Academic literature on the topic 'Lateral extrusion model'

 In the early generation of the Indian 220 MWe pressurized heavy water reactor (PHWR220), Zr-2.5Nb pressure tubes (PT) were manufactured from doublemelted (DM) ingots. Later on, quadruple melted (QM) ingots were used to achieve enhanced performance. These pressure tubes were fabricated by hot extrusion followed by double pilgering with intermediate annealing and this fabrication route is designated as an old route (OR). These tubes have performed reasonably well. However, some of these tubes showed higher in-reactor deformation. Subsequently, both alloy chemistry and manufacturing practice were revisited and changes in alloy chemistry and ingot diameter, mode of hot working for breaking the cast structure and hot extrusion of billets with higher extrusion ratio and single pilgering steps have been employed. This route is designated as a new route (NR) and is being used for manufacturing pressure tubes for the current generation of 220MWe pressurized heavy water reactors. <br><br>Over the years, changes in Chlorine (Cl), Carbon (C), Phosphorous (P), Iron (Fe) and Hydrogen (H) specification and narrowing down the specification for Niobium (Nb) and Oxygen (O) have been implemented to exploit their beneficial effect on in-reactor deformation and hydrogen pickup. The changes in manufacturing practices had resulted in changes in microstructure and texture. In the old route (OR), pressure tube (PT) microstructure was characterized by the presence of discrete beta-phase precipitates along the interfaces of alpha lamellae while the new route (NR) pressure tube (PT) exhibits more continuous beta film and relatively coarser α lamellae. In terms of crystallographic texture too, the new route (NR) pressure tubes (PTs) had higher FT values (in the order of 0.65) in comparison to old route (OR) pressure tubes (PTs) (FT~0.55 to 0.6).<br><br>Because of crystallographic and microstructural anisotropy, the tensile behavior of this material is also anisotropic with the transverse direction exhibiting higher flow stress and lower ductility at and below reactor operating temperatures. The transverse tensile strength of pressure tube (PTs) fabricated from new route (NR) is higher than that fabricated from old route (OR). The fracture toughness of pressure tubes (PT) manufactured from quadruple melted (QM) ingots are significantly higher than that of the pressure tubes (PTs) manufactured from double melted (DM) ingots, which is attributed to the deleterious effect of Chlorine (Cl), Carbon (C), Phosphorous (P) and their complexes. The variation in fracture toughness of pressure tubes (PTs) was evaluated as a function of temperature, hydrogen content and hydride orientation. The hydrided material exhibited a typical S curve showing lower-shelf, transition and upper shelf regimes. Delayed hydride cracking velocity and threshold stress intensity factor were determined as a function of temperature, direction of approach to test temperature and hydride orientation. Threshold stress for hydride reorientation (σth) determined using ex-situ and in-situ methods between 250 and 300oC was observed to decrease with an increase in temperature. Thermal creep behavior was investigated for these tubes at 350, 400 and 450 °C at different stress levels and comparison of the minimum creep rate and the rupture life is presented. This article describes the evolution of the alloy chemistry, microstructural features, texture and mechanical properties and hydride induced embrittlement of the pressure tubes (PTs) used in Indian pressurized heavy water reactor (PHWR) and life extension approaches. An attempt has been made to rationalize the observed properties in terms of alloy chemistry and microstructure.

The default roughness parameter values used in industry to determine the pressure loss through small diameter pipeline systems are much higher than the values employed in typical large diameter gas transmission and lateral systems. It is uncertain whether these higher roughness values are due to higher topological roughness of the internal wall of the small diameter pipes or if they are a result of other factors. Measurements were taken on 17 small diameter pipe samples in order to evaluate the pipe-wall roughness parameter. A model to calculate the effective roughness parameter, which takes i

At the conceptual product design stage, designers prefer sketching initial design ideas on paper before using more sophisticated 3D CAD systems for their creativity and flexible design changes. At the later detailed design stages, however, precise 3D CAD modeling is a better choice for design analyses and downstream manufacturing applications. For an integrated digital product development, the 2D drawings need to be converted to 3D CAD models manually through some laborious and time-consuming processes. For decades, many researchers have contributed to the studies on reconstructing 3D geometri

Abstract Providing vehicle occupant protection with advanced structural design for crash energy management is an important consideration in vehicle development. In most cases energy absorption by structural deformation requires a material that is able to accommodate high strain levels in order to prevent or limit material separation which could lead to an undesirable collapse mode and poor energy absorption. Therefore, the development of crashworthy alloys and design concepts is critical to the application of new, lightweight materials in automotive structures. To this end, analytical methods

Abstract Context is everything. Not all thick sands pay out and not all thin sands are poorly productive. It is important to understand a basin's palaeogeographical drivers, the resultant palaeoenvironments and their constituent sedimentary architecture. Development of a depositional model can be predictive with respect to the magnitude of accessible pore space for potential development. We present a multi-field study of the Dneipr-Donets basin. Over 600 wells were studied with >4500 lithostratigraphical picks being made. Over 7500 sedimentological picks were made allowing mapping of fa

ABSTRACT: Simultaneous fracturing and zipper fracturing of horizontal wells has rapidly evolved to the development of unconventional oil and gas. The fracture interference when multiple fractures propagate needs further study. This paper experimentally investigates the sequential propagation of multiple fractures in horizontal wells. Eight artificial rocks, each with dimensions of 400 mm ×400 mm × 400 mm and equipped with two horizontal wells, are sequentially fractured. The effects of the horizontal stress difference, the fracturing sequence, and the arrangement of perforations were discussed