Elastic-Plastic Compaction of Geopressured Sandstone

1991 ◽  
Vol 113 (1) ◽  
pp. 57-61
Author(s):  
E. P. Fahrenthold
Keyword(s):  
Geothermal Energy ◽  
Field Experiments ◽  
Mechanical Response ◽  
Gulf Coast ◽  
Three Dimensional ◽  
Reservoir Rock ◽  
Elastic Plastic ◽  
Well Production ◽  
Production Problems

The economic development of United States Gulf Coast geopressured-geothermal energy resources depends in part upon an improved understanding of reservoir rock response to long-term aquifer production. Although field experiments have shown that rock mechanical response can significantly influence well production rates and that sand production problems can prevent efficient reservoir depletion, the absence of general reservoir rock models has hindered analytical studies of such problems. This paper provides experimental property measurements and a three-dimensional elastic-plastic constitutive model for sandstone cored from the most active Gulf Coast geopressured well currently in operation.

scholarly journals Probabilistic Elastic-plastic Fracture Mechanics Analysis of Propagation of Cracks in Pipes under Internal Pressure

2020 ◽  
Vol 14 (54) ◽  
pp. 202-210
Author(s):  
Belaïd Mechab ◽  
Medjahdi Malika ◽  
Mokadem Salem ◽  
Serier Boualem
Keyword(s):  
Distribution Function ◽  
Internal Pressure ◽  
Structural Reliability ◽  
Mechanical Response ◽  
Crack Depth ◽  
Three Dimensional ◽  
Crack Size ◽  
Elastic Plastic ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This study presents a three dimensional finite element method analysis of semi-elliptical surface cracks in pipes under internal pressure load. In the elastic–plastic case, estimates of the J-integral are presented for various ratios including crack depth to pipe thickness (a/t) and strain hardening index in the (R-O) Ramberg-Osgood (n).  Finally, failure probability is accessed by a statistical analysis for uncertainties in loads and material properties, and structural reliability and crack size. The Monte Carlo method is used to predict the distribution function of the mechanical response. According to the obtained results, we note that the stress variation and the crack size are important factors influencing on the distribution function of (J/Je).

Ice shell construction in Hokkaido of Japan during 1980–2012

2021 ◽  
Vol 36 (1) ◽  
pp. 26-36
Author(s):  
Tsutomu Kokawa
Keyword(s):  
Shell Thickness ◽  
Field Experiments ◽  
Three Dimensional ◽  
Structural Safety ◽  
Circular Membrane ◽  
Snow Layer ◽  
Construction Technique ◽  
Thin Walled ◽  
Ice Shell

This paper summarizes research and development of an ice shell construction carried out in inland Hokkaido of Japan from 1980 to 2012.The ice shell is made of thin-walled curved ice plate and constructed according to the following method. (1) Building up a three-dimensional formwork by inflating a two-dimensional membrane bag covered with ropes anchored to the snow-ice foundation ring. (2) Covering the formwork with a thin saturated snow layer of less than 1 cm thickness by blowing milled snow with a rotary snow blower and spraying water with an adjustable nozzle, and letting it freeze naturally at temperatures below −10°C. (3) Repeating (2) until shell thickness reaches to the design thickness, then removing the bag and ropes for reuse. A number of ice shells were constructed as temporary winter structures while improving the construction technique through the repeated construction experiences. Based on the field experiments of 10–30 m ice domes (“ Xm ice dome” means the ice dome constructed by using Xm diameter of circular membrane bag in the formwork before inflation) which measured the deflection and temperature under long term period after the completion and further observed the behavior of the collapse, it was recognized that understanding the creep behavior is extremely important for evaluating the structural safety of the ice shell.

scholarly journals Simplified methods for designing thermo-active retaining walls

2020 ◽  
Vol 205 ◽  
pp. 06011 ◽  
Author(s):  
Eleonora Sailer ◽  
David M. G. Taborda ◽  
Lidija Zdravkovic ◽  
David M. Potts
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Mechanical Response ◽  
Mechanical Design ◽  
Retaining Wall ◽  
Three Dimensional ◽  
Finite Element Analyses ◽  
Factors Affecting ◽  
Heating And Cooling

