Proactive In-Situ Welding Stress Control for Laser Repair Welding of Irradiated Austenitic Materials

2017 ◽  
Author(s):  
Jian Chen ◽  
Jonathan Tatman ◽  
Zongyao Chen ◽  
Zhili Feng ◽  
Greg Frederick
Keyword(s):  
Numerical Simulations ◽  
Technology Development ◽  
Welding Process ◽  
Steel Plates ◽  
Image Correlation ◽  
Process Conditions ◽  
Welding Stress ◽  
Repair Welding ◽  
Materials Used

Substantial research has been performed in recent years to determine the effects and feasibility of welding on highly irradiated austenitic materials. This research has been driven by the need to preemptively develop welding techniques capable of repairing highly irradiated light water reactor (LWR) components susceptible to detrimental corrosion and cracking. However, the materials used to fabricate internal LWR components become increasingly difficult to weld with in-service age due to irradiation-induced generation of helium in the material matrix over time. This paper introduces a patent-pending technology that proactively manages the stresses during laser repair welding of highly irradiated reactor internals to avoid the occurrence of intergranular helium-induced cracking. The technology development relied on numerical simulations that made it possible to refine and optimize the innovative welding concept and to identify specific process conditions achieving significant reduction of tensile stress (or even formation of compressive stress) near the weld pool in the heat-affected zone on cooling. The candidate welding process conditions identified by the numerical simulations were experimentally tested on stainless steel plates (Type 304L) with a laser welding system purposely designed and engineered to incorporate the proactive stress management concept. In-situ temperature and strain measurement technique based on digital image correlation were applied to validate the numerical simulations.

scholarly journals Examination of chromium-based coating properties deposited by means of TIG

Mechanik ◽  
2017 ◽  
Vol 90 (11) ◽  
pp. 1057-1059
Author(s):  
Dominik Dudek ◽  
Konrad Stefańczyk ◽  
Ewelina Skowron ◽  
Radosław Mijas
Keyword(s):  
Steel Sheet ◽  
Welding Process ◽  
Steel Plates ◽  
Coating Properties ◽  
Inverted Microscope ◽  
Materials Used

The paper presents results of the deposition tests on the steel plates made of X10CrMoNb9-1. The steel sheet has been TIG-deposited using two different materials. Welding process has been performed applying Electric Invertec V270-T pulse device. The materials used for the deposition were W CrMo2Si and W CrMo91. After the process, samples have been cut from the deposited plates, from which the metallographic welds have been made. The paper presents photographs of microstructures recorded during observation of welds under Nikon Eclipse MA 200 inverted microscope.

Weldability Studies on the Replacement Repair Welded Joints of a Damaged Steel Bridge

2008 ◽  
Vol 580-582 ◽  
pp. 655-658 ◽  
Author(s):  
Kyong Ho Chang ◽  
H.C. Park ◽  
Chin Hyung Lee ◽  
Gab Chul Jang ◽  
Sang Hyong Lee ◽  
...  
Keyword(s):  
Welded Joints ◽  
Welding Process ◽  
Hardness Test ◽  
Steel Plates ◽  
Composition Analysis ◽  
Steel Bridge ◽  
Repair Welding ◽  
Repair Method ◽  
Flux Cored Arc Welding ◽  
Safety And Reliability

In recent years, the replacement repair welding, through which damaged bridges are repaired by replacing of the damaged sections with new steel plates through cutting and welding under in-service conditions, has been highlighted for its brilliant features i.e. it can be achieved without incurring traffic dislocation. However, the validity of the repair method is not fully verified because of its lack of safety and reliability. Moreover, repair method by welding inevitably involves cutting and welding process, and the weldability of the replacement repair welded joints has not yet been clarified. In this paper, the weldability of the replacement-repair-welded joints was investigated in order to improve reliability in the repair welded joints of the aged steel bridge. A Steel plate was extracted from the steel bridge after the period of prolonged service, and was welded with a new plate, using replacement repair welding technique, in order to construct a specimen. Flux Cored Arc Welding (FCAW) process was used to fabricate the double "V" butt joints. Welded joints were characterized on the basis of chemical composition analysis, hardness test and micro-structural analysis.

