Zeitschriftenartikel: „Extensión Creel“

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García Ramírez, Amelia. „El proceso de enseñanza-aprendizaje de las y los estudiantes rarámuri de la Licenciatura en Antropología Social de la EAHNM-Extensión Creel“. Revista Latinoamericana de Estudios Educativos 51, Nr. 3 (03.09.2021): 153–78. http://dx.doi.org/10.48102/rlee.2021.51.3.403.

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El artículo tiene como finalidad analizar el proceso de enseñanza-aprendizaje de las y los estudiantes rarámuri de la licenciatura en antropología social, a partir de un enfoque cualitativo con una metodología etnográfica basada en la observación y la entrevista semiestructurada. Se retoma la experiencia de la Escuela de Antropología e Historia del Norte de México (EAHNM) en su Plantel Creel, ubicado en la Sierra Tarahumara, al suroeste del estado de Chihuahua. Se concluye con una propuesta para trabajar con la diversidad cultural en la educación superior, haciendo referencia al modelo educativo interactivo y al aprendizaje cooperativo como estrategia didáctica.

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Oliver, MJ, und LT Twomey. „Extension creep in the lumbar spine“. Clinical Biomechanics 10, Nr. 7 (Oktober 1995): 363–68. http://dx.doi.org/10.1016/0268-0033(95)00001-2.

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3

Anderson, Neil L., und Ralph Knapp. „An overview of some of the large scale mechanisms of salt dissolution in western Canada“. GEOPHYSICS 58, Nr. 9 (September 1993): 1375–87. http://dx.doi.org/10.1190/1.1443520.

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Well log and seismic data indicate that the bedded rock salts (salts) of the Devonian Age Prairie Formation were widely distributed and uniformly deposited in the Lloydminster area, Western Canada (T45-65, R20W3M-R5W4M); however, as a result of extensive leaching, the distribution of these salts is not now what it once was. The Lloydminster area is now bisected by the north‐south trending main dissolutional edge of the Prairie salt. Thick salt (up to 150 m) is preserved to the west of this edge; to the east the salt is mostly absent. Analyses of remnant salt and patterns of subsurface structural relief suggests that the dissolution of the Prairie salt in the Lloydminster area was triggered and/or accentuated in part by several different large scale mechanisms including: near‐surface exposure, centripetal flow of unsaturated waters, regional faulting/fracturing, glacial loading and/or unloading, dissolution of the underlying salt, and salt creep. These mechanisms are supported by the incorporated seismic and well log control that indicate a direct relationship between the thicknesses of remnant salt and post‐salt strata. Well log and seismic data also indicate that the bedded salts of the Devonian Age Black Creek Member were uniformly deposited within the Black Creek sub‐basin, Rainbow Lake area, western Canada (T105-112, R5-R10W6M); however, as a result of extensive leaching, distribution of these salts is not now what it once was. The Black Creek salts are now preserved only as discontinuous remnants with maximum gross thicknesses on the order of 80 m. Seismic and well log control suggests that the dissolution of the Black Creek salt in the Rainbow Lake study area was triggered and/or accentuated in part by several different large scale mechanisms including: centrifugal flow of unsaturated waters, regional faulting/fracturing and salt creep. Bedded salt is preserved within five other Devonian Age evaporitic units in Alberta, Canada: the Lotsberg Formation, Cold Lake Formation, Beaverhill Lake Group, Leduc Formation, and Wabamun Group. Each of these salts has also been extensively leached in places. In the literature, dissolution is generally attributed to one or more of the previously noted large scale mechanisms. Herein we present an overview of the envisioned principal mechanisms of salt dissolution. In support of these hypothesized mechanisms, we present seismic and geologic control from both the Lloydminster and Rainbow Lake areas of western Canada, which illustrate that the dissolution of subsurface salts is accompanied by the subsidence of post‐salt strata and that the analyses of this information can be used to elucidate the timing and large scale mechanisms of salt dissolution.

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Pekařová, Lenla, und Zdeněk Kuboň. „Material Degradation of Steam Pipe Elbow after Long-Term Exposure“. Key Engineering Materials 647 (Mai 2015): 162–69. http://dx.doi.org/10.4028/www.scientific.net/kem.647.162.

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Routine non-destructive examination of the steam pipe elbow after more than 240 000 hours of operation at elevated temperature revealed the extensive creep damage on the outer surface of the pipe elbow. Complex metallographic analysis made in this area confirmed creep damage as well as the non-uniform nature of the cavitation. The density of cavities continuously decreased from the outer pipe surface towards the inner surface, but also its density rapidly waned beyond the damaged area in both directions, along the circumference as well as the length of the elbow. The actual extent of the material degradation was then evaluated by testing of mechanical properties, Charpy-V and fracture toughness testing and the results were used in calculation of the residual life of the pipe elbow. It was shown that although the creep damage was perhaps one of the worst detected in Czech Republic, the cracks in the pipe elbow would spread by the stable growth until the half of the pipe wall thickness. This result thus confirms the possibility of creep life extension far beyond the limit criteria used so far.

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Lian, Ye Da, Li Qiang Gao, Qian Yin, Zhuang Zhuang Xu und Zhi Xun Wen. „Low-Cycle Fatigue-Creep Interaction Behavior of GH4169 Supperalloy“. Materials Science Forum 1018 (Januar 2021): 43–48. http://dx.doi.org/10.4028/www.scientific.net/msf.1018.43.

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Effects of different loading and uninstalling and safe loading time on the low-cycle fatigue-creep interaction behavior of GH4169 superalloy at 650°C/850MPa have been investigated. The study found that under the safe loading time, with the longer the loading and unistalling time, the fatigue-creep property and life of this alloy were gradually improved. However, under the same loading and uninstalling time, with the extension of the loading time, property of the fatigue-Creep of the alloy was gradually reduced, and its life was gradually shortened. In addition, The fracture failure behavior of the alloy under different conditions was studied in detail. Interestingly, With the extension of the holding time, the fracture failure of the alloy was changed from fatigue damage to creep damage, which makes its fracture mode transition the transgranular fracture into intergranular fracture extension.

