Variation Of Bending Stiffness Research Articles

불균일 강성을 갖는 폰툰형 구조물의 유탄성 응답 특성에 관한 실험 연구

Very Large Floating Structure(VLFS) is regarded as one of promising candidates for the future utilization of ocean space. VLFS has the merits of small environmental effect. short construction term, easiness for extension and removal. It is well known that hydroelastic response is one of major design concerns of such a huge structure. Most of studies on the hydroelastic analysis of VLFS assumed uniform mass and bending stiffness. In case of a floating hotel where noticeable change of mass and stiffness at the hotel part is expected. it is necessary to investigate the effect of nonuniform mass and bending stiffness on the hydroelastic response. A model test of a pontoon type VLFS with nonuniform bending stiffness carried out for performance evaluation of a floating marina-hotel-convention center is described in this paper. Through investigation of model test results and comparison with numerical analysis using eigenfunction method, effect of the variation of bending stiffness is discussed.

Modeling of Gossamer Space Structures with Distributed Transfer Function Method

A new structural modeling and analysis method, the distributed transfer function method, is presented for application to gossamer space structures. The distributed transfer function method uses distributed transfer functions, instead of shape function used by traditional finite element solvers, to represent the displacement field. The distributed transfer function method maintains the modeling flexibility of the finite element method, so that it is capable of modeling multibody complex structures, but it requires much fewer nodes and results in a significant reduction of computational time. The distributed transfer functions give rise to closed-form analytical solutions of both displacement and strain fields. As a result, the distributed transfer function method only decomposes a structure at those points where multiple components are connected, to keep each component as large as possible. Gossamer space structures are generally composed of several long booms and large membranes. Therefore, the distributed transfer function method can be used to model a gossamer structure with a small number of unknowns and matrices of low order. It offers very accurate results with high computational efficiency. The distributed transfer function method is applied to investigate the sensitivity of buckling strength of an inflatable/rigidizable boom to the variations in bending stiffness.

Practical use of statistically modified laminate model for injection moldings

Injection molded fiber reinforced materials offer designers the opportunity to reduce part count in a wide range of consumer products. However, flow induced orientation of the fiber results in anisotropy of material properties, and can lead to concerns regarding stiffness and warpage. In previous work the authors introduced a method for predicting anisotropic stiffness, and evaluating warpage, for this class of materials using empirical data derived from tests performed under conditions close to those used in manufacturing. In this paper the method is used to predict with a high degree of accuracy the variation in bending stiffness within a corner injected plate. It is also used to illustrate sensitivity in linear and buckling warpage modes, and show how small changes in process conditions can completely change the predicted warpage pattern.

Simplified Analysis of Rectangular Plates with Stepped Thickness

This paper presents a simplified analytical method for rectangular plates with arbitrarily and eccentrically stepped thickness, such as building slabs, under the validity of the Kirchhoff-Love hypotheses. The discontinuous variation in bending stiffness due to the variation of the thickness can be expressed continuously by the use of an extended Heaviside function, which is defined as a Dirac function existing continuously in a prescribed region. Since the bending stiffness used here is given exactly by the actual bending stiffness at each point, a modification of the bending stiffness used in an equivalent plate analogy is unnecessary. The governing equations are formulated by means of Hamilton’s principle. Static and dynamic approximate but accurate solutions are obtained from the proposed governing equation by the use of the Galerkin method. The numerical results obtained from the proposed theory for simply supported and clamped plates with stepped thickness show good agreement with results obtained from the finite element method using the code NASTRAN.

Study of acoustic response of anisotropic steel structures

The purpose of our experiment is to learn the influence of stiffening on the acoustic response of steel plates. The investigation is carried out on a rectangular plate that is clamped in an opening (1.20 × 2 m2) between a reverberant room and a test room. The sound transmission loss is determined by using two different methods: a method that is based on the sound pressure measurement and the two‐microphone intensity method. The mean radiation efficiency is obtained by measuring the panel vibration velocity with a regular mesh. The measurements are made over a frequency range from 250 to 10 000 Hz for a diffuse field excitation. The following series of samples is tested: a 1.5‐mm‐thick‐steel plate; a plate reinforced with uniformly spaced tubular stiffeners; a plate reinforced with uniformly spaced line stiffeners; and a corrugated panel (the space between the corrugations is the same as the space between the stiffeners). The acoustic effect of variation of bending stiffness is discussed, and all the exper...

The Tenth Sir Richard Fairey Memorial Lecture: Sound transmission in buildings

Sound transmission through walls, ceilings, windows, doors, etc., depends on (1) mass per unit area, (2) bending stiffness, (3) damping, (4) variation in bending stiffness (because of struts or other anisotropies), (5) stiffness and damping of interlayers and sound bridges (in cases of double walls), (6) size and shape of partitions, (7) mounting conditions, (8) influence of flanking walls, (9) unwanted effects such as slits, etc. The first three parameters and to a certain degree also the fourth and fifth can be dealt with theoretically by investigating walls of infinite size. In this way many of the results obtained in buildings can be explained at least qualitatively. The influences of size, shape, mounting conditions and the influence of flanking transmission can be understood best by applying energy balance equations, and in this way the average behaviour of reasonably large constructions can be explained. Even though sound transmission has been investigated for approximately 80 years, there still remain some open questions especially with respect to inhomogeneous walls and multiple walls of finite size.

A Three-Dimensional Geometrically Nonlinear Analysis of Pipelaying in an Ocean Environment

A three-dimensional analysis for pipelines suspended between the ocean floor and a laying barge or a stinger is presented. The analysis performed is capable of handling not only variations in bending stiffness, weight and buoyancy, crosscurrents and lateral bay drift, but also the effects of external hydrostatic pressure and buckling of the pipes. For this purpose a total Lagrangian geometrically nonlinear analysis in space. Examples are given which demonstrate the versatility of the analysis proposed.

Equilibrium of offshore cables and pipelines during laying

An efficient solution technique for determination of the static equilibrium form of a cable or a pipeline suspended between the ocean floor and a laying barge or a stinger is presented. Variations in bending stiffness, weight and buoyancy and forces

Finite-Difference Methods for Plate Vibration Problems

A finite-difference method is developed to determine the transverse deflections of a vibrating plate. Explicit and implicit difference formulas are considered. The implicit formulation, which has been programmed for a digital computer, is derived to permit variations in bending stiffness, support stiffness, mass density, and loading. Numerical results demonstrate that the method is applicable to a wide range of problems involving both transient and steady-state response of plates.