scholarly journals Haynes 242 Alloy for Lares 2 Satellite

2021 ◽  
Vol 15 (56) ◽  
pp. 56-64
Author(s):  
Daniela Pilone ◽  
Andrea brotzu ◽  
Ferdinando Felli ◽  
Ignazio Ciufolini ◽  
Barbara Negri ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
General Relativity ◽  
Point Of View ◽  
Metallographic Analysis ◽  
Nominal Composition ◽  
Frame Dragging ◽  
Hardness Tests ◽  
Inertial Frames ◽  
Space Construction ◽  
Metallic Parts

The satellite LARES 2 is designed to test dragging of inertial frames, or frame-dragging, predicted by Einstein’s theory of General Relativity, with accuracy of a few parts in a thousand. For this purpose, besides the typical requirements for a space construction, a high density alloy must be used. In this paper are reported the studies performed on a nickel alloy, the Haynes 242, that is considered a possible candidate for manufacturing all the metallic parts of LARES 2 and other passive geodetic satellites. Haynes 242 density and mechanical properties are compliant with the requirements of the mission. Three different casting with the nominal composition of the alloy have been prepared and tested along with a commercial bar of Haynes 242. The results of tensile and hardness tests on several specimens with different aging time are reported, along with the relevant metallographic analysis. Furthermore, a test on the machinability, performed on a screw, which is the most demanding item from the manufacturing point of view, is reported.

On the statistics of the orbital residuals of the LAGEOS satellites

2015 ◽  
Vol 30 (19) ◽  
pp. 1550091
Author(s):  
Catia Canoci ◽  
Ignazio Ciufolini ◽  
Angelo Coluccia ◽  
Claudio Paris ◽  
Giuseppe Ricci ◽  
...  
Keyword(s):  
General Relativity ◽  
Statistical Analysis ◽  
Gaussian Model ◽  
Laser Ranging ◽  
Frame Dragging ◽  
Inertial Frames ◽  
Nonzero Mean ◽  
The One

We present a statistical analysis of the laser ranging data of LAGEOS and LAGEOS 2 satellites which have provided a test of dragging of inertial frames, or frame-dragging, by rotating mass as predicted by General Relativity. As a result, the analysis of the residuals, after filtering out the periodic effects, is consistent with a Gaussian model, with a nonzero mean in agreement with the one predicted by Lense–Thirring effect.

scholarly journals Prediction Of Mechanical Properties Of Quench Hardening Steel

2015 ◽  
Vol 46 (1) ◽  
pp. 26-32 ◽  
Author(s):  
R. Chotěborský ◽  
M. Linda
Keyword(s):  
Mechanical Properties ◽  
Avrami Equation ◽  
Metallographic Analysis ◽  
Continuous Cooling ◽  
Hardness Tests ◽  
Alloy Steels ◽  
Diffusion Phase ◽  
Quench Hardening ◽  
Prediction Of Mechanical Properties ◽  
Kinetics Of

Abstract The present study investigated the application of finite element method for prediction of mechanical properties of quench hardening steel. Based on the experimental results obtained, a numerical model for simulation of continuous cooling of quench hardening steel was developed. For the simulation of the kinetics of diffusion phase transformations, the Avrami equation and additive rule were applied. A new model was also developed for martensitic transformation which was validated using metallographic analysis and hardness tests. Experimental and simulation results indicated a good agreement. The developed model information provided here could be used for simulation of continuous cooling and kinetics phase transformation as well as for prediction of final distribution of microstructures and hardness of alloy steels.

Build Orientation Influence on some Mechanical Properties of 3D-Printed Polyamide Specimens

2019 ◽  
Vol 34 ◽  
pp. 3-9
Author(s):  
Alexandra Nitoi ◽  
Mihai Alin Pop ◽  
Ting Ting Peng ◽  
Tibor Bedő ◽  
Sorin Ion Munteanu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Raw Material ◽  
Processing Technologies ◽  
Build Orientation ◽  
Hardness Tests ◽  
Metallic Parts ◽  
Polyamide Powder

Additive manufacturing [AM] is a type of production technology characterized by the additive nature of stacking and unifying individual layers, with the main advantage that parts with complex geometries can easily be obtained, compared to conventional production methods. Due to its working principle, i.e. stacking layers, obtained by melting and solidification, the mechanical characteristics of the built part might be influenced by the build orientation chosen for the specific part. The mechanical behavior, cyclic deformation and fatigue behaviors of additively manufactured metallic parts as compared to their counterparts obtained by conventional processing technologies was reported to be highly dependent on the build orientation. The aim of this study was to assess whether the build orientation will have an impact on the mechanical properties of parts built by Selective Laser Sintering, using polyamide powder as raw material. Samples were built at various inclination degrees, and were further tested in terms of bending, compressive, impact and hardness tests. It was observed that the build orientation has a significant effect on the mechanical properties of parts additively manufactured from polyamide, compared to the behavior presented on the technical sheet of the material, provided by the manufacturer. Keywords: additive manufacturing, mechanical properties, build orientation, Selective Laser Sintering

