Academic literature on the topic 'St Paul Fracture Zone'

Effect of post-welded heat treatment (PWHT) on the microstructure and mechanical properties of friction stir welded 7A04-O aluminum alloy was investigated. Solution heat treatment (ST) and artificial aging (T6) were given to specimens to improve the mechanical properties of the joints. The results show that defect-free joint was obtained via FSW and the microstructure of nugget zone was characterized by fine and equiaxed grains. After ST, most second phases dissolve in the matrix and the α-Al grains became coarse. Second phases precipitated in the α-Al matrix uniformly after T6 treatment. The Vickers hardness test shows that PWHT made the hardness distribution of the joints more evenly. The tensile test results indicate that the tensile strength of the joint increased from 228 MPa (in as-welded condition) to 440 MPa and 528 MPa after ST and T6 treatment respectively, but the elongation decreased to a certain extent. SEM fracture morphologies indicate that the joint failed through ductile fracture for the as-welded and ST states, and failed in a mixture mode of brittle fracture and ductile fracture for the T6 state.

SUMMARY Crack nucleation and rock failure processes in a fine-grained siltstone (Montney Formation) under triaxial compression are investigated using combined diagnostic techniques, including ultrasonic-wave measurement, acoustic-emission (AE) monitoring, computed tomography (CT) scanning, and thin-section imaging. The sample displays a weak-to-moderate inherent seismic anisotropy and noticeable stress-induced anisotropy prior to failure. No AE event was detected until the applied axial stress reached 95 per cent of the peak value. The signal-to-noise ratio is relatively low, however, and detectable AE events are more diffuse than those observed in highly brittle rocks. The AE locations correlate with a shear fracture zone imaged by CT scanning. AE moment-tensor analysis reveals that events with larger relative magnitudes are characterized by high volumetric (tensile or compressive) components, and the initiation of the failure zone is dominated by combined shear-tensile (ST) failure. Stress inversion of the AE events with high tensile components is in good agreement with the known applied stress. Microscopic imaging of thin sections from the failed sample shows that the failure zone is an en echelon structure consisting of a major fracture with branching micro and minor cracks. This failure mechanism is consistent with a ST source mechanism and is interpreted to be associated with the fine granular structure and mineral composition of Montney siltstone.

Eocene rocks of the Waseiyit Formation are exposed at Gebel Hammam Faraun, on the eastern coast of the Gulf of Suez in west central Sinai (Egypt). The formation represents gravity flow sediments deposited in response to early Eocene tectonic activity. Three species of the genus Nummulites were encountered in this formation: Nummulites burdigalensis de la Harpe 1926, Nummulites alpinus Schaub 1951 and Ruetimeyerina murchisoni (Rütimeyer 1850) n.gen. The three species assign the Waseiyit Formation to the Early Eocene, at the base of the Late Ypresian (shallow benthic zone SBZ 10). These findings show that granulated Nummulites such as N. burdigalensis first occurred at the base of the Late Ypresian, just after the appearance of non-granulated Nummulites in the earliest Ypresian. The Nummulites assemblage recorded by Boukhary et al. (1998) differs from assemblages previously collected from the Monastery of St. Paul area (Eastern Desert, Egypt). The St. Paul assemblage contains Nummulites praeatacicus, Nummulites sahariensis and Bassiounina sanctipauli and is therefore older than the material recorded by Boukhary et.al. (1998) from theWaseiyit Formation. Biotic differences between the two sites suggest that specific faunal elements are indicative for early and late Ypresian deposits.

