A Method of Estimating the Permissible Fatigue Life of the Wing Structure of A Transport Aircraft

1961 ◽  
Vol 65 (611) ◽  
pp. 729-738 ◽  
Author(s):  
K. D. Raithby
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Atmospheric Turbulence ◽  
Fatigue Failure ◽  
Transport Aircraft ◽  
Safety Standards ◽  
Safe Life ◽  
Flight Loads ◽  
Wing Structure ◽  
Working Method

For types of structure where safety standards cannot be preserved by reliance on inspection, a permissible “safe life” has to be determined by relating the loads experienced by the aircraft in service to the fatigue performance of the structure, with due allowance for scatter in fatigue strength and in the frequency with which loads are encountered. This paper gives a working method for estimating the “safe life”—at which the risk of fatigue failure is negligible—of the wing structure of a transport aircraft, where the flight loads giving rise to fatigue are overwhelmingly due to atmospheric turbulence but where allowance has also to be made for “ground-to-air” loads.

Propagation of Contact Fatigue From Surface and Subsurface Origins

1966 ◽  
Vol 88 (3) ◽  
pp. 624-635 ◽  
Author(s):  
W. E. Littmann ◽  
R. L. Widner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Contact Stress ◽  
Environmental Conditions ◽  
Failure Modes ◽  
Contact Fatigue ◽  
Initiation And Propagation ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Fatigue life of tapered roller bearings and other elements subject to cyclic contact stress reflects the fatigue strength of the selected material under given environmental conditions. The various modes of contact-fatigue failure have been classified according to their appearance and the factors which promote their initiation and propagation. Illustrations of the various failure modes include rig test specimens and bearings representing normal catalog-rated life under laboratory and application environments. Evidence is presented for the propagation of contact fatigue from surface and subsurface origins.

Airframe Fatigue

1955 ◽  
Vol 59 (538) ◽  
pp. 701-702
Author(s):  
L. P. Coombes
Keyword(s):  
Fatigue Failure ◽  
Research Laboratory ◽  
Fatigue Tests ◽  
Aircraft Structures ◽  
Aircraft Wings ◽  
Safe Life ◽  
Welded Tube ◽  
Wing Structure ◽  
Work Done

The Journal in which Mr. W. Tye's Second Barnwell Lecture has been published (“ The Outlook on Airframe Fatigue,” May 1955 Journal) has now reached Australia. I felt that some comment was called for when I discovered that Mr. Tye had not mentioned the work done in Australia on the life of aircraft structures.What I believe to be the facts are as follows. Australian concern regarding fatigue was awakened in January 1945, when a Stinson air liner VH-UYY crashed with the loss of ten lives. The analysis made by the C.S.I.R. Aeronautical Research Laboratory confirmed that it was caused by a fatigue failure in the welded tube of the primary wing structure.Mr. H. A. Wills, in charge of structural and metallurgical research at the Laboratory, initiated a programme of fatigue tests on actual aircraft wings, designed to give factual answers to the problem of determining the safe life of aircraft structures. The basic idea that this could be done had been suggested in a paper by Bland and Sandorf0, and the Stinson accident provided the necessary urge.

scholarly journals Experimental Study on the Effect of Annealing on Fatigue Life of SS 304 Steels

2020 ◽  
pp. 164-169 ◽  
Author(s):  
Ramawath Prashanth Naik ◽  
Madhukar Samatham ◽  
Vinay Kumar Patangay ◽  
Mitikiri Sree Teja
Keyword(s):  
Heat Treatment ◽  
Experimental Study ◽  
Wear Resistance ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Quantitative Measurement ◽  
Complex Geometries ◽  
Definite Improvement ◽  
Ss 304

Fatigue failure is one of the main reasons for the mechanical failure in engineering materials. To improve the fatigue strength of the material one of the most used method is heat treatment of the materials in which hardness, wear resistance and aesthetics is improved. Of late, the complexity of predicting fatigue life of engineering components is increasing exponentially due to the varied and multi-facet loading conditions, complex geometries, and newer materials coming up in the market. In this paper the the quantitative measurement of the influence of Annealing on the fatigue life of SS 304 steels. Theresults conculed clearly clearly that there is a definite improvement in the fatigue life due to Annealing in steel. However the extent of improvement in fatigue life was more in SS 304 (after annealing) when compared to SS 304(before annealing).

scholarly journals A Study on Improvement of Fatigue Life of materials by Surface Coatings

2018 ◽  
Vol 8 (01) ◽  
Author(s):  
Samatham Madhukarϯ ◽  
Birudala Raga Harshith Reddy ◽  
Gyara Ajay Kumar ◽  
Ramawath Prashanth Naikϯ
Keyword(s):  
Wear Resistance ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Surface Treatment ◽  
Fatigue Failure ◽  
Fatigue Testing ◽  
Mechanical Failure ◽  
Surface Coatings ◽  
Engineering Materials

Fatigue failure is one of the main reasons for the mechanical failure in engineering materials. To improve the fatigue strength of the material one of the most used method is surface treatment of the materials in which hardness, wear resistance and aesthetics is improved. In this paper the different methods of surface coatings, types of fractures that occur in the material during fatigue testing and effect of the fatigue life on the material is studied

scholarly journals Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2171
Author(s):  
Armin Yousefi ◽  
Ahmad Serjouei ◽  
Reza Hedayati ◽  
Mahdi Bodaghi
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Element Model ◽  
Plastic Strain Amplitude ◽  
Friction Stir ◽  
Probe Hole ◽  
Good Agreement

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.