Ti-Mo-Zr-Ta Alloy for Biomedical Applications: Microstructures and Mechanical Properties

2017 ◽  
Vol 750 ◽  
pp. 184-188 ◽  
Author(s):  
Mădălina Simona Bălţatu ◽  
Petrică Vizureanu ◽  
Marcelin Benchea ◽  
Mirabela Georgiana Minciună ◽  
Dragoş Cristian Achiţei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Biomedical Applications ◽  
Toxic Elements ◽  
Medical Application ◽  
Point Of View ◽  
Hardness Tests ◽  
Indentation And Hardness ◽  
Low Modulus ◽  
Microstructures And Mechanical Properties ◽  
Micro Indentation

Titanium alloys are widely used as biomaterials for their excellent properties. In the last years, low modulus β-type Ti-based alloys are being developed. The aim of this paper is developing of an original Ti-based alloy improved with non-toxic elements, characterized from point of view of microstructures and mechanical properties: micro-indentation and hardness tests. Results shown that TiMoZrTa have a small elastic modulus closer to the bone with possible medical application.

scholarly journals THE CHRONO-GEOMETRICAL STRUCTURE OF SPECIAL AND GENERAL RELATIVITY: A RE-VISITATION OF CANONICAL GEOMETRODYNAMICS

2007 ◽  
Vol 04 (01) ◽  
pp. 79-114 ◽  
Author(s):  
LUCA LUSANNA
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Special Relativity ◽  
Geometrical Structure ◽  
Clock Synchronization ◽  
Space Time ◽  
Point Of View ◽  
Field Equations ◽  
Relativistic Limit ◽  
Inertial Frames

A modern re-visitation of the consequences of the lack of an intrinsic notion of instantaneous 3-space in relativistic theories leads to a reformulation of their kinematical basis emphasizing the role of non-inertial frames centered on an arbitrary accelerated observer. In special relativity the exigence of predictability implies the adoption of the 3 + 1 point of view, which leads to a well posed initial value problem for field equations in a framework where the change of the convention of synchronization of distant clocks is realized by means of a gauge transformation. This point of view is also at the heart of the canonical approach to metric and tetrad gravity in globally hyperbolic asymptotically flat space-times, where the use of Shanmugadhasan canonical transformations allows the separation of the physical degrees of freedom of the gravitational field (the tidal effects) from the arbitrary gauge variables. Since a global vision of the equivalence principle implies that only global non-inertial frames can exist in general relativity, the gauge variables are naturally interpreted as generalized relativistic inertial effects, which have to be fixed to get a deterministic evolution in a given non-inertial frame. As a consequence, in each Einstein's space-time in this class the whole chrono-geometrical structure, including also the clock synchronization convention, is dynamically determined and a new approach to the Hole Argument leads to the conclusion that "gravitational field" and "space-time" are two faces of the same entity. This view allows to get a classical scenario for the unification of the four interactions in a scheme suited to the description of the solar system or our galaxy with a deparametrization to special relativity and the subsequent possibility to take the non-relativistic limit.

scholarly journals Lorentz Boosts and Wigner Rotations: Self-Adjoint Complexified Quaternions

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 352-366
Author(s):  
Thomas Berry ◽  
Matt Visser
Keyword(s):  
Point Of View ◽  
Sufficient Condition ◽  
Use Of Self ◽  
Necessary And Sufficient Condition ◽  
Wigner Rotation ◽  
Inertial Frames ◽  
Explicit Formulae ◽  
Specific Implementation ◽  
Necessary And Sufficient ◽  
Lorentz Boosts

In this paper, Lorentz boosts and Wigner rotations are considered from a (complexified) quaternionic point of view. It is demonstrated that, for a suitably defined self-adjoint complex quaternionic 4-velocity, pure Lorentz boosts can be phrased in terms of the quaternion square root of the relative 4-velocity connecting the two inertial frames. Straightforward computations then lead to quite explicit and relatively simple algebraic formulae for the composition of 4-velocities and the Wigner angle. The Wigner rotation is subsequently related to the generic non-associativity of the composition of three 4-velocities, and a necessary and sufficient condition is developed for the associativity to hold. Finally, the authors relate the composition of 4-velocities to a specific implementation of the Baker–Campbell–Hausdorff theorem. As compared to ordinary 4×4 Lorentz transformations, the use of self-adjoint complexified quaternions leads, from a computational view, to storage savings and more rapid computations, and from a pedagogical view to to relatively simple and explicit formulae.

