Comparison of Fatigue Crack Propagation Behavior of Al 2024 and Al-Li 8090 Helicopter Fuselage Panels PDF Download
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Author: M. Giglio Publisher: ISBN: Category : Crack Languages : en Pages : 10
Book Description
A comparison between two types of helicopter fuselage panels with a traditional design of skin and stringers was carried out. Panels were made with the same geometrical shape and dimensions but with two different aluminium alloys for the skin: Conventional 2024 and 8090 Al-Li alloy. Two different crack locations were considered to be taken into account for the damage tolerant behavior of the two panel typologies: A crack into the skin between two stringers and a crack into the skin under the stringer after the removal of a complete section of the stringer. The crack growth was monitored during the fatigue load application, and a finite element (FE) model was utilized in order to calculate the fracture mechanics parameters. The experimental data (crack growth rate da/dN) and the FE results (stress intensity range ?KI) were checked with the crack propagation material data, with good agreement. According to these results, it is possible to compare the damage tolerant behaviors of the panels made by the two different materials, with the purpose of optimizing crack propagation behavior versus weight in this fundamental helicopter component.
Author: M. Giglio Publisher: ISBN: Category : Crack Languages : en Pages : 10
Book Description
A comparison between two types of helicopter fuselage panels with a traditional design of skin and stringers was carried out. Panels were made with the same geometrical shape and dimensions but with two different aluminium alloys for the skin: Conventional 2024 and 8090 Al-Li alloy. Two different crack locations were considered to be taken into account for the damage tolerant behavior of the two panel typologies: A crack into the skin between two stringers and a crack into the skin under the stringer after the removal of a complete section of the stringer. The crack growth was monitored during the fatigue load application, and a finite element (FE) model was utilized in order to calculate the fracture mechanics parameters. The experimental data (crack growth rate da/dN) and the FE results (stress intensity range ?KI) were checked with the crack propagation material data, with good agreement. According to these results, it is possible to compare the damage tolerant behaviors of the panels made by the two different materials, with the purpose of optimizing crack propagation behavior versus weight in this fundamental helicopter component.
Author: Publisher: ScholarlyEditions ISBN: 1464965528 Category : Education Languages : en Pages : 1132
Book Description
Issues in Teaching and Education Policy, Research, and Special Topics: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Teaching and Education Policy, Research, and Special Topics. The editors have built Issues in Teaching and Education Policy, Research, and Special Topics: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Teaching and Education Policy, Research, and Special Topics in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Teaching and Education Policy, Research, and Special Topics: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: Alan L Buchman Publisher: CRC Press ISBN: 1138001236 Category : Medical Languages : en Pages : 3428
Book Description
This evidence-based book serves as a clinical manual as well as a reference guide for the diagnosis and management of common nutritional issues in relation to gastrointestinal disease. Chapters cover nutrition assessment; macro- and micronutrient absorption; malabsorption; food allergies; prebiotics and dietary fiber; probiotics and intestinal microflora; nutrition and GI cancer; nutritional management of reflux; nutrition in IBS and IBD; nutrition in acute and chronic pancreatitis; enteral nutrition; parenteral nutrition; medical and endoscopic therapy of obesity; surgical therapy of obesity; pharmacologic nutrition, and nutritional counseling.
Author: Richard E. Whaley Publisher: ISBN: Category : Languages : en Pages : 32
Book Description
Results are presented of a series of fatigue tests to study crack propagation and the resulting stress distributions in tension panels. The panels were all of the same general design, and configurations varied mainly in the relative amount of cross-sectional area in the skin, stiffeners, and flanges. The panels were constructed of 2024-T3 and 7075-T6 aluminum alloys. It was found that the average rate of crack growth was slower in panels made of 2024-T3 aluminum alloy than in panels made of 7075-T6 aluminum alloy. All cracks initiated in the skin, and the slowest crack growth was measured in configurations where the highest percentage of cross-sectional area was in the stiffeners. Strain-gage surveys were made to determine the redistribution of stress as the crack grew across the panels. As a crack approached a given point in the skin, the stress at that point increased rapidly. The stress in the stiffeners also increased as the crack approached the stiffeners. During the propagation of the crack the stress was not distributed uniformly in the remaining area.
Author: S. H. Smith Publisher: ISBN: Category : Airframes Languages : en Pages : 27
Book Description
This paper presents the results of an experimental investigation of the fatigue crack growth characteristics of some airframe materials under sinusoidal, narrow-band, and broad-band random loadings. Prerecorded random-time histories, generated by filtering the output of a white-noise generator to produce desired power spectral shapes, were utilized as input loadings to an electrohydraulic fatigue crack growth testing system. Uniform tension-tension loadings were applied to centrally cracked panels, and the fatigue crack growth behavior was observed. Alloys studied include 7075-T6 bare aluminum alloy, 2024-T3 bare aluminum alloy, Ti-8Al-1Mo-1V duplex and mill anneal, and Ti-6Al-4V mill anneal. Fracture-mechanics concepts are applied in correlating and comparing the fatigue crack growth behavior of the alloys. A comparison of sinusoidal- and random-loading behavior, based on the average of the greatest rise or fall in stress intensity between mean-level crossings, shows a faster fatigue crack growth rate for sinusoidal loading at the higher stress-intensity levels and a slower rate at the lower stress-intensity levels.
Author: C. E. Harris Publisher: ISBN: Category : Airframes Languages : en Pages : 28
Book Description
An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.
Author: B. M. Hillberry Publisher: ISBN: Category : Metals Languages : en Pages : 61
Book Description
The fatigue crack delay behavior due to single overload/underload sequences was studied in center crack panel specimens of 2024-T3 aluminum alloy. The applied loading consisted of constant amplitude loading, an applied overload immediately followed by an underload and then constant amplitude loading at the pre-overload level. The loading parameters investigated are the stress intensity ratios, overload level to maximum fatigue level, underload level to overload level, and minimum fatigue level to overload level. The results show that increasing the amount of underload decreases the number of delay cycles. Also, it is shown that the number of delay cycles is directly related to the minimum growth rate following the overload. The concept of crack closure is extended to include the effects of the overload/underload sequence. From this the maximum value of the opening stress intensity level and the minimum growth rate are determined. This is used to predict the number of delay cycles.
Author: B. M. Hillberry Publisher: ISBN: Category : Metals Languages : en Pages : 0
Book Description
The fatigue crack delay behavior due to single overload/underload sequences was studied in center crack panel specimens of 2024-T3 aluminum alloy. The applied loading consisted of constant amplitude loading, an applied overload immediately followed by an underload and then constant amplitude loading at the pre-overload level. The loading parameters investigated are the stress intensity ratios, overload level to maximum fatigue level, underload level to overload level, and minimum fatigue level to overload level. The results show that increasing the amount of underload decreases the number of delay cycles. Also, it is shown that the number of delay cycles is directly related to the minimum growth rate following the overload. The concept of crack closure is extended to include the effects of the overload/underload sequence. From this the maximum value of the opening stress intensity level and the minimum growth rate are determined. This is used to predict the number of delay cycles.
Author: M. Giglio
Author: M. Giglio
Author: 
Author: Alan L Buchman
Author: Richard E. Whaley
Author: S. H. Smith
Author: International Committee on Aeronautical Fatigue. Conference
Author: C. E. Harris
Author: B. M. Hillberry
Author: 
Author: B. M. Hillberry