Compressive Deformation Behaviour of a Closed-Cell Aluminum

2006 ◽  
Vol 510-511 ◽  
pp. 150-153
Author(s):  
Yasuo Yamada ◽  
Takumi Banno ◽  
Zhen Kai Xie ◽  
Cui E Wen
Keyword(s):  
Deformation Mechanism ◽  
Deformation Behaviour ◽  
Compressive Loading ◽  
Peak Stress ◽  
Cell Diameter ◽  
Deformation Bands ◽  
Closed Cell ◽  
A Cell ◽  
Deformation Modes ◽  
Compressive Tests

The mechanical properties of a closed-cell aluminium foam were investigated by compressive tests, and the deformation behaviours of the aluminium foams were studied using Xray microtomography. The results indicate that the deformation of the aluminium foams under compressive loading was localized in narrow continuous deformation bands having widths of order of a cell diameter. The cells in the deformation bands collapsed by a mixed deformation mechanism, which includes mainly bending and minor buckling and yielding. Different fractions of the three deformation modes led to variations in the peak stress and energy absorption for different foam samples with the same density. It was also found that the cell morphology affects the deformation mechanism significantly, whilst the cell size shows little influence.

scholarly journals MULTIAXIAL INVESTIGATION OF PVC FOAMS AND ANALYSIS OF THE DEFORMATION MECHANISM BY 3D-DIC

2019 ◽  
Vol 25 ◽  
pp. 6-11
Author(s):  
Francesca Concas ◽  
Stefan Diebels ◽  
Anne Jung
Keyword(s):  
Deformation Mechanism ◽  
High Performance ◽  
Deformation Bands ◽  
Pure Torsion ◽  
Camera System ◽  
Strain Fields ◽  
Failure Data ◽  
Closed Cell ◽  
Wide Range ◽  
Pure Compression

Closed-cell polyvinylchloride (PVC) foams are widely used as core for sandwich composites for applications, in which multiaxial loads are involved. In the present work a wide range of uniaxial (tension, compression and torsion) and multiaxial experiments (both simultaneous tension-torsion and compression-torsion) were conducted on a high performance PVC foam. Failure data for each experiment were collected and depicted in the invariants plane. The whole cylindrical surface of the specimen was monitored by means of an 8-camera-system, strain fields were obtained by 3D-DIC. Hence, the occurrence and the evolution of deformation bands were inspected. The usage of an 8-camera system was essential for the observation of the deformation mechanism, especially for pure compression, pure torsion and combined axial load-torsion, in which the arising of deformation bands is affected by the occurrence of buckling and the orthotropy of the foam.

Development of High Performance Magnesium Alloys via Microstructure and Texture Control

2009 ◽  
Vol 618-619 ◽  
pp. 249-252 ◽  
Author(s):  
Jung Woo Choi ◽  
Kwang Seon Shin
Keyword(s):  
Plastic Deformation ◽  
High Performance ◽  
Deformation Behaviour ◽  
Extrusion Direction ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Content ◽  
Deformation Modes ◽  
Compressive Tests

The mechanical properties of extruded ZA (Mg-Zn-Al) alloys with different Al contents were examined. The effects of Al on deformation behaviour were examined by tensile and compressive tests. The changes in texture due to plastic deformation were examined using the X-ray diffraction method. It was found that the basal poles of the extruded ZA alloy were parallel to the normal direction with a slight tendency to incline toward the extrusion direction. The degree of inclination increased with increasing Al content. The inclination degree of the basal poles was found to be closely related to the change in the deformation behaviour of the ZA alloy. Computer simulations were also carried out using the VPSC (visco-plastic self-consistent) theory in order to predict the contributions of various deformation modes to the plastic deformation behaviour of the ZA alloy.

scholarly journals A novel method for processing adipose-derived stromal stem cells using a closed cell washing concentration device with a hollow fiber membrane module

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Shinji Hayashi ◽  
Rieko Yagi ◽  
Shuhei Taniguchi ◽  
Masami Uji ◽  
Hidaka Urano ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Membrane Module ◽  
Fiber Membrane ◽  
Cell Processing ◽  
Closed Cell ◽  
A Cell ◽  
Novel Method ◽  
Stromal Stem Cells

AbstractCell-assisted lipotransfer (CAL) is an advanced lipoinjection method that uses autologous lipotransfer with addition of a stromal vascular fraction (SVF) containing adipose-derived stromal stem cells (ASCs). The CAL procedure of manual isolation of cells from fat requires cell processing to be performed in clean environment. To isolate cells from fat without the need for a cell processing center, such as in a procedure in an operation theater, we developed a novel method for processing SVF using a closed cell washing concentration device (CCD) with a hollow fiber membrane module. The CCD consists of a sterilized closed circuit, bags and hollow fiber, semi-automatic device and the device allows removal of >99.97% of collagenase from SVF while maintaining sterility. The number of nucleated cells, ASCs and viability in SVF processed by this method were equivalent to those in SVF processed using conventional manual isolation. Our results suggest that the CCD system is as reliable as manual isolation and may also be useful for CAL. This approach will help in the development of regenerative medicine at clinics without a cell processing center.