Thermo-active retaining structures are geotechnical structures employed to provide thermal energy to buildings for space heating and cooling through heat exchanger pipes embedded within the concrete structure. Consequently, the design of these structures needs to consider both the long-term energy efficiency as well as the thermo-mechanical response in terms of stability and serviceability. Transient finite element analyses can be carried out to evaluate the behaviour of thermo-active walls, where the heat exchanger pipes are explicitly modelled, thus requiring three-dimensional (3D) analyses. However, performing long-term 3D finite element analyses is computationally expensive. For this reason, in this study, new approaches are presented that allow the thermal or thermo-mechanical design of thermo-active walls to be carried out by performing two-dimensional (2D) plane strain analyses. Two methods, which are based on different design criteria, are proposed and their performance in replicating the three-dimensional behaviour is assessed. Furthermore, the factors affecting the 2D approximations for the two modelling approaches are evaluated, where particular emphasis is given to the influence of the simulated boundary condition along the exposed face of the retaining wall.

Practical electron tomography

1995 ◽  
Vol 53 ◽  
pp. 742-743
Author(s):  
C.L. Woodcock
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3D Shape ◽  
Computational Resources ◽  
Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

Custom Presurgical Planning for Midfacial Reconstruction

2020 ◽  
Vol 36 (06) ◽  
pp. 696-702
Author(s):  
Nolan B. Seim ◽  
Enver Ozer ◽  
Sasha Valentin ◽  
Amit Agrawal ◽  
Mead VanPutten ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Functional Performance ◽  
Three Dimensional ◽  
Free Tissue Transfer ◽  
Long Term Effects ◽  
Presurgical Planning ◽  
Dental Rehabilitation ◽  
Midface Reconstruction ◽  
Reconstructive Algorithm

AbstractResection and reconstruction of midface involve complex ablative and reconstructive tools in head and oncology and maxillofacial prosthodontics. This region is extraordinarily important for long-term aesthetic and functional performance. From a reconstructive standpoint, this region has always been known to present challenges to a reconstructive surgeon due to the complex three-dimensional anatomy, the variable defects created, combination of the medical and dental functionalities, and the distance from reliable donor vessels for free tissue transfer. Another challenge one faces is the unique features of each individual resection defect as well as individual patient factors making each preoperative planning session and reconstruction unique. Understanding the long-term effects on speech, swallowing, and vision, one should routinely utilize a multidisciplinary approach to resection and reconstruction, including head and neck reconstructive surgeons, prosthodontists, speech language pathologists, oculoplastic surgeons, dentists, and/or craniofacial teams as indicated and with each practice pattern. With this in mind, we present our planning and reconstructive algorithm in midface reconstruction, including a dedicated focus on dental rehabilitation via custom presurgical planning.

scholarly journals Effects of disk tillage on soil condition, crop yield and weed infestation

2011 ◽  
Vol 48 (No. 1) ◽  
pp. 20-26
Author(s):  
M. Birkás ◽  
T. Szalai ◽  
C. Gyuricza ◽  
M. Gecse ◽  
K. Bordás
Keyword(s):  
Winter Wheat ◽  
Crop Yield ◽  
Field Experiments ◽  
Soil Layer ◽  
Soil Condition ◽  
Perennial Weeds ◽  
Weed Infestation ◽  
Set Up ◽  
Different Levels

This research was instigated by the fact that during the last decade annually repeated shallow disk tillage on the same field became frequent practice in Hungary. In order to study the changes of soil condition associated with disk tillage and to assess it is consequences, long-term tillage field experiments with different levels of nutrients were set up in 1991 (A) and in 1994 (B) on Chromic Luvisol at Gödöllö. The effects of disk tillage (D) and disk tillage combined with loosening (LD) on soil condition, on yield of maize and winter wheat, and on weed infestation were examined. The evaluation of soil condition measured by cone index and bulk density indicated that use of disking annually resulted in a dense soil layer below the disking depth (diskpan-compaction). It was found, that soil condition deteriorated by diskpan-compaction decreased the yield of maize significantly by 20 and 42% (w/w), and that of wheat by 13 and 15% (w/w) when compared to soils with no diskpan-compaction. Averaged over seven years, and three fertilizer levels, the cover % of the total, grass and perennial weeds on loosened soils were 73, 69 and 65% of soils contained diskpan-compaction.

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