| Pumps, water jet cutting equipment, tubular polyethylene reactors, isostatic compaction and hydrostatic extrusion equipment, armament, etc... are examples of high pressure applications. In general, pressures of 135 to 1375 Mpa are used with most applications less than 685 Mpa and with fatigue lives of the order of 10('3) to 10('8) cycles being expected. Thick-walled cylinders, which usually have a diameter ratio of between 1.2 and 3.0, are the most common geometry.;Static design procedures to choose initial dimensions for non-cylindrical areas, autofrettage residual stress calculations, fatigue design procedures for autofrettaged and non-autofrettaged vessels and crack-tip stress intensity factors for detailed areas such as blind-ends and cross-bores are often key points occurring in the design of these vessels.;Based on elastic analysis of a range of geometries and elastic/plastic analysis of several geometries the finite element method has been used to: (a) Propose a design curve for choosing the thickness of a blind-end and determine the effect of the inner corner radius of the blind-end and a small central hole. (b) Introduce a new set of design curves for the stress concentration factors in the cross-bore corner region of a thick-walled cylinder and show the effect of the corner radius and the cross-bore diameter on the maximum stresses. (c) Develop a general method to evaluate residual stresses at any location of a vessel taking due account of the Bauschinger effect of the high strength materials normally used. (d) Evaluate the stress intensity factors in plain cylinders, blind-ends and cross-bore regions including residual stress fields and to evaluate the fatigue crack propagation life of these components using an appropriate fatigue crack growth rate equation. (e) Propose an (S-N) fatigue design curves for autofrettaged and non-autofrettaged vessels based on fracture mechanics calculations.;The results of the present work should help in the preparation of a new division of Section 8 of the ASME Pressure Vessel Code which is intended to cover design pressure up to 1400 Mpa.;To improve the static and fatigue resistance of these vessels under operating conditions one often uses prestressing. Perhaps, the most common method is "autofrettage". Evaluation of the autofrettage residual stresses is very difficult, particularly in regions such as cross-bores, blind-ends and threaded ends, due to the Bauschinger effect of the material. |
