Furthermore, it describes the process of selecting strain gage and load cell measurement systems (bridge, half bridge, quarter bridge) and its influence on the test results. What is more the technological process is presented, taking into account the strain gage installation adhesive technology and sensor protection against external conditions, performance of the measurement system and connection to the data acquisition system. Continuing with the process description of calibrating a load cell system for measuring the occurring forces. The article is summed up with an analysis of the problems which arise during the installation and measurement process using strain gages, and includes a description of advantages and disadvantages that occur while applying strain gages while preforming force measurement.

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Metodyka pomiarów i rejestracji obciążeń w locie statku powietrznego o konstrukcji kompozytowej

Rodzewicz M

Mechanik

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2012

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R. 85, nr 7CD

841--848

PL

W pracy zaproponowano metodykę pomiarów i rejestracji obciążeń w locie statku powietrznego konstrukcji kompozytowej, przedstawiono podstawowy cel rejestracji obciążeń w locie. Następnie odniesiono się do dotychczasowej praktyki przeprowadzania takich pomiarów oraz ograniczeń występujących na etapie akwizycji danych i sposobów ich kompensacji. Na zakończenie przedstawiono metody akwizycji danych pomiarowych do spektrum obciążeń.

EN

There is described in the paper a methodology of measurement and registration of in-fligh loads which acting on the aircraft composite structures, futher there is shown a basic purpose of the registration of loads during the flight. The reference was made to the previous practice of carrying out such measurements and constraints on the stage of data acquisition and methods for their compensation. In conclusion, presented data acquisition methods for load spectrum estimation.