Abstract This case report demonstrates a technique that is useful for precompressing mandibular fractures and obtaining anatomical reduction of the fracture edges without the use of peroperative intermaxillary fixation (IMF) in a mandibular fracture by using two modified reduction forceps. The first forcep is positioned at the inferior mandibular border and the other in the neutral zone where it is an ideal location to place a fixation plate in mandibular fractures. This technique is indicated for the anatomic reduction in mandibular fractures of the partial dentate patient. Citation Shinohara EH, Mitsuda ST, Miyagusko JM, Horikawa FK. Mandibular Fracture Reduction without Intraoperative Intermaxillary Fixation: A Technique Using Two Modified Reduction Forceps. J Contemp Dent Pract 2006 February;(7)1:150-156.

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.

Carpal tunnel syndrome is a common complication associated with distal radius fractures. Open carpal tunnel release in the same setting as open reduction and internal fixation of distal radius fractures is widely accepted. In this paper, we describe the technical details of a minimally invasive carpal tunnel release in the same setting as the fixation of a distal radius fracture via the same incision. Two options of minimally invasive techniques are described: The Knifelight® (Stryker, Kalamazoo, Michigan, USA) instrument and the single portal carpal tunnel release system (Agee, 3M Healthcare, St Paul, Minnesota, USA). Being well known and accepted techniques of carpal tunnel release, we believe that the techniques described in this paper provide a viable alternative for carpal tunnel release in the setting of distal radius fracture fixation; with the added advantages of the original minimally invasive techniques.

ABSTRACT An examination of topographic lineaments detectable in Landsat TM images and measurement of joints in outcrop in the Balsam Lake area reveals a systematic bedrock fracture pattern with three principal sets oriented 091°, 027°, and 152°. The 027° trend is parallel to a major aeromagnetic anomaly, the Niagara-Pickering Linear Zone (NPLZ), which underlies the Balsam Lake area and is thought to mark the sub-Paleozoic continuation of the Proterozoic Central Metasedimentary Belt Boundary Zone (CMBBZ). Possible origins of the main joint sets due to Acadian (091° set), Alleghanian (152° set) and St. Lawrence rift system tectonics (091° and 027° sets) are discussed. En-echelon pop-up structures have a mean principal trend of 118°. They displace Lake Algonquin paleobeaches, suggesting formation less than 12,500 years ago. The orientation of the pop-up structures is subnormal to the current in situ maximum horizontal stress direction, SHmax (020°), and is parallel to members of the 091° joint set, indicating possible nuclea-tion on favourably-oriented pre-existing joints. These pop-ups are the only features in the Balsam Lake area with strong evidence for a neotectonic age.

