Stress intensity factors are calculated for a cracked plate reinforced locally subject to mode I loading.The stiffeners are considered to have both longitudinal and transverse stiffness.There is no relative displaceme...Stress intensity factors are calculated for a cracked plate reinforced locally subject to mode I loading.The stiffeners are considered to have both longitudinal and transverse stiffness.There is no relative displacement between the plate and the stiffener.It is considered that the shear stresses are lumped at a finite number of locations,the result is obtained by summation.The influence of the stiffener location and the stiffener relative stiffness on cracked plate is included.The stress intensity factor depends on all these factors.Case study shows that the shear stress acting parallel to the stiffener gives more effect on the stress intensity factor than the shear stress acting perpendicular to the stiffener.To increase the relative stiffness of stiffener avails to reduce the stress intensity factor of the cracked plate.展开更多
A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)...A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.展开更多
The conservation law of J-integral in two-media with a crack paralleling to the interface of the two media was firstly proved by analytical and numerical finite element method. Then a schedule model was established th...The conservation law of J-integral in two-media with a crack paralleling to the interface of the two media was firstly proved by analytical and numerical finite element method. Then a schedule model was established that an interface crack is inserted in four media. According to the J-integral conservation law on multi-media, the energy release ratio of Ⅰ-type crack was considered to be conservation when the middle medium layers are very thin. And the conservation law was also convinced by numerical method. By means of the dimension analysis on the model, the asymptotic results and formula calculating the energy release ratio and complex stress intensity factor are presented.展开更多
文摘Stress intensity factors are calculated for a cracked plate reinforced locally subject to mode I loading.The stiffeners are considered to have both longitudinal and transverse stiffness.There is no relative displacement between the plate and the stiffener.It is considered that the shear stresses are lumped at a finite number of locations,the result is obtained by summation.The influence of the stiffener location and the stiffener relative stiffness on cracked plate is included.The stress intensity factor depends on all these factors.Case study shows that the shear stress acting parallel to the stiffener gives more effect on the stress intensity factor than the shear stress acting perpendicular to the stiffener.To increase the relative stiffness of stiffener avails to reduce the stress intensity factor of the cracked plate.
文摘A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.
基金Supported by National Natural Science Foundation of China(11171260)Science and Technology Foundation of Education Department of Fujian Province,China(JA11341)
文摘The conservation law of J-integral in two-media with a crack paralleling to the interface of the two media was firstly proved by analytical and numerical finite element method. Then a schedule model was established that an interface crack is inserted in four media. According to the J-integral conservation law on multi-media, the energy release ratio of Ⅰ-type crack was considered to be conservation when the middle medium layers are very thin. And the conservation law was also convinced by numerical method. By means of the dimension analysis on the model, the asymptotic results and formula calculating the energy release ratio and complex stress intensity factor are presented.