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Ling, Xiang, Shan-Tung Tu und Jian-Ming Gong. „Damage Mechanics Considerations for Life Extension of High-Temperature Components“. Journal of Pressure Vessel Technology 122, Nr. 2 (15.12.1999): 174–79. http://dx.doi.org/10.1115/1.556167.

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Continuum damage theory has proven to be an effective tool in creep damage simulation. In order to establish some mechanical principles for life extension of components at elevated temperature, a numerical scheme based on the localized creep damage theory is introduced. To illustrate the strength potential of structures for life extension, the method is first applied to a simple case of two-bar structure. Typical components of geometrical discontinuity, material discontinuity, and temperature inhomogenity are then analyzed. In terms of the damage distribution or life exhaustion of the components, some principles for life extension are proposed. [S0094-9930(00)00202-X]

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Wang, Zhixia, Xufeng Liang, Xue Guangwu, Tao Meng und Jigang Zhang. „Creep Fracture Characteristics and the Constitutive Model of Salt Rock under a Coupled Thermo-Mechanical Environment“. Mathematical Problems in Engineering 2022 (24.08.2022): 1–14. http://dx.doi.org/10.1155/2022/4926917.

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The fracture extension characteristics of salt rocks under creep play an important role in the long-term safety and stability assessment of underground compressed air storage reservoirs. To study the fracture evolution characteristics of salt rock with time, the present study modified the Charles creep fracture intrinsic model and calibrated the A and n of the fracture extension coefficient parameters by creep fracture experiments with a constant stress rate loading method for salt rock under different temperature conditions. Finally, the modified Charles model was embedded into PFC (particle flow code) to simulate the fracture of salt rock numerically and the results were verified theoretically. The results show that (1) the fracture extension rate is related to the parameters A and n in addition to the stress intensity factor; (2) both n and A gradually decrease with the increase of temperature, and an decrease of n and A represents the decrease of fracture creep extension rate; and (3) the longer the initial fracture length of the specimen, the smaller the fracture time. The results of this study can provide theoretical guidance for evaluating the confinement of underground compressed air storage reservoirs.

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MacKay, Kathryn L. „The Uncompahgre Reservation and the Hill Creek Extension“. Utah Historical Quarterly 83, Nr. 3 (01.07.2015): 180–93. http://dx.doi.org/10.5406/utahhistquar.83.3.0180.

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Hellen, T. K. „THE VIRTUAL CRACK EXTENSION METHOD FOR CREEP FRACTURE“. Fatigue & Fracture of Engineering Materials and Structures 14, Nr. 6 (Juni 1991): 627–36. http://dx.doi.org/10.1111/j.1460-2695.1991.tb00692.x.

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Baltussen, J. J. M., und M. G. Northolt. „The viscoelastic extension of polymer fibres: creep behaviour“. Polymer 42, Nr. 8 (April 2001): 3835–46. http://dx.doi.org/10.1016/s0032-3861(00)00604-2.

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Robinson, Laura N., und Bruce E. Barnum. „Southeastern Extension of the Lake Basin Fault Zone in South-Central Montana: Implications for Coal and Hydrocarbon Exploration“. Mountain Geologist 23, Nr. 2 (01.04.1986): 37–44. http://dx.doi.org/10.31582/rmag.mg.23.2.37.

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The Lake Basin fault zone, which is the eastern extension of the Lewis and Clark line, is a structural lineament extending west-northwest across central Montana and consists mainly of en echelon northeast-striking normal faults that have been interpreted to be surface expressions of left-lateral movement along a basement wrench fault. Information gathered from recent field mapping of coal beds and from shallow, closely-spaced drill holes resulted in detailed coal bed correlations, which revealed another linear zone of en echelon faulting directly on the extended trend of the Lake Basin fault zone. This faulted area, referred to as the Sarpy Creek area, is located 30 mi (48 km) east of Hardin, Montana. It is about 10 mi (16 km) long, 8 mi (13 km) wide, and contains 21 en echelon normal faults that have an average strike of N 63° E. We therefore extend the Lake Basin fault zone 20 mi (32 km) farther southeast than previously mapped to include the Sarpy Creek area. The Ash Creek oil field, Wyoming, 60 mi (97 km) due south of the Sarpy Creek area, produces from faulted anticlinal structures that have been interpreted to be genetically related to the primary wrench-fault system known as the Nye-Bowler fault zone. The structural similarities between the Sarpy Creek area and the Ash Creek area indicate that the Sarpy Creek area is a possible site for hydrocarbon accumulation.

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Wang, Yan Fang, Zhi Gang Zhou und Zheng Yin Cai. „Studies about the Drained Creep Characteristic of Silt Soil on k₀Consolidation“. Advanced Materials Research 941-944 (Juni 2014): 2631–35. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2631.

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The creep characteristic of saturated silt soil was studied by k0 consolidation creep test through two stress paths of axial loading and lateral lightening. According to test datas, some conclusions were submitted. First, the axial creep laws between the two stress paths were consistent on drainage conditions. Volume strains were much smaller than Axial strains. Volume strains presented alternation characteristic between shear shrinkage and shear dilatancy along with time extension. The silt soil creep constitutive model was presented. The results suggested combining the NHRI model describing the transient elastic-plastic strain with the creep empirical formula describing creep strain to establish the creep constitutive model.

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Kimura, Kazuhiro, Kota Sawada, Yoshiaki Toda und Hideaki Kushima. „Creep Strength Assessment of High Chromium Ferritic Creep Resistant Steels“. Materials Science Forum 539-543 (März 2007): 3112–17. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3112.

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Degradation mechanism and life prediction method of high chromium ferritic creep resistant steels have been investigated. In the high stress condition, easy and rapid extension of recovered soft region results in significant decrease in creep strength, however, ductility is high. In the low stress condition, extension of recovered soft region is mainly controlled by diffusion and it is slow, therefore, deformation is concentrated in the recovered soft region along grain boundaries and ductility is extremely low. Delta-ferrite produces concentration gap due to difference in equilibrium composition of austenite and ferrite phases at the normalizing temperature. It increases driving force of diffusion and promotes recovery of tempered martensite adjacent to delta-ferrite. Concentration gap may be produced also in heat affected zone (HAZ), especially in fine grain HAZ similar to dual phase steel, and it has possibilities to promote recovery and, therefore, to decrease creep strength. It has been confirmed the advantage of region splitting analysis of creep rupture strength for high chromium ferritic creep resistant steels, through a residual error analysis. It is important to avoid a generation of concentration gap in order to improve stability of microstructure and to maintain high creep strength.

