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Digital twins are nothing but the 3D digital replica of a physical thing. They have been in existence since the days computer-aided design became mainstream during the 1990s. However, they remained standalone replicas for the next 20 years until augmented reality (AR) became prominent in the gaming and entertainment industries. As TechNewsWorld notes, AR—often referred to as mixed reality—is an immersive and "interactive experience of a real-world environment where computer-generated perceptual information enhances real-world objects." The technology expands our physical world by adding a digital layer and generating the AR.
Echevarría, Gerardo González-Cela (University Defense Center at Naval Academy, Marín) | Campo Cabana, Marco Antonio (Engineering School, University of A Coruña) | Torres, Javier Martínez (University of Vigo, Pontevedra) | Carreño Morales, Rafael María (University of Vigo, Pontevedra) | Rivera, Roberto Bellas (University of Vigo, Pontevedra) | Touza, Ramón (Naval Academy of Spanish Navy, Cádiz) | Arto, Angeles Dena (University Defense Center at Army Academy, Zaragoza)
The design process of the F-110 frigate for the Spanish Navy is still underway. This work aims to support the decision of the Navy, on the configuration of secondary artillery of the new F-110 frigate. To do this, in this case study, we use and develop a methodology based on an analytical decision maker built ad hoc. This decision-making methodology allows reducing the present subjectivity based on an analytic hierarchy process algorithm. Using objective tools such as numerical simulation and statistical techniques, we are able to evaluate objectively the contributions of the alternatives to different criteria.
Chikkam, Anil Kumar (Matergenics Inc) | Zamanzadeh, Mehrooz (Matergenics Inc) | Pulagam, Sunil Kumar (Element Materials Technology) | Dhandabani, Ganesh P (Element Materials Technology) | Murali, Bangaru (Element Materials Technology) | Shanmugam, Jeevanandam
During plant shutdown maintenance, some components cannot be removed out of service immediately for metallurgical examination due to high cost involved and loss of production hours. The best alternative is to replicate the lab based metallography work under the field conditions. Field Metallography and Replication (FMR) also known as in-situ metallography is a powerful non-destructive test (NDT) tool used to examine the microstructure of the component when it is still in service. Moreover, FMR is also used to study the microstructural alterations for the fitness for service assessment.
This paper provides case studies of materials in Natural Gas Processing facility where FMR was used as an NDT tool without sectioning the component. This paper discusses the damage mechanisms such as sigma phase embrittlement, stress relaxation cracking and creep.
Field metallography and replication (FMR) is a non-destructive technique (NDT) that can be used as a substitute for standard laboratory metallography. The test simulates the procedure of standard laboratory practice. The FMR technique involves making a replica of the polished and etched surface of a component with a cellulose acetate tape.
ASTM(1) E31 describes the surface preparation methods for laboratory based metallography. For field metallography and replication, the surface preparation method can be modified as appropriate to obtain polished areas free from scratches, micro pits and other artifacts that might yield false results.
The selected area has to be ground with grinding stone using potable grinder. Proper measures should be taken to avoid overheating of the ground area. Later, coarse grinding should be performed using Silicon Carbide 60 and then 100 grit emery papers.
Later, coarse to fine grinding should be performed using the emery papers in the order: 240→320→400→600→1200 Grits. It is very important to make sure that the polished area is free from scratches before proceeding to next grit. The best practice to avoid scratches is to ensure that the next grinding step is 90° to that of the previous step. After fine grinding, final polishing has to be performed with 6, 3 and 1 μm diamond paste until a mirror-like surface was obtained. Between each grinding and polishing step, the polished area should be cleaned with ethanol to remove debris and dirt. The polished surface should be examined using portable optical microscope to make sure that no scratches were present.
