To investigate the spring-back behavior of dual-phase （DP） steel, V-shape spring-back experiments with different bending angles, relative bending radii and blank holding forces were carried out in this paper. It is ...To investigate the spring-back behavior of dual-phase （DP） steel, V-shape spring-back experiments with different bending angles, relative bending radii and blank holding forces were carried out in this paper. It is concluded that with the increase of V-shape angle or blank holding force, the spring-back of DP steel sheets decreases; while raising fiIlet radius of punch, which has the most apparent effects on spring-back, advances spring-back angle. Among DP590, DP780 and DP980, higher strength yields more notable spring-back due to larger elastic deformation. The difference of spring-back among these materials is relevant with the microstructure and mechanical properties. The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.展开更多
Based on the theory of nonlocal elasticity,a nonlocal shell model accounting for the small scale effect is developed for the bending characteristics of CNTs subjected to the concentrated load.With this nonlocal shell ...Based on the theory of nonlocal elasticity,a nonlocal shell model accounting for the small scale effect is developed for the bending characteristics of CNTs subjected to the concentrated load.With this nonlocal shell model,explicit expressions are derived for the bending solutions.To extract the proper values of nonlocal scale parameter,we have made molecular dynamics(MD) simulations for various radii and lengths of armchair and zigzag CNTs,the results of which are matched with those of nonlocal continuum model.It is found that the present nonlocal elastic shell model with its appropriate values of nonlocal scale parameter has the capability to predict the bending behavior of CNTs,which is comparable with the results of MD simulations.Moreover,exact closed form solutions for the nonlocal scale parameter for zigzag and armchair CNTs are obtained.The results show that nonlocal scale parameter is independent of the length of CNTs,and dependent on the radius of CNTs.展开更多
文摘To investigate the spring-back behavior of dual-phase （DP） steel, V-shape spring-back experiments with different bending angles, relative bending radii and blank holding forces were carried out in this paper. It is concluded that with the increase of V-shape angle or blank holding force, the spring-back of DP steel sheets decreases; while raising fiIlet radius of punch, which has the most apparent effects on spring-back, advances spring-back angle. Among DP590, DP780 and DP980, higher strength yields more notable spring-back due to larger elastic deformation. The difference of spring-back among these materials is relevant with the microstructure and mechanical properties. The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.
基金supported by the National Natural Science Foundation of China (Grant No. 11132002)Guangdong Province (Grant No.10151064101000062)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20110172110031)
文摘Based on the theory of nonlocal elasticity,a nonlocal shell model accounting for the small scale effect is developed for the bending characteristics of CNTs subjected to the concentrated load.With this nonlocal shell model,explicit expressions are derived for the bending solutions.To extract the proper values of nonlocal scale parameter,we have made molecular dynamics(MD) simulations for various radii and lengths of armchair and zigzag CNTs,the results of which are matched with those of nonlocal continuum model.It is found that the present nonlocal elastic shell model with its appropriate values of nonlocal scale parameter has the capability to predict the bending behavior of CNTs,which is comparable with the results of MD simulations.Moreover,exact closed form solutions for the nonlocal scale parameter for zigzag and armchair CNTs are obtained.The results show that nonlocal scale parameter is independent of the length of CNTs,and dependent on the radius of CNTs.
