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EN
The study investigates the sensitivity of numerical crack propagation estimations based on the Nasgro equation. The equation is widely used for crack propagation calculations since it considers the whole range of crack propagation speed from threshold to critical values of stress intensity factor range (∆K). The presented investigation is based on the actual results of the full scale fatigue test (FSFT) of the PZL-130 ‘Orlik’ TC-II aircraft. We provide a brief description of the test and the general approach followed in crack propagation estimations originally carried out after the test. The obtained results are verified in terms of variation of the input data. Overall results are compared and discussed.
EN
The Su-22 fighter-bomber is a military aircraft used in the Polish Air Force since the mid 1980’s. By the decision of the Polish Ministry of Defense the predicted service life for this type of aircraft will be extended to 3200 flight hours. Due to the fact that some aircraft were nearing the end of the service life guaranteed by the manufacturer, the actual service life, determined based on the flight profile in the Polish Air Force, had to be validated. Consequently, the Full Scale Fatigue Test (FSFT) had to be carried out in order to verify that the required service life was attainable. This article describes the process of preparation of the load spectra used in the Su-22 FSFT. Due to the fact that the Su-22 has a variable sweep wing the whole test was divided into three Stages (landing, flight and flap loads) carried out at different wing sweep angles (30°/45°/30°). The spectra were developed using the historical data gathered from Flight Data Recorders (FDR), strain signals acquired during the Operational Load Monitoring program (OLM) and aerodynamic calculations.
EN
This article presents a concept of the full scale fatigue test of a Su-22 fighter bomber. The authors define the general concept and goals of the test as well as the tasks to be accomplished in the preparation stage. The current work status is summarized and future tasks are defined.
EN
Providing a reliable and universal Structural Health Monitoring (SHM) system allowing for remote aircraft inspections and a reduction of maintenance costs is a major challenge confronting the aerospace industry today. SHM based on guided Lamb waves is one of the approaches capable of addressing the issue while satisfying all the associated requirements. This paper presents a holistic approach to the continuous real time damage growth monitoring and early damage detection in aircraft structure. The main component of the system is a piezoelectric transducers (PZT) network. It is complemented by other SHM methods: Comparative Vacuum Monitoring (CVMTM) and Resistance Gauges at selected aircraft hot spots. The paper offers the description of damage detection capabilities including the analysis of data collected from the PZL-130 Orlik aircraft full-scale fatigue test.
EN
This article presents preparation of the Full Scale Fatigue Test of the PZL-130 "Orlik" TC-II. After completing the flight load acquisition stage [1] a load block representing 200 Simulated Flight Hours in 194 flights was developed. This load block was further modified in order to introduce fatigue markers on the crack surface [2] visible during Quantitative Fractography, planned to take place during the Teardown Inspection of the structure after completion of the test. Meanwhile, the test rig along with the loading system and the test specimen were prepared at Výzkumný a Zkušební Letecký Ústav (VZLU, Prague, Czech Republic). The test specimen, consisting of the overhauled fuselage, modernized wings and the landing gear, was instrumented with the identical strain gauge measuring system as presented in [3], which was calibrated before the commencement of fatigue testing. Finally, some preliminary issues encountered during the fatigue test startup were highlighted and the outline for future work was described.
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.
EN
This paper presents an approach to damage growth monitoring and early damage detection in the structure of PZL – 130 ORLIK TC II turbo-prop military trainer aft using the statistical models elaborated by the Polish Air Force Institute of Technology (AFIT) and the network of the sensors attached to the structure. Drawing on the previous experiences of the AFIT and AGH in structural health monitoring, the present research will deploy an array of the PZT sensors in the structure of the PZL -130 Orlik TC II aircraft. The aircraft has just started Full Scale Fatigue Test (FSFT) that will continue up to 2013. The FSFT of the structure is necessary as a consequence of the structure modification and the change of the maintenance system - the transition to Condition Based Maintenance. In this paper, a novel approach to the monitoring of the aircraft hot-spots will be presented. Special attention will be paid to the preliminary results of the statistical models that provide an automated tool to infer about the presence of damage and its size. In particular, the effectiveness of the selected signal characteristics will be assessed using dimensional reduction methods (PCA) and the so-called averaged damage indices will be delivered. Moreover, the results of the signal classification based on the neural network will be presented alongside the numerical model of the wave propagation. The work contains selected information about the project scope and the results achieved at the preliminary stage of the project.
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.
EN
The following paper concerns the structural integrity program (SEWST) for the PZL-130 Orlik TCII trainer aircraft. The origin of the program is defined as well as the most important tasks necessary to fulfill the assumed goal.
EN
The following article presents the research conducted under a complex structure integrity program for PZL-130 "Orlik" TC-II trainer aircraft. The aim of the research was to obtain the actual flight loads characteristic for the Polish Air Force which further on will be used to determine characteristic load spectrum for the Full Scale Fatigue Test purpose. This paper presents the methodology as well as a brief discussion of the obtained results.
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