The calculation of the hardness profile is a powerful tool for the selection of the right steel for a given purpose. Computer programs INC-PHATRAN and INDUCTER-B were formerly developed by the authors for the calculat...The calculation of the hardness profile is a powerful tool for the selection of the right steel for a given purpose. Computer programs INC-PHATRAN and INDUCTER-B were formerly developed by the authors for the calculation of hardness profiles after heat treatment processes of low alloy and carbon steels. The first one simulates quenching as well as through hardening operations, and the second one models electromagnetic induction heat treatments processes. These codes make use of the SAE Standard 3406 in order to obtain the hardness profile, with enhanced regression coefficients recently obtained by the authors. The present work broadens the field of application of this method, allowing to apply it for low hardenability tool steels such as the ASTM O1 Tool Steel. The method used for the calculation of the hardness profile is here summarized, and an example of application is described, which shows good correspondence between the calculated and measured values.展开更多
The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of ro...The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of rock mass. The Burgers and generalized Kelvin models were applied to the soft and hard rock respectively and the rheological parameters were obtained based on the method of optimum separation. By using the simulated code FLAC^(3D), the stability of surrounding rocks of a certain underground plant was analyzed. The effect of surface load and weakening the parameters intensity of argillaceous and bioclastic interlayers between soft and hard rock on rheological behavior of layer composite rock mass was investigated. The results indicate that the rheological characteristics of soft and hard rock layer in composite rock mass can be described well with above two rheological models.展开更多
The accumulative roll-bonding(ARB)process was applied on the strips of aluminum alloy 1050 in two processing conditions:cold ARB and warm ARB.The results of tensile tests and microhardness measurement show that the wa...The accumulative roll-bonding(ARB)process was applied on the strips of aluminum alloy 1050 in two processing conditions:cold ARB and warm ARB.The results of tensile tests and microhardness measurement show that the warm ARB process exhibits the lower tensile strength and microhardness,more homogeneous distribution of the microhardness,higher elongation,and especially superior planar isotropy of the tensile properties in comparison to the cold ARB,because of the intermediate heat treatment as well as the elevated temperature rolling in the warm ARB process.Furthermore,with increasing the cycles of both processes,the planar isotropy decreases progressively.展开更多
A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based ...A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based on macrostructural analysis, the friction stir welding window was constructed. The strength values of joints at different regions of friction stir welding window were analyzed using tensile properties, microstructural studies, and the fracture location of joints was correlated with the lowest hardness distribution profiles. These windows will act as reference maps for selecting appropriate friction stir welding process parameters to get good quality welds of AA2219 aluminium alloys.展开更多
The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity...The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity is considerably decreased after the first pass, while subsequent passes result in better hardness behavior for the processed material. Also, the elongated grains formed in the first pass of the CGP are gradually converted to the equiaxed counterparts by adding pass numbers. Eventually, higher corrosion resistance of the sample by imposing the CGP process is related to the quick formation of passivation film and the change in the morphology of the second phase and precipitates which hinder their electrochemical reactions and decrease the potential localized attack sites.展开更多
A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard ...A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard alpha anomaly distribution, which reflects the occurrence rate and size of anomalies present in the finished part material of titanium rotors. Since anomalies rarely occur naturally, an experimental method is proposed to obtain the anomaly distribution for titanium alloy aeroengine disks to reflect and equivalently replace the manufacturing development in titanium industry. In general, the anomaly distribution information can be divided into two parts: the Probability of Detection(POD) curve and the detected anomaly distribution, which contains the size and frequency data of the detected anomalies. The distribution can be established based on several appropriate assumptions and derivation steps with different confidence levels of POD curves and detected anomaly distributions. In this case, the distribution can be obtained in a relatively short time as a key input to the probability-based damage tolerance methodology. Then the Probability of Failure(POF) can be calculated, and the value is found to vary with different confidence levels. On this basis, the conservative estimated POF can be obtained in conjunction with confidence levels.展开更多
