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Nikolas W. Hrabe - One of the best experts on this subject based on the ideXlab platform.
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effects of processing on microstructure and mechanical properties of a titanium alloy ti 6al 4v fabricated using electron beam melting ebm part 2 Energy Input orientation and location
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Nikolas W. Hrabe, Timothy P. QuinnAbstract:Abstract Selective electron beam melting (EBM) is a layer-by-layer additive manufacturing technique that shows great promise for fabrication of medical devices and aerospace components. Before its potential can be fully realized, however, a comprehensive understanding of processing-microstructure-properties relationships is necessary. Titanium alloy (Ti–6Al–4V) parts were built in a newly developed, unique geometry to allow accurate investigation of the following intra-build processing parameters: Energy Input, orientation, and location. Microstructure evaluation (qualitative prior-β grain size, quantitative α lath thickness), tensile testing, and Vickers microhardness were performed for each specimen. For a wide range of Energy Input (speed factor 30–40), small differences in mechanical properties (2% change in ultimate tensile strength (UTS) and 3% change in yield strength (YS)) were measured. Vertically built parts were found to have no difference in UTS or YS compared to horizontally built parts, but the percent elongation at break (% EL) was 30% lower. The difference in % EL was attributed to a different orientation of the tensile axis for horizontal and vertical parts compared to the elongated prior-β grain and microstructural texture direction in EBM Ti–6Al–4V. Orientation within the x – y plane as well as location were found to have less than 3% effect on mechanical properties, and it is possible a second order effect of thermal mass contributed to these results.
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effects of processing on microstructure and mechanical properties of a titanium alloy ti 6al 4v fabricated using electron beam melting ebm part 2 Energy Input orientation and location
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Nikolas W. Hrabe, Timothy P QuiAbstract:Abstract Selective electron beam melting (EBM) is a layer-by-layer additive manufacturing technique that shows great promise for fabrication of medical devices and aerospace components. Before its potential can be fully realized, however, a comprehensive understanding of processing-microstructure-properties relationships is necessary. Titanium alloy (Ti–6Al–4V) parts were built in a newly developed, unique geometry to allow accurate investigation of the following intra-build processing parameters: Energy Input, orientation, and location. Microstructure evaluation (qualitative prior-β grain size, quantitative α lath thickness), tensile testing, and Vickers microhardness were performed for each specimen. For a wide range of Energy Input (speed factor 30–40), small differences in mechanical properties (2% change in ultimate tensile strength (UTS) and 3% change in yield strength (YS)) were measured. Vertically built parts were found to have no difference in UTS or YS compared to horizontally built parts, but the percent elongation at break (% EL) was 30% lower. The difference in % EL was attributed to a different orientation of the tensile axis for horizontal and vertical parts compared to the elongated prior-β grain and microstructural texture direction in EBM Ti–6Al–4V. Orientation within the x – y plane as well as location were found to have less than 3% effect on mechanical properties, and it is possible a second order effect of thermal mass contributed to these results.
Timothy P. Quinn - One of the best experts on this subject based on the ideXlab platform.
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effects of processing on microstructure and mechanical properties of a titanium alloy ti 6al 4v fabricated using electron beam melting ebm part 2 Energy Input orientation and location
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Nikolas W. Hrabe, Timothy P. QuinnAbstract:Abstract Selective electron beam melting (EBM) is a layer-by-layer additive manufacturing technique that shows great promise for fabrication of medical devices and aerospace components. Before its potential can be fully realized, however, a comprehensive understanding of processing-microstructure-properties relationships is necessary. Titanium alloy (Ti–6Al–4V) parts were built in a newly developed, unique geometry to allow accurate investigation of the following intra-build processing parameters: Energy Input, orientation, and location. Microstructure evaluation (qualitative prior-β grain size, quantitative α lath thickness), tensile testing, and Vickers microhardness were performed for each specimen. For a wide range of Energy Input (speed factor 30–40), small differences in mechanical properties (2% change in ultimate tensile strength (UTS) and 3% change in yield strength (YS)) were measured. Vertically built parts were found to have no difference in UTS or YS compared to horizontally built parts, but the percent elongation at break (% EL) was 30% lower. The difference in % EL was attributed to a different orientation of the tensile axis for horizontal and vertical parts compared to the elongated prior-β grain and microstructural texture direction in EBM Ti–6Al–4V. Orientation within the x – y plane as well as location were found to have less than 3% effect on mechanical properties, and it is possible a second order effect of thermal mass contributed to these results.
Timothy P Qui - One of the best experts on this subject based on the ideXlab platform.
