Andrzej Leski

Damage Size Estimation of the Aircraft Structure with Use of Embedded Sensor Network Generating Elastic Waves

One of the approach to develop a system of continues, automated monitoring of the health of the structures is to use elastic waves excited in a given medium by piezoelectric transducers network. Elastic waves depending on their source and the geometry of the structure under consideration can propagate over significant distance. They are also sensitive to local structure discontinuities and deformations providing a tool to detect local damage of large aerospace structures. In the paper the issue of fatigue crack growth monitoring by means of elastic guided waves actuated by a sparse array of sensors will be presented. In particular we propose signal characteristics, robust enough to detect different kinds of damages: Barely Visible Impact Damages (BVIDs) in composite materials and fatigue cracks of metallic structures. The model description and the results of specimen tests verifying damage detection capabilities of the proposed signal characteristics are delivered in the paper. Some issues concerning the proposed damage indices and its application to damage detection and its monitoring are also discussed.

Development of Load Spectrum for Full Scale Fatigue Test of a Trainer Aircraft

PZL-130 “Orlik” is a turbo-propeller engine trainer airplane, entirely designed and build in Poland. This plane is used in Polish Air Force mainly for primary training of polish military pilots.

The Fatigue Life Assessment of PZL-130 Orlik Structures Based on Historical Usage Data

The Fatigue Life Assessment of PZL-130 Orlik Structures Based on Historical Usage Data Material fatigue is the basic factor limiting aircrafts durability. It comes from the fact that changing loads affect aircraft structure as well as from the fact that aircrafts mass restrictions do not allow for diminishing stress to the level when material fatigue does not occur. Estimating fatigue durability of a particular structure as well as its actual fatigue damage degree is possible when the history of loads affecting the structure is known. Accuracy of loads monitoring influences the accuracy of indicated fatigue wear. In case of older structures, which have been maintained according to safe life principle, the number of hours have been commonly used as a fatigue wear indicator. After aircraft structure reaches flying time estimated by the produces, it is considered as fatigue wear and it is no longer in service. In case of a lack of results of loads spectrum measurements, results of tests conducted for other aircraft (of similar structure and assignment) can be used. For this purpose, average loads spectrum has been elaborated for particular aircraft groups, for example, HELIX, FELIX, FALSTAFF, ENSTAFF, TWIST(10). In the case of small aircraft, the data from FAA (2) report have been often used. This article describes the way of fatigue wear estimation for PZL-130 Orlik aircraft on the basis of historical data from flight recorders.

An Approach to Damage Detection in the Aircraft Structure with the Use of Integrated Sensors – The Symost Project

Abstract 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

Damage Detection and Size Quantification of FML with the Use of NDE

Abstract Composite materials have been developed in recent years. A new generation of structural composite materials for advanced aircraft is Fibre Metal Laminates (FML). They are hybrid composites consisting of alternating thin layers of metal sheets and fiber-reinforced composite material. FMLs have both low weight and good mechanical properties (high damage tolerance: fatigue and impact characteristics, corrosion and fire resistance). Quality control of materials and structures in aircraft is an important issue, also for Fibre Metal Laminates. For FML parts, a 100% non-destructive inspection for internal quality during the manufacturing process is required. In the case of FML composites, the most relevant defects that should be detected by non-destructive testing are porosity and delaminations. In this paper, a number of different non-destructive methods for the inspection of Fibre Metal Laminates were studied. The possibility of quality control of manufactured FML laminates - detection of defects as well as the procedures and processes are presented and discussed

Structural Load Monitoring Systems for Military Aircraft in the Polish Armed Forces with Examples of Selected Activities

Airplanes and helicopters currently operated by the Polish Armed Forces have been introduced into service without any load monitoring systems. The only exception is the F-16 and its Aircraft Structural Integrity Program.

Service Life Assessment Program of PZL-130 Orlik TCII Structure

Service Life Assessment Program of PZL-130 Orlik TCII Structure 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.

REPRESENTATIVE LOAD SEQUENCE FOR THE PZL-130 ORLIK

Representative Load Sequence for the PZL-130 Orlik

Predictive Models for Transient Loads of Vertical Stabilizer of an Aircraft Using Canonical Correlation Analysis

The knowledge about loads of the structure occurring during aircraft operation, is one of the fundamental element of the so called damage tolerance approach to aircraft design. In the optimal case, such information could be available from a network of sensors, e.g. strain gauges, FBGs, deployed in the aircraft structure and measuring its local stress. However, systems of operational loads monitoring (OLM) are still not widely applied. Instead, what is available, is a set of flight parameters, which by the laws of inertia and aerodynamics should determine dominant part of loads, acting on a given element. In this paper, canonical correlation analysis (CCA) will be discussed as an useful method for selection of flight parameters proper for prediction of aircraft loads.

Introduction of an Individual Aircraft Tracking Program for the Polish SU-22

Abstract The Su-22 fighter-bomber is a military aircraft used in the Polish Air Force (PLAF) since the mid 1980’s. By decision of the Ministry of National Defence Republic of Poland, the assumed service life for this type of aircraft was prolonged up to 3200 flight hours based on the Full Scale Fatigue Test (FSFT) results. The FSFT was conducted using the real load profile defined during the Operational Load Monitoring Program (OLM) and the 3200 hour service life was also based on this load profile. In order to assure safe operation of all the 18 Su-22 aircraft, the Individual Aircraft Tracking program was introduced. The program was based on the results of the FSFT as well as the analysis of the flight parameters recorded by the THETYS onboard flight recorder. In this paper, the authors present the methodology, assumed fatigue hypothesis and preliminary results of the IAT program for the Polish Su-22.