in this research, softening and ratcheting behaviors of ck20 alloy steel cylindrical shells were studied under displacement-control and force-control cyclic axial loading and the behavior of hysteresis curves of specimens was also investigated. experimental tests were performed by a servo-hydraulic instron 8802 machine. the mechanical properties of specimens were determined according to astm e8...

This article investigates the collapse characteristics of thin-walled tubes with octagonal cross sections during axial crushing. The tubes’ axial crushing resistance (the relationship between crushing force and axial deformation) is described with a series of mathematical equations, which are derived applying global energy equilibrium theory. The derived axial crushing resistance is then used f...

this study aims to numerically investigate on the crashworthiness of thin-walled square tubes by consideration of 3-d oblique loading. in this type of loading, direction of loading is defined by using two spatial angles relative to the position of the tube. to this aim, finite element (fe) analysis is employed to simulate the loading for 8 different numerical models with different loading orien...

in iran, for column design, double i shape section is used due to lack of ipb profile. double i shape column performance is ambiguous in existing steel structures, especially when subjected to seismic loading. in this paper, double i shape column behavior is evaluated with 3d nonlinear analyses. monotonic behavior of 6 specimens and hysteretic behavior of other six specimens have been simulated...

the collapse of a compression member gives rise to decrease of the load carrying capacity of the member. to perform a nonlinear analysis, in addition to the precritical behavior, the post-critical behavior of the compression member also must be determined. in this study, because of certain advantages of the finite element method, this method has been selected to evaluate the axial load-axial di...

Why do starless cores appear more flattened than protostellar cores? ABSTRACT We evaluate the intrinsic three dimensional shapes of molecular cores, by analysing their projected shapes. We use the recent catalogue of molecular line observations of Jijina et al. and model the data by the method originally devised for elliptical galaxies. Our analysis broadly supports the conclusion of Jones et a...

The lung parenchyma as a tissue has a rather unusual stress-strain relationship. A theoretical derivation of this relationship is presented which connects the surface tension and the tissue elastic stress in the alveolar septa with the alveolar geometry. The mathematical expression contains a few meaningful physical constants which can be determined by in vitro and in vivo experiments. With thi...