Estimation of the Total Fatigue Life of Metallic Structures

2016 ◽  
Author(s):  
Peter Abdo ◽  
Farouk Fardoun ◽  
Phuoc Huynh
Keyword(s):  
Finite Element Method ◽  
Fatigue Life ◽  
Analytical Methods ◽  
Critical Section ◽  
The Finite Element Method ◽  
Local Conditions ◽  
Metallic Structures ◽  
Final Failure ◽  
Local Stresses ◽  
Number Of Cycles

The fatigue life of a component is defined as the total number of cycles or time to induce fatigue damage and to initiate a dominant fatigue flaw which is propagated to final failure.(Shigley & Mischke 2002) The aim of this project is to calculate the total fatigue life of metallic structures under cyclic loading by applying equations found by Basquin and Manson-Coffin. The local stresses and strains necessary for the calculation are determined by the finite element method. Former studies concerning this subject have used analytical methods to find the local conditions at the critical section. The analytical methods, based on Neuber and Molski-Glinka’s approaches, permit the calculation of the local stresses and strains at the critical section of the structure’s geometry as a function of the nominal stress (forces) applied. For the finite elements method, ABAQUS is used to determine the local conditions at the critical section of a T-shaped model.

scholarly journals Cold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered Mandrels

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5536
Author(s):  
David Curto-Cárdenas ◽  
Jose Calaf-Chica ◽  
Pedro Miguel Bravo Díez ◽  
Mónica Preciado Calzada ◽  
Maria-Jose Garcia-Tarrago
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Experimental Tests ◽  
The Finite Element Method ◽  
Expansion Process ◽  
Cold Expansion ◽  
Hoop Stresses ◽  
Element Method

Cold expansion technology is an extended method used in aeronautics to increase fatigue life of holes and hence extending inspection intervals. During the cold expansion process, a mechanical mandrel is forced to pass along the hole generating compressive residual hoop stresses. The most widely accepted geometry for this mandrel is the tapered one and simpler options like balls have generally been rejected based on the non-conforming residual hoop stresses derived from their use. In this investigation a novelty process using multiple balls with incremental interference, instead of a single one, was simulated. Experimental tests were performed to validate the finite element method (FEM) models and residual hoop stresses from multiple balls simulation were compared with one ball and tapered mandrel simulations. Results showed that the use of three incremental balls significantly reduced the magnitude of non-conforming residual hoop stresses and the extension of these detrimental zone.

On the Use of the Finite Element Method on Some Acoustical Problems

1982 ◽  
Vol 104 (1) ◽  
pp. 108-112 ◽  
Author(s):  
L. Cederfeldt
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Analytical Methods ◽  
The Finite Element Method ◽  
Expansion Chamber ◽  
Low Frequencies ◽  
Angle Bend ◽  
Complicated Geometry ◽  
Sound Reduction ◽  
Element Method

In a project carried out in 1974-1975, financially supported by the National Swedish Council for Building Research, the finite element method was applied on some acoustical problems to illustrate the possibilities of the method. Calculations have been made for the following examples; sound attenuation of a lined right angle bend, a lined straight duct, and expansion chamber and the sound reduction of a resilient skin. The FEM has its power for small geometries particularly at low frequencies, that is, when analytical methods usually are weak. The more complicated geometry and boundary conditions of the studied problem may be the more powerful the FEM is compared to analytical methods.

Simple Stress Formulae for a Thin-Rimmed Spur Gear. Part 1: Derivation of Approximation Formulae for Tooth Fillet and Root Stresses

1985 ◽  
Vol 107 (3) ◽  
pp. 406-411 ◽  
Author(s):  
Tae Hyong Chong ◽  
A. Kubo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Spur Gear ◽  
Critical Section ◽  
Radius Of Curvature ◽  
The Finite Element Method ◽  
Calculated Stress ◽  
Supporting Condition ◽  
Simple Stress ◽  
Good Agreement

Using the finite element method, influences of chordal tooth thickness at the critical section of tooth, radius of curvature of fillet, rim thickness, and supporting condition of a thin-rimmed spur gear on the tooth fillet and root stresses are investigated. Summing up a lot of FEM calculated results, a set of approximate formulae is derived for the calculation of tooth fillet and root stresses of a thin-rimmed spur gear. A comparison between the FEM calculated stress values and the values from these approximation formulae has shown good agreement.

A New Finite Element for Gas Turbine Engine Fatigue Life Prediction

2007 ◽  
Author(s):  
Wasim Tarar ◽  
Onome Scott-Emuakpor ◽  
M.-H. Herman Shen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Gas Turbine ◽  
Life Prediction ◽  
Constitutive Law ◽  
Fatigue Life Prediction ◽  
Turbine Engine ◽  
Number Of Cycles ◽  
Cycles To Failure

An energy-based fatigue life prediction framework was previously developed by the authors [1–4] for prediction of axial and bending fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In this study, the energy expressions that construct the new constitutive law is integrated into minimum potential energy formulation to develop a new finite element for fatigue life prediction. The comparison of Finite element method (FEM) results to existing experimental fatigue data, verifies the new finite element method for fatigue life prediction. The final output of this finite element analysis is in the form of number of cycles to failure for each element in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure for each element in gas turbine engine structural components. The performance of the fatigue finite element is demonstrated by the fatigue life predictions from 6061-T6 aluminum and Ti-6Al-4V. Results are compared with experimental results and analytical predictions [1].