Le système transformant de St. Paul (SPTS) affiche l’un des contextes tectoniques les plus complexes, composé de quatre failles transformantes, trois segments de dorsale (intra-transformants) qui décalent de 630 km la dorsale équatoriale médio-atlantique. Cette région est connue pour ses roches mantelliques uniques qui émergent dans les îlots Saint-Pierre et Saint-Paul, toujours en cours d’élévation. Le SPTS montre une transition depuis une zone de cisaillement régionale au nord vers une région dominée par des Ocean Core Complexes (OCCs) au sud. Les tectonites recueillies tout le long du système transformant ont subi une déformation généralisée dans des conditions ductiles et fragiles et ont été regroupées de la façon suivante : des ultramylonites ultrabasiques, basiques et intermédiaires. Les mylonites ultrabasiques sont des harzburgites porphyroblastiques à porphyroclastiques avec des restes d’amphiboles équilibrées dans le faciès granulite. Les mylonites basiques sont principalement des gabbros porphyroclastiques fortement transformés en amphibolites. Les mylonites intermédiaires sont des schistes riches en talc-chlorite composés de proportions variables de roches basiques et ultrabasiques fortement déformées et hydratées. Toutes les roches ont une matrice très fine (<0.1 mm), une foliation à bandes très marquées qui ont subi une altération tardive à faible température. La géothermométrie donne des températures d'équilibre comprises entre 700 et 900 ° C pour les péridotites et entre 700 et 850 ° C pour les roches gabbroiques. Les teneurs en éléments majeurs et traces des mylonites ultrabasiques se situent dans le champ des péridotites abyssales épuisé, provoquées par une faible fusion fractionnelle (jusqu’à 9%), mais elles présentent un enrichissement marqué en terres rares légères et une anomalie positive en Eu. Les mylonites basiques et intermédiaires présentent des spectres de terres rares plats à enrichis (jusqu'à 100 fois les chondrites de classe CI) et des anomalies variables en Eu. Une interaction entre les roches et le fondu est suggérée pour l’enrichissement en terres rares légères pour les mylonites péridotitiques et les fluides hydrothermaux, en particulier pour l’enrichissement global en terres rares des mylonites serpentinisées. Ces caractéristiques de composition suggèrent une assimilation variable de N-MORB et d’E-MORB au cours de la mylonitisation ou au cours d’une interaction précoce entre la fusion et le magma et une évolution hydrothermale dans des conditions métamorphiques variables. Les failles transformantes sont des milieux mécaniquement résistants qui ne sont pas affaiblis par les minéraux lubrifiants comme le talc ou la serpentine et la déformation se produit principalement en milieu anhydre. Le premier profil de contrainte pour cette région est présenté et suggère une transition plastique-fragile à une profondeur d'environ 15 km
The St. Paul Transform System (SPTS) displays one of the most complex tectonic settings composed by four transform faults, three intra-transform ridge segments that offset by 630 km the Equatorial Mid Atlantic Ridge. This region is known by having unique mantle rocks exposed above the sea level, the St. Peter and St. Paul islets that are still rising. The SPTS shows a transition from a transpressive, hot spot affected, regional-scale shear zone to the North to a region dominated by a particular oceanic core complex spreading to the South. The tectonized samples collected along the whole transform system experienced pervasive deformation at both ductile and brittle conditions, and are grouped in ultramafic, mafic and intermediate mylonites. Ultramafic mylonites are porphyroblastic to porphyroclastic harzburgites with remnants of amphiboles equilibrated at granulite facies. Mafic mylonites are mainly porphyroclastic gabbros strongly transformed to amphibolites. Intermediate mylonites are talc-chlorite rich schist with composed by variable proportions of highly deformed and hydrated mafic and ultramafic rocks. All rocks have micrograin size groundmass, banded foliation and are overprinted by late low-T alteration.Geothermometry yield temperatures of equilibration between 700 and 900 °C for the peridotites and 700 to 850 °C for the gabbroic rocks. Major and trace element contents of the ultramafic mylonites plot in the depleted field of the abyssalperidotites originated by low degrees of fractional melting (up to 9%), however, they present marked LREE enrichment and Eu positive anomaly. Mafic and intermediate mylonites display REEenriched flat patterns (up to 100 x CI) and variable Eu anomalies. Rock-melt interaction is suggested for the enrichmentof the LREE for the peridotitic mylonites and hydrothermal fluids specifically for the overall REE enrichment of the serpentinized mylonites. These compositional characteristics suggest variable assimilation of N-MORB and E-MORB during mylonisis or early melt-rock interaction and hydrothermal evolution at variable metamorphic conditions. Transform faults are resistant and not weakened by lubricating minerals as talc or serpentine and the deformation takes place mainly under dry conditions. The first stress profile for this region is presented and suggests a deep Brittle Plastic Transition at depth of around 15 km

