scholarly journals Correlation Modeling between Morphology and Compression Behavior of Closed-Cell Al Foams Based on X-Ray Computed Tomography Observations

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1370
Author(s):  
Girolamo Costanza ◽  
Fabio Giudice ◽  
Andrea Sili ◽  
Maria Elisa Tata
Keyword(s):  
Computed Tomography ◽  
Local Level ◽  
Strain Curve ◽  
Equivalent Diameter ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
X Ray ◽  
Closed Cell ◽  
X Ray Computed ◽  
Al Foams

In the last decades, great attention has been focused on the characterization of cellular foams, because of their morphological peculiarities that allow for obtaining effective combinations of structural properties. A predictive analytical model for the compressive behavior of closed-cell Al foams, based on the correlation between the morphology of the cellular structure and its mechanical response, was developed. The cells’ morphology of cylindrical specimens was investigated at different steps of compression by X-ray computed tomography, in order to detect the collapse evolution. The structure, typically inhomogeneous at local level, was represented by developing a global virtual model consisting of homogeneous cells ordered in space, that was fitted on the experimentally detected structure at each deformation step. As a result, the main parameters characterizing the two-dimensional cells morphology (equivalent diameter, circularity), processed by the model, allowed to simulate the whole compression stress–strain curve by enveloping those obtained for each step. The model, fitted on the previous foam, was validated by comparing the simulated stress–strain curve and the corresponding experimental one, detected for similar foams obtained by different powder compositions. The effectiveness in terms of an accurate prediction of the compression response up to the final densification regime has been confirmed.

scholarly journals On the inhomogeneity of plastic deformation in the crystals of an aggregate

1948 ◽  
Vol 193 (1032) ◽  
pp. 89-97 ◽  
Keyword(s):  
Plastic Deformation ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Tensile Deformation ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
X Ray

The variation of plastic deformation in aluminium specimens consisting of large crystals has been determined by measuring elongation and hardness at various points after tensile deformation. The deformation varied from grain to grain, and also within each grain the deformation near the boundary was greater or smaller than at the centre according to whether the neighbour was more or less deformed, i. e. there is not necessarily inhibition of slip near grain boundaries. These results were supported by metallographic and X-ray observations. Their importance with respect to the calculation of the stress-strain curve of aggregates from those of single crystals is discussed. It is suggested that a mechanism other than slip operates near the grain boundaries during deformation, and even within the crystals during large extensions.

Numerical Study on the Mechanical Behavior of Aluminum Foam Material Using CT Image

2009 ◽  
Vol 79-82 ◽  
pp. 1297-1300 ◽  
Author(s):  
Hyup Jae Chung ◽  
Kyong Yop Rhee ◽  
Beom Suck Han ◽  
Yong Mun Ryu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Foam ◽  
Three Dimensional ◽  
Strain Curve ◽  
Foam Material ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
X Ray

In this study, finite element analysis was made to predict the tensile and compressive behaviors of aluminum foam material. The predicted tensile and compressive behaviors were compared with those determined from the tensile and compressive tests. X-ray imaging technique was used to determine internal structure of aluminum foam material. That is, X-ray computed tomography (CT) was used to model the porosities of the material. Three-dimensional finite element modeling was made by stacking two-dimensional tomography of aluminum foam material determined from CT images. The stackings of CT images were processed by three-dimensional modeling program. The results showed that the tensile stress-strain curve predicted from the finite element analysis was similar to that determined by the experiment. The simulated compressive stress-strain curve also showed similar tendency with that of experiment up to about 0.4 strain but exhibited a different behavior from the experimental one after 0.4 strain. The discrepancy of compressive stress-strain curves in a high strain range was associated with the contact of aluminum foam walls broken by the large deformation.

Tensile Behavior of Foamed Aluminum with Closed-Cell

2011 ◽  
Vol 480-481 ◽  
pp. 117-119
Author(s):  
Fang Wang ◽  
Lu Cai Wang ◽  
Jian Guo Wu
Keyword(s):  
Deformation Process ◽  
Tensile Deformation ◽  
Strain Curve ◽  
Tensile Behavior ◽  
Deformation Mechanisms ◽  
Compression Stress ◽  
Plastic Yielding ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Closed Cell

Foamed aluminum has been applied in many fields due mainly to its excellent properties. The tensile deformation process and characteristics of foamed aluminum with closed-cell were studied in this paper and the deformation mechanisms were discussed. The results show that foamed aluminum fractured without necking. The tensile stress-strain curves have similar characteristics, the linear elasticity at a low stresses followed by plastic yielding, strain hardening and rupture, which has obvious difference with compression stress-strain curve. The fracture mechanism is neither brittle fracture nor plastic fracture. The defects existed in foamed aluminum interior have important influence on tensile property.