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Tian, Su Gui, Keun Yong Sohn und Kyung Hyun Kim. „Effect of Sb Addition on the Creep Property of AZ31 Alloy“. Materials Science Forum 449-452 (März 2004): 641–44. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.641.

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The effects of antimony addition on the microstructures and creep behavior of AZ31 have been studied. Constant load creep tests were carried out at 200°C and an initial stress of 50MPa for AZ31 alloys containing antimony up to 0.84% by weight. Results show that Small additions of antimony to AZ31 effectively decreased the creep extension and steady state creep rates. The steady state creep rate of AZ31 was reduced 2.5 times by the addition of 0.84% of antimony by weight. The main reason for the higher creep resistance is due to the presence of high volume fraction (~20%) of second phases including Mg3Sb2, which effectively hindered the movement of dislocations during the elevated temperature creep.

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Lemoal, P., und D. Perreux. „Extension of Classical Laminate Theory to the Anelastic Domain“. Advanced Composites Letters 2, Nr. 5 (September 1993): 096369359300200. http://dx.doi.org/10.1177/096369359300200501.

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An extension of classical laminate theory to the anelastic domain is proposed. It is based on numerical methods which describe the laminate's response to mechanical loading not analytically but step by step. This approach is applied to a behaviour model of a non linear viscoelastic layer and its application to multiaxial creep tests on filament wound tubes ± 55°is discussed.

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Viswanathan, R. „Dissimilar Metal Weld and Boiler Creep Damage Evaluation for Plant Life Extension“. Journal of Pressure Vessel Technology 107, Nr. 3 (01.08.1985): 218–25. http://dx.doi.org/10.1115/1.3264439.

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The basic causes of dissimilar metal weld (DMW) failures in boilers are now well understood. Guidelines have emerged for achieving significantly improved DMW life, in terms of operational parameters, weld filler metals, and weld designs. Analytical, as well as experimental, nondestructive techniques have been developed that enable assessment of the condition of DMWs in service so that intelligent run-replace decisions can be made. Techniques for assessing the remaining life of superheater/reheater (SH/RH) tubes are under development. The techniques utilize information on steamside oxide scale growth and dimensional changes on the fireside due to corrosion to compile the temperature–stress profile of operation in the tubes. This information is then combined with standard creep data to estimate the remaining life of the tubes more accurately than was possible heretofore. The potential of a replication technique that allows nondestructive monitoring of creep damage in heavy section pipes has been successfully demonstrated at several utility sites. It has been possible to detect early stages of incipient creep damage and to recommend specific courses of action to affected utilities. Laboratory and field studies currently in progress are expected to result in metallographic and miniature test specimen techniques that would further augment the capabilities of the replication technique, and render it into a more quantitative tool for life assessment of heavy section components.

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Knighton, A. David, Kevin Mills und Colin D. Woodroffe. „Tidal-creek extension and saltwater intrusion in northern Australia“. Geology 19, Nr. 8 (1991): 831. http://dx.doi.org/10.1130/0091-7613(1991)019<0831:tceasi>2.3.co;2.

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Chokshi, Atul H. „Diffusion creep in metals and ceramics: Extension to nanocrystals“. Materials Science and Engineering: A 483-484 (Juni 2008): 485–91. http://dx.doi.org/10.1016/j.msea.2006.10.197.

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19

Foriero, A., B. Ladanyi, S. R. Dallimore, P. A. Egginton und F. M. Nixon. „Modelling of deep seated hill slope creep in permafrost“. Canadian Geotechnical Journal 35, Nr. 4 (01.08.1998): 560–78. http://dx.doi.org/10.1139/t98-024.

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Attempts have been made to simulate hillslope creep observations at a site near the village of Tuktoyaktuk, Northwest Territories. Unlike other creep studies in permafrost, this site was unique in that the deformations occurred within a massive ice body, forming the core of a 30 m high concentric hill approximately 1200 m long and 700 m wide. The described simulation model of slope creep is based on both an extension of a closed-form solution originally proposed for two- and three-dimensional ice caps and a finite element creep analysis. The solution covers cyclic temperature fluctuations and incorporates spatial variations of the temperature-dependent creep parameters. Results of simulations are compared with in situ measurements of creep displacements in the hill.Key words: permafrost, slope, creep, in situ measurements, numerical simulation.

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Wu, Xijia, Rong Liu und Fadila Khelfaoui. „Creep Phenomena, Mechanisms, and Modeling of Complex Engineering Alloys“. Modelling 5, Nr. 3 (15.07.2024): 819–40. http://dx.doi.org/10.3390/modelling5030043.

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Metal creep has been a subject of extensive study for more than 110 years because it affects the useful life of engineering components operating at high temperatures. This is even more true with ever-increasing operating temperatures of propulsion/power-generation systems and the environmental regulations to reduce greenhouse emissions. This review summarizes the recent development in creep modeling with regards to creep strain evolution, creep rate, creep ductility, creep life, and fracture mode, attempting to provide a comprehensive mechanism-based framework to address all the important creep phenomena and the long-standing issue of long-term creep life prediction with microstructural evolution and environmental effects.

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Bao, Yi Wang, und Yan Chun Zhou. „Bending Creep and Stress Relaxation of Ti₃AlC₂ at High Temperature“. Key Engineering Materials 280-283 (Februar 2007): 1373–78. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1373.

