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Tsukimori, Kazuyuki; ; ;
Nuclear Engineering and Design, 157(1-2), p.65 - 79, 1995/07
Times Cited Count：16 Percentile：80.74(Nuclear Science & Technology)None
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PNC TN9410 93-086, 81 Pages, 1992/11
Since vessels of fast breeder reactors (FBRs) are relatively thin wallcd, the prevention of buckling against seismic loading is one of the key issues in their structural design. This paper is the first report on buckling analysis by use of FEM to rationalize a design method for FBR components. In this paper, we conducted FEM analyses with the FINAS computer code modelling the test conditions precisely, especially the initial shape imperfections and material nonlinearity of the test specimens. Further, the effect of the initial shape imperfections on buckling strength was evaluated quantitatively, and the applicability of FEM to the present problem was studied. The following results were obtained. (1)It was confirmed that the initial shapes of test specimens could be modeled precisely by use of SAXON and the measured data by CIMD. (2)By modelling precisely the initial shape imperfections and material nonlinearity of the test specimens, FEM results agreed well with the test data in terms of the buckling strength, regardless of the buckling mode. The deferences of buckling strength between FEM and experiment results were within -2.5% 
4.5% of experimental results. (3)Concerning the case in which the ratio of length to radius is 2.0, we confirmed that the buckling mode was changed by the existence of initial shape imperfections.
; *; ; Tsukimori, Kazuyuki;
PNC TN9410 92-191, 93 Pages, 1992/04
The development of advanced constitutive models which can represent material behaviors precisely are key ingredients for occurate inelastic analyses. The aim of this research is to prove the performance of the two surface cyclic plasticity model which has been developed to represent detailed material behaviors of austenite stainless steel. Cyclic loading tests for slitted plate (CPVT:Cyclic Plasticity Verification Test) were conducted and cyclic hardening behaviors at the strain concentrated port was observed. The detailed elastoplastic analyses by the two surface cyclic plosticity model were performed using general purpose structural analysis program FINAS. The following conclusions were obtained. (1)The magnification of stress range and the reduction of strain range at strain concentrated region of specimen was predicted from detailed elastopllastic analysis by the two surface cyclic plasticity model. (2)Strain concentration behaviors were analyzed by CPVT in plastic region. But the strain behaviors greater than 2% by range at which the typical cyclic hardening would reveal could not be measured, because most of the strain gauge come to peel off. (3)The experimental results coincided well with the analytical results small strain range region where the experimental data were available but the cyclic plasticity effect would not dominant.
; *; Tsukimori, Kazuyuki; ;
PNC TN9410 92-100, 91 Pages, 1992/03
Since vessel and piping components of FBR plants are generally thin wall structures, prevention of buckling against seismic loadings is important. This paper is the first report on buckling tests of circular cylindrical shells by shear forces with the purpose of rationalizing the design method for FBR components. In this report, we tries to classify the type of buckling behaviors for different shapes by using shell parameters and explain the effects of initial shape imperfection and edge constraint conditions on the bending behavior. Test specimens are thin wall circular cylindrical shells made of SUS304 with the inner diameter of 500mm. In these tests, shear displacements were applied statically at the free end of the specimens. The characteristics or bending or shear buckling behavior were analyzed from the measured data of the force, displacements, strains and deformed shapes. The following results were obtained. (1)Bending buckling deformation is characterized by bulging near the fixed end, while shear buckling deformation is characterized by oblique wrinkle of both sides between both ends of the shell. (2)Buckling mode changes from shear to bending type with the increase of the ratio of length to radius(L/R). The transition boundary of these modes is the line of L/R 
2.0. (3)The effect of plasticity on buckling behaviors becomes small, as the ratio of radius to thickness(R/t) increases. (4)The buckling load(Q 
) of the shell with 2-wave artificial axial imperfection was 7% smaller and Q of the shell with 6-wave artificial circumferential imperfection was 8% smaller than that of the shell without imperfection. (5)The buckling load of the shell with TIG welded end was 5% smaller than that with squeezing type constraint end. (6)The value of Q decreases with the increase of R/t and L/R. This tendency can be explained by the effect or plasticity, that is, the plastic buckling load(Q , 
). In order to develop a ...
; ; ; Tsukimori, Kazuyuki
PNC TN9410 91-346, 43 Pages, 1991/09
Since vessels and piping components of FBR plants are generally thin wall structures, the prevention of buckling against under the seismic loadings is important. In this paper, for the purpose of rationalizing the design method for FBR's components, a simplified evaluation method for the buckling of circular cylindrical shells subjected to shear forces is presented in consideration of material properties and initial shape imperfection effects. In the first place, we express plasticity and initial shape imperfection effects on buckling strength as the plasticity-reduction factor and the imperfection reduction factor, respectively. Secondly, we derive inelastic buckling equations both for bending and for shear buckling, by multiplying elastic evaluation equations for each buckling mode by these factors. Finally we define the equation which gives the smaller of the two as a simplified buckling evaluation equation for buckling of circular cylindrical shells under shear forces on the assumption that bending-shear interaction can be ignored. In this process the way to lead a plasticity-reduction factor is based on Gerard's study on the assumeption that the shell material properties are descrived by the Ramberg-Osgood type stress-strain relation. And the imperfection reduction factor is derived to represent the lower bound of available experimental results (
= (R/t) 
(
/E) = 00.6, where R=radius, t=thickness, = 0.2% proof stress, E = Young's modulus) by use of shell parameter and material properties. The following results were obtained. (1)The simplified buckling evaluation methods are presented, taking into account the effects of plasticity and initial shape imperfection by use of shell parameter and material properties. (2)It is confirmed that the evaluation method gives the lower confidence limit of 95% of all the experimental results in the region of plastic buckling ( = 00.6).
; Tsukimori, Kazuyuki; Iwata, Koji;
Transactions of 12th International Conference on Structural Mechanics in Reactor Technology (SMiRT-12), ,
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