Search results for "drilling"

ERROR AND UNCERTAINTY ANALYSIS OF THE RESIDUAL STRESSES COMPUTED BY USING THE HOLE DRILLING METHOD

2011

The hole-drilling method is one of the most used techniques for the experimental analysis of the residual stresses in mechanical components. For both through-thickness uniform and non-uniform residual stresses, its practical application is standardised by the ASTM E837-08. For uniform residual stresses, to which the present work deals with, the use of the method in accordance with the ASTM limitations, leads to results with a bias of about 10%. Unfortunately, although some experimental parameters can be frequently out of the corresponding standard limitation, the user does not have appropriate procedures to correct the obtained results which, in accordance with the ASTM standard, have to be…

Advances in Strain Gauge Measurement on Composite Materials

2010

Abstract:  This article gives an overview on the application of strain gauge techniques to the analysis of the strains in composite materials. The orthotropic behaviour of the composite influences the performance of strain gauges that are calibrated for use on isotropic materials. The article considers therefore the typical topics of the strain gauge technology applied to composites with particular reference to the compensation of thermal output, the measurement of the coefficients of thermal expansion, the determination of the strain and stress state, the influence of the misalignment error, the reinforcement effect, the determination of the stress intensification factor, the analysis of r…

Device for Processing Micro-bores by Electrical Discharge Machining

2021

In recent years, there has been a growing trend to miniaturization parts. As a result, the processing technology must be partially evolved to produce a small surface, and then a microscopic surface. There are many of these technologies, and each has its advantages and disadvantages in the industry. Among these technologies, electric shock processing is used as an alternative with the required precision. Processing of very small wells by the method of electric emission is similar to that used in the processing of normal-sized machines and will be noted on paper. In this research, the authors developed a device for drilling holes 0.01–1 mm in diameter that can be installed in traditional non-…

Flow and thixotropy of non-contaminating oil drilling fluids formulated with bentonite and sodium carboxymethyl cellulose

2007

Abstract A study has been made of low-contaminating oil drilling mud in water base, composed of bentonite, at concentrations in the range of 6–12% (w/w), and sodium carboxymethyl cellulose at two different concentrations. Flow analysis yielded an empirical formula indicating shear stress as a function of the formulation concentrations of bentonite and sodium carboxymethyl cellulose, stirring time and shear rate. To study the thixotropy of the different formulations the cycles' method has been used. Calculations were made of the thixotropic areas, obtaining a semi-empirical equation for these areas. The results are analyzed on the base of relative thixotropic area and total relative thixotro…

The role of hydrochlorofluorocarbon densifiers in the formation of clathrate hydrates in deep boreholes and subglacial environments

2007

AbstractClear evidence for the formation of mixed clathrate hydrates of air and hydrochlorofluorocarbon densifier (known as HCFC-141b, sometimes also called R-141b) is found by means of synchrotron X-ray diffraction and Raman spectroscopy on a sample recovered from the bottom of the EPICA Dronning Maud Land deep borehole in Antarctica. Subglacial water (SGW) appears to have reacted with the drilling liquid to build a large lump of clathrate hydrate. The hydrate growth may well have been accelerated by the stirring of the SGW–densifier mixture during drilling. Moreover, dissolved air in the SGW appears to have participated in the formation of mixed hydrates of air and HCFC-141b as evidenced …

2015

Large volcanic eruptions are major geohazards, so identifying their frequency in the geologic record is critical for making predictions and hazard assessments. Following the discovery of a thick (18 cm) tephra layer in marine sediments from Integrated Ocean Drilling Program (IODP) Site U1396 between Montserrat and Guadeloupe in the Caribbean Sea, we document here how high-precision Pb isotopes, trace elements, and grain morphological analyses of the tephra can be used, together with volcanological models, to identify a large (Volcanic Explosivity Index ?6) Plinian eruption from Basse-Terre, Guadeloupe, at ca. 2.36 Ma. This previously unrecognized eruption is believed to be the largest docum…

Evaporite karst in Sicily

2007

Karst areas are distributed over most of Sicily. The most widespread karst rocks are carbonates, particularly limestones, but karst phenomena can also be seen in evaporites and particularly in salt mines. This report provides an overview of evaporite karst in Sicily, along with a “case history” that shows some of the evaporite karst risks to the environment. In the centre and south of Sicily, a thick sequence of Messinian evaporite rocks are subject to dissolution from meteoric and formation waters. In areas where potassium salts and rock salts are being mined, some geomorphologic changes result from the drilling of boreholes and the collapse of underground mines, thus lowering or collapsin…

2020

Abstract. New Zealand's Alpine Fault is a large, plate-bounding strike-slip fault, which ruptures in large (Mw>8) earthquakes. We conducted field and laboratory analyses of fault rocks to assess its fault zone architecture. Results reveal that the Alpine Fault Zone has a complex geometry, comprising an anastomosing network of multiple slip planes that have accommodated different amounts of displacement. This contrasts with the previous perception of the Alpine Fault Zone, which assumes a single principal slip zone accommodated all displacement. This interpretation is supported by results of drilling projects and geophysical investigations. Furthermore, observations presented here show th…

Hidden attractors in electromechanical systems with and without equilibria

2016

This paper studies hidden oscillations appearing in electromechanical systems with and without equilibria. Three different systems with such effects are considered: translational oscillator-rotational actuator, drilling system actuated by a DC-motor and drilling system actuated by induction motor. We demonstrate that three systems experience hidden oscillations in sense of mathematical definition. While some of these hidden oscillations can be easily seen in natural physical experiments, the localization of others requires special efforts. peerReviewed

Towards a Real-time Mitigation of High Temperature while Drilling using a Multi-agent System

2018

International audience; In oilfield wells, while drilling for several kilometers below surface, high temperature damages the drilling tools. This costs money and time for tripping operations to change the damaged tool. Existing temperature mitigation techniques have several drawbacks including a long response time, analogue signal issues and human intervention. In this work, we empower the down-hole tools with a coordination mechanism to mitigate high temperature in soft real time by controlling a down-hole actuator through a voting process. The tools are represented by agents that control the sensors and actuators embedded in these tools. To implement the proposed system properly, a model …