scholarly journals Quasi-soft opto-mechanical behavior of photochromic liquid crystal elastomer: Linearized stress–strain relations and finite element simulations

2012 ◽  
Vol 49 (18) ◽  
pp. 2668-2680 ◽  
Author(s):  
Yin Lin ◽  
Lihua Jin ◽  
Yongzhong Huo
Keyword(s):  
Finite Element ◽  
Liquid Crystal ◽  
Mechanical Behavior ◽  
Finite Element Simulations ◽  
Stress Strain ◽  
Liquid Crystal Elastomer

Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer

Polymer ◽  
2018 ◽  
Vol 158 ◽  
pp. 96-102 ◽  
Author(s):  
Andraž Rešetič ◽  
Jerneja Milavec ◽  
Valentina Domenici ◽  
Blaž Zupančič ◽  
Alexey Bubnov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Stress Strain ◽  
Liquid Crystal Elastomer ◽  
Smectic A ◽  
Thermomechanical Characterization

scholarly journals Determination of Plastic Properties of Polycrystalline Metallic Materials by Nanoindentation – Experiments and Finite Element Simulations

2004 ◽  
Vol 841 ◽  
Author(s):  
Karsten Durst ◽  
Björn Backes ◽  
Mathias Göken
Keyword(s):  
Finite Element ◽  
Strain Curve ◽  
Finite Element Simulations ◽  
Metallic Materials ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Plastic Properties ◽  
Ultrafine Grained ◽  
Indentation Tests

ABSTRACTThe determination of plastic properties of metallic materials by nanoindentation requires the analysis of the indentation process and the evaluation methods. Particular effects on the nanoscale, like the indentation size effect or piling up of the material around the indentation, need to be considered. Nanoindentation experiments were performed on conventional grain sized (CG) as well as on ultrafine-grained (UFG) copper and brass. The indentation experiments were complemented with finite element simulations using the monotonic stress-strain curve as input data. All indentation tests were carried out using cube-corner and Berkovich geometry and thus different amount of plastic strain was applied to the material, according to Tabors theory. We find an excellent agreement between simulations and experiments for the UFG materials from which a representative strain of εB ≈ 0.1 and εcc ≈ 0.2 is determined. With these data, the slope of the stress-strain curve is predicted for all materials down to an indentation depth of 800 nm.

Finite Element Stent Design: Parametric Modeling of Braided Wirestents Using PyFormex

2007 ◽  
Author(s):  
Matthieu De Beule ◽  
Benedict Verhegghe ◽  
Peter Mortier ◽  
Kim Van Loo ◽  
Rudy Van Impe ◽  
...  
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Stent Graft ◽  
Computer Model ◽  
Geometrical Model ◽  
Parametric Modeling ◽  
Finite Element Simulations ◽  
Stent Design ◽  
Wide Range

Selfexpandable stent(graft)s are supporting tubular mesh devices used for the treatment of occlusive diseases and for the ‘exclusion’ of aneurysms. Wirestents are a class of flexible stents braided from a set of ultra fine wires and currently manufactured in a wide range of materials (e.g. phynox, nitinol, polymers) and compositions (single or multilayer). For design purposes as well as for studying the mechanical behavior of such a device by finite element simulations, a geometrical model using 1D elements will usually be appropriate. However, the computer model will contain a very large number of such elements, and building the geometrical model using classical CAD methodologies may become laborious. Consequently, literature dedicated to the mechanical behavior of braided wirestents is (very) scarce and the stent(graft)s are simplified as virtual single sheets [1].

Mechanics of Wavy Network With Diamond-Shaped Inclusions

2017 ◽  
Author(s):  
Mona Monsef Khoshhesab ◽  
Yaning Li
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Mechanical Behavior ◽  
Geometric Constraints ◽  
Cellular Solids ◽  
Biomedical Devices ◽  
Stress Strain ◽  
Engineering Applications ◽  
Smart Composites ◽  
Strain Behavior

In this investigation, mechanical behavior of periodic cellular solids with diamond-shaped inclusions connected via wavy network were explored. Two families of cellular solids within this category were designed based on two different geometric constraints. Auxetic effects and snap-through instability were observed for each family, respectively. The mechanical properties, including the stress-strain behavior, stiffness and Poisson’s ratio, were systematically quantified via finite element (FE) simulations. The parametric space for auxetic effects and snap-through instability was numerically identified. This study demonstrates the connection and transition between mechanical auxeticity and snap-through instability. The materials designed have potential engineering applications, such as lightweight supporting and protective foams, biomedical devices, smart composites or fabrics with switchable properties responsive to external environments.

Formability Enhancement for Tailor-Welded Blanks Using Blank Holding Force Control

2003 ◽  
Vol 125 (3) ◽  
pp. 461-467 ◽  
Author(s):  
Sijun He ◽  
Xin Wu ◽  
S. Jack Hu
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Strain Distribution ◽  
Weld Line ◽  
Finite Element Simulations ◽  
Stress Strain ◽  
Tailor Welded Blanks ◽  
Blank Holding Force ◽  
Weld Line Movement ◽  
Line Movement

Tailor-welded blanks (TWB) are widely used for stamped auto body panels because of their great benefits in weight and cost reduction. However, the weld line in a tailor-welded blank causes serious concerns in formability because of material discontinuity and additional inhomogeneous stress/strain distribution. This paper proposes a blank holding force (BHF) control strategy to control the weld line movement, distribute the deformation more uniformly and thereby improve TWB formability. The control methodology is developed based on a simplified 2-D sectional analytical model that estimates the stress/strain distribution and the BHFs required for each side of the flange with dissimilar materials. The model can be further extended to 3-D analysis by superimposing the 2-D sectional analysis results around the entire binder ring and thus determining the required BHF for the whole panel. Finite element simulations are performed to study the effects of forming parameters on the weld line movement. Experiments have been conducted to verify the analytical model and partial finite element simulations. Both analysis and experiments demonstrated that a lower BHF should be applied on the thicker blank side to allow more metal to flow-in for obtaining more uniform strain distribution. The proposed BHF control is proven to be a good approach to enhancing TWB formability.

The Mechanical Behavior and Martensitic Transformation of Porous NiTi Alloys Based on Geometrical Reconstruction

2017 ◽  
Vol 09 (03) ◽  
pp. 1750038 ◽  
Author(s):  
Xiaofeng Lu ◽  
Chaojie Wang ◽  
Gang Li ◽  
Yang Liu ◽  
Xiaolei Zhu ◽  
...  
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Strain Curve ◽  
Element Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
The Real ◽  
Porous Niti ◽  
Niti Shape Memory Alloys

The finite element analysis (FEA) of porous NiTi shape memory alloys (SMAs) remains a challenge due to irregularity and complexity of pore structure. In this paper, the real finite element model (FEM) is established based on the geometrical reconstruction. Through a SMA constitutive model, the mechanical behavior and stress-induced martensitic (SIM) phase transformation are analyzed with the real FEM. The results show that the stress–strain curve of FEA is in good agreement with the experimental curve and the calculation can reflect the mechanical behavior well in the compressive process. With the increase of load, the SIM first appears pore walls or weak parts of struts, then spreads to the center of matrix, and finally happens to most of matrix. When the slope of the stress–strain curve shows obvious changes, the SIM has happened in quite a part of matrix.

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