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Creep and stress relaxation of Ti3AlC2 were investigated using three-point bending tests at 800-1200°C under various load levels. The results show that the creep rate significantly increases with increasing temperature in the rang of 1000-1200°C. Subcritical crack growth during the creep process was found to be the main failure mechanism, i.e., the stress intensity factor increases with the creep-induced crack growth and results in the ultimate fracture. The lower limit of stress relaxation was considered as the threshold value of zero-creep stresses, and the ratio of the threshold stress to the applied stress was defined to be a parameter of creep resistance for estimating deformation behavior at high temperature. SEM examination confirmed that the creep failure in Ti3AlC2 was governed by such a damage evolution: cavitation ® crack initiation ® crack extension ® fracture.

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Penny, R. K., und M. A. Weber. „Integrity Assessments of Components in the Creep Range“. Journal of Engineering for Gas Turbines and Power 113, Nr. 4 (01.10.1991): 574–81. http://dx.doi.org/10.1115/1.2906280.

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Robust methods for the predictions of deformations and lifetimes of components operating in the creep range are presented. The ingredients used for this are well-tried numerical techniques, combined with the concepts of continuum damage and so-called reference stresses. The methods described are derived in order to obtain the maximum benefit during the early stages of design where broad assessments of the influences of material choice, loadings, and geometry need to be made quickly and with economical use of computers. It is also intended that the same methods will be of value during operation if estimates of damage or if exercises in life extension are required. Results of the suggested method are amenable to tabular or graphic representation. To illustrate the use of these in parametric studies, three brief case studies are included. These involve a notched rod, a perforated plate, and a pipe for which lifetime estimates based upon failure criteria involving different degrees of conservatism are calculated. In addition, an illustration is given of the use of the charts presented in deciding inspection intervals and lifetime extensions. Finally, a brief excursion into the possibility for using the suggested methods for the mapping of designs within given regional constraints is given.

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Tsukada, Yutaka, Hideo Nishimura, Hiroki Yamamoto und Masao Sakane. „A Strain Rate Ratio Approach for Assessing Creep-Fatigue Life of 63Sn-37Pb Solder Under Shear Loading“. Journal of Electronic Packaging 127, Nr. 4 (24.12.2004): 407–14. http://dx.doi.org/10.1115/1.2070091.

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This paper studies creep-fatigue life prediction under shear loading by making extensive torsion creep-fatigue experiments using four kinds of strain waves. The linear damage rule, strain range partitioning method, frequency modified fatigue life, and ductility exhaustion model were applied to the experimental data, but no methods accurately predicted the creep-fatigue life. A new method based on the strain rate ratio, which predicted the creep-fatigue life within a factor of 4 scatter band, was developed.

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Dyson, B. F., und F. A. Leckie. „Life Extension of High Temperature Components“. Applied Mechanics Reviews 46, Nr. 5 (01.05.1993): 229–31. http://dx.doi.org/10.1115/1.3120343.

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Power producing plant operating at high temperature are designed for finite life. This is necessary because the operating conditions are sufficiently high to cause continuous growth of material damage. Failure occurs when damage reaches a critical value. Design is based on stress levels with an appropriate factor of safety. Since life is dependent on a strongly non-linear function of stress the actual life can be many times greater than the design life. In these circumstances it is then natural to explore the possibility of extending the working life. To increase the working life it is necessary to decrease the factor of safety, but it may be possible to follow this course of action provided the growth of physical damage is carefully monitored. In this paper creep damage mechanisms are reported and growth laws are proposed.

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Nozaki, Mineo, Masao Sakane, Yutaka Tsukada und Hideo Nishimura. „Creep-Fatigue Life Evaluation for Sn-3.5Ag Solder“. Journal of Engineering Materials and Technology 128, Nr. 2 (11.05.2005): 142–50. http://dx.doi.org/10.1115/1.2172273.

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This paper studies the creep-fatigue life evaluation of Sn-3.5Ag solder under push-pull loading using fast-fast, fast-slow, slow-fast, slow-slow, and strain-hold strain waves. Extensive creep-fatigue data were generated using these strain waves and the applicability of four conventional creep-fatigue damage rules, the linear damage rule, the frequency modified fatigue life, the ductility exhaustion model, and the strain range partitioning method, was examined. No conventional damage rules evaluated creep-fatigue lives accurately. Only the grain boundary sliding model, developed recently for solders, predicted creep-fatigue lives with a small scatter.

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Isono, Yoshitada, Masao Sakane, Masateru Ohnami und Kazunari Fujiyama. „Multiaxial Low-Cycle Fatigue Damage Evaluation Using A. C. Potential Method for Alloy 738LC Superalloy“. Journal of Engineering Materials and Technology 116, Nr. 4 (01.10.1994): 488–94. http://dx.doi.org/10.1115/1.2904318.

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This paper studies tension/torsion multiaxial low-cycle fatigue lives and creep-fatigue damage evaluation for Alloy 738LC superalloy. Tension/torsion creep-fatigue tests were carried out using hollow cylinder specimens and multiaxial creep-fatigue lives were obtained. The Mises’ equivalent strain correlated the multiaxial low cycle fatigue lives within a factor of two scatter band. An a.c. potential method is developed to detect the creep-fatigue damage associated with crack nucleation and extension. A.c. potentials at high frequencies accurately detect the creep-fatigue damage from the early stage of life while those at low frequencies detect that in the final stage of life. A.c. potentials at high frequencies detect the crack density, defined as the total crack length per unit area, and maximum crack length more sensitively than those at low frequencies.

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Ray, Dipa, Mahuya Das und Debarati Mitra. „Influence of alkali treatment on creep properties and crystallinity of jute fibres“. BioResources 4, Nr. 2 (16.04.2009): 730–39. http://dx.doi.org/10.15376/biores.4.2.730-739.

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In this work, the effect of the alkali-treatment and its variables viz., time and concentration of alkali, on the creep properties of jute fibre were studied. It was demonstrated that this kind of treatment leads to several changes in fine structure, such as voids creation and fibre fibrillation. The creep behaviour was measured for the alkali treated as well as the dewaxed fibres. Creep value was much higher in the 17.5% NaOH treated fibres compared to the dewaxed fibres. In the 8 hrs treated fibres, the creep was slightly more than the 20 mins treated fibres. XRD study revealed that experimental alkali treatment conditions resulted in closer packing of cellulose chains or rather increased crystallinity. Hence closer arrangement of the molecular chains (higher crystallinity) will reduce the creep extension, as expected.