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effects of processing on microstructure and mechanical properties of a titanium alloy ti 6al 4v fabricated using electron beam melting ebm part 2 Energy Input orientation and location
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Nikolas W. Hrabe, Timothy P QuiAbstract:Abstract Selective electron beam melting (EBM) is a layer-by-layer additive manufacturing technique that shows great promise for fabrication of medical devices and aerospace components. Before its potential can be fully realized, however, a comprehensive understanding of processing-microstructure-properties relationships is necessary. Titanium alloy (Ti–6Al–4V) parts were built in a newly developed, unique geometry to allow accurate investigation of the following intra-build processing parameters: Energy Input, orientation, and location. Microstructure evaluation (qualitative prior-β grain size, quantitative α lath thickness), tensile testing, and Vickers microhardness were performed for each specimen. For a wide range of Energy Input (speed factor 30–40), small differences in mechanical properties (2% change in ultimate tensile strength (UTS) and 3% change in yield strength (YS)) were measured. Vertically built parts were found to have no difference in UTS or YS compared to horizontally built parts, but the percent elongation at break (% EL) was 30% lower. The difference in % EL was attributed to a different orientation of the tensile axis for horizontal and vertical parts compared to the elongated prior-β grain and microstructural texture direction in EBM Ti–6Al–4V. Orientation within the x – y plane as well as location were found to have less than 3% effect on mechanical properties, and it is possible a second order effect of thermal mass contributed to these results.
Bin Liu - One of the best experts on this subject based on the ideXlab platform.
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wind Energy Input to the ekman stokes layer reply to comment by jeff a polton
Journal of Oceanography, 2009Co-Authors: Bin Liu, Changlong GuanAbstract:This reply corrects the estimate of the wind and wave Energy Inputs into the Ekman layer by using the Ekman-Stokes layer Energy budget as suggested in Polton (2009). Using the data and method in Liu et al. (2007), the global wind Energy Input was recalculated. The estimated global total Energy Input to the Ekman-Stokes layer is 2.22 TW, including 1.93 TW direct wind Energy Input and 0.29 TW wave-induced Energy Input. Compared to that in Liu et al. (2007), the recalculated wave-induced Energy Input was increased by 0.03 TW.
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stokes drift induced and direct wind Energy Inputs into the ekman layer within the antarctic circumpolar current
Journal of Geophysical Research, 2008Co-Authors: Bin LiuAbstract:[1] Theoretical analysis of energetics of the Ekman layer by incorporating the CoriolisStokes forcing into the classical Ekman model shows that the wind Energy Input to the Ekman layer has two components: the work done by the wind stress on the surface Ekman current and that done by the Coriolis-Stokes forcing on the whole body of water in the mixed layer. Under the assumption of constant vertical diffusivity, analytical forms of the direct wind Energy Input and the Stokes drift–induced Energy Input are derived. Assessments of relative importance of surface waves are made by comparing the wind Energy Input into the Ekman layer with and without wave-induced Stokes drift effects included. Using the European Centre for Medium-Range Weather Forecasts 40-year reanalysis wind stress and surface wave data sets, the total rate of wind Energy Input into the Ekman layer within the Antarctic Circumpolar Current (ACC) is estimated to be 833 GW, in which the direct wind Energy Input is 650 GW (78%), and the Stokes drift– induced Energy Input is 183 GW (22%). The total mechanical Energy Input into the ACC due to wave effects is increased by approximately 4% (30 GW) compared to that into the classical Ekman layer. Long-term variability of direct wind and Stokes drift–induced Energy Inputs to the ACC is also examined.
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global estimates of wind Energy Input to subinertial motions in the ekman stokes layer
Journal of Oceanography, 2007Co-Authors: Bin Liu, Changlong GuanAbstract:By incorporating the wave-induced Coriolis-Stokes forcing into the classical Ekman model, the wind Energy Input to the Ekman-Stokes layer is investigated, with an emphasis on the surface wave effects when the direction of Stokes drift deviates from that of wind stress. Theoretical analysis of the kinetic Energy balance of the Ekman-Stokes layer shows that the total wind Energy Input consists of the direct wind Energy Input and the wave-induced Energy Input. Details of the direct wind and wave-induced Energy Input are discussed. Based on the ECMWF ERA-40 Re-Analysis wind stress and surface wave data, the global total wind Energy Input to subinertial motions in the Ekman-Stokes layer is estimated at 2.19 TW, including 0.26 TW (12%) wave-induced Energy Input and 1.93 TW (88%) direct wind Energy Input. The effect of sea-ice coverage on the Energy Input to the Ekman-Stokes layer is also considered. It is shown that the global total Energy Input could be overestimated by 0.08 TW (about 4%) without taking the sea-ice coverage into account.
Izuru Takewaki - One of the best experts on this subject based on the ideXlab platform.
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Critical Excitation for Earthquake Energy Input Rate
Critical Excitation Methods in Earthquake Engineering, 2013Co-Authors: Izuru TakewakiAbstract:This chapter discusses a critical excitation method for earthquake Energy Input rate. It explores a new probabilistic critical excitation method for identifying the critical frequency content of ground motions maximizing the mean earthquake Energy Input rate to structures. The critical excitation problem includes a double maximization procedure with respect to time and to the power spectral density (PSD) function. The key to finding the critical frequency content is the order exchange in the double maximization procedure. No mathematical programming technique is required in the proposed method. It is shown that the proposed technique is systematic and the critical excitation can be found extremely efficiently within a reasonable accuracy. Extension of the proposed method is discussed for a more general ground motion model. The chapter discusses the process to derive a new expression on the probabilistic earthquake Input Energy and its rate in terms of uniformly modulated and nonuniformly modulated ground motion models. The process to formulate a new critical excitation problem with the probabilistic earthquake Energy Input rate as the criticality measure is mentioned. A deterministic expression of earthquake Energy Input rate to a base-isolated building model is also presented in order to capture the properties of earthquake Energy Input rate in more detail.