scholarly journals In Situ Evolution of Pores in Lithium Hydride at Elevated Temperatures Characterized by X-ray Computed Tomography

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1093
Author(s):  
Yifan Shi ◽  
Lei Peng ◽  
Wangzi Zhang ◽  
Qiang Li ◽  
Qishou Li ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Elevated Temperatures ◽  
3D Structure ◽  
Lithium Hydride ◽  
Equivalent Diameter ◽  
X Ray ◽  
Residual Hydrogen ◽  
X Ray Computed ◽  
Increasing Temperature

The evolution of defects such as pores at elevated temperatures is crucial for revealing the thermal stability of lithium hydride ceramic. The in situ evolution of pores in sintered lithium hydride ceramic from 25 °C to 500 °C, such as the statistics of pores and the 3D structure of pores, was investigated by X-ray computed tomography. Based on the statistics of pores, the porosity significantly increased from 25 °C to 200 °C and decreased after 200 °C, due to the significant change in the number and total volume of the round-shaped pores and the branched crack-like pores with an increasing temperature. According to the 3D structure of pores, the positions of pores did not change, and the sizes of pores went up in the range of 25–200 °C and went down after 200 °C. Some small round-shaped pores with an Equivalent Diameter of less than 9 μm appeared at 200 °C and disappeared at elevated temperatures. Some adjacent pores of all types connected at 200 °C, and some branched crack-like pores gradually disconnected with an increasing temperature. The expansion of pores at 200 °C caused by the release of residual hydrogen and the contraction of pores after 200 °C because of the migration and diffusion of some hydrogen in pores might be the reason for the evolution of pores with an increasing temperature.

scholarly journals How does vacuum forming affect Pelite mechanical properties?

1994 ◽  
Vol 18 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J. E. Sanders ◽  
C. H. Daly
Keyword(s):  
Mechanical Properties ◽  
Strain Curve ◽  
Shear Loading ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Closed Cell ◽  
Vacuum Forming ◽  
Interface Mechanics ◽  
Computer Aided ◽  
Cell Foam

Pelite® is a polyethylene closed cell foam commonly used as an interface material in prosthetics. Both normal and vacuum-formed Pelite were tested under compression and under shear loading. For shear testing, the results were not significantly different for normal and vacuum-formed Pelite. For normal Pelite, the slope of the stress-strain curve was 1.17MPa (±0.14) while for vacuum-formed Pelite it was 1.24MPa (±0.22). Compressive results, however, were significantly different. Below 80kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.99MPa (±0.11) while for vacuum formed Pelite it was 0.72MPa (±0.12). Between 80kPa and 200kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.45MPa (±0.03) while for vacuum formed Pelite it was 0.55MPa (±0.05). Reasons for the differences and their significance to interface mechanics and computer-aided prosthesis design are discussed.

Three-Dimensional Analysis of High-Resolution X-Ray Computed Tomography Data with Morpho+

2011 ◽  
Vol 17 (2) ◽  
pp. 252-263 ◽  
Author(s):  
Loes Brabant ◽  
Jelle Vlassenbroeck ◽  
Yoni De Witte ◽  
Veerle Cnudde ◽  
Matthieu N. Boone ◽  
...  
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Complete Analysis ◽  
Equivalent Diameter ◽  
3D Analysis ◽  
X Ray ◽  
X Ray Computed ◽  
Quantitative Results

AbstractThree-dimensional (3D) analysis is an essential tool to obtain quantitative results from 3D datasets. Considerable progress has been made in 3D imaging techniques, resulting in a growing need for more flexible, complete analysis packages containing advanced algorithms. At the Centre for X-ray Tomography of the Ghent University (UGCT), research is being done on the improvement of both hardware and software for high-resolution X-ray computed tomography (CT). UGCT collaborates with research groups from different disciplines, each having specific needs. To meet these requirements the analysis software package, Morpho+, was developed in-house. Morpho+ contains an extensive set of high-performance 3D operations to obtain object segmentation, separation, and parameterization (orientation, maximum opening, equivalent diameter, sphericity, connectivity, etc.), or to extract a 3D geometrical representation (surface mesh or skeleton) for further modeling. These algorithms have a relatively short processing time when analyzing large datasets. Additionally, Morpho+ is equipped with an interactive and intuitive user interface in which the results are visualized. The package allows scientists from various fields to obtain the necessary quantitative results when applying high-resolution X-ray CT as a research tool to the nondestructive investigation of the microstructure of materials.

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