Plastic yielding of I-beams under shear, and shear and axial loading

Plane strain and plane stress slip-line field solutions previously published by the authors for cantilevers of rectangular cross-section are utilized to estimate the plastic collapse loads of corresponding I-sectioned beams. Uniform I-beams, tapered and haunched beams, and beams with rectangular holes and castellated beams are studied. Previous works in each case are reviewed and for uniform-section cantilevers with end shear loading, the results are compared with the theoretical results of others and with the experimental results of Green and Hundy.     

An Investigation into some Mechanical and Metallurgical Properties of Stainless Steel Reinforced Aluminium Alloy Powder Compacts

An experimental investigation into uniaxial tension and transverse bending of thin rectangular sheets made of stainless steel wire mesh and microcable reinforced sintered 6061 aluminium alloy powder compacts was made in order to determine some of their mechanical and metallurgical properties. Theoretical predictions based on the rule of mixtures were made for the ultimate tensile strength and for the Youngs modulus and were compared with the experimental results. Metallographic analysis involved optical and SEM photography on selected specimens and also an "EDAX" analysis on the intermetallic phase formed between the matrix and the reinforcement in order to establish its composition. In general, it was observed that the introduction of the stainless steel reinforcement resulted in extra strength of the reinforced material compared to that based on the net density of the combination.     

Working Pressure, Deformation Modes and Fracture in Open-Piercing of Cylindrical Disks Made of Compacted Sintered Aluminium Powder

An experimental investigation into the quasi-static open-piercing of sintered aluminium powder compacts made initially in the form of thin and thick disks was made, using four different shaped punches, i.e. solid circular, annular (circular ring-type), triangular, and square. Typical results of punch load with punch movement and progressive changes in shapes of the specimens were observed and the onset of fracture was noted in each case. Available theory for calculating the piercing force was applied in a few cases and the results were compared with the experiments. These and other observations on the mechanical and metallurgical aspects of the deformation are given and the results commented upon.     

Dynamic Forging of Splines and Spur Gear Forms: A Modified Upper Bound Analysis that Includes the Effects of Inertia and Some Experiments

To analyse dynamic forging of splines and spur gear forms, the upper bound solutions developed earlier for similar quasistatic cases for spline and spur gear form forging were modified suitably to take account of the inertia forces. In the experimental investigation, initially solid cylindrical billets made of tellurium lead were deformed into these shapes, i.e. splines and spur gear forms, using low velocity dropweight impact conditions and the characteristic die load–time and die movement–time results observed. From these results, the typical die load–die movement curves were evaluated in each of these cases, and compared with the estimates based on the modified analysis. Though the dynamic forging loads in each of these cases were, in general, 20%–40% higher than those observed when tested under similar quasistatic conditions, the estimated dynamic forging loads employing the modified upper bound analysis, taking account of the inertia, as given here, showed good correlations with the experiments. These and other results observed on the progressive changes in shapes of the specimens under dynamic loading conditions are given and the results commented upon.     

Axi-symmetric tube extrusion/piercing using die–mandrel combinations: some experiments and a generalised upper bound analysis

A generalised upper bound technique is applied to the solution of working pressures in extrusion–piercing of hollow tubes starting from either solid circular or initially hollow billets by using axi-symmetric die–mandrel combinations of different shapes. Characteristic deformation modes during processing of these tubes made of tellurium lead and commercially pure aluminium were studied experimentally and the results presented. Estimates of working pressures based on the generalised upper bound analysis are compared with the experimental and with those estimated earlier from the slab method of analysis given in Chitkara and Aleem (International Journal of Mechanical Sciences, submitted for publication). These show good co-relations with each other and with the experiments.     

Extrusion of axi-symmetric tubes from hollow and solid circular billets: : a generalised slab method of analysis and some experiments

To analyse the mechanics of extrusion of an axi-symmetric tube starting from either a hollow or a solid circular billet, a generalised analytical approach based on the slab method of analysis is developed for a somewhat general case of tube extrusion through a general profile-shaped die and over a general profile-shaped mandrel. The results of mean extrusion pressures obtained from the theoretical analysis for the various die–mandrel combinations are compared with the experimental investigation carried out on a model material and with the work of other authors. These show reasonably good agreements.     

Medical management of interstitial ectopic pregnancy: a case report and literature review

Recent reports describe successful treatment of interstitial ectopic pregnancies using methotrexate. While the number of reported cases is increasing, no consensus exists regarding the management of this complication of pregnancy. We present the successful use of combined systemic and direct intrasac injection of methotrexate for an interstitial pregnancy with the highest yet reported initial beta-human chorionic gonadotrophin concentration (102,000 mIU/ml). We also describe the use of Doppler ultrasound for monitoring treatment progression. Through a review of the current literature, we propose to facilitate management decisions and increase outcome success by summarizing previously reported treatment regimens and by describing enhanced parameters for patient selection and monitoring.     

Axisymmetric Rod Extrusion Through Smooth andPartially Rough Conical,Cosine, and Flat-Faced Circular Dies: Slip-Line Field Solutions Using Numerical Methods and Some Experiments

The numerical method of construction of axisymmetric slip-line fields is followed to obtain indirect type slip-line field solutions to axisymmetric rod extrusion using some smooth and partially rough conical, cosine, and flat-faced dies. A detailed computer program was written that calculates and plots both the slip-line field and the velocity field and carries out the entire procedure of estimating stresses and velocities in an iterative manner to reach either the desired or a reasonably valid solution, to each of these extrusion problems. The resultant values of the mean extrusion pressures are compared with those given by other authors and with some of the authors own experimental work in rod extrusion (tellurium lead) through conical dies of cone semi-angles, α varying from 11° to 26.5° and at reductions of 36–75%.     

Near net shape spline forging: An experimental investigation and a simple upper bound analysis

A simple analysis based on an upper bound elemental technique is presented for the incremental forging of a near-net shaped splined rotor shaft-type component formed using a cylindrical rod-type specimen. The results of an experimental investigation made into the working pressures and deformation modes observed during progressive forging of tellurium-lead specimens of different aspect (length to diameter) ratios into spline shaped components are compared with those predicted theoretically. The agreement was found to be reasonable and encouraging.     

Post-collapse cross-sectional flattening of thick pipes in plastic bending

Post-collapse cross-sectional flattening of a thick pipe at the centre of a plastic hinge formed during excessive bending due to unrestrained pipe whip is analysed with an aim to ascertain the extent of flow choking and consequent reduction of blowdown force. Based on the experimentally observed similarity between the plastic collapse mode of the critical pipe section during bending and plastic deformation of a ring under lateral compression, the effect of excessive bending on pipe section flattening is simulated using some well known analytical models for section collapse. A theoretical relationship between post-collapse bend curvature and section flattening is proposed for relatively thick pipes made of strain hardening material. The calculations made using the above relationship are found to compare well with those observed experimentally.