Larsson, J. (RISE Research Institutes of Sweden) | Flansbjer, M. (RISE Research Institutes of Sweden) | Portal, N. W. (RISE Research Institutes of Sweden) | Johnson, E. (RISE Research Institutes of Sweden) | Johansson, F. (KTH Royal Institute of Technology) | Ivars, D. Mas (SKB Swedish Nuclear Fuel and Waste Management Co / KTH Royal Institute of Technology)
The presence of joints in rock masses influences the structural integrity of geotechnical structures. A critical failure mode is shearing, thus making the shearing process of importance to understand. Historically, studies have been mainly executed on the basis of laboratory experiments, since full-scale in situ tests are seldom performed due to technical and economic considerations. Since each rock joint is unique by nature, the utilization of replicas is applied to carry out controlled experimental parameter studies. However, the manufacturing process of replicas introduces many sources of uncertainty. Therefore, in this work the influence of geometrical variations in replicas on the shear strength characteristics is evaluated, mutually as well as in relation to the mother rock specimen of the replicas. The joint surfaces were 3D scanned and the contact area of the joint was measured using pressure sensitive film before direct shear tests. Deviations in morphology were evaluated by surface comparisons between the joint surfaces of the mother rock and replicas. The initial matching of the joints was evaluated by calibrating the scanning data with respect to the contact area measurements. It could be visualized that geometrical deviations were caused by rock fragments coming off during mould production, positioning of the moulds and pores resulting from replica casting. These factors were found to influence the shear strength characteristics of the replicas. The influence of the deviations originating from morphology on the joint matching is demonstrated. In summary, it is shown that replicas with similar shear strength characteristics as rock can be manufactured, but even small deviations affect the characteristics, in particular the peak strength. Therefore, parameters relevant for geometrical quality assurance should be identified along with required value ranges. Selected introductory results on quantified parameters for geometrical quality assurance are presented, serving as a basis for continued work.
Joints in rock masses influence the structural integrity of geotechnical structures. A critical failure mode is shearing (Barton 1973). Research work aiming to understand the shearing process is therefore of importance. A few examples on the broad range of topics covered by performed research are Casagrande et al. (2018), Hencher et al. (2015), Johansson et al. (2014) and Li et al. (2015). However, the research work is to large extent executed on basis of laboratory experiments, since full-scale tests are not always feasible with respect to technical and economic considerations (Bandis et al. 1981).
ABSTRACT: International gravity dam foundation design guidelines are suggesting to consider the rock-concrete foundation interface as unbonded and to use the Mohr-Coulomb criterion to assess the structure sliding safety factor. Engineers are invited to use the apparent cohesion with care but no consensus on the determination or on its influence parameters exists. Thus, an experimental study was developed and new insights on the apparent cohesion influence parameters (roughness, interlocking, material mechanical properties, contact type and normal load) were found. 64 direct shear tests were performed under CNL conditions at normal stresses similar to those found inside a large gravity dam foundation (from 100 to 1000 kPa). Results showed that higher the roughness is, higher is the apparent cohesion values. The degree of interlocking also plays a role on the apparent cohesion. Indeed, for the same roughness, a significant drop of the apparent cohesion was observed between the perfect and good interlocked joints. For the same roughness and interlocking conditions, it appeared that the apparent cohesion is also affected by the joint material mechanical properties. However, the influence of the material on the apparent cohesion is lower than that of the roughness or interlocking. An increase of the normal load also led to an increase of the apparent cohesion. These observations on the apparent cohesion influence parameters suggest that using the apparent cohesion in calculations or in numerical modeling for assessing the shear strength of rock joints may be realistic.
To design gravity dam foundations against sliding, several guidelines recommend 1) to consider the rockconcrete dam contact as an unbonded joint and, 2) to use the Mohr-Coulomb (M-C) criterion to assess the sliding stability (USBR, 1987; USACE, 1995; CFBR, 2012; FERC, 2016). The safety factor against sliding (SF) is determined as the ratio between resultant stability forces and resultant displacement forces as expressed by Eq.(1), where C is the cohesion, A the area of the dam foundation, σN the normal stress, φ the friction angle and τ the shear resultant forces.
