Dielectric and pyroelectric properties of Pb_(0.97)La_(0.02)(Zr_(0.42)Sn_(0.40)Ti_(0.18))O_(3) ceramics are investigated as functions of temperature and dc bias field.Induced and intrinsic pyroelectric coefficients pi...Dielectric and pyroelectric properties of Pb_(0.97)La_(0.02)(Zr_(0.42)Sn_(0.40)Ti_(0.18))O_(3) ceramics are investigated as functions of temperature and dc bias field.Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed.It is found that the sign,value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases.Polarization and depolarization processes under dc biases are analyzed.Besides the contribution of pind,the diffuse and decreased pyroelectric response under dc bias compared with that of an identical field poled sample without dc bias is mainly attributed to the depolarization process under dc bias.展开更多
Failure wave generations on both impacted surface and internal surface inside the sample have been observed for K9 glass under planar shock wave loading,which demonstrates that formation of failure wave is a process r...Failure wave generations on both impacted surface and internal surface inside the sample have been observed for K9 glass under planar shock wave loading,which demonstrates that formation of failure wave is a process related to the surface microcracks nuclei developing.Based on these observations,a hypothesis is suggested that the large local strains resulting from the rearrangement of SiO4 tetrahedral within the permanent densification region behind the shock wave front and then strains releasing due to the surface microcracks developing could be responsible for the failure wave generation.展开更多
A series of plate-experiments are carried out to acquire ultrapure aluminum （purity,. 99.999%） samples with damage. Based on the metallographic of all ＂soft-recovered＂ samples, the characteristics of damage evolut...A series of plate-experiments are carried out to acquire ultrapure aluminum （purity,. 99.999%） samples with damage. Based on the metallographic of all ＂soft-recovered＂ samples, the characteristics of damage evolution and spallation damage mechanism in ultrapure aluminum are analyzed in detail. Results show that the damage will increase regularly with increasing loading＂ strength. Most of voids appear in the grain boundary and grow alone under tensile loading＂ before they coalesce each other to form big irregular voids. These analysis results are helpful to understand the evolution process of ductile metal dynamic fracture and establish the damage evolution model.展开更多
基金Acknowledgements： This work Was supported by National Natural Science Foundation of China （No. 50472101）, Foundation of Science and Technology of CAEP （No. 20050864） and Foundation for Key Applied Basis Project of Sichuan Province （No. 05JY029-112）.
基金by the Natural Science Associate Foundation(NSAF)of China,the Major Program for the Fundamental Research of Shanghai under Grant No 10DJ1400203the Hundred Talents Programme of Chinese Academic of Sciencesthe Shanghai Rising-Star Program(09QH1402400).
文摘Dielectric and pyroelectric properties of Pb_(0.97)La_(0.02)(Zr_(0.42)Sn_(0.40)Ti_(0.18))O_(3) ceramics are investigated as functions of temperature and dc bias field.Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed.It is found that the sign,value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases.Polarization and depolarization processes under dc biases are analyzed.Besides the contribution of pind,the diffuse and decreased pyroelectric response under dc bias compared with that of an identical field poled sample without dc bias is mainly attributed to the depolarization process under dc bias.
基金Supported by the Science Foundation of China Academy of Engineering Physics,Contract No.9401001.
文摘Failure wave generations on both impacted surface and internal surface inside the sample have been observed for K9 glass under planar shock wave loading,which demonstrates that formation of failure wave is a process related to the surface microcracks nuclei developing.Based on these observations,a hypothesis is suggested that the large local strains resulting from the rearrangement of SiO4 tetrahedral within the permanent densification region behind the shock wave front and then strains releasing due to the surface microcracks developing could be responsible for the failure wave generation.
基金Supported by the National Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China under Grant Nos 10876014, 2010-1a-017and 11072119.
文摘A series of plate-experiments are carried out to acquire ultrapure aluminum （purity,. 99.999%） samples with damage. Based on the metallographic of all ＂soft-recovered＂ samples, the characteristics of damage evolution and spallation damage mechanism in ultrapure aluminum are analyzed in detail. Results show that the damage will increase regularly with increasing loading＂ strength. Most of voids appear in the grain boundary and grow alone under tensile loading＂ before they coalesce each other to form big irregular voids. These analysis results are helpful to understand the evolution process of ductile metal dynamic fracture and establish the damage evolution model.
