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CONTENTS
Volume 3, Number 1, January 1995
 

Abstract
This study presents a methodology for the system reliability analysis of cracked structures with random material properties, which are modeled as random fields, and crack geometry under random static loads. The finite element method provides the computational framework to obtain the stress intensity solutions, and the first-order reliability method provides the basis for modeling and analysis of uncertainties. The ultimate structural system reliability is effectively evaluated by the stable configuration approach. Numerical examples are given for the case of random fracture toughness and load.

Key Words
BRITTLE FRACTURE, STOCHASTIC FINITE ELEMENT, RANDOM FIELD, SYSTEMS RELIABILITY, STABLE CONFIGURATION APPROACH

Address
LEE JC, UNIV CALIF IRVINE,DEPT CIVIL & ENVIRONM ENGN,IRVINE,CA 92717

Abstract
The examined model consists of two substructures linked by a right angle rigid line joint. One element is a wall loaded externally along its upper edge by an uneven vertical load. The other element, defined as a plate, is not loaded. Stresses and displacements in the vicinity of the joint are analysed, considering the lateral distribution which leads to three-dimensional effects. The proposed solution combines classical approach with numerical means, using appropriate stress distribution polynomial functions along the joint. Space structure constructions supply cases of interest.

Key Words
JOINTS, COLUMNS, WALLS, BEAMS PLATES, DEFLECTION AND STRESS ANALYSIS, FINITE ELEMENTS, 3-D ANALYSIS

Address
ROSENHOUSE G, TECHNION ISRAEL INST TECHNOL,FAC CIVIL ENGN,IL-32000 HAIFA,ISRAEL

Abstract
General free vibration characteristics of cantilevered circular cylindrical tanks are analyzed using the integral equations technique with the cubic spline functions. For computations, the partial differential equations for thin shallow shells as given by Flugge\'s have been employed after the addition of the inertia forces.

The application of the method is illustrated with a numerical examples of tanks which are free at the top edge and fixed at the bottom. The results obtained by this method have been compared with the available results and a good agreement was found.


Key Words
FREE VIBRATION, CYLINDRICAL TANKS, CYLINDRICAL SHELLS, CANTILEVER CYLINDRICAL SHELLS

Address
HADID HA, UNIV MOSUL,DEPT CIVIL ENGN,MOSUL,IRAQ

Abstract
This paper presents new frequency results for elliptical and semi-elliptical Mindlin plates of various aspect ratios, thicknesses and boundary conditions. The results were obtained using the recently developed computerized Rayleigh-Ritz method for thick plate analysis. For simply supported elliptical plates, it is proposed that the penalty function method be used to enforce the condition of zero rotation of the midplane normal in the tangent plane to the plate boundary.

Key Words
ELLIPTIC PLATE, SEMIELLIPTIC PLATE, MINDLIN THEORY, RAYLEIGH-RITZ METHOD, VIBRATION

Address
WANG CM, NATL UNIV SINGAPORE,DEPT CIVIL ENGN,KENT RIDGE,SINGAPORE 0511,SINGAPORE
UNIV QUEENSLAND,DEPT CIVIL ENGN,ST LUCIA,QLD 4072,AUSTRALIA

Abstract
In the present study, a finite strip method for the vibration and stability analyses of anisotropic laminated composite plates is developed according to the higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method based on the first-order shear deformation theory, the present method gives improved results for very thick plates while using approximately the same number of degrees of freedom. It also eliminates the need for shear correction factors in calculating the transverse shear stiffness.
A number of numerical examples are presented to show the effect of aspect ratio, length-to-thickness ratio, number of plies, fibre orientation and stacking sequence on the natural frequencies and critical buckling loads of simply supported rectangular cross-ply and arbitrary angle-ply composite laminates.



Key Words
COMPOSITE PLATES, VIBRATION, STABILITY, HIGHER ORDER SHEAR DEFORMATION, FINITE STRIP METHOD

Address
AKHRAS G, ROYAL MIL COLL CANADA,DEPT CIVIL ENGN,KINGSTON,ON K7K 5L0,CANADA
UNIV OTTAWA,DEPT CIVIL ENGN,OTTAWA,ON K1N 9B4,CANADA

Abstract
A linearly tapered, doubly symmetric thin-walled closed member, such as power-transmission towers and tourist towers, are often characterized by local variation in mass and/or rigidity, due to additional mass and rigidity. On the preliminary stage of design the closed-form solution is more effective than the finite element method. In order to propose approximate solutions, the discontinuous and local variation in mass and/or rigidity is treated continuously by means of a usable function proposed by Takabatake(1988, 1991, 1993). Thus, a simplified analytical method and approximate solutions for the free and forced transverse vibrations in linear elasticity are demonstrated in general by means of the Galerkin method. The solutions proposed here are examined from the results obtained using the Galerkin method and Wilson-theta method and from the results obtained using NASTRAN.

Key Words
ELASTIC ANALYSIS, DYNAMIC STRUCTURES, LOCAL MASS, LOCAL RIGIDITY, NATURAL FREQUENCY, VARIABLE THIN-WALLED MEMBER

Address
TAKABATAKE H, KANAZAWA INST TECHNOL,DEPT ARCHITECTURE,KANAZAWA,ISHIKAWA 921,JAPAN
KAWADA IND INC,DEPT TECH,TOYAMA 93915,JAPAN

Abstract
A transition membrane element designated as CLM which has variable mid-side nodes with drilling freedoms has been presented in this paper. The functional for the linear problem, in which the drilling rotations are introduced as independent variables, has been formulated. The transition elements with variable side nodes can be efficiently used in the local mesh refinement for the in-plane structures, which have stress concentrations. A modified Gaussian quadrature is needed to be adopted to evaluate the stiffness matrices of these transition elements mainly due to the slope discontinuity of displacement within the elements. Detailed numerical studies show the excellent performance of the new transition elements developed in this study.

Key Words
FINITE ELEMENT, MEMBRANE TRANSITION ELEMENT, DRILLING DOF, IRREGULAR NODE, VARIABLE-NODE

Address
CHOI CK, KOREA ADV INST SCI & TECHNOL,DEPT CIVIL ENGN,TAEJON 305701,SOUTH KOREA

Abstract
An analysis to determine shear centers for anisotropic elastic thin-walled composite beams, cantilevered and loaded transversely at the free end is presented. The shear center is formulated based on familiar strength of material procedures analogous to those for isotropic beams. These procedures call for a balancing of torsional moments on the cross sectional surface and lead to a condition of zero resultant torsional couple. As a consequence, due the presence of anisotropic coupling; certain non-classical effects are manifested and are illustrated in two example problems. The most distinguishing result is that twisting may occur for composite beams even if shear forces are applied at the shear center. The derived shear center locations do not depend on any specific anisotropic bending theories per se, but only on the values of bending and shear stresses which such theories produce.

Key Words
ANISOTROPIC ELASTICITY, COMPOSITES, SHEAR CENTER, THIN-WALLED BEAMS

Address
POLLOCK GD, UNIV ILLINOIS,DEPT AERONAUT & ASTRONAUT ENGN,URBANA,IL 61801
UNIV ILLINOIS,NATL CTR SUPERCOMP APPLICAT,URBANA,IL 61801


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