Full-Scale Fatigue Testing from a Structural Analysis Perspective

Daverschot, Derk; Mattheij, Paul; Renner, M. S.; Ardianto, Yudi; Araújo, Maria Madalena Teixeira de; Graham, Kyle

doi:10.1007/978-3-030-21503-3_62

Cited by 5 publications

(4 citation statements)

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“…For older aircraft designed according to the safe life approach, it is a common practice to carry out a Full-Scale Fatigue Test (FSFT) to verify the possibility of introducing the damage tolerance approach [9][10][11]. The most comprehensive fatigue test is the actual usage, but due to possible critical damage FSFT are commonly used in order to predict any possible cracking [10][11][12][13] before the aircraft is certified to roll out. As with most tests FSFT is a representation of the actual service load conditions [14,15] and simplifies the complexity of the actual load spectrum by neglecting some effects.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, due to discrete load application FSFT may cause some local effects that are absent from actual service. That said, the load spectrum used in FSFT is usually developed from a welldefined flight profile [9][10][11][12], which is basically a good representation of actual operation loads. Nevertheless, it may differ between individual aircraft or from future operational loads of the whole fleet.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test

Reymer

Leski

Dziendzikowski

2022

Sensors

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Military aircraft are subjected to variable loads, which are the main cause of initiation and propagation of cracks in the most stressed locations of the airframe. The aim of a Full-Scale Fatigue Test (FSFT) is to represent actual load conditions in such a way that the results obtained are a good representation of the actual loads and may be used as data that give insight into the development of real fatigue damage in critical locations. The FSFT load spectrum is a generalized depiction of the expected service loads and is designed to give an overall good representation of loads exerted on the airframe’s structural elements during operation. Moreover, the discrete method of load application on the structure (exerting loads with hydraulic actuators rather than pressure fields or inertia loads expected in actual operation) may cause some local effects, which may not be present in operation. The proposed usage of direct strain data from the test include such local effects. Moreover, operational loads may vary between individual aircraft, therefore it is crucial to understand the whole process of fatigue crack onset and development in order to determine safe inspection intervals and thereby mitigate risk. This paper presents crack propagation calculations regarding the development of a crack in a critical location of the PZL-130 “Orlik” TC-II aircraft, discovered during FSFT. The discussed crack was found already developed, hence the information about nucleation and initial propagation of the crack was not available. Therefore, there was a need to recreate the whole propagation process by means of numerical estimations using the FSFT results like location of the crack and total life for model validation. Moreover, in order to gather real load data for calculations a dedicated stain gage was installed on the damaged load path to monitor the actual remote strain in the element during the FSFT. This allowed for the definition of load sequence exerted on the damaged element directly during the test rather than estimating it from the general load conditions of the wing. The calculations allowed for the estimation of crack propagation curves from initiation to critical crack length causing fatal damage. The obtained curves allowed to visualize the crack behavior due to applied load and furthermore define initial and recurring inspection intervals for the entire fleet during operation, which allowed to define which cracks could be found before they reach critical size in order to carry out mitigation actions like repair or replacement of the damaged part. The authors present the methodology for load spectrum development based on direct strain measurements and furthermore crack propagation curves estimation, validated with the actual FSFT results, which allowed to propose nondestructive inspection intervals for future operation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test

Reymer

Leski

Dziendzikowski

2022

Sensors

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“…Fatigue cracks are one of the most common factors (beside corrosion) influencing structural integrity of aging aircraft over the course of operation (Daverschot et al, 2020;B. G. Nesterenko, Nesterenko, Konovalov, & Senik, 2020;Balicki, Głowacki, & Uchanin, 2021;Loroch, 2022).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of the Nasgro Equation Based on the PZL-130 TC-II Orlik Trainer Aircraft Full Scale Fatigue Test

Reymer

Leski

Kurdelski

2022

Fatigue of Aircraft Structures

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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.

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“…In aerospace, the beginnings of system solutions focused on a high level of safety date back to the early post-war years, when the safe-life design concept was introduced, in order to preserve human health and life as well as mitigating potential material losses [ 2 , 3 ]. Due to the advancement of aircraft structures, complexity of different types of connections and variable geometry of structural elements, the most reliable method for determining the service life is the subcomponent or full scale fatigue tests of aircraft structures [ 4 , 5 , 6 ]. After the F-111 aircraft crash in 1969 [ 7 , 8 ], a new design and maintenance concept was introduced—the damage tolerance approach [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Application of Operational Load Monitoring System for Fatigue Estimation of Main Landing Gear Attachment Frame of an Aircraft

et al. 2021

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In this paper, we present an approach to fatigue estimation of a Main Landing Gear (MLG) attachment frame due to vertical landing forces based on Operational Loads Monitoring (OLM) system records. In particular, the impact of different phases of landing and on ground operations and fatigue wear of the MLG frame is analyzed. The main functionality of the developed OLM system is the individual assessment of fatigue of the main landing gear node structure for Su-22UM3K aircraft due to standard and Touch-And-Go (T&G) landings. Furthermore, the system allows for assessment of stress cumulation in the main landing gear node structure during touchdown and allows for detection of hard landings. Determination of selected stages of flight, classification of different types of load cycles of the structure recorded by strain gauge sensors during standard full stop landings and taxiing are also implemented in the developed system. Based on those capabilities, it is possible to monitor and compare equivalents of landing fatigue wear between airplanes and landing fatigue wear across all flights of a given airplane, which can be incorporated into fleet management paradigms for the purpose of optimal maintenance of aircraft. In this article, a detailed description of the system and algorithms used for landing gear node fatigue assessment is provided, and the results obtained during the 3-year period of system operation for the fleet of six aircraft are delivered and discussed.

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Full-Scale Fatigue Testing from a Structural Analysis Perspective

Cited by 5 publications

References 1 publication

Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test

Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test

Sensitivity Analysis of the Nasgro Equation Based on the PZL-130 TC-II Orlik Trainer Aircraft Full Scale Fatigue Test

Application of Operational Load Monitoring System for Fatigue Estimation of Main Landing Gear Attachment Frame of an Aircraft

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