Buckling of a Heated Ring Enclosed in a Rigid Case

Abstract

We propose to solve the buckling problem for metal rings subjected to compression loading when externally enclosed in a rigid medium as a contact problem of deformation of a composite solid with a unilateral constraint. This method is based on manufacturing deviations characteristic of real structures; general state of stress; real-time operation. With this approach, the method makes it possible to determine the moment of local buckling of the ring visually and quantitatively from the changes in the stress-strain state of the ring. We implemented our method in the LS-DYNA software package in the dynamic formulation using solid finite elements. The geometrically and physically non-linear computation problem statement allows for taking large displacements and plastic strains into account. External compression loading of the ring is stated by its heating inside a rigid enclosing medium (the case), which is considered thermally insulated. We do not solve the heat conduction problem. We computed buckling parameters of a thin steel ring for two manufacturing deviation types relating to local variations of ring and case thicknesses at different lengths. We show how these two types lead to differences at the initial ring deformation stage and subsequent loop formation ("inward lobe"). We present strain field images for the ring and the case, which made it possible to visually detect the ring buckling moment. We plotted the stress, strain and displacement curves in the local delamination area. These curves enabled us to quantitatively detect the ring buckling moment. Qualitative and quantitative estimates of ring buckling matched.

A new Diancta species of the family Diplommatinidae (Cyclophoroidea) from Vanua Levu Island, Fiji

“… Diplommatinidae are mainly still assessed using shell characters. The original descriptions of the three genera from Fiji are quite short and have been emended via additional shell characters by subsequent authors such as Kobelt (1902) and Egorov (2013) The classification into genera, subgenera and species has already been regarded as difficult when focusing only on shell characters ( Rundell 2008 ; Webster et al 2012 ; Neubert and Bouchet 2015 ). For example, Köhler and Kessner (2020) found a high variation in shell ribbing in a single population of Diplommatina fluminis B. Rensch, 1931.…”

“…In addition, the doubled peristome, mentioned in the original description of Opisthostoma by Blanford (1860), is missing. Usually, Plectostoma has a detached last whorl ( Kobelt 1902 ; Egorov 2013 ; Liew et al 2014b ) and an “extraordinary prolongation backwards of the free portion” ( Adams 1865 ). This is not the case for D. phoenix sp.…”

Development of Interparticle Bonding during Sintering of Metal Powders with the Addition of Carbon

“…С начала двухтысячных годов отмечается растущий интерес ученых к данной теме [1][2][3][4][5][6][7]. Изучалось, например, межчастичное сращивание при формировании порошковых горячедеформированных материалов.…”