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Ray, G. E. „The Hozameen fault system and related Coquihalla serpentine belt of southwestern British Columbia“. Canadian Journal of Earth Sciences 23, Nr. 7 (01.07.1986): 1022–41. http://dx.doi.org/10.1139/e86-103.

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The Hozameen Fault of southwestern British Columbia is associated with the Coquihalla serpentine belt and separates two distinct crustal units. Northeast of the fault are greenstones of the Early Triassic (?) Spider Peak Formation, which are unconformably overlain by Jurassic to Cretaceous turbidite and successor basin deposits of the Pasayten Trough. The oldest sedimentary rocks in the trough, the Ladner Group, contain a locally developed basal unit that hosts the Carolin mine gold orebody. Southwest of the fault, the Permian to Jurassic Hozameen Group represents a dismembered ophiolite succession comprising ultramafic rocks of the Petch Creek serpentine belt, overlain in turn by greenstone and chert units. The greenstones in the Hozameen Group and the Spider Peak Formation are geochemically distinguishable; the latter represent sodic, ocean-floor, subalkaline basalts formed in a spreading ridge environment, while the former include both arc tholeiites and oceanic island–seamount subalkaline basalts.Farther west, the major Petch Creek Fault separates the Hozameen Group from the Custer–Skagit Gneiss. This fault is locally associated with the Petch Creek serpentine belt and is considered to be a northern extension of the Ross Lake Fault of Washington State.The rocks in the Hozameen Group, Spider Peak Formation, and Pasayten Trough were probably deposited within a single basin that initiated as an extensive, multirifted, marginal back-arc basin and eventually evolved into the steadily narrowing Pasayten Trough.Following Early to Middle Cretaceous closure of the Pasayten Trough, oblique, easterly-directed movement along westerly-dipping thrusts caused the Custer–Skagit Gneiss to override the Hozameen Group, which in turn overrode rocks of the Pasayten Trough farther east; these boundary thrusts formed precursor structures for the Hozameen and Petch Creek faults. Ultramafic basement material underlying the Spider Peak Formation and the Hozameen Group was thrust up the bounding fractures, producing the Coquihalla and Petch Creek serpentine belts, respectively.Large-scale dextral transcurrent displacement, possibly related to movement along the Fraser Fault system, occurred subsequently along the Petch Creek and Hozameen faults. This wrench movement was preceded by the Mid-Eocene (?) intrusion of the Needle Peak pluton and was followed by emplacement of the 16–35 Ma Chilliwack batholith.

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Dai, Yanwei, Yinghua Liu, Fei Qin, Yuh J. Chao und Guian Qian. „C(t) dominance of the mixed I/II creep crack: Part II. Extensive creep“. Theoretical and Applied Fracture Mechanics 106 (April 2020): 102489. http://dx.doi.org/10.1016/j.tafmec.2020.102489.

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Liu, Zhan Wei, Hui Min Xie, Peng Wan Chen und Feng Lei Huang. „A Study of Creep Properties of Polymer Bonded Explosives“. Advanced Materials Research 33-37 (März 2008): 407–12. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.407.

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Creep properties of polymer bonded explosives (PBXs), a particulate composite, was studied by using the method of moiré interferometry in this paper. The specimens fabricated by different heat pressing technology were used. Extensive creep deformation of PBXs material was indirectly measured by the aid of compressive circular disk test. The obtained results shown that creep properties are greatly influenced by pressing pressures and temperature of heat pressing technology. The results indicated that the higher the temperature and the pressing pressure are in the heat pressing technology to some degree, the better the PBXs material creep resistance is. The creep fracture surfaces of PBXs were also observed using Scanning Electronic Microscopy (SEM). It was shown that most of the fracture crack was initiated and propagated along the explosives crystal surface during creep.

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Petalas, Alexandros L., Mats Karlsson und Minna Karstunen. „Modelling of undrained shearing of soft natural clays“. E3S Web of Conferences 92 (2019): 15001. http://dx.doi.org/10.1051/e3sconf/20199215001.

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stress-strain response of soft natural clays is characterised by anisotropy, destructuration and rate-dependency. An accurate constitutive description of these materials should take into consideration all of the characteristics above. In this paper, two constitutive models for soft soils, namely the SCLAY1S and Creep-SCLAY1S models are used to simulate the undrained response of two soft natural clays, Gothenburg clay from Sweden and Otaniemi clay from Finland. The SCLAY1S model accounts for the effect of inherent and induced anisotropy and destructuration, while the Creep-SCLAY1S accounts also for the creep and rate effects. The model simulations are compared against triaxial compression and extension tests on anisotropically consolidated samples. The results demonstrate the need to incorporate all features represented in the Creep-SCLAY1S model when modelling structured natural clays.

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Anderson, Duane C. „The Wittrock Excavations: Implications for the Study of Culture Process within the Initial Variant of the Middle Missouri Tradition“. North American Archaeologist 7, Nr. 3 (Januar 1987): 215–41. http://dx.doi.org/10.2190/4mxy-1r3h-v0uv-j895.

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The Wittrock National Historic Landmark site is a fortified Mill Creek village in northwest Iowa. Although it has been excavated on four occasions, detailed reports on the two most extensive projects have only recently been made available. The purpose of this article is to utilize data derived from the Wittrock site to inform models of Mill Creek midden formation and Mill Creek culture process recently proposed by Anderson (1985a; 1985b). The article concludes that 1) the Wittrock midden resulted from the “banked house” method of trash dispersal; 2) a series of changes are warranted in Anderson's model of Mill Creek culture process; and 3) the Mill Creek model has a bearing on our understanding of the entire Initial Variant of the Middle Missouri Tradition.

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Heckl, Astrid, Ralf Rettig und Robert F. Singer. „Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys“. Advanced Materials Research 278 (Juli 2011): 339–44. http://dx.doi.org/10.4028/www.scientific.net/amr.278.339.

