scholarly journals Thermomechanical Modelling and Simulation of C38 Thixoextrusion Steel

2014 ◽  
Vol 217-218 ◽  
pp. 130-137 ◽  
Author(s):  
Eric Becker ◽  
Laurent Langlois ◽  
Véronique Favier ◽  
Régis Bigot
Keyword(s):  
Solid Phase ◽  
Solid Material ◽  
Displacement Curve ◽  
Multi Scale ◽  
Thermal Boundary Conditions ◽  
Plastic Dissipation ◽  
Scale Modelling ◽  
Semi Solid ◽  
Complex Temperature ◽  
Force Displacement

The present paper focuses the modelling and the simulation of a direct thixoextrusion test achieved on C38 semi-solid steel. Many parameters related to thermal, mechanical, material features are involved but are currently unknown. Consequently to validate the modelling and the simulation, it is important to get various experimental informations during the test and to correlate them with simulated results. In a previous paper (Becker et al, 2008), the force-displacement curve, the temperature within the die, the macro and micro structure obtained for different process parameters during thixoextrusion of C38 were investigated. In this work, those results are correlated to those obtained by simulations of the processing. The simulations were performed using the commercial software Forge®. The thermal modelling is based on the heat equation and the thermal boundary conditions involving the heat losses, the thermal conduction within the semi-solid slug and the die and the plastic dissipation as heat source. The latent heat associated to the liquid-solid phase transformation is not considered here. The constitutive equation of the material is given by a multi-scale modelling based on micromechanics and homogenization techniques, labelled as micro-macro modelling (Favier et al, 2009). Friction is modelled using the usual modified Tresca equation. The parameters of the model are determined (i) using literature results and (ii) to match various experimental measurements obtained during the test and described in Becker et al (2008) such as the die temperature during the test and the load-displacement curve. Comparisons between experimental and simulated reveal the presence of complex temperature field and the presence of zones having very low viscosities. These zones contribute actively to the semi-solid material flow.

Ductile Separation and Its Role in the Evolution of Gold Contacts

2007 ◽  
Author(s):  
Lei Chen ◽  
Yan Du ◽  
Nicol E. McGruer ◽  
George G. Adams
Keyword(s):  
Plastic Deformation ◽  
Displacement Curve ◽  
Plateau Region ◽  
Rate Dependent ◽  
Plastic Dissipation ◽  
Random Modification ◽  
Contact Surfaces ◽  
The Difference ◽  
Force Displacement

In this paper, we study the role of ductile separation on the evolution of gold-on-gold micro-contacts. A specially designed SPM contact test station has been used to conduct the cycling tests. The evolution of contacts is studied by monitoring the characteristics of the pull-off force. The magnitude of the pull-off force, the force vs. displacement curves, and the rate-dependent pull-off force are sampled during cycling. It is found that ductile separation causes significant and random modification of the contact surfaces. The magnitude of the pull-off force also changes due to the variation of surface morphology. Significant plastic deformation during ductile separation can form a plateau region in the force-displacement curve which is characteristic of ductile separation. This deformation can also contribute to a higher pull-off force when the contacts are cycled at 300Hz compared with cycling at 0.5Hz. The difference between these rate-dependent pull-off forces can be used to indicate the degree of plastic dissipation during each separation.

Multi-scale modelling of woven carbon fibre reinforced epoxy

2021 ◽  
Author(s):  
Alexandru Szabo ◽  
Radu Negru ◽  
Alexandru-Viorel Coşa ◽  
Liviu Marşavina ◽  
Dan-Andrei Şerban
Keyword(s):  
Carbon Fibre ◽  
Multi Scale ◽  
Scale Modelling

scholarly journals Study on improvement of prefolded energy absorption device to constant resistance and its mechanical properties

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110368
Author(s):  
Dong An ◽  
Jiaqi Song ◽  
Hailiang Xu ◽  
Jingzong Zhang ◽  
Yimin Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Compression Test ◽  
Side Wall ◽  
Concave Side ◽  
Displacement Curve ◽  
Static Compression ◽  
Constant Resistance ◽  
The Impact ◽  
Force Displacement

