Commercially pure titanium( CP Ti) sheets show typical planar anisotropy due to inherently crystallographic texture and rolling process. To characterize the initial,planar,plastic anisotropy of CP Ti sheets in forming...Commercially pure titanium( CP Ti) sheets show typical planar anisotropy due to inherently crystallographic texture and rolling process. To characterize the initial,planar,plastic anisotropy of CP Ti sheets in forming process,uniaxial tensile tests of cold-rolled TA1 sheets at 0°,45° and 90° to the rolling direction were performed at room temperature,corresponding stress-strain curves and Lankford coefficient( r value) were obtained. Based on Hill'48 and Barlat'89 yield criteria,the anisotropic behavior of TA1 sheets was investigated. In order to verify the accuracy of two models,the experimental values of yield stress and r were compared with predicted ones. It revealed that Barlat '89 criterion with M = 6 is the best agreement with experimental data,and the obtained model can be used in the simulation of forming process.展开更多
This paper is aimed at presenting some suggestions to candidates who are taking the IELTS to get higher marks in speaking section.The first suggestion is from psychological aspect,using a variety of self-help material...This paper is aimed at presenting some suggestions to candidates who are taking the IELTS to get higher marks in speaking section.The first suggestion is from psychological aspect,using a variety of self-help materials to improve confidence.The second is to take a close look at the marking criteria of IELTS and make good use of it.The third encourages students to form a habit of thinking critically through invoking a range of academic perspectives.Evidences show that the suggestions are effective in raising scores on the speaking component since they have ever been applied to some students of the author.展开更多
基金Sponsored by the Key Technologies R&D Program(Grant No.2011BAE13B05)the National Natural Science Foundation of China(Grant No.51075031)
文摘Commercially pure titanium( CP Ti) sheets show typical planar anisotropy due to inherently crystallographic texture and rolling process. To characterize the initial,planar,plastic anisotropy of CP Ti sheets in forming process,uniaxial tensile tests of cold-rolled TA1 sheets at 0°,45° and 90° to the rolling direction were performed at room temperature,corresponding stress-strain curves and Lankford coefficient( r value) were obtained. Based on Hill'48 and Barlat'89 yield criteria,the anisotropic behavior of TA1 sheets was investigated. In order to verify the accuracy of two models,the experimental values of yield stress and r were compared with predicted ones. It revealed that Barlat '89 criterion with M = 6 is the best agreement with experimental data,and the obtained model can be used in the simulation of forming process.
文摘This paper is aimed at presenting some suggestions to candidates who are taking the IELTS to get higher marks in speaking section.The first suggestion is from psychological aspect,using a variety of self-help materials to improve confidence.The second is to take a close look at the marking criteria of IELTS and make good use of it.The third encourages students to form a habit of thinking critically through invoking a range of academic perspectives.Evidences show that the suggestions are effective in raising scores on the speaking component since they have ever been applied to some students of the author.
