scholarly journals Towards Understanding Fatigue Disbond Growth via Cyclic Strain Energy

2014 ◽  
Vol 3 ◽  
pp. 610-615 ◽  
Author(s):  
J.A. Pascoe ◽  
R.C. Alderliesten ◽  
R. Benedictus
Keyword(s):  
Strain Energy ◽  
Cyclic Strain

Variations of Mechanical Parameters and Strain Energy Dissipated During Tension-Torsion Loading

2012 ◽  
Vol 57 (1) ◽  
pp. 193-197 ◽  
Author(s):  
T. Szymczak ◽  
Z. Kowalewski
Keyword(s):  
Yield Point ◽  
Strain Energy ◽  
Tensile Deformation ◽  
Complex Loading ◽  
Cyclic Strain ◽  
Plane Stress State ◽  
Mechanical Parameters ◽  
Hardening Modulus ◽  
Plastic Strain Energy ◽  
Energy Dissipated

Variations of Mechanical Parameters and Strain Energy Dissipated During Tension-Torsion LoadingThe paper presents behaviour of materials under complex loading being combinations of torsion-reverse-torsion cycles superimposed on monotonic tensile deformation. The 2024 aluminium alloy, P91 steel and M1E copper were investigated under plane stress state using thin-walled tubular specimens. All tests were strain controlled and a total strain was less than 1%. An influence of torsion cycles on tensile characteristic was manifested by lowering of the proportional limit and yield point. This effect was increased with magnification of cyclic strain amplitude and in the case of copper a reduction of yield point was equal around 90%. A character of this effect was checked using the yield surface concept after each test. The papers also presents, variations of tangential hardening modulus and plastic strain energy dissipation.

Damage Parameter Assessment for Energy Based Fatigue Life Prediction Methods

2012 ◽  
Author(s):  
Casey M. Holycross ◽  
John N. Wertz ◽  
Todd Letcher ◽  
M.-H. Herman Shen ◽  
Onome E. Scott-Emuakpor ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Strain Energy ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Cyclic Strain ◽  
Damage Parameter ◽  
Fatigue Life Prediction ◽  
Cyclic Behavior ◽  
Fracture Processes

An energy-based method used to predict fatigue life and critical life of various materials has been previously developed, correlating strain energy dissipated during monotonic fracture to total cyclic strain energy dissipation in fatigue fracture. This method is based on the assumption that the monotonic strain energy and total hysteretic strain energy to fracture is equivalent. The fracture processes of monotonic and cyclic failure modes can be of stark contrast, with ductile and brittle fracture dominating each respectively. This study proposes that a more appropriate damage parameter for predicting fatigue life may be to use low cycle fatigue (LCF) strain energy rather than monotonic energy. Thus, the new damage parameter would capture similar fracture processes and cyclic behavior. Round tensile specimens machined from commercially supplied Al 6061-T6511 were tested to acquire LCF failure data in fully reversed loading at various alternating stresses. Results are compared to both monotonic and cyclic strain energy dissipation to determine if LCF strain energy dissipation is a more suitable damage parameter for fatigue life prediction.

scholarly journals Interlaminar Fatigue Crack Propagation in Mode I of Carbon Fiber/PEEK Composites

1993 ◽  
Vol 2 (1) ◽  
pp. 096369359300200
Author(s):  
G C Christopoulos ◽  
S A Paipetis
Keyword(s):  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Double Cantilever Beam ◽  
Cyclic Strain ◽  
Strain Energy Release ◽  
Mode I ◽  
Interlaminar Fracture Toughness ◽  
Fatigue Cycle ◽  
Delamination Growth ◽  
Thermoplastic Matrix

A study of the mode I interlaminar fracture toughness of a unidirectional carbon fibre reinforced thermoplastic matrix composite has been made using Double Cantilever Beam, DCB, specimens. Delamination growth per fatigue cycle, da/dN, was related with the maximum applied cyclic strain energy release rate, GIMAX, using a power law.

scholarly journals The Effect of Concrete Footing Shape in Differential Settlement: A Seismic Design

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Abdoullah Namdar ◽  
Yun Dong ◽  
Yin Deyu
Keyword(s):  
Strain Energy ◽  
Damping Ratio ◽  
Research Work ◽  
Interaction Mechanism ◽  
Cyclic Strain ◽  
Differential Settlement ◽  
Failure Patterns ◽  
Carry Capacity ◽  
Soil Foundation ◽  
Concrete Footing

This paper presents the numerical results of concrete footing-soil foundation seismic interaction mechanism. The concrete footing has been made with two different shapes, but with the equal volume of concrete material. The concrete footing-soil foundation has been analyzed using nonlinear finite elements, with the fixed-base state. The simulated near-fault ground motions have been applied to the concrete footing-soil foundation. The problem has been formulated based on the settlement controlled analysis. The local geotechnical conditions of all configurations have been analyzed. The numerical analysis results indicate that the shape of a concrete footing alters seismic response, revises inertial interaction, enhances damping ratio, improves load carry capacity, modifies cyclic differential settlement, revises failure patterns, minimizes nonlinear deformation, and changes cyclic strain energy dissipation. The novelty of this research work is the strain energy has more been dissipated with artistic concrete footing design.

