Effect of Low Cycle Fatigue Damage on Ultimate Strength of Aged Ship Structures

2011 ◽  
Author(s):  
Yu Tian ◽  
Zhuo-shang Ji
Keyword(s):  
Ultimate Strength ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Simple Procedure ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Strength Reduction ◽  
Cycle Fatigue ◽  
Theoretical Results

The main objective of this paper is to study the effects of general low cycle fatigue (LCF) damage on ultimate strength of unstiffened ship plates under uniaxial compression. A nonlinear LCF damage model has been derived on basis of continuum damage mechanics (CDM) coupled with plastic mechanics in order to define the deterioration of materials. The theoretical results show that the damage variable D can be measured by a simple procedure and it can be related to the mechanical property of material directly. Formulae predicting ultimate strength reduction have been proposed based on amended Faulkner’s simple and useful expression. Nonlinear finite element analyses (FEA) of panels with various material damages have been carried out. The results indicate that the deterioration of materials is important factors determining the amount of strength reduction. It was also found that the proposed formulae can accurately predict the residual ultimate strength of unstiffened plate with general fatigue damage.

Identification and Validation of a Low Cycle Fatigue Damage Model for Al 7075-T6 Alloy

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Saeed Masih ◽  
Mohammad Mashayekhi ◽  
Noushin Torabian
Keyword(s):  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Crack Initiation ◽  
Life Time ◽  
Continuum Damage Mechanics ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Explicit Finite Element ◽  
Al 7075

In this paper, the behavior of 7075-T6 aluminum alloy under low cycle fatigue (LCF) loading is experimentally and numerically investigated using continuum damage mechanics (CDM). An experimental procedure is established to identify the damage parameters for Al 7075-T6. A damage-coupled explicit finite element code is developed using the experimentally extracted damage parameters to study the material behavior under LCF loading. Moreover, fractographic examinations are conducted to identify the fatigue crack initiation locations and propagation mechanisms. The model is employed for life-time assessment of stringer-skin connection of a fuselage and the results are compared with the data available in the literature.

Low Cycle Fatigue Study for GH901 Material Based on Damage Mechanics Theory

2014 ◽  
Vol 711 ◽  
pp. 40-43 ◽  
Author(s):  
Yong Qi Wang ◽  
Hai Bing Zhang
Keyword(s):  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Practical Method ◽  
Test Results ◽  
Cycle Fatigue ◽  
Mechanics Model

The low cycle fatigue damage of turbine disc which is made of GH901 material is systematic analyzed and studied in the article that is based on the theory of continuum damage mechanics and fatigue testing, we improved the common Lemaitre’s low cycle fatigue damage mechanics model, the damage evolution law that the model describes is in good agreement with the test results throughout the course of the fatigue damage. The simplified analysis method for low cycle fatigue damage evolution and life prediction is proposed based on the GH901 low cycle damage features, the practical method of getting damaged material’s constants by existing data is proposed as well.

A Damage Model for Low Cycle Fatigue Analysis of Stiffened Plates

2014 ◽  
Vol 496-500 ◽  
pp. 561-566
Author(s):  
Qin Dong ◽  
Ping Yang ◽  
Jun Lin Deng ◽  
Hong Wang
Keyword(s):  
Cyclic Loading ◽  
Plastic Strain ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Integral Transformation ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Stiffened Plates ◽  
Cycle Fatigue ◽  
Cyclic Loading Condition

A low-cycle fatigue damage model for stiffened plates has been derived based on the theory of damage mechanics. The fatigue damage variable equation of the stiffened plate under cyclic loading was introduced into the accumulative plastic strain equation. Then by means of integral transformation, the evolution equation of axial plastic strain was derived under low cyclic loading condition. The analysis results by the presented model compare well with those by the finite element method.

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

scholarly journals Extremely-Low-Cycle Fatigue Damage for Beam-to-Column Welded Joints Using Structural Details

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1768
Author(s):  
Lizhen Huang ◽  
Weilian Qu ◽  
Ernian Zhao
Keyword(s):  
Fatigue Damage ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Butt Weld ◽  
Damage Models ◽  
Structural Details

The multiaxial fatigue critical plane method can be used to evaluate the extremely-low-cycle fatigue (ELCF) damage of beam-to-column welded joints in steel frameworks subjected to strong seismic activity. In this paper, fatigue damage models using structural detail parameters are studied. Firstly, the fatigue properties obtained from experiments are adopted to assess ELCF life for steel frameworks. In these experiments, two types of welded specimens, namely, plate butt weld (PB) and cruciform load-carrying groove weld (CLG), are designed according to the structural details of steel beam and box column joints, in which both structural details and welded factors are taken into account. Secondly, experiments are performed on three full-scale steel welded beam-to-column joints to determine the contribution of stress and/or strain to damage parameters. Finally, we introduce a modification of the most popular fatigue damage model of Fatemi and Socie (FS), modified by us in a previous study, for damage evaluation, and compare this with Shang and Wang (SW) in order to examine the applicability of the fatigue properties of PB and CLG. This study shows that the modified FS model using the fatigue properties of CLG can predict the crack initiation life and evaluate the damage of beam-to-column welded joints, and can be subsequently used for further investigation of the damage evolution law.

Fatigue Crack Modeling and Simulation Based on Continuum Damage Mechanics

2006 ◽  
Vol 129 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Masakazu Takagaki ◽  
Toshiya Nakamura
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Present Theory ◽  
Continuum Damage ◽  
Cycle Fatigue

Numerical simulation of fatigue crack propagation based on fracture mechanics and the conventional finite element method requires a huge amount of computational resources when the cracked structure shows a complicated condition such as the multiple site damage or thermal fatigue. The objective of the present study is to develop a simulation technique for fatigue crack propagation that can be applied to complex situations by employing the continuum damage mechanics (CDM). An anisotropic damage tensor is defined to model a macroscopic fatigue crack. The validity of the present theory is examined by comparing the elastic stress distributions around the crack tip with those obtained by a conventional method. Combined with a nonlinear elasto-plastic constitutive equation, numerical simulations are conducted for low cycle fatigue crack propagation in a plate with one or two cracks. The results show good agreement with the experiments. Finally, propagations of multiply distributed cracks under low cycle fatigue loading are simulated to demonstrate the potential application of the present method.

CONTINUUM DAMAGE MECHANICS ANALYSIS OF THIN-WALLED TUBE UNDER CYCLIC BENDING AND INTERNAL CONSTANT PRESSURE

2013 ◽  
Vol 05 (04) ◽  
pp. 1350038 ◽  
Author(s):  
H. YAZDANI ◽  
A. NAYEBI
Keyword(s):  
Internal Pressure ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Cyclic Bending ◽  
Thin Walled Tube ◽  
Thin Walled

Ratcheting and fatigue damage of thin-walled tube under cyclic bending and steady internal pressure is studied. Chaboche's nonlinear kinematic hardening model extended by considering the effect of continuum damage mechanics employed to predict ratcheting. Lemaitre damage model [Lemaitre, J. and Desmorat, R. [2005] Engineering Damage Mechanics (Springer-Verlag, Berlin)] which is appropriate for low cyclic loading is used. Also the evolution features of whole-life ratcheting behavior and low cycle fatigue (LCF) damage of the tube are discussed. A simplified method related to the thin-walled tube under bending and internal pressure is used and compared well with experimental results. Bree's interaction diagram with boundaries between shakedown and ratcheting zone is determined. Whole-life ratcheting of thin-walled tube reduces obviously with increase of internal pressure.

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