Limit analysis and finite element evaluation of lateral pipe–soil interaction resistance

The lateral breakout soil resistance of pipelines supported on undrained cohesive soils determined from limit analysis and finite element methods are compared for a linearly increasing soil strength profile. The limit analysis solution is based on an upper-bound technique. The finite element solutions are developed from coupled Eulerian–Lagrangian simulations. The capacities determined by the two methodologies are in close agreement for the perfectly plastic soil conditions. The relative ease with which the limit analysis solutions are obtained allows rapid investigation of the implications of uncertainty of the soil shear strength profile and pipe embedment via Monte Carlo simulations. Monte Carlo simulations illustrate the implications of correlated random variables describing the shear strength profile and pipe embedment.

An Analytical study of Optimal Die Design of Elliptic Tube

In this study, die profile of the elliptic tube extrusion is analysis to predict the optimum die design by using upper bound theory. Developed manner in determining the relative extrusion power by dividing the extrusion die for different sector and calculate the relative deformation power of each sector under different condition which are reduction of area, friction factor and relative die length. The study predicts a new equation for determining the optimum die length with taking in the count the effects of those variables. The surface of the die is generated by an envelope of straight lines drawn from the points on the perimeter at the entry section to corresponding points at exist of the die. An upper bound technique based on the kinematically admissible velocity field is used to determine the forming stress. A complex program built in Visual Fortran V5.0 used to calculate relative extrusion power with variable friction factor (relative optimum extrusion power for values of reduction area are changed from 52.6% at area reduction equals to 0.15 to 82.8% at area reduction equals to 0.4). ANSYS program is used to compare the behavior and values of relative extrusion stress for optimum relative die length at constant reduction of area (R.A.=25%). The results are compared with other papers theoretical and experimental results are found to be in a very good agreement.

Limit Analysis of Lateral Extrusion of Gear-Like Components with Radial Tooth Profile

Lateral extrusion of gear- like components with radial tooth profile, has been studied in this paper. To analyze the process, the two types of theoretical approaches, i.e. the upper bound technique and the slab method of analysis have been applied and extrusion load values have been estimated. The theoretical results of load values estimated from the above approaches have been compared with theoretical and experimental results that given by a reference. Good agreement has been found among the predicted load values and those obtained from the experimental results.

A new upper bound solution for the analysis of the twist extrusion process with an elliptical die cross-section

The twist extrusion process is a rather new route to produce highly strained materials. In this process, severe plastic deformation is applied by large shear strains. In this regard, prediction of materials behaviour and extrusion pressure is of importance to die designers and engineers. In this article, utilizing an admissible velocity field together with the upper bound technique, the required energy for twist extrusion is predicted. The proposed model is capable of considering the effect of various parameters such as die geometry and friction conditions. In addition, the model anticipates the critical die design parameters. To verify the proposed model, the predictions are compared with the results of a finite-element analysis and reasonable consistency is observed.

A new upper bound solution for a hollow cylinder subjected to compression and twist

The upper bound technique is adopted to investigate the effect of angular velocity on the load required to compress a circular hollow cylinder between rough parallel plates. The kinematically admissible velocity field accounts for the asymptotic behaviour of the actual velocity field in a vicinity of the friction surface. The theoretical solution is illustrated by numerical examples for different geometrical parameters and friction factors. In particular, the variations in work rate, torsion moment and compression force with the dimensionless angular velocity are shown.