CONSERVATION OF RARE SPECIES PLANTS AND LICHENS IN SITU WITH PLANNED ANTHROPOGENIC ACTIVITIES: BASIC APPROACHES AND IMPLEMENTATION PRINCIPLES

2018 ◽  
Vol 12 (7-8) ◽  
pp. 38-45
Author(s):  
A. N. EFREMOV ◽  
N. V. PLIKINA ◽  
T. ABELI
Keyword(s):  
Rare Species ◽  
Technology Implementation ◽  
Technology Development ◽  
Anthropogenic Activities ◽  
Natural Habitat ◽  
Local Population ◽  
Main Stage ◽  
Social Risks

Rare species are most vulnerable to man-made impacts, due to their biological characteristics or natural resource management. As a rule, the economic impact is associated with the destruction and damage of individual organisms, the destruction or alienation of habitats. Unfortunately, the conservation of habitat integrity is an important protection strategy, which is not always achievable in the implementation of industrial and infrastructural projects. The aim of the publication is to summarize the experience in the field of protection of rare species in the natural habitat (in situ), to evaluate and analyze the possibility of using existing methods in design and survey activities. In this regard, the main methodological approaches to the protection of rare species in the natural habitat (in situ) during the proposed economic activity were reflected. The algorithm suggested by the authors for implementing the in situ project should include a preparatory stage (initial data collection, preliminary risk assessments, technology development, obtaining permitting documentation), the main stage, the content of which is determined by the selected technology and a long monitoring stage, which makes it possible to assess the effectiveness of the taken measures. Among the main risks of in situ technology implementation, the following can be noted: the limited resources of the population that do not allow for the implementation of the procedure without prior reproduction of individuals in situ (in vitro); limited knowledge of the biology of the species; the possibility of invasion; the possibility of crossing for closely related species that сo-exist in the same habitat; social risks and consequences, target species or population may be important for the local population; financial risks during the recovery of the population. The available experience makes it possible to consider the approach to the conservation of rare species in situ as the best available technology that contributes to reducing negative environmental risks.

PENGEMBANGAN ALAT UKUR COMPRESSION TESTER

2019 ◽  
Vol 3 (2) ◽  
pp. 111-118
Author(s):  
Bahtiar Wilantara ◽  
Raharjo Raharjo
Keyword(s):  
Pressure Gauge ◽  
Welding Process ◽  
Field Trials ◽  
Ease Of Use ◽  
Hole Drilling ◽  
Measurement Tool ◽  
Drilling Process ◽  
Measuring Instrument ◽  
Digital Compression ◽  
Materials Used

This study aims to develop an analog compression tester measuring instrument into a digital compression tester as a measurement tool that can provide effectiveness and efficiency to users.                     This research is a research and development or R&D. This research was conducted in several steps, namely: problem identification, information gathering, product design, product manufacture, expert validation, product revision, testing, final production. The development of analog compression tester was first validated by material experts, media experts, and 15 students, and 5 students for field trials. The subjects of this study were vocational students at Taman Karya Madya Teknik Kebumen. Data collection techniques used in this study using instruments in the form of a questionnaire. The data analysis technique of this research is descriptive qualitative and quantitative descriptive percentage.                 The results of the development of digital compression tester designs are: 1) the tools and materials used are electric drill, grinding, cutter, goggles, gloves, masks, ruler, acetaminine welding, screwdriver, scissors, digital dial pressure gauge, hose, spark plugs, clamps , and nepel, 2) the manufacturing process that starts from the cutting process, the hole drilling process, the welding process and the process of connecting between components, 3) the workings of digital compression tester design that is reading the pressure or compression of the machine displayed on the monitor digitally using dial pressure digital gauge, 4) the test results obtained from the validation results from: a) material experts at 89% or Eligible; b) media experts at 85% or reasonable; c) response of field trial students in terms of ease of use and reading of 90% or feasible. Thus, the conclusion that the digital compression tester measuring instrument declared feasible to use for measurement.

