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CONTENTS
Volume 13, Number 6, June 2002
 

Abstract
This paper presents experimental and numerical analyses of the thermomechanical behaviour that takes place in SAE1020 mild steel cylindrical specimens during the conventional tensile test. A set of experiments has been carried out in order to obtain the stress-strain curve and the diameter evolution at the neck which allow, in turn, to derive the elastic and hardening parameters characterizing the material response. Temperature evolutions have also been measured for a high strain rate situation. Moreover, a finite element large strain thermoelastoplasticity-based formulation is proposed and used to simulate the deformation process during the whole test. Some important aspects of this formulation are discussed. Finally, the results provided by the simulation are experimentally validated.

Key Words
This paper presents experimental and numerical analyses of the thermomechanical behaviour that takes place in SAE1020 mild steel cylindrical specimens during the conventional tensile test. A set of experiments has been carried out in order to obtain the stress-strain curve and the diameter evolution at the neck which allow, in turn, to derive the elastic and hardening parameters characterizing the material response. Temperature evolutions have also been measured for a high strain rate situation. Moreover, a finite element large strain thermoelastoplasticity-based formulation is proposed and used to simulate the deformation process during the whole test. Some important aspects of this formulation are discussed. Finally, the results provided by the simulation are experimentally validated.

Address
Celentano DJ, Univ Santiago Chile, Dept Ingn Mecan, Av Bdo OHiggins 3363, Santiago, Chile
Univ Santiago Chile, Dept Ingn Mecan, Santiago, Chile

Abstract
This paper presents a method of seismic analysis for a cylindrical liquid storage structure considering the effects of the interior fluid and exterior soil medium in the frequency domain. The horizontal and rocking motions of the structure are included in this study. The fluid motion is expressed in terms of analytical velocity potential functions, which can be obtained by solving the boundary value problem including the deformed configuration of the structure as well as the sloshing behavior of the fluid. The effect of the fluid is included in the equation of motion as the impulsive added mass and the frequency-dependent convective added mass along the nodes on the wetted boundary of the structure. The structure and the near-field soil medium are represented using the axisymmetric finite elements, while the far-field soil is modeled using dynamic infinite elements. The present method can be applied to the structure embedded in ground as well as on ground, since it models both the soil medium and the structure directly. For the purpose of verification, earthquake response analyses are performed on several cases of liquid tanks on a rigid ground and on a homogeneous elastic half-space. Comparison of the present results with those by other methods shows good agreement. Finally, an application example of a reinforced concrete tank on a horizontally layered soil with a rigid bedrock is presented to demonstrate the importance of the soil-structure interaction effects in the seismic analysis for large liquid storage tanks.

Key Words
cylindrical liquid storage tank, fluid-structure-soil interaction, added mass, infinite element, velocity potential, earthquake response analysis

Address
Kim JM, Yosu Natl Univ, Dept Ocean Civl Engn, Choongnam 550749, South Korea
Yosu Natl Univ, Dept Ocean Civl Engn, Choongnam 550749, South Korea
Korea Adv Inst Sci & Technol, Dept Civil Engn, Taejon 305701, South Korea

Abstract
The present study aims to improve an existing model for the prediction of deceleration time history, penetration depth and forces on ogive and conical nose shaped missiles under normal impact into geo-material targets. The actual ogive nose shaped missile has been considered in the analysis and the results thus obtained have been compared with the existing model and significant improvements are found. A close proximity in the results has also been observed with the experimental values. The results of ogive nose shaped missile have also been compared with equivalent conical nose shaped missile. Variation of radial stresses along nose length and radial direction has been studied. Effect of CRH on missile penetrating performance has been investigated.

