A New Approach for Single Crystal Materials Analysis: Theory and Application to Initial Yielding

2005 ◽  
Vol 127 (1) ◽  
pp. 119-129 ◽  
Author(s):  
G. Bande ◽  
J. A. Nemes
Keyword(s):  
Single Crystal ◽  
Material Behavior ◽  
Combined Approach ◽  
Global State ◽  
New Approach ◽  
Materials Analysis ◽  
Analysis Theory ◽  
Nickel Base ◽  
Tension Compression Asymmetry

A new approach used for single crystal (SC) materials analysis is described. Its principle is based on the extension of predictive models for isotropic material behavior to anisotropic materials such as SC nickel base superalloys. A viscoplastic model describes the material in the macroscopic level while a factor, based on the crystallographic approach, accounts for the global state of micro slip on the crystal. The combination of both elements defines the so-called “combined approach” (CA). This paper presents the development of the theory and its applications to the determination of initial yielding and tension–compression asymmetry.

scholarly journals A New Approach for RRR Determination of Niobium Single Crystal Based on AC Magnetic Susceptibility

2011 ◽  
Author(s):  
Alexey Ermakov ◽  
Alexander V. Korolev ◽  
Waldemar Singer ◽  
Xenia Singer
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Ac Magnetic Susceptibility ◽  
New Approach

scholarly journals Modelling of TMF Crack Initiation in Smooth Single-Crystal Superalloy Specimens

2014 ◽  
Vol 891-892 ◽  
pp. 1283-1288 ◽  
Author(s):  
Daniel Leidermark ◽  
Mikael Segersäll ◽  
Johan Moverare ◽  
Kjell Simonsson
Keyword(s):  
Stress Relaxation ◽  
Crack Initiation ◽  
Single Crystal ◽  
Fatigue Behaviour ◽  
Creep Model ◽  
Critical Plane ◽  
Critical Plane Approach ◽  
Nickel Base ◽  
As Stress ◽  
Tension Compression Asymmetry

In this paper the TMF crack initiation behaviour of the single-crystal nickel-base superalloyMD2 is investigated and modelled. TMF tests were performed in both IP and OP for varying mechanicalstrain ranges in the [001] crystallographic direction until TMF crack initiation was obtained. Acrystal plasticity-creep model was used in conjunction with a critical-plane approach, to evaluate thenumber of cycles to TMF crack initiation. The critical-plane model was evaluated and calibrated ata stable TMF cycle, where the effect of the stress relaxation had attenuated. This calibrated criticalplanemodel is able to describe the TMF crack initiation, taking tension/compression asymmetry aswell as stress relaxation anisotropy into account, with good correlation to the real fatigue behaviour.

Analysis of Residual Stress States in Coarse Grained and Single Crystal Nickel-Base Superalloys

1995 ◽  
Vol 39 ◽  
pp. 211-223
Author(s):  
W. Reimers
Keyword(s):  
Single Crystal ◽  
Strain Tensor ◽  
Coarse Grained ◽  
Evaluation Technique ◽  
Crystalline Materials ◽  
Nickel Base Superalloys ◽  
Stress States ◽  
Nickel Base ◽  
Individual Crystallite

The single crystal measuring and evaluation technique allows the analysis of stress states in large grained and single crystalline materials. The technique is based on the analysis of the orientation of crystallites under study. Using a fouf-circle-diffractometer, the knowledge of the orientation matrix allows the calculation of the diffractometer setting for every given reflection (hkl). After experimental determination of the precise diffraction angles 20 for at least six reflections of an individual crystallite, its strain tensor components can be obtained by applying least-squares methods. The stress tensor referred to the crystal axes system is calculated using the single crystal elastic constants.The practical use of this measuring and evaluation technique is demonstrated on coarse grained and single crystal nickel-base superalloys and monocrystalline materials.

The Dudley Lee Case: A new approach to factual causation and its implications for transformative jurisprudence

2017 ◽  
Vol 30 (1) ◽  
pp. 273-289
Author(s):  
Anmari Meerkotter
Keyword(s):  
Case Note ◽  
Constitutional Court ◽  
Recent Contribution ◽  
New Approach ◽  
State Accountability ◽  
The Law ◽  
Transformative Impact ◽  
Constitutional Jurisprudence ◽  
Law Of Delict

The Constitutional Court (CC) judgment of Lee v Minister of Correction Services 2013 2SA 144 (CC) is a recent contribution to transformative constitutional jurisprudence in the field of the law of delict. This matter turned on the issue of factual causation in the context of wrongful and negligent systemic omissions by the state. In this case note, I explore the law relating to this element of delictual liability with specific regard to the traditional test for factual causation – the conditio sine qua non (‘but-for’) test. In particular, I note the problems occasioned by formalistic adherence to this test in the context of systemic state omissions as evidenced by the SCA judgment in the same matter. I also consider the manner in which English courts have addressed this problem. Thereafter, I analyse the CC’s broader approach to the determination of factual causation as one based on common sense and justice. I argue that this approach endorses a break from a formalistic application of the test and constitutes a step towards an approach which resonates with the foundational constitutional values of freedom, dignity and equality. Furthermore, it presents an appropriate solution to the problems associated with factual causation where systemic omissions are concerned. I then consider the transformative impact of the Lee judgment. In particular, I argue that the broader enquiry favoured by the CC facilitates the realisation of constitutionally guaranteed state accountability, and amounts to an extension of the existing norm of accountability jurisprudence. Hence, I contend that the judgment presents a further effort by the Constitutional Court to effect wholesale the constitutionalisation of the law of delict, as well as a vindicatory tool to be used by litigants who have been adversely affected by systemic state omissions.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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