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The influence of Re and Ru on creep rupture strength has been investigated using a new in-house designed alloy-series comprising 9 experimental nickel-base superalloys with stepwise increased Re and Ru additions. The presented creep data reveals a significant increase in creep rupture strength by additions of Re. For additions of Ru an increase of creep rupture strength can only be found for low Re contents. The present article, which is part of an extensive and systematic investigation on Re and Ru influences, shows, that an improved creep resistance by an influence of Re and Ru on the γ’-solvus temperature is rather improbable. Likewise, the influence of Re and Ru on liquidus temperature is not expected to play an important role. However, the creep rupture strength is suggested to be highly modified by γ/γ’-microstructure changes.

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Kooi, Henk, und Gilles Erkens. „Creep consolidation in land subsidence modelling; integrating geotechnical and hydrological approaches in a new MODFLOW package (SUB-CR)“. Proceedings of the International Association of Hydrological Sciences 382 (22.04.2020): 499–503. http://dx.doi.org/10.5194/piahs-382-499-2020.

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Abstract. Creep and secondary consolidation are important phenomena in settlement caused by surface loads, but not commonly considered in land subsidence driven by groundwater extraction. To explore the role of creep in such settings, a new MODFLOW-2005 land subsidence package was developed that incorporates a creep formulation gleaned from geotechnical software. This formulation, which is based on the isotache concept, is an extension of, and incorporates the classical elastoplastic compression model of Terzaghi as a limiting case. The package is introduced, and results are presented of an application to a site in northern Jakarta. It is shown that the isotache model requires considerably higher overconsolidation levels of clays than the Terzaghi model, and that creep contributes to subsidence long after drawdown in pumped aquifers has stabilized, a phenomenon that is traditionally attributed to “hydrodynamic lag”.

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35

Sakurada, Eisaku, und Takashi Matsuo. „Change in Stress Axis with Creep Deformation in PST Crystal“. Advanced Materials Research 15-17 (Februar 2006): 858–63. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.858.

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The superiority of creep in Ti-48at%Al alloy with fully transformed lamellar structure to that in Ti-50at%Al alloy with γ single phase is characterized by the extension of transient stage. This extension of the transient stage derives by the retarding effect of α2 plate on the onset of the accelerating stage, through suppressing the dynamically recrystallization which is the main reason of the accelerating stage. This superiority in Ti-48at%Al alloy will become more clear by investigating the creep of the single crystal designated as the PST crystal, because of removing the grain boundaries which is the formation site of dynamic recrystallization. By using the PST crystal, the predominant deformation using primary slip plane of γ plate will continue, because the α2 plate restricts the operation of other slip planes. In PST crystals with the angle between the stress axis and the lamellar plates, designated as φ, less than 45°, the uniform deformation will proceed, because of the decrease in creep rate due to the decreasing in Schmid factor through the monotonous decrease in φ. But these suppositions have not confirmed. In this study, the deformation manner of the PST crystals with φ of less than 45° is investigated by the analyzing of creep curve, macrostructure and inverse pole figure of the PST crystals interrupted the creep tests at 1148K/68.6MPa at the strains of 0.20 and 0.65. Inverse pole figures of PST crystal are obtained using SEM-EBSD method. By accepting the creep deformation, the stress axes of the PST crystals move for [001]-[1, – 11] line with slip system of (111)<1, – 01>, and after reaching at this line, the stress axis turn to [1, – 11] pole position with (111)<1, – 10> slip system. The change in stress axis is not homogeneous in gauge portion accepting small strain, by subjecting the further creep deformation up to the onset of the accelerating stage, this heterogeneous deformation in gauge portion disappeared.

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Herranz, L. E., und F. Feria. „Extension of the FRAPCON-3.3 creep model to dry storage conditions“. Progress in Nuclear Energy 52, Nr. 7 (September 2010): 634–39. http://dx.doi.org/10.1016/j.pnucene.2010.04.003.

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37

Wilshire, B. „New high-precision creep procedures for accurate life extension of plant“. International Journal of Pressure Vessels and Piping 39, Nr. 1-2 (Januar 1989): 73–82. http://dx.doi.org/10.1016/0308-0161(89)90039-2.

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38

Ghosh, R. N., S. Chaudhuri, N. Roy und L. Chattopadhyay. „Creep life extension of high temperature components under wall thinning conditions“. Sadhana 20, Nr. 1 (Februar 1995): 331–39. http://dx.doi.org/10.1007/bf02747296.

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39

Kun, Ferenc, Raul Cruz Hidalgo, Frank Raischel und Hans J. Herrmann. „Extension of fibre bundle models for creep rupture and interface failure“. International Journal of Fracture 140, Nr. 1-4 (Juli 2006): 255–65. http://dx.doi.org/10.1007/s10704-005-2556-4.

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40

Ainsworth, R. A., M. B. Ruggles und Y. Takahashi. „Flaw Assessment Procedure for High-Temperature Reactor Components“. Journal of Pressure Vessel Technology 114, Nr. 2 (01.05.1992): 166–70. http://dx.doi.org/10.1115/1.2929024.

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An interim high-temperature flaw assessment procedure is described. This is a result of a collaborative effort between Electric Power Research Institute in the US, Central Research Institute of Electric Power Industry in Japan, and Nuclear Electric plc in the UK. The procedure addresses pre-existing defects subject to creep-fatigue loading conditions. Laws employed to calculate the crack growth per cycle are defined in terms of fracture mechanics parameters and constants related to the component material. The crack growth laws may be integrated to calculate the remaining life of a component or to predict the amount of crack extension in a given period. Fatigue and creep crack growth per cycle are calculated separately, and the total crack extension is taken as the simple sum of the two contributions. An interaction between the two propagation modes is accounted for in the material properties in the separate calculations. In producing the procedure, limitations of the approach have been identified. Some of these limitations are to be addressed in an extension of the current collaborative program.

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Fujiyama, Kazunari, Shuhei Higashide und Kazuki Nomoto. „Notched Creep Damage Assessment Based on EBSD Observation for Austenitic Stainless Steel“. Materials Science Forum 941 (Dezember 2018): 420–25. http://dx.doi.org/10.4028/www.scientific.net/msf.941.420.