scholarly journals Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
S. Talebi ◽  
R. Hedayati ◽  
M. Sadighi
Keyword(s):  
Surface Area ◽  
Dynamic Behavior ◽  
Energy Absorption ◽  
Peak Stress ◽  
Absorption Capacity ◽  
Unit Cell ◽  
Lattice Structures ◽  
Energy Absorption Capacity ◽  
Closed Cell ◽  
Unit Cells

AbstractClosed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

2016 ◽  
Vol 47 (6) ◽  
pp. 2783-2794 ◽  
Author(s):  
Jinwoo Lee ◽  
Se-Jong Kim ◽  
Myoung-Gyu Lee ◽  
Jung Han Song ◽  
Seogou Choi ◽  
...  
Keyword(s):  
Deformation Mechanism ◽  
Numerical Study ◽  
Mg Alloy ◽  
Compressive Tests

Atomistic Simulation Study of Mechanical Deformation of Al-Mg-Si Alloys

2021 ◽  
Vol 52 ◽  
pp. 149-163
Author(s):  
Hanae Chabba ◽  
Driss Dafir
Keyword(s):  
Deformation Behaviour ◽  
Compressive Loading ◽  
Embedded Atom Method ◽  
Stress Strain ◽  
Elasticity Limit ◽  
Embedded Atom ◽  
High Elasticity ◽  
Strain Relationship ◽  
Atomic Simulations ◽  
Strain Responses

Aluminum alloys have been attracting significant attention. Especially Al-Mg-Si alloys can exhibit an excellent balance between strength and ductility. Deformation mechanisms and microstructural evolution are still challenging issues. Accordingly, to describe how the type of phase influence mechanical behaviour of Al/Mg/Si alloys, in this paper atomic simulations are performed to investigate the uniaxial compressive behaviour of Al-Mg-Si ternary phases. The compression is at the same strain rate (3.1010 s−1); using Modified Embedded Atom Method (MEAM) potential to model the deformation behaviour. From these simulations, we get the total radial distribution function; the stress-strain responses to describe the elastic and plastic behaviors of GP-AlMg4Si6, U2-Al4Mg4Si4 and β-Al3Mg2Si6 phases. For a Detailed description of which phase influence hardness and ductility of these alloys; the mechanical properties are determined and presented. These stress-strain curves obtained show a rapid increase in stress up to a maximum followed by a gradual drop when the specimen fails by ductile fracture. From the results, it was found that GP-AlMg4Si6 & U2-Al4Mg4Si4 phases are brittle under uniaxial compressive loading while β-Al3Mg2Si6 phase is very ductile under the same compressive loading. The engineering stress-strain relationship suggests that β-Al3Mg2Si6 phase have high elasticity limit, ability to resist deformation and have the advantage of being highly malleable. Molecular dynamics software LAMMPS was used to simulate and build the Al-Mg-Si ternary system.

scholarly journals Numerical Modeling and Experimental Behavior of Closed-Cell Aluminum Foam Fabricated by the Gas Blowing Method under Compressive Loading

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1582 ◽  
Author(s):  
Varun Sharma ◽  
Fatima Zivic ◽  
Nenad Grujovic ◽  
Norbert Babcsan ◽  
Judith Babcsan
Keyword(s):  
Numerical Modeling ◽  
Compressive Loading ◽  
Material Behavior ◽  
Small Cells ◽  
Uniaxial Compression Test ◽  
Average Cell ◽  
Tensile Stresses ◽  
Closed Cell ◽  
Gas Blowing ◽  
Over The Top

This paper deals with the experimental and numerical study of closed-cell aluminum-based foam under compressive loading. Experimental samples were produced by the gas blowing method. Foam samples had an average cell size of around 1 mm, with sizes in the range 0.5–5 mm, and foam density of 0.6 g/cm3. Foam samples were subjected to a uniaxial compression test, at a displacement rate of 0.001 mm/s. Load and stress were monitored as the functions of extension and strain, respectively. For numerical modeling, CT scan images of experimental samples were used to create a volume model. Solid 3D quadratic tetrahedron mesh with TETRA 10-node elements was applied, with isotropic material behavior. A nonlinear static test with an elasto-plastic model was used in the numerical simulation, with von Mises criteria, and strain was kept below 10% by the software. Uniform compressive loading was set up over the top sample surface, in the y-axis direction only. Experimental tests showed that a 90 kN load produced complete failure of the sample, and three zones were exhibited: an elastic region, a rather uniform plateau region (around 23 MPa) and a densification region that started around 35 MPa. Yielding, or collapse stress, was achieved around 20 MPa. The densification region and a rapid rise in stress began at around 52% of sample deformation. The numerical model showed both compressive and tensile stresses within the complex stress field, indicating that shear also had a prominent role. Mainly compressive stresses were exhibited in the zones of the larger cells, whereas tensile stresses occurred in zones with an increased number of small cells and thin cell walls.