ABSTRACT: 3D-printed core-plug replicas have wide applications in oil and gas industry. We can use synthetic plugs for repeatable set of experiments in which pore network geometry is accurately described for experiments’ simulation purposes. We can also eliminate the complex effects of rock compositions on flow/transport characteristics. That will enhance our understanding for the physics of fluid flow processes in porous media. It is challenging to ensure that synthetic core-plug is accurately duplicating the original core-plug. The pore network accuracy in the 3D-printed replicas is controlled by the computed microtomography (CT) images resolution (both planar and longitudinal), 3D-printing file generation steps, and 3D-printer resolution limitations. We generated a robust workflow by combining CT scanning, image processing tools, and 3D-printing technology to create accurate synthetic replicas for core-plugs. Geostatistical tools (multi-azimuth variograms) and image processing tools (polynomial interpolation) were utilized to tune XY and Z resolution of a CT scan for Berea sandstone core-plug to fit current 3D-printing technology requirements, reduce the needed processing computational power, and construct a 3D-printable continuous volume. Based on the generated conceptual volume, 3D-printed sandstone replica was created and presented a close agreement with the petrophysical and transport behavior (porosity and permeability) of the original Berea core-plug.
3D printing of core plugs starts with processing a series of consecutive 2D grayscale CT images (Almetwally and Jabbari, 2019). Each image has its array of specially defined attributes. These attributes include image number, height, width, minimum and maximum grayscale values, and the image data of each pixel (i.e. square picture element).
Next, adjusting and tuning the attributes of CT images to prepare the required optimal mesh file for creating 3D-printed synthetic porous core plugs and replicating the actual pore networks with identical petrophysical properties (porosity and permeability). The attributes of the CT images, which need to be tuned, enhanced, and tweaked in order to create accurate pore networks, include the CT image 2D width and height (i.e. number of pixels in each CT image), the number of images/slices along the core plug, and the grayscale of each pixel to distinguish between pores and grains. We discuss this process in details in this work.
Petro, M. J. (Montana Tech of the University of Montana) | Sordo, B. (Montana Tech of the University of Montana) | Berry, S. M. (Montana Tech of the University of Montana) | MacLaughlin, M. M. (Montana Tech of the University of Montana) | Berry, K. G. (Freeport-McMoRan)
ABSTRACT: Current standard multi-stage direct shear test methods for rock joints do not consider the individually unique asperity profile and nature of the testing specimens. These techniques require either the shearing of a single sample under multiple normal loads, or the shearing of individual “similar” specimens also under multiple normal loads. “Similar” specimens of natural rock joints with identical asperity profiles are extremely difficult or impossible to locate, and continuous shearing of the same specimen causes damage to the asperity profile which will impact successive test data. Seeking to minimize this testing-inherent error, previous research at Montana Tech has demonstrated the alternate method of limited displacement multi-stage direct shear (LDMDS) testing to yield more accurate strength parameters when shearing a single unique specimen under multiple normal stresses. The LDMDS test procedure minimizes initial shear displacement and corresponding specimen surface damage, allowing the specimen to more closely retain its original asperity and strength profile as observed via undamaged single-stage testing. Replicas of a granitic rock joint (Specimen M3) were cast with Type III cement and sheared at normal stresses of 90, 180, and 270 kPa via Standard multi-stage, LDMDS, and undamaged single-stage methods. Average friction angle (φ) and joint shear intercept (Sj) values yielded by LDMDS tests (φ = 45°, Sj = 49 kPa) were significantly more similar to values calculated by undamaged single-stage tests (φ = 51°, Sj = 22 kPa), as compared to the Standard multistage parameters which, as expected, produced a significantly underestimated friction angle (φ = 22°) and overestimated joint shear intercept (Sj = 100 kPa).
Obtaining accurate shear strength parameters for rock mass discontinuities through the use of direct shear tests is of critical importance to the design of safe slopes and underground openings. Evaluation of the standard Mohr-Coulomb strength parameters (joint friction angle and joint shear strength intercept) requires determination of the shear strength at a minimum of three different normal stress values.
