Shoji Iwasaki

Plastic limit analyses of circular plates with respect to unified yield criterion

Plastic limit analysis of a circular plate under uniform transverse loading is presented in terms of an unified yield criterion (UYC). Exact and unified solutions of load-carrying capacities, moment fields and velocity fields for simply supported circular plate, clamped circular plate and annular plate in plastic limit state are derived. Moment fields of the three typical circular plates correspond to different distribution fields on the yield curves. Maximum and minimum plastic limit solutions are deduced for the three types of circular plates by selecting the weighted coefficients with upper and lower bound values in the unified yield criterion. Moment fields and velocity fields with respect to the three special criteria, namely the Tresca criterion, the Mises criterion (close-form solution) and the twin shear stress criterion are illustrated and compared. The paper presents an effective analytical method to compute the exact plastic limit solution for circular plates in terms of a piecewise linear yield criterion.

Dynamic plastic behavior of circular plate usingunified yield criterion

Abstract Dynamic plastic behavior of a rigid-plastic simply supported circular plate undermoderate partial uniformly distributed impulsive load is complemented by using a unified yieldcriterion which consists of a generic of convex piecewise linear yield criteria. Upper bound andlower bound plastic responses of the plate under rectangular pulse are obtained; responsebehavior of the plate with respect to the Mises criterion is derived by a proximal manner. Theinconstant circumferential moment distribution and the non-linear flow velocity distribution in theperiods corresponding to the two motion phases are suggested in this paper. Static and kinematicadmissibility of the dynamic plastic solutions is discussed and two types of moment profiles forthe plates under intense dynamic load are supposed for studying in the future.

5-node hybrid/mixed finite element for Reissner-Mindlin plate

Abstract In this paper, a new quadrilateral 5-node plate bending element (HP5) for hybrid/mixed finite element method is presented in the global Cartesian coordinates by the Hellinger–Reissner functional. This new element is based on the independent interpolations for displacement and stress. Its convergence is proven by theory and through detailed numerical investigations. The numerical studies demonstrate the validity of the resulting new element HP5 and show that the present element possesses many ideal qualities, i.e. remarkable convergence for thin and thick plates, a lower sensitivity to geometric distortion and invariability to the rotation of coordinates, freedom of shear locking phenomenon in the thin plate limit, suppression of spurious zero energy deformation modes, and the accuracy of solution is improved over that of 4-node hybrid/mixed finite element (HP4). Very good results have been obtained for thin and thick plates and show that it is a satisfactory foundation of developing h-version and p-version adaptive hybrid/mixed finite element method.

On Shape Optimization Study with Automatic Mesh Division of Two-dimensional Bodies by BEM

ABSTRACT A FORTRAN program consisting of numerical optimization techniques was created and coupled with the 2-dimensional BEM anlysis program. When the models are repeatedly calculated by BEM during optimization, equal mesh divisions are automatically produced in the computational calculation. These automatically produced equal mesh divisions are effective for numerical accuracy. It is easier to make a BEM program for automatically produced mesh divisions than one for FEM. As for an example of this optimization computer program, a simple beam with deep height subjected to uniform load is computed. Advantages and disadvantages of using this automatically produced equal mesh division program are explained.

How the arch bridges were introduced in Japan

Arch bridge is one of the bridges which have long time history in the world. It is supposed that the first arch bridge was constructed in the Middle and Near East. From the Middle and Near East, arch bridge technique were transmitted to Rome, China or another country. It is sure that the arch bridge technique was transmitted from China to Japan in the Edo period.We examine in this paper the possibility that the arch bridge technique was transmitted from China to Japan before the Edo period.We are proposing that the transmission of the arch bridge technique should be studied with considering another cultural transmission.