Parametric Study on Fatigue Life Design of Shaft with Holes

2011 ◽  
Vol 295-297 ◽  
pp. 2366-2369
Author(s):  
Xing Guo Wang ◽  
Ran Li ◽  
Wei Sun ◽  
Thomas H. Hyde
Keyword(s):  
Driving Force ◽  
Hoop Stress ◽  
Fatigue Crack Initiation ◽  
Initiation Site ◽  
Small Scale ◽  
Finite Element Analyses ◽  
Short Cracks ◽  
Von Mises ◽  
Hollow Shafts ◽  
Life Design

The prevention of fatigue failure is an important consideration in the design of aeroengine shafts. In this paper, based on the elastic and elstic-plastic finite element analyses, for a series of small-scale hollow shafts with transverse holes, the maximum princple stress and von Mises stresss around the hole have been obtained. Hence, using McDiarmid and Von Mises criteria, the fatigue crack initiation site and life can be determined. The hoop stress, which is the driving force for the Mode I growth of short cracks initiated around the hole, has been characterised as well.

Comparison of Fatigue of Girth-Welds in Full-Scale Pipes and Small-Scale Strip Specimens

2008 ◽  
Author(s):  
Stephen J. Maddox ◽  
Yan-Hui Zhang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Initiation ◽  
Fatigue Behaviour ◽  
Initiation Site ◽  
Full Scale ◽  
Fatigue Properties ◽  
Small Scale ◽  
Welded Steel ◽  
Steel Pipes ◽  
Girth Welds

As part of a study of fatigue in girth-welded steel pipes, tests were performed under constant amplitude loading on both full-scale pipes and strip specimens cut from such pipes. Significant differences were found in their high-cycle fatigue lives, which extended to around 108 cycles, and apparent fatigue endurance limits, the small-scale strips displaying superior fatigue properties. The reasons for this were investigated considering the fatigue crack initiation site, weld geometry, type of pipe, loading conditions, residual stresses, the re-testing of unfailed specimens and size effects. Fracture mechanics fatigue crack growth calculations were also performed using a K solution specially calculated by FEA for the girth weld. Conclusions are drawn about the suitability of strip fatigue test specimens for representing the fatigue behaviour of full-scale girth welded pipes and the scope for re-testing unfailed full-scale pipes.

scholarly journals Finite Element Analysis of Composite Repair for Damaged Steel Pipeline

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 301
Author(s):  
Jiaqi Chen ◽  
Hao Wang ◽  
Milad Salemi ◽  
Perumalsamy N. Balaguru
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Hoop Stress ◽  
Pipe Wall ◽  
Von Mises Stress ◽  
Repair System ◽  
Composite Repair ◽  
Steel Pipeline ◽  
Von Mises ◽  
Infill Material

Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.

Short fatigue crack initiation and growth modeling in aluminum 7075-T6

2014 ◽  
Vol 229 (7) ◽  
pp. 1206-1214 ◽  
Author(s):  
M Amiri ◽  
M Modarres
Keyword(s):  
Crack Initiation ◽  
Damage Mechanics ◽  
Fatigue Crack Initiation ◽  
Estimation Method ◽  
Continuum Damage Mechanics ◽  
Fatigue Tests ◽  
Short Cracks ◽  
Al 7075 ◽  
Edge Notch ◽  
Aluminum 7075

A series of fatigue tests is carried out to investigate the behavior of microcrack initiation and propagation in Al 7075-T6. Plate specimens with semi-circular single edge notch are tested under uniaxial loading at different load amplitudes. Optical microscopy is used to detect the initiation and growth of short cracks. Continuum damage mechanics is used to model the crack initiation. After the initiation, crack growth is studied using fracture mechanics models. For both regions of crack initiation and growth, Bayesian estimation method is used to account for uncertainties in the parameters of the model. Results of the entire fatigue life, including initiation and growth, are compared with experiments. Good agreement is observed.

Low Cycle Fatigue and Fracture Behavior of Nickel-Base Superalloy CM247LC at 760°C

2004 ◽  
Vol 449-452 ◽  
pp. 561-564 ◽  
Author(s):  
Seong Moon Seo ◽  
In Sup Kim ◽  
Chang Yong Jo
Keyword(s):  
Fatigue Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Strain Range ◽  
Initiation Site ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Fine Grained

Low cycle fatigue (LCF) behavior of coarse and fine grained superalloy CM247LC at 760°C has been investigated. Both coarse and fine grained CM247LC showed similar cyclic stress response, however, the fine grained CM247LC specimen exhibited relatively uniform and superior fatigue properties to the coarse grained one. It was found that fatigue crack initiation of the alloy was keen to the applied strain range. Fatigue crack initiated at the surface of the specimen with high strain range (∆εt≥( 0.7%) while the initiation site moved to the internal defects at low strain range (∆εt≤0.6%).