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Critical Excitation for Earthquake Energy Input in MDOF System
Critical Excitation Methods in Earthquake Engineering, 2013Co-Authors: Izuru TakewakiAbstract:This chapter explores a new general critical excitation method for a damped linear elastic single-degree-of-freedom (SDOF) system. It introduces the Input Energy to the SDOF system during an earthquake as a new measure of criticality. It is shown that the formulation of the earthquake Input Energy in the frequency domain is essential for solving the critical excitation problem. It is also essential for deriving a bound on the earthquake Input Energy for a class of ground motions. The criticality is expressed in terms of degree of concentration of Input motion components on the maximum portion of the characteristic function defining the earthquake Input Energy. It is remarkable that no mathematical programming technique is required in the solution procedure. The constancy of earthquake Input Energy for various natural periods and damping ratios is discussed from a new point of view based on an original sophisticated mathematical treatment. It is shown that the constancy of earthquake Input Energy is directly related to the uniformity of “the Fourier amplitude spectrum” of ground motion acceleration. It is not directly related to the uniformity of the velocity response spectrum. The bounds under acceleration and velocity constraints are clarified through numerical examinations for recorded ground motions.
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Critical Excitation for Earthquake Energy Input In Soil-Structure Interaction System
Critical Excitation Methods in Earthquake Engineering, 2013Co-Authors: Izuru TakewakiAbstract:This chapter discusses the method of critical excitation for earthquake Energy Input in a soil-structure interaction (SSI) system. It is true that, while the analysis of SSI effects has been focused on the investigation in terms of deformation and force, not much has been done for the investigation in terms of earthquake Input Energy to the SSI system. This chapter explains a new evaluation method of earthquake Input Energy to SSI systems. It is an approach in the frequency domain. Because the inertial interaction and the kinematic interaction are well described by frequency-dependent functions, the present approach based on the frequency-domain analysis is appropriate and effective. Especially, it is demonstrated that even SSI systems including embedded foundations can be treated in a simple way. The effects of the foundation embedment on the earthquake Input energies to the super-structure and to the structure-foundation-soil system can be clarified systematically. The works by boundary forces on their corresponding displacements defined for various boundaries are utilized in evaluating the Energy flow in SSI systems. The evaluation of earthquake Input Energy in the time domain is suitable for the evaluation of the time history of Input Energy.
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critical excitation for earthquake Energy Input in structure pile soil system
Critical Excitation Methods in Earthquake Engineering (Second edition), 2013Co-Authors: Izuru TakewakiAbstract:This chapter discusses a new method in the frequency domain for the computation of earthquake Input energies both to a structure–pile system and a structure only. In investigating the Energy flow in the structure–pile system, many difficulties arise resulting from the dynamic interaction between the pile and the surrounding soil. It can be shown that the formulation of the earthquake Input Energy in the frequency domain is effective for deriving the earthquake Input Energy both to a structure–pile system and a structure only. An efficient continuum model consisting of a dynamic Winkler-type soil element and a pile is used to express the dynamic behavior of the structure–pile system accurately. The formulation of the earthquake Input Energy in the frequency domain is appropriate for introducing the frequency-dependent vibration property of the surface ground. It is demonstrated that the present formulation is effective for various Input levels and ground properties. The Energy Input mechanism in the building structure–pile system can be well described by the newly introduced Energy transfer function. The chapter introduces a new concept called the Input Energy densities at various underground levels, which is used to disclose the Energy Input mechanism in the building structure–pile system.
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chapter 12 critical excitation for earthquake Energy Input rate
Critical Excitation Methods in Earthquake Engineering, 2007Co-Authors: Izuru TakewakiAbstract:Publisher Summary This chapter discusses a critical excitation method for earthquake Energy Input rate. It explores a new probabilistic critical excitation method for identifying the critical frequency content of ground motions maximizing the mean earthquake Energy Input rate to structures. The critical excitation problem includes a double maximization procedure with respect to time and to the power spectral density (PSD) function. The key for finding the critical frequency content is the order interchange in the double maximization procedure. No mathematical programming technique is required in the proposed method. It is shown that the proposed technique is systematic and the critical excitation can be found extremely efficiently within a reasonable accuracy. Extension of the proposed method is discussed to a more general ground motion model. The chapter discusses the process to derive a new expression on the probabilistic earthquake Input Energy and its rate in terms of uniformly modulated and non-uniformly modulated ground motion models. The process to formulate a new critical excitation problem with the probabilistic earthquake Energy Input rate as the criticality measure is mentioned.