Influence of Melt Temperature on Compressive Plasticity of a Cu-Zr-Al Bulk Metallic Glass

2010 ◽  
Vol 146-147 ◽  
pp. 517-521
Author(s):  
Sheng Hui Xie ◽  
Xie Rong Zeng ◽  
Dong Ju Fu ◽  
Lei Zhao ◽  
Qiang Hu
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Metallic Glasses ◽  
Mechanical Performance ◽  
Casting Temperature ◽  
Thermal And Mechanical Properties ◽  
Micro Hardness ◽  
Melt Temperature ◽  
Hardness Tests ◽  
Important Solution

Cu47.5Zr47.5Al5 bulk metallic glasses (BMGs) were cast from the melt temperature 1143 to 1373 K. The structure, thermal and mechanical properties of the BMGs were investigated by XRD, DSC, HRTEM, dilatometric measurements, micro-hardness tests and uniaxial compression. The results indicate that the microstructure and mechanical performance of BMGs are closely affected by the casting temperature. Proper casting temperature ensures the BMGs with large relaxed excess free volume (REFV) and nano-crystallites, which favor the plastic deformation in Cu47.5Zr47.5Al5 BMGs. Regulating the preparing parameters is an important solution to good plasticity in BMGs.

Rheology of hydrocarbon gels

1950 ◽  
Vol 200 (1061) ◽  
pp. 183-188 ◽  
Keyword(s):  
Mechanical Properties ◽  
Experimental Measurement ◽  
Theoretical Basis ◽  
Continuous Media ◽  
Point Of View ◽  
Coarse Grained ◽  
Testing Instrument ◽  
Fine Grained ◽  
Mineral Oils ◽  
Space And Time

Hydrocarbon gels contain a number of materials, such as rubber, greases, saponified mineral oils, etc., of great interest for various engineering purposes. Specific requirements in mechanical properties have been met by producing gels in appropriately chosen patterns of constituent components of visible, colloidal, molecular and atomic sizes, ranging from coarse-grained aggregates, represented by sponges, foams, emulsions, etc.; to fine-grained and apparently homogeneous ones, represented by optically clear compounds. The engineer who has to deal with the whole range of such materials will adopt a macroscopic point of view, based on an apparent continuity of all the material structures and of the distributions in space and time of the displacements and forces occurring under mechanical actions. It has been possible to determine these distributions in the framework of a comprehensive scheme in which the fundamental principles of the mechanics of continuous media provide the theoretical basis, and a testing instrument of new design, termed Rheogoniometer, the means of experimental measurement (Weissenberg 1931, 1934, 1946, 1947, 1948).

scholarly journals EFFECTS OF POROSITY ON ULTRASONIC CHARACTERISTIC PARAMETERS AND MECHANICAL PROPERTIES OF GLASS FIBER REINFORCED COMPOSITES

2012 ◽  
Vol 06 ◽  
pp. 646-651 ◽  
Author(s):  
Wen Ma ◽  
Fushun Liu
Keyword(s):  
Mechanical Properties ◽  
Ultrasonic Attenuation ◽  
Ultrasonic Inspection ◽  
Fiber Reinforced Composites ◽  
Metallographic Analysis ◽  
Void Content ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Characteristic Parameters ◽  
Distribution Shape

Voids are inevitable in the fabrication of fiber reinforced composites and have a detrimental impact on mechanical properties of composites. Different void contents were acquired by applying different vacuum bag pressures. Ultrasonic inspection and ablation density method were adopted to measure the ultrasonic characteristic parameters and average porosity, the characterization of voids' distribution, shape and size were carried out through metallographic analysis. Effects of void content on the tensile, flexural and interlaminar shear properties and the ultrasonic characteristic parameters were discussed. The results showed that, as vacuum bag pressure went from -50kPa to -98kPa, the voids content decreased from 4.36 to 0.34, the ultrasonic attenuation coefficient decreased, but the mechanical strengths all increased.

Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 255-260 ◽  
Author(s):  
G. Zhang ◽  
L. Hu ◽  
W. Hu ◽  
G. Gottstein ◽  
S. Bogner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Creep Resistance ◽  
Room Temperature ◽  
Growth Direction ◽  
Nominal Composition ◽  
Potential Candidate ◽  
In Situ Composites

ABSTRACTMo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

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