Modelling Tow Compression in Textile Preforms During Composites Processing

Aerospace ◽  
2004 ◽  
Author(s):  
P. Potluri ◽  
V. S. Thammandra ◽  
R. B. Ramgulam
Keyword(s):  
Deformation Behaviour ◽  
Compressive Loading ◽  
Final Part ◽  
Initial Part ◽  
Transverse Compression ◽  
Fiber Assembly ◽  
Compression Model ◽  
Out Of Plane ◽  
Composites Processing ◽  
Transfer Moulding

Fiber assemblies, in the form of woven, braided, nonwoven or knitted structures, are used as reinforcements in composites. These textile structures are subjected to in-plane membrane stresses such as tensile and shear, and out-of-plane stresses such as bending and transverse compression. Amongst various modes of deformation, transverse compaction behaviour is the least understood mode; however this mode is very important for composites processing using vacuum forming, resin transfer moulding, thermoforming and hot compaction methods. The present paper reports a computational approach to predicting the load-deformation behaviour of textile structures under compressive loading. During the compression of a random fiber assembly, fibers are subjected to kinematic displacements, bending and finally transverse compression of individual fibres. In the case of interlaced architectures, such as woven and braided structures, it is convenient to deal with deformations at meso-scale involving yarns or tows, and deal with inter-fiber friction and fibre compression at yarn/tow level. It can be seen from the load deformation graphs that the initial part is dominated by bending energy and the final part by compression energy. A combined yarn bending and compression model was in good agreement with the experimental curve during the entire load-deformation cycle. On the other hand, an elastica-based bending model predicts well during the initial part while tow compression model predicts well during the final part. Inter-fiber friction was initially ignored — this is being introduced in the refined model for both the dry and wet states.

On Prediction for Structural Performance of Ship Side Structures in Head-On Collision Scenario

2015 ◽  
Author(s):  
Bin Sun ◽  
Zhiqiang Hu ◽  
Jin Wang
Keyword(s):  
Deformation Mechanism ◽  
Analytical Method ◽  
Structural Design ◽  
Deformation Process ◽  
Predictive Accuracy ◽  
Structural Performance ◽  
Resistance Force ◽  
Tearing Modes ◽  
Deformation Modes

The crashworthiness of ship side structures should be taken into consideration during the structural design phase. When a ship is struck by a head-on collision, the main participants of the side structures include outer plating, longitudinal girders, transverse frames and the stiffeners attached on them. This paper is centered on establishing an integrated deformation mechanism program by identifying the theoretical deformation modes of the side structures, including the plating and stiffeners. The primary failure models of plating structures are the crushing, stretching and tearing modes, and a new crushing model of side plating structures subject to an ellipsoid-shaped indenter is proposed. As for the stiffeners on outer plating, the smeared thickness method is often used, but the role of the stiffeners cannot be traced clearly during the deformation process and the structural performance predictive accuracy may not be guaranteed. Therefore, a theoretical model of stiffeners is established in this paper, on purpose of providing deep insight of the deformation mechanism with reasonable accuracy. The expressions of resistance force of the side structures are also derived based on a study of the progressive deformation process of numerical simulation results and the plastic analytical methods. The accuracy of the analytical method is verified by numerical simulations using code LS_DYNA. The proposed analytical method can be used for quick assessment of the performances of ship side structures during ship collision.

Research on the Effect of Concentration and Type of De-Icing Salt on Concrete Salt-Scaling

2012 ◽  
Vol 450-451 ◽  
pp. 14-20
Author(s):  
Qiang Li ◽  
Zhi Yun Zhou
Keyword(s):  
Elastic Modulus ◽  
Compressive Loading ◽  
Peak Stress ◽  
Test Results ◽  
Reasonable Explanation ◽  
Salt Scaling ◽  
Relationship Of ◽  
The Relationship

To study the effect of concentration and type of de-icing salt on salt scaling based on the mechanism of glue spaling proposed by John J. Valenza II and George W. Scherer, the de-icing solution of NaCI andCaCI2 on the concentration of 1%、3%、5% and 7% were frozen into brine ice . Order to obtain the relationship of elastic modulus between the type and concentration of de-icing ,all brine ice specimens were tested under uni-axial compressive loading. The test results show: with the increase of concentration, the elastic modulus and peak stress of bring ice were decreased;when the same concentration ,the elastic modulus and peak stress of NaCl brine ice were higher than CaCI2.Based on the test results ,a reasonable explanation of the following phenomenon were given:The different type of de-icing salt all can lead to salt scaling of concrete;when the concentration of de-icing salt is moderate,it is will occur the most serious salt scaling.

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