In this paper, a generalized expression for the flow field in axisymmetric extrusion process is suggested to be valid for any dies and the boundary shapes of the plastic deformation zone. The general power terms are derived and the extrusion force is calculated by applying upper bound technique for a streamlined die shape and exponential functions for shear boundaries. It is shown that assuming...

Investigations were conducted on low-carbon steel and the steel with same chemical composition with addition of microalloying element niobium. While tensile testing was carried out, the thermographic measurement was tacking place simultaneously. A specific behavior of niobium microalloyed steel was noticed. Test results have shown that, in the elastic deformation region, thermoelastic effect oc...

This paper deals with the effects of friction material properties on thermoelastic instability (TEI) and the associated dominant deformation mode. Both analytical and finite element models are constructed for determining the variation of the critical speed and the dominant TEI mode. Some important factors, e.g. the nonconductive friction material as well as the symmetric and anti-symmetric TEI ...

Thin shell torispherical pressure vessel heads are known to exhibit complex elasticplastic deformation and buckling behaviour under static pressure. In pressure vessel Design by Analysis, the designer is required to assess both of these behaviour modes when specifying the allowable static load. The EN and ASME Boiler and Pressure Vessel Codes permit the use of inelastic analysis in design by an...

Thin shell torispherical pressure vessel heads are known to exhibit complex elasticplastic deformation and buckling behaviour under static pressure. In pressure vessel Design by Analysis, the designer is required to assess both of these behaviour modes when specifying the allowable static load. The EN and ASME Boiler and Pressure Vessel Codes permit the use of inelastic analysis in design by an...

A ­ nite-element method is developed for determining the critical sliding speed for thermoelastic instability of an axisymmetric clutch or brake. Linear perturbations on the constant-speed solution are sought that vary sinusoidally in the circumferential direction and grow exponentially in time. These factors cancel in the governing thermoelastic and heat-conduction equations, leading to a line...

Stretching process of sheet metals in both cases of axisymmetric and non-axisymmetric is analyzed. A rigid-plastic, normal anisotrop material is assumed and large strain formulation is applied. Triangular elements are used and stiffness equations of elements are obtained from virtual work principle. These nonlinear equations are linearized by Newton-Raphsons method and are solved by Gaussian el...

We report on the first three-dimensional hydrodynamic simulations of secular and dynamical nonaxisymmetric instabilities in collapsing, rapidly rotating stellar cores which extend well beyond core bounce. The resulting gravitational radiation has been calculated using the quadrupole approximation. We find that secular instabilities do not occur during the simulated time interval of several 10ms...

Thermoelastic behavior of temperature-dependent (TD) and independent (TID) functionally graded variable thickness cantilever beam subjected to mechanical and thermal loadings is studied based on shear deformation theory using a semi-analytical method. Loading is composed of a transverse distributed force, a longitudinal distributed temperature field due to steady-state heat conduction from root...