scholarly journals Multistable Shape-Shifting Surfaces

2012 ◽  
Author(s):  
Paul Montalbano ◽  
Craig Lusk
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rigid Body ◽  
Unit Cell ◽  
Physical Barrier ◽  
Element Analysis ◽  
Out Of Plane ◽  
Unit Cells ◽  
Planar Shapes ◽  
Deformable Walls

This paper presents designs for Multistable Shape-Shifting Surfaces (MSSS) by introducing bistability into the Shape-Shifting Surface (SSS). SSSs are defined as surfaces that retain their effectiveness as a physical barrier while undergoing changes in shape. The addition of bistability to the SSS gives the surface multiple distinct positions in which it remains when shifted to, i.e. by designing bistability into a single SSS link, the SSS unit cell can change into multiple shapes, and stabilize within the resulting shape, while maintaining integrity against various forms of external assaults normal to its surface. Planar stable configurations of the unit cell include, expanded, compressed, sheared, half-compressed, and partially-compressed, resulting in the planar shapes of a large square, small square, rhombus, rectangle, and trapezoid respectively. Tiling methods were introduced which gave the ability to produce out-of-plane assemblies using planar MSSS unit cells. Applications for MSSSs include size-changing vehicle beds, expandable laptop screens, deformable walls, and volume-changing rigid-storage containers. Analysis of the MSSS was done using Pseudo-rigid-Body Models (PRBMs) and Finite Element Analysis (FEA) which ensured bistable characteristics before prototypes were fabricated.

Mechanical Design, Additive Manufacturing, and Performance of Equal Volume Metamaterials

2021 ◽  
Author(s):  
Richárd Horváth ◽  
Vendel Barth ◽  
Viktor Gonda ◽  
Mihály Réger ◽  
Imre Felde
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Absorption ◽  
Mechanical Design ◽  
Area Under The Curve ◽  
Cell Number ◽  
Element Analysis ◽  
Cross Sectional ◽  
Unit Cells ◽  
And Performance

Abstract In this paper, we study the energy absorption of metamaterials composed of unit cells whose special geometry makes the cross-sectional area and the volume of the bodies generated from them constant (for the same enclosing box dimensions). After a parametric description of such special geometries, we analyzed by finite element analysis the deformation of the metamaterials we have designed during compression. We 3D printed the designed metamaterials from plastic to subject them to real compression. The results of the finite element analysis were compared with the real compaction results. Then, for each test specimen, we plotted its compaction curve. By fitting a polynomial to the compaction curves and integrating it (area under the curve), the energy absorption of the samples can be obtained. As a result of these investigations, we drew a conclusion about the relationship between energy absorption and cell number.

Experimental and numerical study on stiffness and damage of glass/epoxy biaxial weft-knitted reinforced composites

2020 ◽  
pp. 073168442093844 ◽  
Author(s):  
Navid Shekarchizadeh ◽  
Reza Jafari Nedoushan ◽  
Tohid Dastan ◽  
Hossein Hasani
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Study ◽  
Unit Cell ◽  
Analytical Equation ◽  
Reinforced Composites ◽  
Element Analysis ◽  
Composite Strength ◽  
Failure Theories ◽  
Meso Scale

This paper deals with investigating the tensile characteristics of biaxial weft-knitted reinforced composites in terms of stiffness, strength and failure mechanism. The biaxial weft-knitted fabric was produced on an electronic flat knitting machine by E-glass yarns and then was impregnated with epoxy resin. Using an accurate geometrical model, the composite unit cell was designed in Abaqus software’s environment. Tensile tests were simulated in different directions on the created unit cell and the stiffness was calculated. By applying the proper failure theories, the composite strength was predicted and then critical regions of the unit cell were determined. In the next step, a micromechanical approach was also applied to estimate the same tensile features. Failure theories were also applied to predict the strength and most susceptible areas for failure phenomenon in the composite unit cell. The tensile properties of the produced composites were measured and compared with outputs of the finite element and micromechanical approaches. The results showed that the meso-scale finite element analysis approach can well predict the composite strength. In contrast, the meso-scale analytical equation model was not able to predict it acceptably because this model ignores the strain concentration. Both meso-scale finite element analysis and meso-scale analytical equation approaches predicted the similar locations for the composite failure in wale and course directions.