Probabilistic damage tolerance is a critical method to understand and communicate risk and safety.This paper reviews recent research on the probabilistic damage tolerance design for life-limited parts.The vision of th...Probabilistic damage tolerance is a critical method to understand and communicate risk and safety.This paper reviews recent research on the probabilistic damage tolerance design for life-limited parts.The vision of the probabilistic damage tolerance assessment is provided.Five core parts of the probabilistic damage tolerance method are introduced separately,including the anomaly distribution,stress processing and zone definition,fatigue and fracture calculation method,probability of failure(POF)calculation method,and the combination with residual stress induced by the manufacturing process.The above currently-available risk assessment methods provide practical tools for failure risk predictions and are applied by the airworthiness regulations.However,new problems are exposed with the development of the aeroengines.The time-consuming anomaly distribution derivation process restricts the development of the anomaly distribution,especially for the developing aviation industries with little empirical data.Additionally,the strong transient characteristic is prominent because of the significant temperature differences during the take-off and climbing periods.The complex loads then challenge the fatigue and fracture calculation model.Besides,high computational efficiency is required because various variables are considered to calculate the POF.Therefore,new technologies for the probabilistic damage tolerance assessment are provided,including the efficient anomaly distribution acquisition method based on small samples,the zone definition method considering transient process,and stress intensity factor(SIF)solutions under arbitrary stress distributions combined with the machine learning method.Then,an efficient numerical integration method for calculating failure risk based on the probability density evolution theory is proposed.Meanwhile,the influence of the manufacturing process on residual stress and the failure risk of the rotors is explored.The development of the probabilistic damage tolerance method can meet the requirement of the published airworthiness regulation Federal Aviation Regulation(FAR)33.70 and guide the modification or amendment of new regulations to ensure the safety of the high-energy rotors.展开更多
CeO2 nanoparticles(nano-CeO2p) were added into laser cladded NiCoCrAlY coatings on Ni-based superalloy substrate to improve the microstructure and properties.Scanning electron microscope(SEM),X-ray diffractometer(XRD)...CeO2 nanoparticles(nano-CeO2p) were added into laser cladded NiCoCrAlY coatings on Ni-based superalloy substrate to improve the microstructure and properties.Scanning electron microscope(SEM),X-ray diffractometer(XRD),micro-hardness tester,and heat treatment furnace were employed to investigate their morphologies,phases,micro-hardness and thermal shock resistance,compared with the coating without nanoparticles added.The results showed that the microstructure and properties of the coatings with the addition ...展开更多
A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during t...A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during the first pass of tubular ECAP process. The investigation included the efect of various tube wall thicknesses on the efective strain magnitude and strain distribution uniformity. It is shown that tube wall thickness of 3.5 mm gives the optimum value for strain behavior. In addition, copper tube specimens with 3.5 mm wall thickness have been successfully ECAPed up to four passes with the die channel angle of 90 using flexible polyurethane rubber pad. Micro-hardness measurements on both annealed and ECAPed tubes show that 33% and 57% increases in hardness value and also, 50% and 70% reductions in the grain size were achieved after the first and fourth passes respectively. Furthermore, tube wall thickness measurements show that the process does not change the dimension of deformed specimens.展开更多
文摘The calculation of the hardness profile is a powerful tool for the selection of the right steel for a given purpose. Computer programs INC-PHATRAN and INDUCTER-B were formerly developed by the authors for the calculation of hardness profiles after heat treatment processes of low alloy and carbon steels. The first one simulates quenching as well as through hardening operations, and the second one models electromagnetic induction heat treatments processes. These codes make use of the SAE Standard 3406 in order to obtain the hardness profile, with enhanced regression coefficients recently obtained by the authors. The present work broadens the field of application of this method, allowing to apply it for low hardenability tool steels such as the ASTM O1 Tool Steel. The method used for the calculation of the hardness profile is here summarized, and an example of application is described, which shows good correspondence between the calculated and measured values.
基金Supported by the National Natural Science Foundation of China (50374049)
文摘The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of rock mass. The Burgers and generalized Kelvin models were applied to the soft and hard rock respectively and the rheological parameters were obtained based on the method of optimum separation. By using the simulated code FLAC^(3D), the stability of surrounding rocks of a certain underground plant was analyzed. The effect of surface load and weakening the parameters intensity of argillaceous and bioclastic interlayers between soft and hard rock on rheological behavior of layer composite rock mass was investigated. The results indicate that the rheological characteristics of soft and hard rock layer in composite rock mass can be described well with above two rheological models.
文摘The accumulative roll-bonding(ARB)process was applied on the strips of aluminum alloy 1050 in two processing conditions:cold ARB and warm ARB.The results of tensile tests and microhardness measurement show that the warm ARB process exhibits the lower tensile strength and microhardness,more homogeneous distribution of the microhardness,higher elongation,and especially superior planar isotropy of the tensile properties in comparison to the cold ARB,because of the intermediate heat treatment as well as the elevated temperature rolling in the warm ARB process.Furthermore,with increasing the cycles of both processes,the planar isotropy decreases progressively.
文摘A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based on macrostructural analysis, the friction stir welding window was constructed. The strength values of joints at different regions of friction stir welding window were analyzed using tensile properties, microstructural studies, and the fracture location of joints was correlated with the lowest hardness distribution profiles. These windows will act as reference maps for selecting appropriate friction stir welding process parameters to get good quality welds of AA2219 aluminium alloys.