Key Words
missile penetration, axisymmetric impact, projectiles, deceleration, geo-material targets

Address
Siddiqui NA, Aligarh Muslim Univ, Dept Civil Engn, Aligarh 202002, Uttar Pradesh, India
Aligarh Muslim Univ, Dept Civil Engn, Aligarh 202002, Uttar Pradesh, India

Abstract
In order to ensure the structural dynamic stability of moving liquid-storage containers, the flow motion of interior liquid should be appropriately suppressed by means of mechanical devices such as the disc-type elastic baffle. In practice, the design of a suitable baffle requires a priori the parametric dynamic characteristics of storage containers, with respect to the design parameters of baffle, such as the installation location and inner-hole size, the baffle number, and so on. In this paper, we intend to investigate the parametric effect of the baffle parameters on the transient dynamic behavior of a cylindrical fuel-storage tank in an abrupt vertical acceleration motion. For this goal, we employ the ALE (arbitrary Lagrangian-Eulerian) kinematic description method incorporated with the finite element method.

Key Words
baffled fuel-storage container, installation location and inner-hole size, transient dynamic characteristics, parametric numerical analysis, ALE method

Address
Lee SY, Pusan Natl Univ, Sch Mech Engn, Pusan 609735, South Korea
Pusan Natl Univ, Sch Mech Engn, Pusan 609735, South Korea
Agcy Def Dev, Taejon 305600, South Korea

Abstract
This paper presents theoretical investigation on the cross correlation between torsional vibration (u(theta)) and translation vibration (u(x)) of asymmetrical structure under white noise excitation. The formula reveals that the cross correlation coefficient (p) is a function of uncoupled frequency ratio (Omega = omega(theta)/omega(x)), eccentricity, and damping ratio (xi). Simulations involving acceleration records from fifteen different earthquakes show correlation coefficients results similar to the theoretical correlation coefficients. The uncoupled frequency ratio is the dominating parameter to p; generally, p is positive for omega(theta)/omega(x) > 1.0, negative for omega(theta)/omega(x) < 1.0, and close to zero for omega(theta)/omega(x) = 1.0. When the eccentricity or damping ratio increases, p increases moderately for small Omega (< 1.0) only. The relation among u(x), u(theta) and corner displacement are best presented by p; a simple way to hand-calculate the theoretical dynamic corner displacements from u(x), u(theta) and p is proposed as an alternative to dynamic analysis.

Key Words
dynamic, torsion, seismic response, effective eccentricity, cross correlation, static design, design eccentricity, white noise

Address
Jeng V, Natl Taiwan Univ Sci & Technol, 43 Keelung Rd,Sec 4,POB 90-130, Taipei, Taiwan
Natl Taiwan Univ Sci & Technol, Taipei, Taiwan

Abstract
Here, the dynamic response characteristics of thick cross-ply laminated composite cylindrical shells are studied using a higher-order displacement model. The formulation accounts for the nonlinear variation of the in-plane and transverse displacements through the thickness, and abrupt discontinuity in slope of the in-plane displacements at any interface. The effect of inplane and rotary inertia terms is included. The analysis is carried out using finite element approach. The influences of various terms in the higher-order displacement field on the free vibrations, and transient dynamic response characteristics of cylindrical composite shells subjected to thermal and mechanical loads are analyzed.

Key Words
laminated shell, cross-ply, free vibration, transient response, higher-order, finite element, panels

Address
Ganapathi M, Inst Armament Technol, Pune 411025, Maharashtra, India
Inst Armament Technol, Pune 411025, Maharashtra, India

Abstract
This paper presents a finite element approach for determining the natural frequencies for planar inclined arches of various shapes vibrating in three-dimensional space. The profile of inclined arches, represented by undeformed centriodal axis of cross-section, is defined by the equation of plane curves expressed in the rectangular coordinates which are : circular, parabolic, sine, elliptic, and catenary shapes. In free vibration state, the arch is slightly displaced from its undeformed position. The linear relationship between curvature-torsion and axial strain is expressed in terms of the displacements in three-dimensional space. The finite element discretization along the span length is used rather than the total are length. Numerical results for arches of various shapes are given and they are in good agreement with those reported in literature. The natural frequency parameters and mode shapes are reported as functions of two nondimensional parameters: the span to cord length ratio (e) and the rise to cord length ratio (f).

Key Words
finite elements, free vibrations, inclined elastic arches, mode shapes

Address
Chucheepsakul S, King Mongkuts Univ Technol, Dept Civil Engn, Bangkok 10140, Thailand
King Mongkuts Univ Technol, Dept Civil Engn, Bangkok 10140, Thailand


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