Abstract The standardization of any mechanical material characterization is aiming to get homogenization on the testing physical execution by independent laboratories and to drive for accurate material evaluation between different entities. However, from time to time, standard tests may be reconsidered in order to improve their efficacy, execution time and incorporate new testing techniques or technologies without compromising the testing results and consistency. In the present work, fracture toughness crack tip opening displacement (CTOD) testing is addressed and particularly the need to perform fatigue pre-cracking prior monotonic testing. Without the fatigue pre-cracking, CTOD testing time can be significantly reduced during the preparation of specimens, meaning that specimens can be tested as soon as they are machined. Wire electro-discharge machining (EDM) technique allows generating sharp tip notches, and presents a good alternative to the standards specified fatigue pre-cracking [1–2]. In addition, this machining technology reduces the risk of rejecting the specimen testing, particularly when targeting weld heat affected zone/fusion line (HAZ/FL) microstructure on specimens with surface notch DNV-ST-F101 Figure B-9 [3], where it is specified that the crack tip shall be within a narrow distance (0.5 mm) from the fusion line (FL) or assess grain coarsened heat affected zone (GCHAZ) microstructure as indicated in DNV-ST-F101 section B.2.8.7 [3]. Herein, it is presented an assessment carried out in order to identify the notch type effect over the fracture toughness (CTOD) considering notches conditions as standard fatigue pre-crack and wire electro-discharge machining (EDM). Fifteen (15) CTOD specimens were manufactured from plain pipe material (same pipe), 251.3 mm OD × 20.9 mm WT, SMLS 450PD and tested according to ISO 12135 recommendations [1], they were distributed as follow; five (5) specimens according to standard recommendations with fatigue pre-cracking length ≥ 1.3 mm or 2.5%W (whichever is bigger), five (5) specimens with a fatigue pre-cracking length &lt; 1.3 mm (between 0.5 mm to 1 mm), and five (5) specimens without fatigue pre-cracking (EDM notch), additionally, results from five (5) specimens previously tested in a round robin (RR) testing performed internally by Tenaris using the same LP material and standard fatigue pre-crack length. The crack length target (a/W) was kept 0.5 for all cases. Even if the sampling population is relatively small considering the three notch conditions, it seems that EDM might be an alternative to the standard specified fatigue pre-cracking. Thus, this experimental assessment aims to open the discussion on the use of EDM notch as alternative.

Abstract A common method to strengthening or stiffening a weak part of an airplane structure is to adhere a patch over the inferior surface. Typically, this is done in order to prevent a crack from initiating, or to prevent an already existing crack from growing. Evaluation of the efficiency of the patch has traditionally been done with respect to the extent of crack growth, (e.g. Park et al. 1992, and Paul and Jones, 1992), which of course is of crucial interest. However, the integrity of the patched system needs to be considered as well, since the failure of the composite system (formed by the patch and the base structure) may lead to a rapid growth of the preexisting crack in the base structure and may have overall catastrophic consequences. In this study we are therefore interested in investigating the initiation of debonding between the patch and the base structure, as well as the extent and stability of the debonding. Early studies we conducted with respect to debonding suggested that relative long and relative compliant patches were preferred. Furthermore, an investigation regarding the effects of edge tapering on the debonding behavior showed that there are situations where a beveled edge may increase the propensity for debonding, requiring careful selection to achieve a suitable taper angle. In the present study, we investigate the integrity of the composite system for a base structure made from aluminum, and the patch made from aluminum or fiber reinforced epoxy, where both carbon and glass fiber are studied. In particular, we compare the materials selection in the patch, and for the case of a fiber-reinforced epoxy we also discuss the lay-up sequence. To model the debonding behavior, an analytical model developed previous is extended to allow for the current materials properties. This model is fully self consistent and includes a Griffith type fracture criteria which yields the condition for the propagating bond zone boundary. The model also considers the unbonded part of the patch, which has earlier been shown to be in either of three configurations: (i) full sliding contact between the unbonded part of the patch and the base structure, (ii) only the edge of the patch remains in sliding contact with the base structure, or (iii) the patch has totally lifted of the base structure. Results for both flat and curved structures are presented, as well as for a range of loading and boundary conditions. Among other results, it is seen that the degree of tapering is a more important parameter than the stacking sequence is with respect to the initiation and extent of debonding. Furthermore, a simplified testing method is discussed. In this method, the critical load for a case of simple boundary and loading conditions for a particular material system can be directly translated to the critical load for a more complicated structure.