基金funded by“Quality Engineering Project of Anhui Province of China in 2016”entitled mold design and manufacturing experimental training center(2016sxzx050)。
文摘The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity is considerably decreased after the first pass, while subsequent passes result in better hardness behavior for the processed material. Also, the elongated grains formed in the first pass of the CGP are gradually converted to the equiaxed counterparts by adding pass numbers. Eventually, higher corrosion resistance of the sample by imposing the CGP process is related to the quick formation of passivation film and the change in the morphology of the second phase and precipitates which hinder their electrochemical reactions and decrease the potential localized attack sites.
基金funded by the National Natural Science Foundation of China and Civil Aviation Administration of China(No.U1833109)the Innovation Team of Complex System Safety and Airworthiness of Aero Engine from the Co-Innovation Center for Advanced Aeroengine of China。
文摘A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard alpha anomaly distribution, which reflects the occurrence rate and size of anomalies present in the finished part material of titanium rotors. Since anomalies rarely occur naturally, an experimental method is proposed to obtain the anomaly distribution for titanium alloy aeroengine disks to reflect and equivalently replace the manufacturing development in titanium industry. In general, the anomaly distribution information can be divided into two parts: the Probability of Detection(POD) curve and the detected anomaly distribution, which contains the size and frequency data of the detected anomalies. The distribution can be established based on several appropriate assumptions and derivation steps with different confidence levels of POD curves and detected anomaly distributions. In this case, the distribution can be obtained in a relatively short time as a key input to the probability-based damage tolerance methodology. Then the Probability of Failure(POF) can be calculated, and the value is found to vary with different confidence levels. On this basis, the conservative estimated POF can be obtained in conjunction with confidence levels.
基金the National Natural Science Foundation of China,grant number U2233213.
文摘Probabilistic damage tolerance is a critical method to understand and communicate risk and safety.This paper reviews recent research on the probabilistic damage tolerance design for life-limited parts.The vision of the probabilistic damage tolerance assessment is provided.Five core parts of the probabilistic damage tolerance method are introduced separately,including the anomaly distribution,stress processing and zone definition,fatigue and fracture calculation method,probability of failure(POF)calculation method,and the combination with residual stress induced by the manufacturing process.The above currently-available risk assessment methods provide practical tools for failure risk predictions and are applied by the airworthiness regulations.However,new problems are exposed with the development of the aeroengines.The time-consuming anomaly distribution derivation process restricts the development of the anomaly distribution,especially for the developing aviation industries with little empirical data.Additionally,the strong transient characteristic is prominent because of the significant temperature differences during the take-off and climbing periods.The complex loads then challenge the fatigue and fracture calculation model.Besides,high computational efficiency is required because various variables are considered to calculate the POF.Therefore,new technologies for the probabilistic damage tolerance assessment are provided,including the efficient anomaly distribution acquisition method based on small samples,the zone definition method considering transient process,and stress intensity factor(SIF)solutions under arbitrary stress distributions combined with the machine learning method.Then,an efficient numerical integration method for calculating failure risk based on the probability density evolution theory is proposed.Meanwhile,the influence of the manufacturing process on residual stress and the failure risk of the rotors is explored.The development of the probabilistic damage tolerance method can meet the requirement of the published airworthiness regulation Federal Aviation Regulation(FAR)33.70 and guide the modification or amendment of new regulations to ensure the safety of the high-energy rotors.
基金supported by the Doctoral Program of Higher Education of China (20060287019)the Opening Research Fund of Jiangsu Key Laboratory of Tribology of China (kjsmcx07001)Graduate Innovation Foundation of Jiangsu Province of China (CX08B-039Z)
文摘CeO2 nanoparticles(nano-CeO2p) were added into laser cladded NiCoCrAlY coatings on Ni-based superalloy substrate to improve the microstructure and properties.Scanning electron microscope(SEM),X-ray diffractometer(XRD),micro-hardness tester,and heat treatment furnace were employed to investigate their morphologies,phases,micro-hardness and thermal shock resistance,compared with the coating without nanoparticles added.The results showed that the microstructure and properties of the coatings with the addition ...
文摘A new technique to equal channel angular pressing of tubular samples has been proposed and investigated through experiments and simulations. Deformation behavior of copper tube sample was numerically analyzed during the first pass of tubular ECAP process. The investigation included the efect of various tube wall thicknesses on the efective strain magnitude and strain distribution uniformity. It is shown that tube wall thickness of 3.5 mm gives the optimum value for strain behavior. In addition, copper tube specimens with 3.5 mm wall thickness have been successfully ECAPed up to four passes with the die channel angle of 90 using flexible polyurethane rubber pad. Micro-hardness measurements on both annealed and ECAPed tubes show that 33% and 57% increases in hardness value and also, 50% and 70% reductions in the grain size were achieved after the first and fourth passes respectively. Furthermore, tube wall thickness measurements show that the process does not change the dimension of deformed specimens.