When the rock burst occurs, energy absorption support is an important method to solve the impact failure. To achieve constant resistance performance of energy absorption device, as an important component of the support, the mechanical properties of one kind of prefolded tube is analyzed by quasi-static compression test. The deformation process of compression test is simulated by ABAQUS and plastic strain nephogram of the numerical model are studied. It is found that the main factors affecting the fluctuation of force-displacement curve is the stiffness of concave side wall. The original tube is improved to constant resistance by changing the side wall. The friction coefficient affects the folding order and form of the energy absorbing device. Lifting the concave side wall stiffness can improve the overall stiffness of energy absorption device and slow down the falling section of force-displacement curve. It is always squeezed by adjacent convex side wall in the process of folding, with large plastic deformation. Compared with the original one, the improved prefolded tube designed in this paper can keep the maximum bearing capacity ( Pmax), increase the total energy absorption ( E), improve the specific energy absorption (SEA), and decrease the variance ( S2) of force-displacement curve.

scholarly journals Multi-scale modelling of a large scale shell-and-tube latent heat storage system for direct steam generation power plants

2020 ◽  
Author(s):  
Clément Beust ◽  
Erwin Franquet ◽  
Jean-Pierre Bédécarrats ◽  
Pierre Garcia ◽  
Jérôme Pouvreau ◽  
...  
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Storage System ◽  
Steam Generation ◽  
Latent Heat Storage ◽  
Multi Scale ◽  
Direct Steam ◽  
Scale Modelling ◽  
Shell And Tube ◽  
Generation Power

Effect of Pouring Temperature and Holding Time at Semi-Solid Region on the Morphology of Primary Solid Phase in Semi-Solid Slurry

2006 ◽  
Vol 510-511 ◽  
pp. 782-785 ◽  
Author(s):  
Suk Won Kang ◽  
Ki Bae Kim ◽  
Dock Young Lee ◽  
Jung-Hwa Mun ◽  
Eui Pak Yoon
Keyword(s):  
Solid Phase ◽  
Holding Time ◽  
Pouring Temperature ◽  
Solid Region ◽  
Semi Solid

scholarly journals Micro Salting-Out Assisted Matrix Solid-Phase Dispersion: A Simple and Fast Sample Preparation Method for the Analysis of Bisphenol Contaminants in Bee Pollen

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2350
Author(s):  
Jianing Zhang ◽  
Fengjie Yu ◽  
Yunmin Tao ◽  
Chunping Du ◽  
Wenchao Yang ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Preparation Method ◽  
Solid Phase ◽  
Sample Preparation Method ◽  
Salting Out ◽  
Bee Pollen ◽  
Matrix Solid Phase Dispersion ◽  
Phase Dispersion ◽  
New Strategy ◽  
Semi Solid

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample preparation methodologies, matrix solid-phase dispersion (MSPD) and homogenous liquid-liquid extraction (HLLE), to simplify and speed-up the preparation process. Parameters of μ-SOA-MSPD were systematically investigated, and results indicated the significant effect of salt and ACN-H2O extractant on the signal response of analytes. In addition, excellent clean-up ability in removing matrix components was observed when primary secondary amine (PSA) sorbent was introduced into the blending operation. The developed method was fully validated, and the limits of detection for BPA and BPB were 20 μg/kg and 30 μg/kg, respectively. Average recoveries and precisions were ranged from 83.03% to 94.64% and 1.76% to 5.45%, respectively. This is the first report on the analysis of bisphenol contaminants in bee pollen sample, and also on the combination of MSPD and HLLE. The present method might provide a new strategy for simple and fast sample preparation of solid and semi-solid samples.

scholarly journals Young’s Modulus of Polycrystalline Titania Microspheres Determined by In Situ Nanoindentation and Finite Element Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Peida Hao ◽  
Yanping Liu ◽  
Yuanming Du ◽  
Yuefei Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Deformation Mechanisms ◽  
Displacement Curve ◽  
Element Simulation ◽  
Nanoindentation Experiment ◽  
Force Displacement

In situ nanoindentation was employed to probe the mechanical properties of individual polycrystalline titania (TiO2) microspheres. The force-displacement curves captured by a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM) system were analyzed based on Hertz’s theory of contact mechanics. However, the deformation mechanisms of the nano/microspheres in the nanoindentation tests are not very clear. Finite element simulation was employed to investigate the deformation of spheres at the nanoscale under the pressure of an AFM tip. Then a revised method for the calculation of Young’s modulus of the microspheres was presented based on the deformation mechanisms of the spheres and Hertz’s theory. Meanwhile, a new force-displacement curve was reproduced by finite element simulation with the new calculation, and it was compared with the curve obtained by the nanoindentation experiment. The results of the comparison show that utilization of this revised model produces more accurate results. The calculated results showed that Young’s modulus of a polycrystalline TiO2microsphere was approximately 30% larger than that of the bulk counterpart.

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