scholarly journals Mesoscopic constitutive law with nonlinear elasticity and phase transformation for the twinning-buckling of TATB under dynamic loading

2019 ◽  
Vol 3 (5) ◽  
Author(s):  
Paul Lafourcade ◽  
Christophe Denoual ◽  
Jean-Bernard Maillet
Keyword(s):  
Phase Transformation ◽  
Dynamic Loading ◽  
Nonlinear Elasticity ◽  
Constitutive Law

scholarly journals In-situ Experiments to Capture the Evolution of Microstructure During Phase Transformation of Titanium Under Dynamic Loading

2018 ◽  
Vol 183 ◽  
pp. 03020
Author(s):  
Benjamin M. Morrow ◽  
David R. Jones ◽  
Paulo A. Rigg ◽  
George T. Gray ◽  
Ellen K. Cerreta
Keyword(s):  
Phase Transformation ◽  
Dynamic Loading ◽  
Microstructural Analysis ◽  
Alpha Phase ◽  
Material Behavior ◽  
High Rate ◽  
Omega Phase ◽  
In Situ Experiments ◽  
Consistent Picture ◽  
Underlying Mechanisms

Under sufficient stresses, such as during dynamic loading, titanium experiences a phase transformation from hcp alpha phase to hexagonal omega phase. Omega phase is often retained in the microstructure after unloading, and has a strong influence on subsequent mechanical properties. Simulations suggest there are multiple pathways and underlying mechanisms for this transformation. Due to the incredibly short timescales involved, experimental measurements for model validation have been difficult. However, new capabilities at the Advanced Photon Source have enabled diffraction measurements during plate impact experiments to study the evolution of titanium during transformation. These high-rate data allow us to probe the mechanism and kinetics of phase transformations in new ways. Recent results will be presented and compared to post-mortem characterization of soft-recovered shocked specimens. Comparisons are made with previous tests where material was shock-loaded and soft recovered for microstructural analysis. Together these techniques create a consistent picture of material behavior during the shock-induced ff–! phase transformation in titanium.

A Numerical Homogenization Scheme for Glass Particle-Toughened Polymers Under Dynamic Loading

2017 ◽  
Vol 08 (01) ◽  
pp. 1750001 ◽  
Author(s):  
Amin Karamnejad ◽  
Awais Ahmed ◽  
Lambertus Johannes Sluys
Keyword(s):  
Dynamic Loading ◽  
Polymer Material ◽  
Glass Particle ◽  
Multiscale Model ◽  
Constitutive Law ◽  
Polymer Materials ◽  
Numerical Homogenization ◽  
Material Parameters ◽  
Model Glass ◽  
Homogenization Scheme

A numerical homogenization scheme is presented to model glass particle-toughened polymer materials under dynamic loading. A constitutive law is developed for the polymer material and validated by comparing the results to experimental test data. A similar constitutive law as that of the polymer material with unknown material parameters is assumed for the glass particle-toughened polymer. A homogenization scheme is used to determine the unknown material parameters from the boundary value problem (BVP) of a representative volume element. Unlike the standard computational homogenization scheme, the proposed numerical homogenization scheme can be used after localization occurs in the material. The proposed multiscale model is then verified against direct numerical simulation.

On the Optimal Damping of a Vibrating Shape Memory Alloy Rod

2002 ◽  
Vol 124 (2) ◽  
pp. 97-102 ◽  
Author(s):  
Eduard R. Oberaigner ◽  
Franz D. Fischer ◽  
Kikuaki Tanaka
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Stress Wave ◽  
Constitutive Law ◽  
Major Area ◽  
Static Approximation ◽  
Smart Systems ◽  
Optimal Damping ◽  
Basic Equations ◽  
The One

Vibration damping through phase transformation is one major area of application of shape memory alloys in smart systems and structures. The authors of this study have shown in earlier publications, how damping of vibrating rods can be accomplished. This paper is an extension and generalization. On the one side it uses the proper description of the stress-wave phenomenon instead of a quasi-static approximation, on the other side it describes, how the damping could be optimized. The basic equations of the underlying mathematical model are the stress-wave equation, the heat conduction equation, a kinetic and a constitutive law as well as a condition to ensure maximal damping. The major results are the heating history, which governs the phase transformation, and the domain splitting along the rod into elastic and inelastic regions.

Phenomenological Mechanism of Transformation Plasticity and the Constitutive Law Coupled with Thermo-Mechanical Plasticity

2008 ◽  
Vol 33-37 ◽  
pp. 1351-1358 ◽  
Author(s):  
Tatsuo Inoue
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Simple Model ◽  
Constitutive Equation ◽  
Yield Function ◽  
Constitutive Law ◽  
Strain Rates ◽  
Strain Response ◽  
Transformation Plasticity ◽  
New Phase

Phenomenological mechanism of transformation plasticity is proposed in the first part of the paper by use of simple model why stress in mother phase increases to reach yielding due to progressing new phase and to induce plastic deformation even under small applied stress. Based on the discussion, a unified constitutive model including transformation-induced and ordinal thermomechanical plastic strain rates by introducing an effect of varying phases during phase transformation into yield function. Thus derived constitutive equation is applied to describe strain response under varying temperature and stress with some discussions as well as metallo-thermo-mechanical simulation of quenching.

Dynamic Mechanical Behavior of Concrete under Uniaxial Stress

2012 ◽  
Vol 166-169 ◽  
pp. 3273-3276
Author(s):  
Ting Xiu Li ◽  
Yan Zhang ◽  
Lin Hua Jiang
Keyword(s):  
Mechanical Behavior ◽  
Dynamic Loading ◽  
Loading Rate ◽  
Concrete Strength ◽  
Uniaxial Stress ◽  
Constitutive Law ◽  
Elastic Parameters ◽  
Systematic Analysis ◽  
Dynamic Mechanical Behavior ◽  
Stress Strain Relation

According to existing experimental results, a systematic analysis of stress–strain relation of concrete under uniaxial dynamic loading is carried out. Research shows that the dynamic loading rate has a direct effect on concrete strength and elastic parameters. Finally, a constitutive law is proposed in this paper.

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

AEM of reaction-bonded SiC

1992 ◽  
Vol 50 (1) ◽  
pp. 344-345
Author(s):  
K Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
High Temperature ◽  
Epitaxial Growth ◽  
Liquid Silicon ◽  
Structural Ceramic ◽  
Few Data

Research on reaction-bonded SiC (RBSiC) is aimed at developing a reliable structural ceramic with improved mechanical properties. The starting materials for RBSiC were Si,C and α-SiC powder. The formation of the complex microstructure of RBSiC involves (i) solution of carbon in liquid silicon, (ii) nucleation and epitaxial growth of secondary β-SiC on the original α-SiC grains followed by (iii) β>α-SiC phase transformation of newly formed SiC. Due to their coherent nature, epitaxial SiC/SiC interfaces are considered to be segregation-free and “strong” with respect to their effect on the mechanical properties of RBSiC. But the “weak” Si/SiC interface limits its use in high temperature situations. However, few data exist on the structure and chemistry of these interfaces. Microanalytical results obtained by parallel EELS and HREM imaging are reported here.

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