The creep of a skin layer under a distributed surface pressure was solved by ananalysical method using Hankel transform and Laplace transform.The surface stressboundary conditions lead io a Volterra integral equation ...The creep of a skin layer under a distributed surface pressure was solved by ananalysical method using Hankel transform and Laplace transform.The surface stressboundary conditions lead io a Volterra integral equation of the first kind, which was then solved by a numerical method.The IMSL subroutines DINLAP and DGORUL were employed to numerically obtain the Hankel-Laplace inversion. The calculateddisplacements at two distinctive moments were compared respectively with those obtained by an elastic solution for either incompressible or compressible solid. Thetransient creep responses of the skin layer were also presented.展开更多
A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale cr...A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.展开更多
文摘The creep of a skin layer under a distributed surface pressure was solved by ananalysical method using Hankel transform and Laplace transform.The surface stressboundary conditions lead io a Volterra integral equation of the first kind, which was then solved by a numerical method.The IMSL subroutines DINLAP and DGORUL were employed to numerically obtain the Hankel-Laplace inversion. The calculateddisplacements at two distinctive moments were compared respectively with those obtained by an elastic solution for either incompressible or compressible solid. Thetransient creep responses of the skin layer were also presented.
基金supports from the National Natural Science Foundation of China (Nos.12132005,12102094 and 12135008)the Shanghai Sailing Program (21YF1402200)the foundation from the Science and Technology on Reactor System Design Technology Laboratory.
文摘A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.
