The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Michael F. Steakley - One of the best experts on this subject based on the ideXlab platform.
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Tennessee Valley AuthorityPROBABILISTIC ASSESSMENT OF FAILURE BY STRESS CORROSION CRACKING IN SHRUNK-ON DISKS OF LOW PRESSURE TURBINES
2011Co-Authors: Darryl A. Rosario, Blaine W. Roberts, Tony Khalid, Michael F. SteakleyAbstract:Several large LP turbines in the TVA system utilize shrunk-on disks forgings. Additionally, there are 63 other rotors including spares and rotors recommended to be retired by the OEMs. This fleet represents which are keyed to the shaft. The 7th, 8th, and 9th stage disks a diverse cross section of the equipment supplied by Westinghouse, experience wetness in operation which renders them potentially General Electric, Parsons, and Asea Brown-Boveri. subject to stress corrosion cracking (SCC) in the keyway of the shrink In low press (LP) turbines, TVA has several GE machines which fit area. To minimize SCC concerns in the disk keyway, TVA has utilize the shrunk-on wheel design commonly employed by GE since embarked on a phased approach to refurbish the LP rotors with a “fat ” the mid-1940s [1]. At the Paradise Fossil Plant, Units 1 and 2 (650 shaft and a “tab ” design replacing the rectangular Keyways. Non- MW each) and Unit 3 (1150 MW) have this design feature. In all destructive examinations have been performed on rotors being three units, two LP double flow (LPDF) turbines operating at 1800 refurbished and those continuing in service to assure that the schedule RPM are used. This paper addresses the shrunk-on disks for the for refurbishment does not place operating units with the original Paradise Units 1 and 2 LPDF turbines. Each flow in these turbines design at undue risk. consists of nine stages. The major concern is with stress corrosio
Tatsuo Iyoku - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of aseismic integrity in the HTTR core-bottom structure V. On the static and dynamic behavior of graphitic HTTR key-keyway structures
Nuclear Engineering and Design, 1996Co-Authors: Masatoshi Futakawa, Shoji Takada, Hiroyuki Takeishi, Tatsuo IyokuAbstract:Abstract The graphite components in high temperature gas-cooled reactors are connected to each other through a key-keyway structure that has gaps between the key and the keyway to accomodate thermal expansion. Because a dynamic load concentrates on the key-keyway structure during earthquakes, it is considered to be a crucial element for assessing the integrity of the graphite components. A combination of experiments and analyses was employed to investigate the dynamic behavior of the key-keyway structure, i.e. the equivalent stiffness associated with vibrational characteristics of the graphite components and the stress distribution under dynamic loading. The experiments were performed using a graphite scale model and a dynamic photo-elastic method. The analysis was carried out using the finite element method (FEM) code Abaqus , taking account of the contact between the key and the keyway. The following conclusions were derived. (1) The equivalent stiffness of the key-keyway structure shows nonlinearity, owing to the contact deformation. (2) The equivalent stiffness evaluated by the FEM analysis, taking account of the non-inear contact deformation, is applicable for predicting the vibrational characteristics of ky-keyway structure. (3) The stress concentration under dynamic loading is lower than or nearly equal to that under static loading. The maximum stress concentration of the seismic load can be sufficiently evaluated under static loading conditions.
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Evaluation of aseismic integrity in HTTR core-bottom structure II. Vibrational characteristics of keyed graphite components
Nuclear Engineering and Design, 1994Co-Authors: Masatoshi Futakawa, Shoji Takada, Tatsuo Iyoku, Hiroshi Shirai, Masahiro IshiharaAbstract:Abstract The assembly system consisting of keyed graphite components, which is employed in the core bottom structure of a high temperature engineering test reactor (HTTR), has a nonlinear vibrational characteristic. The vibrational test was carried out to grasp the vibrational characteristics using the element model of the key-keyway structure. The analytical code was developed based on the experimental results. The main conclusions are summarized as follows: 1. (i) the stress distribution around the keyway is independent of whether it is induced under a dynamic or a static state; 2. (ii) the stiffness of the key-keyway structure has the nonlinear characteristics due to contact behavior. The stiffness can be evaluated by contact analysis, taking account of the relative slip and the deformation on the contact surface between key and keyway; 3. (iii) the analytical code employing a nonlinear spring for the key-keyway structure is available to predict the vibrational characteristic of the keyed graphite components.
Ben Burgess - One of the best experts on this subject based on the ideXlab platform.
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WOOT - Replication prohibited: attacking restricted Keyways with 3D printing
2015Co-Authors: Ben Burgess, Eric Wustrow, J. Alex HaldermanAbstract:Several attacks against physical pin-tumbler locks require access to one or more key blanks to perform. These attacks include bumping, impressioning, rights-amplification, and teleduplication. To mitigate these attacks, many lock systems rely on restricted Keyways and use blanks that are not sold to the general public, making it harder for attackers to obtain them. Often the key blank designs themselves are patented, further discouraging distribution or manufacture by even skilled machinists. In this paper we investigate the impact that emerging rapid prototyping--or 3D printing--tools have on the security of these restricted keyway systems. We find that commodity 3D printers are able to produce key blanks and pre-cut keys with enough resolution to work in several commonly used pin-tumbler locks and that their material is strong enough to withstand the requirements to perform the aforementioned attacks. In addition, in order to demonstrate the low skill requirements necessary to perform these attacks, we develop a tool that automatically generates a 3D printable CAD model of a key blank using only a single picture of a lock's keyway. This tool allows us to rapidly manufacture key blanks for restricted Keyways that were previously difficult to make or buy. Finally, we discuss possible mitigations for these attacks that lock manufacturers, installers, and users can perform to protect their assets.