Stress Concentration and Stress Intensity for Pressurized Eroded Autofrettaged Thick Cylinders With Bauschinger Effect

2010 ◽  
Author(s):  
Q. Ma ◽  
C. Levy ◽  
M. Perl
Keyword(s):  
Stress Intensity ◽  
Stress Concentration ◽  
Bauschinger Effect ◽  
Thermal Loading ◽  
Yield Criterion ◽  
Pressure Vessels ◽  
Short Cracks ◽  
Finite Element Package ◽  
Von Mises ◽  
Walled Cylinder

Our previous studies have shown that stress intensity factors (SIFs) are influenced considerably from the presence of the Bauschinger Effect (BE) in thick-walled pressurized cracked cylinders. For some types of pressure vessels, such as gun barrels, working in corrosive environment, in addition to acute temperature gradients and repetitive high-pressure impulses, erosions can be practically induced. Those erosions cause stress concentration at the bore, where cracks can readily initiate and propagate. In this study, The BE on the SIFs will be investigated for a crack emanating from an erosion’s deepest point in a multiply eroded autofrettaged, pressurized thick-walled cylinder. A commercial finite element package, ANSYS, was employed to perform this type of analysis. A two-dimensional model, analogous to the authors’ previous studies, has been adopted for this new investigation. Autofrettage with and without BE, based on von Mises yield criterion, is simulated by thermal loading and the SIFs are determined by the nodal displacement method. The SIFs are evaluated for a variety of relative crack lengths, a0/t = 0.01–0.45 emanating from the tip of the erosion of different geometries including (a) semi-circular erosions of relative depths of 1–10 percent of the cylinder’s wall thickness, t; (b) arc erosions for several dimensionless radii of curvature, r′/t = 0.05–0.4; and (c) semi-elliptical erosions with ellipticities of d/h = 0.5–1.5, and erosion span angle, α, from 6 deg to 360 deg. The effective SIFs for relatively short cracks are found to be increased by the presence of the erosion and further increased due to the BE, which may result in a significant decrease in the vessel’s fatigue life. Deep cracks are found to be almost unaffected by the erosion, but are considerably affected by BE.

The Biaxial Strengthening of Textured Titanium

1967 ◽  
Vol 89 (1) ◽  
pp. 13-18 ◽  
Author(s):  
H. W. Babel ◽  
D. A. Eitman ◽  
R. W. McIver
Keyword(s):  
Hoop Stress ◽  
Yield Criterion ◽  
Test Method ◽  
Stress Fields ◽  
Titanium Sheet ◽  
Homogeneous Stress ◽  
Stress States ◽  
Von Mises ◽  
Biaxial Behavior ◽  
Very High

The purpose of this investigation was to develop an understanding of the biaxial behavior of titanium sheet. An experimental test method was developed and found to provide homogeneous stress fields for obtaining biaxial data in a variety of stress states. Data were obtained using the same specimen geometry for 1-to-2 and 1-to-1 axial-to-hoop stress states. Significant increases in the biaxial yield strength were obtained over those predicted by von Mises’ yield criterion for isotropic materials. Very high biaxial burst strengths were also obtained; the maximum was 246 ksi for annealed Ti-5Al-2.5 Sn alloy in a 1-to-1 stress state. The data followed the general form predicted by Hill’s model for anisotropic materials.

Growth of Short Fatigue Cracks at Notches in Woven Fiber Glass Reinforced Polymeric Composites

1989 ◽  
Vol 111 (4) ◽  
pp. 363-367 ◽  
Author(s):  
S. B. Biner ◽  
V. C. Yuhas
Keyword(s):  
Composite System ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Polymeric Composites ◽  
Stress Intensity Factor Range ◽  
Stress Concentrations ◽  
Fiber Glass ◽  
Root Radius ◽  
Short Cracks ◽  
Effective Stress Intensity Factor

The fatigue crack initiation and growth characteristics of short cracks emanating from blunt notches with root radius varying from 1.6 to 6.35 mm at various depths in woven fiber-glass reinforced polymeric composites have been investigated. It is demonstrated that the initiation and growth rate of short cracks emanating from blunt notches can be accurately described by an effective stress intensity factor range ΔKeff. The ply orientations studied, did not have any effect on the analysis. The results provide an adequate engineering approach for designing against failure from range of stress concentrations, at least for this composite system.

scholarly journals Multipurpose Energy Saving Manual Compressor for Artisans in African Countries

2018 ◽  
Vol 8 (4) ◽  
Author(s):  
Dr.Isaac Ali Kwasu ◽  
Dr.Aje Tokan ◽  
Engr.M A Bawa
Keyword(s):  
Driving Force ◽  
Storage Tank ◽  
Research Work ◽  
Daily Activities ◽  
Small Scale ◽  
Pilot Test ◽  
Prime Mover ◽  
African Countries ◽  
Air Compressor ◽  
To Receive

This Research work involves the design, fabrication and testing of a manually operated compressor for use of artisans and small scale vulcanizing activities. The developed machine consists of chain sprocket arrangement to a flywheel attached to a pulley which powers the compressor as well as a storage tank to receive air by foot pedaling. The article is an innovative product to meet the needs of rural African Artisans that uses air compressor for their daily activities . The design is such that the chain sprocket provides the compressor with a driving force in conjunction with the flywheel thereby replacing the prime mover. Prototype pilot test carried out on the developed manual air compressor could generates 10 Psi ie 0.69bar-volume of air in 60 seconds. A new design with better parameter of the machine was done to improve it’s proficiency after testing for broad application even for the handicap Artisans.

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