Thermal Stress and Thermal Cycling Analyses of Microgyroscope Chip Models

2011 ◽  
Vol 462-463 ◽  
pp. 622-627 ◽  
Author(s):  
Meng Kao Yeh ◽  
Chun Lin Lu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Thermal Fatigue ◽  
Simplified Model ◽  
The Finite Element Method ◽  
Nonlinear Analyses ◽  
Thermal Fatigue Life

The thermal stress and thermal fatigue life for three different microgyroscope chip models were investigated in this paper. The deformation and stress distribution in chip, at interface between microgyroscope and chip, and in the spring of microgyroscope were obtained for three different microgyroscope chip models by the finite element method. The results show that for the simplified model, no obvious differences from linear or nonlinear analyses are obtained and the fatigue life of microgyroscope chip can be predicted with the properly simplified model. Also, the model having the same process in fabricating microgyroscope and carrier has better reliability. This paper provides an effective method for the reliability analysis of microgyroscope chip.

scholarly journals The study of the lifting mechanism of the crane arm to a barge

2020 ◽  
Vol 2 (1) ◽  
pp. 91-96
Author(s):  
C. Fratila ◽  
T. Axinte ◽  
R. C. Cojocaru ◽  
C. Berescu ◽  
I.C. Scurtu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Finite Elements ◽  
Safety Factor ◽  
The Finite Element Method ◽  
Ship Owner ◽  
Loading And Unloading ◽  
Lifting Equipment ◽  
Boom Crane

During cargo loading and unloading, the vessels’ lifting gear, even if anchored or moored, is affected by the pitch and roll movements, in addition to the usual stresses, a similar shore crane is subjected to. This paper aims at presenting an analysis of the lifting operations of a boom crane pertaining to a self-propelled barge. The analysis starts with the meshing with triangle elements, the stresses and the embedding using the finite elements method. The crane and the pertaining boom were modeled using CAD design, NX 10.0 from Siemens. The lifting equipment of the ships boom crane may be subject to dangerous defects occurring during the loading and unloading process. Subsequently, the research emphasizes the stresses occurred in the piston rod and in the eye of the lifting equipment, using the finite element method (FEM). After the stress analysis, several fatigue matters are studied: fatigue safety factor, fatigue life, strength safety factor and crack. The damaging or breaking of the eye or of the piston rod from the lifting equipment of the ships boom crane is leading to the blocking of the cylinder with the result of unfavorable events, such as deformation of the boom crane, damaging the loads and even the danger of sinking the barge. The results of this analysis provide ship-owner and maintenance engineers a useful tool to take appropriate decision during inspection of the lifting gear of the ship, prior commencement of the loading and unloading operations.

Design of Hyper Compressor Packing Cup Rings for Optimum Fatigue Life

2006 ◽  
Author(s):  
E. H. Perez ◽  
S. Diab ◽  
R. D. Dixon
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
The Finite Element Method ◽  
Interference Fit ◽  
Analysis Methodology ◽  
Asme Code ◽  
Section Viii ◽  
Internal Pressures ◽  
Compressor Packing

Fatigue analyses of the inner and outer rings of hyper compressor retainers were performed to determine the optimum interference fit and interference fit diameter to maximize the fatigue life of both the inner and outer rings when subjected to cyclic operating internal pressures. The relationships between the optimum interference fit diameter, the amount of interference and cyclic pressures are derived using the fatigue analysis methodology of the ASME Code, Section VIII, Division 3. The effect of axial preload is evaluated, and the results are checked using the finite element method.

APPLICATION OF THE FINITE ELEMENT METHOD IN THE FATIGUE LIFE PREDICTION OF A STENT FOR A PERCUTANEOUS HEART VALVE

2012 ◽  
Vol 12 (01) ◽  
pp. 1250007 ◽  
Author(s):  
A. ESTERHUYSE ◽  
K. VAN DER WESTHUIZEN ◽  
A. DOUBELL ◽  
H. WEICH ◽  
C. SCHEFFER ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Heart Valve ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Life Assessment ◽  
The Finite Element Method ◽  
Element Method

The fatigue failure of the stent component of a percutaneous aortic heart valve (PAHV) is an event that could be fatal to the patient. Therefore, the fatigue life prediction of a stent intended for application in a PAHV is a major consideration during the design and development phase of the device. Since the stent component will be subjected to both cyclic blood pressure as well as cyclic valve-leaflet forces, the combined effect of these loads must be taken into account for the analysis of the fatigue life. This paper expands on a methodology developed by Marrey et al.10 to incorporate the combined loading of both the cyclic blood pressure as well as the cyclic leaflet forces in the fatigue life assessment of stents intended for application in percutaneous aortic heart valves. It was found that the developed methodology, which utilizes the finite element method (FEM), provides a simple and cost-effective tool to quantitatively determine the fatigue resistance of the stent component, thereby enabling the designer to compare different stent designs with respect to their resistance against fatigue. Two different stent designs were analyzed using this approach and it was found that they exhibited similar resistances to fatigue and that resistance to fatigue is influenced by strut width.

Sign in / Sign up

Export Citation Format

Share Document