Fretting fatigue is a complex phenomenon that is affected by multiaxial stress and contact problems. In the contact surface, due to the cyclic load, a relatively small displacement is generated, and the stress concent...
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Fretting fatigue is a complex phenomenon that is affected by multiaxial stress and contact problems. In the contact surface, due to the cyclic load, a relatively small displacement is generated, and the stress concentration is established as well. To assess the fretting fatigue endurance complimentary to experimental efforts, the Finite Element method (FEM) has become a useful tool combined with theoretical approaches. Meanwhile, most (if not all) of commercially available structural materials can be regarded as heterogeneous materials due to the existence of secondary phases and some fabrication defects and porosity. Therefore, to further understand the mechanism of fretting fatigue, knowledge of the material's microstructure is important. In this study, several microstructure characterization techniques are applied to characterize precipitates and micro-voids in aluminium alloy AA2024-T3. These techniques are Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). To account for the precipitates, the homogenization method is adopted in this study. Additionally, a 3D structure non-destructive reconstruction technique is applied to obtain accurate information on micro-voids. The fretting fatigue lifetime is estimated by using the critical plane approach combined with the theory of critical distance. The numerical results are compared with experimental data showing a good agreement. The influence of micro-voids on the fretting fatigue endurance is studied and discussed as well.
A method of model calibration and validation is established for structures with complicated structural features in the presence of multi-level experiments and censored data. Fatigue lifetime models are established com...
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A method of model calibration and validation is established for structures with complicated structural features in the presence of multi-level experiments and censored data. Fatigue lifetime models are established comprised of three levels, where Bayes network was introduced to connect model predictions and experimental data. To avoid iterative calculation, calibration models in component-like and component levels are reconstructed explicitly. Normal distributions are applied to approximate the observed censored data, and the scatter area metric is proposed for model validation. A simulation example and the reliability analysis of the bolt hole in the turbine disc are applied to verify the proposed method.
The paper investigates the fracture behaviour of U-notched specimens made of polymethylmethacrylate at room temperature under mixed mode loading conditions. The specimens are flat and double notched. The notches bisec...
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The paper investigates the fracture behaviour of U-notched specimens made of polymethylmethacrylate at room temperature under mixed mode loading conditions. The specimens are flat and double notched. The notches bisectors lie on the same line that forms an angle β with the loading direction; this specimen shape allows to consider mixed mode loading conditions. With changing β, different contributions of mode I and mode II loading are achieved. The specimens net section, calculated perpendicularly to the load application direction, is maintained constant while the notch fitting radius changes ranging from 1 to 4 mm. The results have been analysed through both the averaged strain energy density method and the theory of critical distance assessing the use of coarse free mesh models for the application of these methods.
Transparent-component-decimation (tcd) method may simplify the aperiodic sequences to the simplest form and one can obtain the transmissive characteristics without complicated calculations. Applying this method to the...
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ISBN:
(纸本)9783037852965
Transparent-component-decimation (tcd) method may simplify the aperiodic sequences to the simplest form and one can obtain the transmissive characteristics without complicated calculations. Applying this method to the Family A of Generalized Thue-Morse [FAGTM(n)] aperiodic superlattices, we obtain directly the formulas of the transmission coefficients at the central wavelength. The results are in accord with the previous published results. It shows that the tcd method can be used to study optical transmission normally through aperiodic multilayers directly and exactly and has bright future.
Transparent-component-decimation(tcd) method may simplify the aperiodic sequences to the simplest form and one can obtain the transmissive characteristics without complicated calculations. Applying this method to the ...
详细信息
ISBN:
(纸本)9783037852965
Transparent-component-decimation(tcd) method may simplify the aperiodic sequences to the simplest form and one can obtain the transmissive characteristics without complicated calculations. Applying this method to the Family A of Generalized Thue-Morse [FAGTM(n)] aperiodic superlattices, we obtain directly the formulas of the transmission coefficients at the central wavelength. The results are in accord with the previous published results. It shows that the tcd method can be used to study optical transmission normally through aperiodic multilayers directly and exactly and has bright future.
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