scholarly journals Evaluation of U10Mo Fuel Plate Irradiation Behavior via Numerical and Experimental Benchmarking

2012 ◽  
Author(s):  
Samuel J. Miller ◽  
Hakan Ozaltun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
3D Models ◽  
Creep Model ◽  
Element Analysis ◽  
Dimensional Changes ◽  
3 Dimensional ◽  
Out Of Plane ◽  
2D And 3D ◽  
Irradiation Behavior

This article analyzes dimensional changes due to irradiation of monolithic plate-type nuclear fuel and compares results with finite element analysis of the plates during fabrication and irradiation. Monolithic fuel plates tested in the Advanced Test Reactor (ATR) at Idaho National Lab (INL) are being used to benchmark the performance of proposed fuel for several high power research reactors. Post-irradiation metallographic images of plates sectioned at the mid-plane were analyzed to determine dimensional changes of the fuel and the cladding response. A constitutive model of the fabrication process and irradiation behavior of the tested plates was developed using the general purpose commercial finite element analysis package, ABAQUS. Using calculated burn-up profiles of irradiated plates to model the power distribution and including irradiation behaviors such as swelling and irradiation enhanced creep, model simulations allow analysis of plate parameters that are either impossible or infeasible in an experimental setting. The development and progression of fabrication induced stress concentrations at the plate edges was of primary interest, as these locations have a unique stress profile during irradiation. Additionally, comparison between 2D and 3D models was performed to optimize analysis methodology. In particular, the ability of 2D and 3D models to account for out of plane stresses which result in 3-dimensional creep behavior that is a product of these components. Results show that assumptions made in 2D models for the out-of-plane stresses and strains cannot capture the 3-dimensional physics accurately and thus 2D approximations are not representative. Stress-strain fields are dependent on plate geometry and irradiation conditions, thus, if stress based criteria is used to predict plate behavior (as opposed to material impurities, fine micro-structural defects, or sharp power gradients), unique 3D finite element formulation for each plate is required.

scholarly journals Analysis of cold formed steel sheet pile for earth retaining wall

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
C. Veena ◽  
S Saravanan ◽  
Robin Davis P. ◽  
Nandakumar Gopalan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Failure Load ◽  
Unit Cell ◽  
Bending Stress ◽  
Sheet Pile ◽  
Element Analysis ◽  
Cold Formed Steel

Failure loads of sheet pile having various profiles such as U, Z and Omega/Hat profiles under compression was carried out by using equations of strength of materials and compared the failure load under various modes such as Euler’s buckling, torsional buckling and failure load due to yielding. Compared the strength of various profiles under flexure by using finite element analysis. Sheet pile can be analyzed as a unit cell for the simplified finite element analysis. For selecting the unit cell sheet pile with omega/Hat section was analyzed for profile containing one to eight numbers and checked the convergence of bending stress and maximum lateral deflection. Interlocks were analyzed for three different conditions such as plane interlock, interlock filled with bitumen and welded interlock. Location of interlock and neutral axis of the wall will affect the stability of the structure. Sheet piles with various cross sections were analyzed and studied the shear stress and bending stress along the cross section. From the structural performance of various cross sections omega/hat section can be considered as the most efficient cross section for the cold formed steel sheet pile because of its more load carrying capacity under compression and high torsion resistance and less bending stress. Results from the finite element analysis for the selection of unit cell shows that the stress and deflection value was converge at the sheet pile having 6 numbers of profiles. Keywords: sheet piles, building, resistance.

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