Measurement of Hysteresis Energy Using Digital Image Correlation With Application to Energy-Based Fatigue Life Prediction

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Dino Celli ◽  
M.-H. Herman Shen ◽  
Casey Holycross ◽  
Onome Scott-Emuakpor ◽  
Tommy George
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Energy ◽  
Life Prediction ◽  
Cyclic Strain ◽  
Fatigue Life Prediction ◽  
Image Correlation ◽  
Prediction Methods

A modified experimental method using digital image correlation (DIC), a noncontact optical method for measuring full-field displacements and strains, is used to interrogate accumulated fatigue damage for low and high cycle fatigue at continuum scales. Previous energy-based fatigue life prediction methods have shown that cyclic strain energy dissipated during fatigue acts as a key damage parameter for accurate determination of total and remaining fatigue life. DIC enables the collection of accurate strain energy measurements or damaging energy of complex geometries that would otherwise be exceedingly difficult and time consuming using traditional strain measurement techniques. Thus, the use of DIC to obtain strain energy measurements of gas turbine engine (GTE) components is highly advantageous for energy-based fatigue life prediction methods. Presented in this study is the experimental characterization of the cyclic strain energy dissipation as a means of predicting fatigue performance and assessment of damage progression of Aluminum 6061 subjected to fully reversed axial fatigue loading utilizing DIC. Validation of total and cyclic strain energy dissipation DIC measurements is accomplished with the simultaneous use of axial extensometery for direct comparison and implementation to strain energy-based life prediction methods.

Measurement of Hysteresis Energy Using Digital Image Correlation With Application to Energy Based Fatigue Life Prediction

2018 ◽  
Author(s):  
Dino Celli ◽  
M.-H. Herman Shen ◽  
Casey Holycross ◽  
Onome Scott-Emuakpor ◽  
Tommy George
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Energy ◽  
Life Prediction ◽  
Cyclic Strain ◽  
Fatigue Life Prediction ◽  
Image Correlation ◽  
Prediction Methods

A modified experimental method using digital image correlation (DIC), a non-contact optical method for measuring full-field displacements and strains, is used to interrogate accumulated fatigue damage for low and high cycle fatigue (LCF/HCF) at continuum scales. Previous energy based fatigue life prediction methods have shown that cyclic strain energy dissipated during fatigue acts as a key damage parameter for accurate determination of total and remaining fatigue life. DIC enables the collection of accurate strain energy measurements or damaging energy of complex geometries that would otherwise be exceedingly difficult and time consuming using traditional strain measurement techniques. Thus, the use of DIC to obtain strain energy measurements of gas turbine engine components is highly advantageous for energy-based fatigue life prediction methods. Presented in this study is the experimental characterization of the cyclic strain energy dissipation as a means of predicting fatigue performance and assessment of damage progression of Aluminum 6061 subjected to fully reversed axial fatigue loading utilizing DIC. Validation of total and cyclic strain energy dissipation DIC measurements are accomplished with the simultaneous use of axial extensometery for direct comparison and implementation to strain energy based life prediction methods.

A unified criterion for fatigue–creep life prediction of high temperature components

2016 ◽  
Vol 231 (4) ◽  
pp. 677-688 ◽  
Author(s):  
Shun-Peng Zhu ◽  
Yuan-Jian Yang ◽  
Hong-Zhong Huang ◽  
Zhiqiang Lv ◽  
Hai-Kun Wang
Keyword(s):  
High Temperature ◽  
Strain Energy ◽  
Life Prediction ◽  
Cyclic Strain ◽  
Creep Life ◽  
Creep Life Prediction ◽  
Model Predictions ◽  
Loading Waveform ◽  
Static Fracture ◽  
High Temperature Components

A unified ductility criterion for fatigue–creep life prediction is presented based on the static fracture toughness exhaustion and dissipated cyclic strain energy density of high temperature components. It provides a general failure criterion for both low and high cycle fatigue regimes. The effects of mean stress, creep and loading waveform on fatigue life are incorporated into this criterion. Applicability and prediction accuracy of the newly proposed criterion was validated through comparing model predictions to experimental results taken from the literature. The results show that the proposed criterion is robust for different loading conditions and more accurate than other existing strain energy/ductility-based methods.

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