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Creep damage processes for smooth and notched specimen of austenitic stainless steel through interrupted creep tests using multiple specimens. The material used was 18-8 stainless steel for boiler tube use. The mid-sections of interrupted creep test specimens were observed through SEM(Scanning Electron Microscope) instrumented with EBSD(Electron BackScatter Diffraction patter) equipment. IPF(Inverse Pole Figure) maps, Phase maps and GOS(Grain Orientation Spread) maps were used for investigating creep damage process. For smooth specimen, the relationship between macroscopic creep time fraction and GOS averaged for all pixels showed linearity, while the relationship between creep strain and the averaged GOS showed non-linearity regressed by Green function successfully. For notched specimen, the EBSD maps became noisy possibly due to extensive phase transformation under highly concentrated notch stress. Obtained GOS data for gamma phase only showed non-monotonic change with time and nominal strain. The evaluated local strains in the vicinity of the notch showed relatively small amount, which might cause the very long creep life compared with smooth specimen under the same nominal stress condition.

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Mehmanparast, Ali, Catrin M. Davies und Kamran Nikbin. „Quantification and Prediction of Residual Stresses in Creep Crack Growth Specimens“. Materials Science Forum 777 (Februar 2014): 25–30. http://dx.doi.org/10.4028/www.scientific.net/msf.777.25.

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An important issue to be considered in the life assessment of power plant components is the effects of prior creep damage on subsequent fatigue crack growth and fracture behavior. To examine these effects, creep damage has been introduced into 316H stainless steel material by interrupting creep crack growth (CCG) tests on compact tension, C(T), specimens at 550 °C. During the CCG tests, the specimen is loaded in tension, crept and unloaded after a small amount of crack extension. This process introduces compressive residual stress fields at the crack tip, which may subsequently affect the fatigue crack growth test results. In this work, neutron diffraction (ND) measurements have been conducted on interrupted CCG test specimens, which contain creep damage local to the crack tip, and the results are compared to predictions obtained from finite element (FE) simulations. Reasonable agreement has been found between the FE predictions and ND measurements.

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Sattar, Mohsin, Abdul Rahim Othman, Maaz Akhtar, Shahrul Kamaruddin, Rashid Khan, Faisal Masood, Mohammad Azad Alam, Mohammad Azeem und Sumiya Mohsin. „Curve Fitting for Damage Evolution through Regression Analysis for the Kachanov–Rabotnov Model to the Norton–Bailey Creep Law of SS-316 Material“. Materials 14, Nr. 19 (23.09.2021): 5518. http://dx.doi.org/10.3390/ma14195518.

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In a number of circumstances, the Kachanov–Rabotnov isotropic creep damage constitutive model has been utilized to assess the creep deformation of high-temperature components. Secondary creep behavior is usually studied using analytical methods, whereas tertiary creep damage constants are determined by the combination of experiments and numerical optimization. To obtain the tertiary creep damage constants, these methods necessitate extensive computational effort and time to determine the tertiary creep damage constants. In this study, a curve-fitting technique was proposed for applying the Kachanov–Rabotnov model into the built-in Norton–Bailey model in Abaqus. It extrapolates the creep behaviour by fitting the Kachanov–Rabotnov model to the limited creep data obtained from the Omega-Norton–Bailey regression model and then simulates beyond the available data points. Through the Omega creep model, several creep strain rates for SS-316 were calculated using API-579/ASME FFS-1 standards. These are dependent on the type of the material, the flow stress, and the temperature. In the present work, FEA creep assessment was carried out on the SS-316 dog bone specimen, which was used as a material coupon to forecast time-dependent permanent plastic deformation as well as creep behavior at elevated temperatures and under uniform stress. The model was validated with the help of published experimental creep test data, and data optimization for sensitivity study was conducted by applying response surface methodology (RSM) and ANOVA techniques. The results showed that the specimen underwent secondary creep deformation for most of the analysis period. Hence, the method is useful in predicting the complete creep behavior of the material and in generating a creep curve.

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Tu, S.-T., und X. Ling. „Interpretation of damage mechanics behaviour of two-bar structures for the life extension of high-temperature components“. Journal of Strain Analysis for Engineering Design 38, Nr. 2 (01.02.2003): 125–32. http://dx.doi.org/10.1243/030932403321163659.

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The creep damage behaviour of two-bar structures of different dimensions and materials is studied in terms of continuum damage theory. The basic model is used to interpret the effectiveness of life extension measures for complicated structures. It is found that replacement of the more damaged component prior to rupture will result in an optimized life extension efficiency, depending on the geometric or material difference between the damaged and less damaged components. This has potential to provide guidance on the effectiveness of life extension repairs in high-temperature plants.

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Cambiotti, Gabriele, Mimmo Palano, Barbara Orecchio, Anna Maria Marotta, Riccardo Barzaghi, Giancarlo Neri und Roberto Sabadini. „New Insights into Long-Term Aseismic Deformation and Regional Strain Rates from GNSS Data Inversion: The Case of the Pollino and Castrovillari Faults“. Remote Sensing 12, Nr. 18 (09.09.2020): 2921. http://dx.doi.org/10.3390/rs12182921.

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We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides a refined estimate of the upper bound of the strain accumulation process. As case study, we apply this method to a six year GNSS campaign (2003–2008) set up in the southern portion of the Pollino Range over the Castrovillari and Pollino faults. We show that regional deformation alone cannot explain the observed deformation pattern and implies high geodetic strain rate, with a WSW-ENE extension of 86±41×10−9/yr. Allowing for the possibility of fault creep, the modelling of GNSS velocities is consistent with their uncertainties and they are mainly explained by a shallow creep over the Pollino fault, with a normal/strike-slip mechanism up to 5 mm/yr. The regional strain rate decrease by about 70 percent and is characterized by WNW-ESE extension of 24±28×10−9/yr. The large uncertainties affecting our estimate of regional strain rate do not allow infering whether the tectonic regime of the area is extensional or strike-slip, although the latter is slightly more likely.

