Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many paral...Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many parallel fine lamellas of ferrite andcementite, a description for the dual-phase pearlitic steel isobtained by making use of a microstructure-based constitutiveequation for a single dual-phase pearlitic colony and the Hill'sself-consistent scheme. The elastoplastic response of dual-phasepearlitic steel BS11 subjected to asymmetrically cyclic loading isanalyzed, and a comparison with the experimental results showssatisfacto- ry agreement. The non-proportional cyclic plasticity ofBS11 is also analyzed, in which stress develops along a semi-circlein a biaxial tension/compression and shear stress plane, as istypically experienced by the sur- face elements in rolling andsliding contact.展开更多
A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part...A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material, if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.展开更多
The quasi-ferrite model is proposed and an appropriate PBE exchange functional with the spin density functional theory （SDFT） is selected for the calculation of the relation between magnetic moment and residual stre...The quasi-ferrite model is proposed and an appropriate PBE exchange functional with the spin density functional theory （SDFT） is selected for the calculation of the relation between magnetic moment and residual stress in ferrite using a quantum mechanics code. The relationship between ferrite magnetism and the carbon content is determined, and then a ferrite interstitial solid solution （ISS） model in a low carbon concentration state is replaced with an a-Fe model in the case of majority magnetic calculation. The band structure of the loaded α-Fe is compared with that of the unloaded a-Fe. The comparison shows that the energy of Fe atomic 3d orbital changes a little, while the energy of electron orbital of iron core below 3d almost keeps un- changed. The relationship between the magnetic moment and the stress appears intermittent due to the Bragg total reflection. The change in the magnetic moment due to lattice mismatch is much larger than that caused by mechanical loading.展开更多
基金the National Natural Science Foundation of China (No.19872079)the Fund of the Ministry of Education of China.
文摘Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many parallel fine lamellas of ferrite andcementite, a description for the dual-phase pearlitic steel isobtained by making use of a microstructure-based constitutiveequation for a single dual-phase pearlitic colony and the Hill'sself-consistent scheme. The elastoplastic response of dual-phasepearlitic steel BS11 subjected to asymmetrically cyclic loading isanalyzed, and a comparison with the experimental results showssatisfacto- ry agreement. The non-proportional cyclic plasticity ofBS11 is also analyzed, in which stress develops along a semi-circlein a biaxial tension/compression and shear stress plane, as istypically experienced by the sur- face elements in rolling andsliding contact.
基金This project is supported by National Natural Science Foundation of China (No.10272119)European Community(No.BRPR-CT98-0742).
文摘A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material, if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.
基金supported by the National Natural Science Foundation of China(Grant Nos.11332013 and 11272364)
文摘The quasi-ferrite model is proposed and an appropriate PBE exchange functional with the spin density functional theory （SDFT） is selected for the calculation of the relation between magnetic moment and residual stress in ferrite using a quantum mechanics code. The relationship between ferrite magnetism and the carbon content is determined, and then a ferrite interstitial solid solution （ISS） model in a low carbon concentration state is replaced with an a-Fe model in the case of majority magnetic calculation. The band structure of the loaded α-Fe is compared with that of the unloaded a-Fe. The comparison shows that the energy of Fe atomic 3d orbital changes a little, while the energy of electron orbital of iron core below 3d almost keeps un- changed. The relationship between the magnetic moment and the stress appears intermittent due to the Bragg total reflection. The change in the magnetic moment due to lattice mismatch is much larger than that caused by mechanical loading.
