Papers - OBATA Makoto
-
FEM estimation of the accuracy of self-consistent averaging method Reviewed
M.OBATA, J. OKUDA, Y.GOTO, S. MATSUURA
Proc. Of JSCE 450 ( 450 ) 103 - 112 1992.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
Self consistent averaging scheme is one of the prominent methods to estimate the finite elasto-plastic deformations of polycrystalline solids. Although it is a unique and potentially powerful method, its accuracy as averaging scheme has remained to be envisaged. To this end, we applied a direct numerical approach based on finite element computation to two dimensional elasto-plastic deformation of polycrystals under uni-axial tention. The results by these two methods depend heavily on the kinematic characteristics of a micro-constituent. While a double slip model yields different overall behaviors, triple or more slip models lead to surprisingly good coincidence. When real 3D behaviors are concerned, the self-consistent method seems to involve very much complicated numerical procedure. Direct numerical approach could be a better alternative.
-
Elastic buckling phenomenon applicable to deployable rings Reviewed
Y. GOTO, Y. WATANABE, T. KASUGAI, M. OBATA
Int. J. Solids Struct. 29 893 - 909 1992.04
Language：English Publishing type：Research paper (scientific journal)
-
An elastic-plastic bifurcation analysis of multiple discrete systems and its application to trusses Reviewed
Y. GOTO, K. OSHIKA, N. KAWANISHI, M. OBATA
Proc. Of JSCE 446 ( 446 ) 117 - 126 1992.04
Language：Japanese Publishing type：Research paper (scientific journal)
-
The ultimate strength of bridge restrainer plates at high speed tension Reviewed
M. OBATA, Y. GOTO, S. MATSUURA, H. FUJIWARA
Proc. Of JSCE 441 ( 441 ) 97 - 105 1992.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
Ultimate strength of bond-type anchorage under tensile force. Reviewed
MAENO Hirofumi, GOTO Yoshiaki, OBATA Makoto, MATSUURA Sei
Doboku Gakkai Ronbunshu 1992 ( 441 ) 185 - 192 1992
Language：Japanese Publisher：Japan Society of Civil Engineers
While the anchorage with a headed anchor bolt in concrete usually fails almost by pulling out a concrete cone, the failure mechanism of the bond-type anchorage becomes complex because both bond and concrete cone failure are involved simultaneously. there have been few theoretical approaches to this bond-concrete-cone failure mechanism of bond type anchorage. In the present study, a new model of failure mechanism is proposed under the assumption that ultimate strength is not the sum of the strength of a stress cone and that of bond on a bolt surface. The assumption is justified because failure by concrete cone is extremely brittle. The validity of this model is confirmed by experimental results. With this mode, it is possible to identify the critical factors to the failure mechanism as well as to estimate the ultimate strength of bond-type anchorage with reasonable accuracy.
-
ELASTIC BUCKLING PHENOMENON APPLICABLE TO DEPLOYABLE RINGS Reviewed
Y GOTO, Y WATANABE, T KASUGAI, M OBATA
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 29 ( 7 ) 893 - 909 1992
Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD
There are various kinds of deployable members developed in order to improve the packing efficiency of space structures. Some of them ingeniously utilize elastic buckling phenomena, such as flexural buckling and torsional buckling. However, their application is primarily restricted to straight members. Herein, we present an interesting buckling phenomenon of a ring which considerably reduces its original volume and could be applied to a deployable ring. First, we show an accurate method which can be used to analyze this buckling phenomenon accompanying finite rotations in space. Then, with this method, we theoretically examine the effect of structural parameters on buckling behavior.
-
Accuracy of the numerical methods for the analysis of plane frames considering finite displacements and finite strains Reviewed
Y. GOTO, T. YOSHIMITSU, M. OBATA, F. NISHINO
Proc. Of JSCE 428 ( 428 ) 67 - 76 1991.04
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
It is accurate to use the theory of finite displacements and finite strains for the analysis of geometrical nonlinearity of structures. However, the governing equation for this theory becomes highly nonlinear and its direct use makes the solution procedure very much complicated. So approximate numerical methods, respectively referred to as the corotational method and the method with the Rigid Bodies-Spring Model, are often used to simplify the solution procedure for the framed structures. Herein, we precisely examine their theoretical accuracy as well as the convergence to the exact solutions. Based on this result, we further discuss an efficient method to be adopted in the analysis of frames considering finite displacements and finite strains.