ABSTRACT Aging offshore hydrocarbon gathering and transmission pipeline systems present a number of unique challenges to identification of the predominant internal corrosion mechanism(s) and the selection of effective mitigation measures, particularly since biotic and abiotic corrosion threats often exist concurrently. Integration of data from design and construction, pipeline operations, fluid composition analysis, maintenance pig returns, and inspection, along with internal surface condition information provided by extended coupon analysis, is often used to develop a basis for selection of effective mitigation. The relationship between the chemical composition, microbiology and physical nature of surface deposits with the corrosion initiation morphology and severity observed on a coupon provides important clues to the mechanisms driving localized corrosion. This understanding resulted in the development of optimal corrosion inhibitor formulations for use in an offshore gathering system. In this paper the systematic use of extended analysis coupons for corrosion mitigation selection is illustrated through detailed case studies. Key Words: Internal corrosion, mitigation, extended analysis coupons, offshore, pipeline, biofilm, deposits, underdeposit corrosion, MIC, biotic, abiotic, corrosion management system. INTRODUCTION This paper describes three case studies of internal corrosion assessment and mitigation in an offshore oil and gas gathering system based on the results from extended analysis coupons. While this monitoring approach facilitated the establishment and optimization of corrosion mitigation, the extended analysis coupon data also revealed unique cases where mitigation measures failed in an unpredictable manner, as well as indicating where mitigation was successful. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. A 600 grit wet sanded finish was applied to the major surfaces of the coupons after which they were ultrasonically cleaned in absolute ethanol and finally rinsed in acetone.
Moradian, Z. (Département de Génie Civil, Université de Sherbrooke) | Gravel, C. (Département de Génie Civil, Université de Sherbrooke) | Fathi, A. (Département de Génie Civil, Université de Sherbrooke) | Ballivy, G. (Département de Génie Civil, Université de Sherbrooke) | Rivard, P. (Département de Génie Civil, Université de Sherbrooke) | Quirion, M. (Hydro-Québec Production, Unité Expertise en barrages, Montréal)
The reliable determination of the shear strength parameters of rock joints is one of the most critical problems in geomechanics. Because of scale effects, there is no simple method for the determination of in situ shear strength parameters from the results of the laboratory tests conducted on small rock joint specimens; for this reason in situ tests on large rock joints have been developed and are sometimes conducted. However these tests are expensive and time consuming; consequently there is a great interest for simulating in situ shear tests in laboratory by developing high capacity apparatus and testing large rock joint samples. For this purpose, a new direct shear test apparatus has been developed in the Laboratoire de mécanique des roches et de caractérisation non destructive at the Université de Sherbrooke, Québec, Canada. This new system offers high shear load (up to 1000 kN) and normal load (up to 250 kN) for testing different samples with surface sizes ranging from 30×30 cm to 100×100 cm. The servo-controlled loading system allows testing of the joints by controlling the force or the displacement under cyclic loading (up to 300 cycles) and dynamic loading (with frequency 3–4 Hz) both in horizontal and vertical directions. This paper presents the characteristic of the apparatus, experimental methodology and some results of the tested joints. A procedure for the preparation of replicas from in situ rock surfaces with a Room Temperature Vulcanizing silicone (RTV) is described. These replicas are used as samples to be tested with the new shear apparatus.
The province of Quebec (Canada) is one of the world largest producers of hydroelectricity. During last decades, more than 6000 dams have been constructed and are distributed all over the province territory. However, some dams are old as they were built in the 1920–1930 and they are still in service. As a consequence, older concrete gravity dams (those over fifty years) are systematically studied by Hydro-Quebec, as a part of the dam safety program in place. However, in some cases, special attention may be paid to the foundation and the rock-concrete interface. For safety evaluation, all the causes are considered and among them are those related to the foundations mainly the shear strength along discontinuities or damrock interfaces. This requires taking into account the most accurate quantification available of the shear strength parameters of these discontinuities. If possible, the shear strength of discontinuities should be measured using the results of in situ tests, as they essentially take into account the scale effect. However, in situ tests are always time consuming in terms of preparation of the specimens and transportation of the equipment and hence, quite expensive. As a result, only a small number of in situ tests can be performed for a given project. To investigate larger samples under stress environments, higher forces are necessary and high capacity loading systems have to be developed (Bidaut et al. 2006, Konietzky et al. 2012). The aim of this project is to bring the concept of in situ direct shear tests performed on dam sites into the laboratories by replicating the real surface roughness of a discontinuity. The paper describes the components, set-up and technical data of an in-house developed system which is capable of testing large samples up to 100 cm×100 cm under different monotonic and dynamic loading conditions.