Calgary, Alberta, Canada T2N IN4
Communicated by Xavier J. R. Avula
(Received March 1984; revised November 1985)
Abstract-The paper presents the creep-stability analysis of viscoelastic cylindrical
shells under axial compression. The mechanical properties of the material are described

by the constitutive equations of the linear viscoelastic theory in terms of convolution
integral operators. The approximate analytical solution to the problem is obtained by
means of a modification of the quasi-elastic method. As a result, the instability condition
for the shell is formulated. It is shown that for viscoelastic materials with limited creep,
there is a safe load limit below which the structure is asymptotically stable. Any load
above the safe load limit leads to buckling at the corresponding critical time.
1. INTRODUCTION
Creep stability of circular cylindrical shells has been studied by numerous researchers
using various concepts and constitutive laws. A number of investigations utilize the initial
imperfection approach followed by the conclusion that under creep conditions initial imperfections
develop with time, leading eventually to collapse of the structure. The critical

یک مطلب دیگر :

time in such analyses is usually defined in terms of infinite deformations or infinite deformation
rates. Comprehensive reviews of these studies are given by Hoffll, 21 and
Kurshin[3].
In recent years an increasing interest has been attracted by applications of the classical
bifurcation theory to the creep-stability research. In particular, creep stability of cylindrical
shells is treated in many publications[4-81 as an instantaneous process which involves
time-dependent constitutive terms and is characterized as branching into a different
equilibrium configuration. Respectively, the critical time is associated with the instant at
which bifurcation first becomes possible. The results from these studies depend upon the
basic assumptions as to the creep properties of the structure.
The present paper is concerned with the stability analysis of circular cylindrical shells
whose material properties are defined by the constitutive equations of the linear viscoelastic
theory. Using the concept of bifurcation the exact linear eigenvalue problem is
formulated in terms of two destabilizing parameters: the compressive load and time. The

must nowadays focus on implementing a CRM strategy that aims to seek, gather and

یک مطلب دیگر :

speed of adjustment can be set forth. Therefore in both cases the question of which
effect is the dominant one becomes an empirical issue.
The information content of EAs in a small stock market has previously been studied
in Kallunki (1996) in the context of the Finnish stock market. However, there are two

rather unique institutional features of the Finnish stock market that make it a less
suitable candidate for isolating the effect of stock market size on the information

یک مطلب دیگر :

content of EAs. First, as mentioned in Kallunki (1996), Finnish accounting standards
are very different from the IAS. Secondly, as also noted by Kallunki (1996),

دانلود مقاله ISI با ترجمه فارسی :تکامل بازیابی ، به صورت مفهومی

یک مطلب دیگر :

and social productivity, and it is essential to grasp the future trends of social needs and technology
advancement to promote the strategic technology policy. Japan embarked on technology foresight in
the early 1970s and has since been conducting a regular Delphi survey approximately every 5 years.
To explore a new intelligent methodology for integrating technological seeds and social needs by
articulating future demands, this paper reviews the following two cases: the Delphi-scenario writing
(DSW) method, which is applied in 1977 for the home/office small facsimile, and the method of
general assessment applied in 1972 for informationalization, which focused on the rapidly advancing
information society, with a matrix scoring and policy-simulation method. Those new approaches were

proved to be a powerful methodology to integrate the technology forecasting and assessment for
comprehensive understanding of the emerging technologies and their social impacts in the form of

یک مطلب دیگر :

integrated technology road mapping, which supports the integrated strategic planning methodology for
enhancing the future innovation system.
D 2002 Elsevier Inc. All rights reserved.
Keywords: Delphi-scenario writing method; General assessment method; Demand articulation; Informationalization
0040-1625/$ – see front matter D 2002 Elsevier Inc. All rights reserved.
doi:10.1016/S0040-1625(02)00397-9
* Corresponding author. Japan Advanced Institute of Science and Technology (JAIST), Tatsunokuchi,
Ishikawa 923-1292, Japan.
E-mail addresses: kameoka@jaist.ac.jp (A. Kameoka), yokoo@nistep.go.jp (Y. Yokoo),
kuwahara@nistep.go.jp (T. Kuwahara).
URLs: http://www.jaist.ac.jp, http://www.nistep.go.jp.
Technological Forecasting & Social Change
71 (2004) 579–598
1. Introduction