Summary.Conditions for initiation of necking and bulging of elastic and elasticplastic cylindrical solids are derived. The possibility of bifurcation of rigid-plastic solids and the conditions for homogeneous deformation with homogeneous stress are also investigated. 1. Introduction. This paper deals with some problems of bifurcation in cylindrical solids of elastic, rigid-plastic and elastic-plastic material. One particular objective of this study is to investigate the effect of hydrostatic pressure on the necking and bulging loads of a specimen in tension and compression tests. elastic-plastic material subjected to an axial load P and lateral hydrostatic pressure of intensity q. Suppose that the body undergoes finite homogeneous deformation due to P and q from some initial state B° to the current state B. The deformed body in the state B is supposed to preserve a cylindrical shape with radius a and length 21; the necessary information for complete description of B is assumed given. To investigate the bifurcation of equilibrium for continuing deformation, the behaviour of the specimen in transition from B to a neighbouring state B', under the infinitesimal increments of the boundary values, is isolated for study. Only axially symmetric deformation will be considered in this paper. Referred to state B, a fixed cylindrical coordinate system , with axes coinciding with axes of symmetry of the specimen, is taken as the reference frame. Whenever convenient the coordinates , x2 , x3 will be replaced by r, 9, z respectively and the velocity components v, , v2 , v3 by u, v, w respectively. In the current state, we have '
The stalks of Polygonum hydropiper L. (PHL) have been traditionally used in clinical practice for thousands of years in China to treat various inflammatory diseases. However, little research has been conducted to investigate the anti-inflammatory effects of PHL on TNBS-induced intestinal inflammation in rats. The aim of the present study was to investigate the anti-inflammatory effects and to explain the underlying mechanism of PHL on TNBS-induced intestinal inflammation in rats. PHL (125, 250, and 500 mg/kg) was given for 7 consecutive days to rats with intestinal inflammation induced by TNBS. Oral administration of an aqueous extract of a high dose of PHL (H-PHL) significantly improved TNBS-induced symptoms such as the macroscopic score and histological examination. H-PHL treatment significantly ameliorated the activity of MPO and improved the GSH content. In addition, there was a downregulation of the TNBS-induced increase in the activity of iNOS and levels of Cox-2, TNF-α, and IL-1β while the protein expression of NF-κB was significantly unregulated after administration of H-PHL. The present findings suggested that H-PHL has a protective effect on experimental intestinal inflammation in rats and its anti-inflammatory effects are closely related to inhibition of NF-κB signal pathways.
SUMMARYA new computational scheme, named the 'Integrated Load Increment' method (ILI), has been developed to handle elasto-plastic analysis of solids by the finite element variational technique. This scheme allows considerably larger loading steps to be applied to the structure without deviating from its nonlinear, load-deformation relationship. It has been shown that these relationships can be evaluated by integrating the nonlinear constitutive equations within each load increment under certain conditions. A numerical example on a pressurized thick-walled. cylinder indicates that a 240 per cent improvement in computational efficiency and substantial reduction of loading steps over the conventional load incremental method can be achieved by the ILI technique.
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