scholarly journals Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

2021 ◽  
Author(s):  
Antonio Pol ◽  
Fabio Gabrieli ◽  
Lorenzo Brezzi
Keyword(s):  
Mechanical Response ◽  
Steel Wire ◽  
Discrete Element ◽  
Wire Mesh ◽  
Steel Plates ◽  
Loading Conditions ◽  
Element Analysis ◽  
In Situ Conditions ◽  
Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

scholarly journals Digital Image Correlation for Evaluation of Cracks in Reinforced Concrete Bridge Slabs

2021 ◽  
Vol 6 (7) ◽  
pp. 99
Author(s):  
Christian Overgaard Christensen ◽  
Jacob Wittrup Schmidt ◽  
Philip Skov Halding ◽  
Medha Kapoor ◽  
Per Goltermann
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Laboratory Test ◽  
Digital Image ◽  
Crack Detection ◽  
Image Correlation ◽  
In Situ Tests ◽  
Stop Criterion

In proof-loading of concrete slab bridges, advanced monitoring methods are required for identification of stop criteria. In this study, Two-Dimensional Digital Image Correlation (2D DIC) is investigated as one of the governing measurement methods for crack detection and evaluation. The investigations are deemed to provide valuable information about DIC capabilities under different environmental conditions and to evaluate the capabilities in relation to stop criterion verifications. Three Overturned T-beam (OT) Reinforced Concrete (RC) slabs are used for the assessment. Of these, two are in situ strips (0.55 × 3.6 × 9.0 m) cut from a full-scale OT-slab bridge with a span of 9 m and one is a downscaled slab tested under laboratory conditions (0.37 × 1.7 × 8.4 m). The 2D DIC results includes full-field plots, investigation of the time of crack detection and monitoring of crack widths. Grey-level transformation was used for the in situ tests to ensure sufficient readability and results comparable to the laboratory test. Crack initiation for the laboratory test (with speckle pattern) and in situ tests (plain concrete surface) were detected at intervals of approximately 0.1 mm to 0.3 mm and 0.2 mm to 0.3 mm, respectively. Consequently, the paper evaluates a more qualitative approach to DIC test results, where crack indications and crack detection can be used as a stop criterion. It was furthermore identified that crack initiation was reached at high load levels, implying the importance of a target load.

scholarly journals Effects of Infills in the Seismic Performance of an RC Factory Building in Pakistan

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 276
Author(s):  
Nisar Ali Khan ◽  
Giorgio Monti ◽  
Camillo Nuti ◽  
Marco Vailati
Keyword(s):  
Numerical Model ◽  
Construction Materials ◽  
Building Codes ◽  
Construction Technique ◽  
Infill Walls ◽  
Mortar Strength ◽  
Materials Used ◽  
Seismic Response Of Buildings

Infilled reinforced concrete (IRC) frames are a very common construction typology, not only in developing countries such as Pakistan but also in southern Europe and Western countries, due to their ease of construction and less technical skills required for the construction. Their performance during past earthquakes has been in some cases satisfactory and in other cases inadequate. Significant effort has been made among researchers to improve such performance, but few have highlighted the influence of construction materials used in the infill walls. In some building codes, infills are still considered as non-structural elements, both in the design of new buildings and, sometimes, in the assessment of existing buildings. This is mainly due to some difficulties in modeling their mechanical behavior and also the large variety of typologies, which are difficult to categorize. Some building codes, for example, Eurocode, already address the influence of infill walls in design, but there is still a lack of homogeneity among different codes. For example, the Pakistan building code (PBC) does not address infills, despite being a common construction technique in the country. Past earthquake survey records show that construction materials and infill types significantly affect the seismic response of buildings, thus highlighting the importance of investigating such parameters. This is the object of this work, where a numerical model for infill walls is introduced, which aims at predicting their failure mode, as a function of some essential parameters, such as the friction coefficient between mortar and brick surface and mortar strength, usually disregarded in previous models. A comprehensive case study is presented of a three-story IRC frame located in the city of Mirpur, Pakistan, hit by an earthquake of magnitude 5.9 on 24 September 2019. The results obtained from the numerical model show good agreement with the damage patterns observed in situ, thus highlighting the importance of correctly modeling the infill walls when seismically designing or assessing Pakistani buildings that make use of this technology.

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