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Tribula, D., und J. W. Morris. „Creep in Shear of Experimental Solder Joints“. Journal of Electronic Packaging 112, Nr. 2 (01.06.1990): 87–93. http://dx.doi.org/10.1115/1.2904363.

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Thermal fatigue failures of solder joints in electronic devices are a great concern in the electronics industry. Since the fatigue load is often in shear the details of thermal fatigue failure in shear are of particular interest. Recent work indicates that similar failure mechanisms operate in both thermal fatigue in shear and unidirectional creep in shear. Additionally, since the operative temperatures during thermal fatigue represent high solder homologous temperatures, creep deformation is certainly involved. These factors and the relative case of conducting creep experiments encourage the study of solder joints under shear creep conditions. This work presents steady state shear creep rate vs. shear stress data for several solder compositions, including the binary eutectic alloy and Pb-Sn alloyed with small amounts of Bi, Cd, In, and Sb, in a joint configuration. These data indicate that conventional creep mechanisms operate in the temperature and shear strain rate ranges studies. Extensive microstructural information is also reported. The microstructural evolution under creep conditions indicates that the instability of the as-cast binary Pb-Sn eutectic microstructure initiates creep failure. Changes of the as-solidified microstructure with the third element addition are reported as are the microstructural responses of each of these alloys to creep deformation. The efficacy of postponing the microstructural instability with the addition of small amounts of ternary elements is discussed.

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Louda, J. William, und John F. Hayford. „Non-Point Sources (Septic Tanks) of Surface Water Nutrient Pollution: A Review and a Study of Taylor Creek, Okeechobee County, Florida“. Environment and Pollution 12, Nr. 2 (18.07.2023): 1. http://dx.doi.org/10.5539/ep.v12n2p1.

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This study investigated the impact of high-density septic systems (aka Onsite Sewerage and Disposal Systems, OSTDS) along the canals located in the communities of the lower Taylor Creek area on water quality at the northern periphery of Lake Okeechobee. Using sucralose as an anthropogenic tracer, we investigated the septic derived non-point sourcing of nutrients which feed harmful algal (cyanobacterial) blooms (HABs) in Lake Okeechobee and adjacent waters. The subdivisions investigated were Treasure Island (TI) and Taylor Creek Isles (TCI) located to the east and west of Taylor Creek. TI homes are all on septic tanks whereas TCI is serviced by a municipal vacuum sewerage system. TI canals had 5.3 times the mean concentration of sucralose relative to TCI canals. On a yearly basis, the Treasure Island sites away from Taylor Creek had 2.25 times the total phosphorus and 1.20 times the total nitrogen compared to the Taylor Creek isles sites. An extensive literature review of non-point pollution is included.

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Adrian, Brent. „Stratigraphic range extension of the turtle Boremys pulchra (Testudinata, Baenidae) through at least the uppermost Cretaceous“. Fossil Record 25, Nr. 2 (25.08.2022): 275–85. http://dx.doi.org/10.3897/fr.25.85563.

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New material of the derived baenid turtle Boremys pulchra from the Hell Creek Formation of Montana extends the stratigraphic range of the taxon through at minimum the latest Maastrichtian. Previously, the species was constrained to the Campanian of Montana and Alberta, so this extension constitutes at least 5 million years. Due to fossil reworking at the Bug Creek Anthills assemblage, where Maastrichtian and Paleocene deposits are mixed, a definitive extension for B. pulchra cannot currently include Paleocene strata. However, the presence of B. pulchra in latest Cretaceous strata, previous identification of Paleocene Boremys sp. and the general success of baenid taxa across the K–Pg boundary, make it quite plausible that B. pulchra survived the extinction event and that previously described Maastrichtian and Paleocene Boremys sp. material probably represents a new taxon. A stratigraphic extension beyond the Campanian indicates that B. pulchra survived the paleoenvironmental conditions of the latest Cretaceous, where adaptation to locally heterogeneous aquatic habitats and paleotemperature fluctuations may have facilitated latest Cretaceous and K–Pg survivorship. Additionally, ectoparasitic bore marks on the Boremys pulchra specimen described here can be attributed to the ichnotaxon Karethraichnus lakkos.

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Busch, James F., Alan D. Rooney, Edward E. Meyer, Caleb F. Town, David P. Moynihan und Justin V. Strauss. „Late Neoproterozoic – early Paleozoic basin evolution in the Coal Creek inlier of Yukon, Canada: implications for the tectonic evolution of northwestern Laurentia“. Canadian Journal of Earth Sciences 58, Nr. 4 (April 2021): 355–77. http://dx.doi.org/10.1139/cjes-2020-0132.

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The age and nature of the Neoproterozoic – early Paleozoic rift–drift transition has been interpreted differently along the length of the North American Cordillera. The Ediacaran “upper” group (herein elevated to the Rackla Group) of the Coal Creek inlier, Yukon, Canada, represents a key succession to reconstruct the sedimentation history of northwestern Laurentia across the Precambrian–Cambrian boundary and elucidate the timing of active tectonism during the protracted breakup of the supercontinent Rodinia. These previously undifferentiated late Neoproterozoic – early Paleozoic map units in the Coal Creek inlier are herein formally defined as the Lone, Cliff Creek, Mount Ina, Last Chance, Shade, and Shell Creek formations. New sedimentological and stratigraphic data from these units is used to reconstruct the depositional setting. In the Last Chance Formation, chemostratigraphic observations indicate a ca. 5‰ δ13Ccarb gradient coincident with the globally recognized ca. 574–567 Ma Shuram carbon isotope excursion. Map and stratigraphic relationships in the overlying Shell Creek Formation provide evidence for latest Ediacaran – middle Cambrian tilting and rift-related sedimentation. This provides evidence for active extension through the Cambrian Miaolingian Series in northwestern Canada, supporting arguments for a multiphase and protracted breakup of Rodinia.

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Harmon, Russell S., Deborah L. Leslie, W. Berry Lyons, Kathleen A. Welch und Diane M. McKnight. „Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica“. E3S Web of Conferences 98 (2019): 01020. http://dx.doi.org/10.1051/e3sconf/20199801020.

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Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.

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