-
Ultimate behaviors of tie plates used as bridge restrainer Reviewed
M. OBATA, S. SUZUKI, Y. GOTO, S. MATSUURA
J. Struct. Engineering 117 2884 - 2899 1991.04
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
-
Some basic issues in dynamic crack growth in elastic-plastic solids Reviewed
S.NEMAT-NASSER, M. OBATA
Int. J. Fracture 42 287 - 300 1990.04
Language：English Publishing type：Research paper (scientific journal)
-
Analysis of strain localization near a blunting crack tipin crystalline solids Reviewed
M.OBATA, J. OKUDA, Y.GOTO, S. MATSUURA
J. Struct. Engineering, JSCE 36A 343 - 351 1990.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
On a new anchorage system for a steel pier Reviewed
Y. GOTO, M. OBATA, S. MATSUURA, H. MAENO, A. Morimoto
Proc. Int. conference on structural engineering and computations 803 - 810 1990.04
Language：English Publishing type：Research paper (international conference proceedings)
-
On the micro and macroscopic approaches to the finite elasto-plastic deformations Reviewed
M. OBATA, Y. GOTO, S. MATSUURA
Proc. Int. conference on structural engineering and computations 96 - 104 1990.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
-
Elliptic integral solutions of plane elastica with axial and shear deformations Reviewed
Y. GOTO, T. YOSHIMITSU, M. OBATA
Int. J. Solids Struct. 26 375 - 390 1990.04
Language：English Publishing type：Research paper (scientific journal)
-
Micromechanical consideration on the theory of elasto-plasticity at finite deformations Reviewed
M. OBATA, Y. GOTO, S. MATSUURA
Int. J. Engrg. Sci. 28 241 - 241 1990.04
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
-
Elasto-plastic analysis of a blunting crack tip in crystalline solids Reviewed
M.OBATA, J. OKUDA, Y.GOTO, S. MATSUURA
Proc. Of JSCE 422 ( 422 ) 235 - 243 1990.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
Large elasto-plastic deformation around a blunting crack tip is analyzed with help of the theory of physically based crystal plasticity. A boundary value problem is formulated by use of boundary layer analysis under the condition of small scale yielding. The results are compared with those predicted by the usual macroscopic (J2) plasticity. It is shown that deformation tends to localize when crystal plasticity is used. The effects of microstructures on the ductile crack growth are also discussed.
-
Analysis of the static ultimate strength of a bridge restrainer plate Reviewed
M.OBATA, S. SUZUKI, Y.GOTO, S. MATSUURA
Proc. Of JSCE 422 ( 422 ) 295 - 302 1990.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
ELLIPTIC INTEGRAL SOLUTIONS OF PLANE ELASTICA WITH AXIAL AND SHEAR DEFORMATIONS Reviewed
Y GOTO, T YOSHIMITSU, M OBATA
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 26 ( 4 ) 375 - 390 1990
Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD
-
MICROMECHANICAL CONSIDERATION ON THE THEORY OF ELASTOPLASTICITY AT FINITE DEFORMATIONS Reviewed
M OBATA, Y GOTO, S MATSUURA
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE 28 ( 3 ) 241 - 252 1990
Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD
-
Residual stress due to overload and their effects on fatigue strength on notched elements Reviewed
M.OBATA, Y.GOTO, M. MITSURU, S. MATSUURA
J. Struct. Engineering, JSCE 35A 301 - 307 1989.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
Micromechanics of dilatancy in brittle materials Reviewed
M. OBATA, S. NEMAT-NASSER
Proc. of the MRS Int. Meeting on Advanced Materials 449 - 453 1989.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