Fatigue Life Improvement of Welded Elements and Structures by Ultrasonic Impact Treatment

2011 ◽  
Author(s):  
Yuriy Kudryavtsev ◽  
Jacob Kleiman
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Testing ◽  
Highway Bridges ◽  
Surface Layers ◽  
Ultrasonic Impact Treatment ◽  
Stress Relieving ◽  
Life Improvement

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of a material, decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. The UP technique is based on the combined effect of high frequency impacts of special strikers and ultrasonic oscillations in treated material. Fatigue testing of welded specimens showed that UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The UP could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. The areas/industries where the UP process was applied successfully include: Shipbuilding, Railway and Highway Bridges, Construction Equipment, Mining, Automotive, Aerospace. The results of fatigue testing of welded elements in as-welded condition and after application of UP are considered in this paper. It is shown that UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

Calculation Error Analysis on the Strain Fatigue Life Predication Formula of Manson-Coffinn and Damage Stain Model

2011 ◽  
Vol 197-198 ◽  
pp. 1599-1603
Author(s):  
Zhen Wei Wang ◽  
Ping An Du ◽  
Ya Ting Yu
Keyword(s):  
Fatigue Life ◽  
Error Analysis ◽  
Fatigue Failure ◽  
High Speed ◽  
Production Cost ◽  
Calculation Error ◽  
Mechanical Components ◽  
Strain Model ◽  
Engine Crankshaft

Mechanical components are subjected heavy alternate load in industries, such as engine crankshaft, wheel axle, etc. The fatigue failure happens after a long work loading, which affects the production cost, safe and time. So the fatigue life predication is fundamental for the mechanical components design. Especially, it is very important for heavy, high-speed machinery. In this paper, both main fatigue life predication formulas are introduced briefly, including Manson-Coffinn formula and Damage strain model. Then, shortages of above life predication formulas are pointed out, and coefficients are explained in detail. Further calculation error analysis is conducted on the basis of experiments on 16 materials. Results show that above life predication formulas lack calculation accuracy. Finally, it is pointed out that coefficients of fatigue life predication formulas are dependent of material performance. So it is unreliable that coefficients are constants for Manson-Coffin and Damage strain model.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

scholarly journals PENGARUH PENGHILANGAN KEKASARAN PERMUKAAN TERHADAP KEKUATAN FATIK = EFFECT OF SURFACE ROUGHNESS REMOVAL TO FATIGUE STRENGTH

2015 ◽  
Vol 9 (3) ◽  
pp. 115-130
Author(s):  
H. Agus Suhartono
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Loading ◽  
Bending Fatigue ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel ◽  
Test Result ◽  
Effect Of Surface

The aim of the study is to investigate and to prove that the fatigue failure of steel is initiated from the surface. Hence the preventif action of smoothening the surface that has been loaded by fatigue loading is very important. The specimen of AISI 1045 Steel is loaded by means of rotary bending fatigue. The fatigue loading will be interupted as the fatigue life reaching 50% of fatigue life and 75% of fatigue life. During the interuption the specimen will be grinded and polished, before tested completely until fatigue fracture occured. The fatigue life of each group of scpecimen based on the art of loading will be compared to the specimen tested by fatigue loading without interuption.The Miner rule is used to evaluated the test result. The influence of interuption and surface treatment is evaluated and analyzed. ABSTRAKTujuan penelitian ini adalah untuk menyelidiki dan membuktikan bahwa kegagalan kelelahan baja dimulai dari permukaan. Oleh karena itu tindakan pencegahan dengan memperhalus permukaan sangat penting untuk mencegah beban kelelahan baja. Spesimen dari AISI 1045 Steel dimuat dengan cara uji kelelahan lentur putar. Kelelahan pemuatan akan disela sebagai umur kelelahan mencapai 50% dari umur kelelahan dan 75% dari umur kelelahan. Selama gangguan lainnya yang spesimen akan digiling dan dipoles, sebelum diuji benar-benar sampai patah akibat kelelahan yang terjadi. Umur kelelahan dari setiap kelompok specimen diuji berdasarkan beban akan dibandingkan dengan spesimen oleh kelelahan bongkar tanpa aturan. The Miner rule digunakan untuk mengevaluasi hasil tes. Pengaruh gangguan lainnya dan perlakuan permukaan dievaluasi dan dianalisis. 

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