Effect of material uncertainties on fatigue life calculations of aircraft fuselages: A cohesive element model

A framework based on a complex dynamical system viewpoint for formulating and solving dynamic ice-structure interaction problems is introduced. Important constituents required for formulating a well posed initial-boundary value problem are discussed. Significance of these constituents is illustrated using a Cohesive Element model of several example problems.

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A cohesive element model for mixed mode loading with frictional contact capability

International Journal for Numerical Methods in Engineering ◽

10.1002/nme.4398 ◽

2012 ◽

Vol 93 (5) ◽

pp. 510-526 ◽

Cited By ~ 46

Author(s):

Leonardo Snozzi ◽

Jean-François Molinari

Keyword(s):

Mixed Mode ◽

Frictional Contact ◽

Element Model ◽

Cohesive Element ◽

Mixed Mode Loading ◽

Cohesive Element Model

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

Materials ◽

10.3390/ma14092171 ◽

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.

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Durability Analysis of the Reduction Gear for High Speed Train Considering Driving Histories

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.586.269 ◽

2012 ◽

Vol 586 ◽

pp. 269-273

Author(s):

Chul Su Kim ◽

Gil Hyun Kang

Keyword(s):

Fatigue Life ◽

High Speed ◽

Element Model ◽

Rolling Stock ◽

Reduction Gear ◽

High Speed Train ◽

Analysis Software ◽

Tractive Effort ◽

Durability Analysis ◽

The Finite Element Model

To assure the safety of the power bogies for train, it is important to perform the durability analysis of reduction gear considering a variation of velocity and traction motor capability. In this study, two types of applied load histories were constructed from driving histories considering the tractive effort and the train running curves by using dynamic analysis software (MSC.ADAMS). Moreover, this study was performed by evaluating fatigue damage of the reduction gears for rolling stock using durability analysis software (MSC.FATIGUE). The finite element model for evaluating the carburizing effect on the gear surface was used for predicting the fatigue life of the gears. The results showed that the fatigue life of the reduction gear would decrease with an increasing numbers of stops at station.

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The structural optimization of roadheader conical picks based on fatigue life

International Journal of Modeling Simulation and Scientific Computing ◽

10.1142/s1793962318500137 ◽

2018 ◽

Vol 09 (02) ◽

pp. 1850013 ◽

Cited By ~ 1

Author(s):

Zhenguo Lu ◽

Lirong Wan ◽

Qingliang Zeng ◽

Xin Zhang ◽

Kuidong Gao

Keyword(s):

Finite Element ◽

Fatigue Life ◽

Static Analysis ◽

Element Model ◽

Cutting Resistance ◽

Strength Failure ◽

New Type ◽

Conical Picks ◽

Fatigue Life Analysis ◽

The Finite Element Model

Conical picks are the key cutting components used on roadheaders, and they are replaced frequently because of the bad working conditions. Picks did not meet the fatigue life when they were damaged by abrasion, so the pick fatigue life and strength are excessive. In the paper, in order to reduce the abrasion and save the materials, structure optimization was carried out. For static analysis and fatigue life prediction, the simulation program was proposed based on mathematical models to obtain the cutting resistance. Furthermore, the finite element models for static analysis and fatigue life analysis were proposed. The results indicated that fatigue life damage and strength failure of the cutting pick would never happen. Subsequently, the initial optimization model and the finite element model of picks were developed. According to the optimized results, a new type of pick was developed based on the working and installing conditions of the traditional pick. Finally, the previous analysis methods used for traditional methods were carried out again for the new type picks. The results show that new type of pick can satisfy the strength and fatigue life requirements.

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Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

Journal of Pressure Vessel Technology ◽

10.1115/1.1320442 ◽

2000 ◽

Vol 123 (1) ◽

pp. 150-154

Author(s):

John H. Underwood ◽

Michael J. Glennon

Keyword(s):

Residual Stress ◽

Finite Element ◽

Fatigue Life ◽

Yield Strength ◽

Residual Stresses ◽

Solid Mechanics ◽

Element Model ◽

Pressure Vessels ◽

Material Strength ◽

Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

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Parameter Sensitivity in Numerical Modelling of Ice-Structure Interaction With Cohesive Element Method

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2016-54687 ◽

2016 ◽

Cited By ~ 3

Author(s):

Dianshi Feng ◽

Sze Dai Pang ◽

Jin Zhang

Keyword(s):

Element Model ◽

Offshore Structures ◽

Parameter Sensitivity ◽

The Arctic ◽

Cohesive Element ◽

Structure Interaction ◽

Marine Structure ◽

Ice Loads ◽

The Stability ◽

Element Method

The increasing marine activities in the Arctic has resulted in a growing demand for reliable structural designs in this region. Ice loads are a major concern to the designer of a marine structure in the arctic, and are often the principal factor that governs the structural design [Palmer and Croasdale, 2013]. With the rapid advancement in computational power, numerical method is becoming a useful tool for design of offshore structures subjected to ice actions. Cohesive element method (CEM), a method which has been widely utilized to simulate fracture in various materials ranging from metals to ceramics and composites as well as bi-material systems, has been recently applied to predict ice-structure interactions. Although it shows promising future for further applications, there are also some challenging issues like high mesh dependency, large variation in cohesive properties etc., yet to be resolved. In this study, a 3D finite element model with the use of CEM was developed in LS-DYNA for simulating ice-structure interaction. The stability of the model was investigated and a parameter sensitivity analysis was carried out for a better understanding of how each material parameter affects the simulation results.

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