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replication prohibited attacking restricted Keyways with 3d printing
WOOT'15 Proceedings of the 9th USENIX Conference on Offensive Technologies, 2015Co-Authors: Ben Burgess, Eric Wustrow, Alex J HaldermanAbstract:Several attacks against physical pin-tumbler locks require access to one or more key blanks to perform. These attacks include bumping, impressioning, rights-amplification, and teleduplication. To mitigate these attacks, many lock systems rely on restricted Keyways and use blanks that are not sold to the general public, making it harder for attackers to obtain them. Often the key blank designs themselves are patented, further discouraging distribution or manufacture by even skilled machinists. In this paper we investigate the impact that emerging rapid prototyping--or 3D printing--tools have on the security of these restricted keyway systems. We find that commodity 3D printers are able to produce key blanks and pre-cut keys with enough resolution to work in several commonly used pin-tumbler locks and that their material is strong enough to withstand the requirements to perform the aforementioned attacks. In addition, in order to demonstrate the low skill requirements necessary to perform these attacks, we develop a tool that automatically generates a 3D printable CAD model of a key blank using only a single picture of a lock's keyway. This tool allows us to rapidly manufacture key blanks for restricted Keyways that were previously difficult to make or buy. Finally, we discuss possible mitigations for these attacks that lock manufacturers, installers, and users can perform to protect their assets.
Masatoshi Futakawa - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of aseismic integrity in the HTTR core-bottom structure V. On the static and dynamic behavior of graphitic HTTR key-keyway structures
Nuclear Engineering and Design, 1996Co-Authors: Masatoshi Futakawa, Shoji Takada, Hiroyuki Takeishi, Tatsuo IyokuAbstract:Abstract The graphite components in high temperature gas-cooled reactors are connected to each other through a key-keyway structure that has gaps between the key and the keyway to accomodate thermal expansion. Because a dynamic load concentrates on the key-keyway structure during earthquakes, it is considered to be a crucial element for assessing the integrity of the graphite components. A combination of experiments and analyses was employed to investigate the dynamic behavior of the key-keyway structure, i.e. the equivalent stiffness associated with vibrational characteristics of the graphite components and the stress distribution under dynamic loading. The experiments were performed using a graphite scale model and a dynamic photo-elastic method. The analysis was carried out using the finite element method (FEM) code Abaqus , taking account of the contact between the key and the keyway. The following conclusions were derived. (1) The equivalent stiffness of the key-keyway structure shows nonlinearity, owing to the contact deformation. (2) The equivalent stiffness evaluated by the FEM analysis, taking account of the non-inear contact deformation, is applicable for predicting the vibrational characteristics of ky-keyway structure. (3) The stress concentration under dynamic loading is lower than or nearly equal to that under static loading. The maximum stress concentration of the seismic load can be sufficiently evaluated under static loading conditions.
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Evaluation of aseismic integrity in HTTR core-bottom structure II. Vibrational characteristics of keyed graphite components
Nuclear Engineering and Design, 1994Co-Authors: Masatoshi Futakawa, Shoji Takada, Tatsuo Iyoku, Hiroshi Shirai, Masahiro IshiharaAbstract:Abstract The assembly system consisting of keyed graphite components, which is employed in the core bottom structure of a high temperature engineering test reactor (HTTR), has a nonlinear vibrational characteristic. The vibrational test was carried out to grasp the vibrational characteristics using the element model of the key-keyway structure. The analytical code was developed based on the experimental results. The main conclusions are summarized as follows: 1. (i) the stress distribution around the keyway is independent of whether it is induced under a dynamic or a static state; 2. (ii) the stiffness of the key-keyway structure has the nonlinear characteristics due to contact behavior. The stiffness can be evaluated by contact analysis, taking account of the relative slip and the deformation on the contact surface between key and keyway; 3. (iii) the analytical code employing a nonlinear spring for the key-keyway structure is available to predict the vibrational characteristic of the keyed graphite components.
Yun Feng - One of the best experts on this subject based on the ideXlab platform.
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Measurement Method for the Symmetry Error of Double Keyway in a Wheel Hub Bore
Advanced Materials Research, 2010Co-Authors: Xiao Ming Zhao, Yun FengAbstract:In this paper, a new measurement method is presented, This method is to use a three-coordinate measuring machine (CMM) to test the symmetry error of double keyway in a wheel hub bore. According to the minimum condition criterion of form and position error evaluation, and making use of the minimum tolerance zone of position error evaluation, two symmetry error formulas of double keyway in a wheel hub bore are deduced by geometric analysis. The problems may be encountered when using the formulas in the practical application are discussed. These formulas solve the measurement principle problem of double keyway in the engineering practice. In the end an example is put forward to verify this method and the formulas.
