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THE RANDOM POROUS STRUCTURE AND MECHANICAL RESPONSE OF LIGHTWEIGHT ALUMINUM FOAMS
- Max Larner, John Acker, Lilian P. Dávila
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1662 / 2014
- Published online by Cambridge University Press:
- 10 March 2014, mrsf13-1662-vv03-09
- Print publication:
- 2014
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Lightweight porous foams have been of particular interest in recent years, since they have a very unique set of properties which can be significantly different from their solid parent materials. These properties arise from their random porous structure which is generated through specialized processing techniques. Their unique structure gives these materials interesting properties which allow them to be used in diverse applications. In particular, highly porous Al foams have been used in aircraft components and sound insulation; however due to the difficulty in processing and the random nature of the foams, they are not well understood and thus have not yet been utilized to their full potential. The objective of this study was to integrate experiments and simulations to determine whether a relationship exists between the relative density (porous density/bulk density) and the mechanical properties of open-cell Al foams. Compression experiments were performed using an Instron Universal Testing Machine (IUTM) on ERG Duocel open-cell Al foams with 5.8% relative density, with compressive loads ranging from 0-6 MPa. Foam models were generated using a combination of an open source code, Voro++, and MATLAB. A Finite Element Method (FEM)-based software, COMSOL Multiphysics 4.3, was used to simulate the mechanical behavior of Al foam structures under compressive loads ranging from 0-2 MPa. From these simulated structures, the maximum von Mises stress, volumetric strain, and other properties were calculated. These simulation results were compared against data from compression experiments. CES EduPack software, a materials design program, was also used to estimate the mechanical properties of open-cell foams for values not available experimentally, and for comparison purposes. This program allowed for accurate prediction of the mechanical properties for a given percent density foam, and also provided a baseline for the Al foam samples tested via the IUTM method. Predicted results from CES EduPack indicate that a 5.8% relative density foam will have a Young’s Modulus of 0.02-0.92 GPa while its compressive strength will be 0.34-3.37 MPa. Overall results revealed a relationship between pores per inch and selected mechanical properties of Al foams. The methods developed in this study can be used to efficiently generate open-cell foam models, and to combine experiments and simulations to calculate structure-property relationships and predict yielding and failure, which may help in the pursuit of simulation-based design of metallic foams. This study can help to improve the current methods of characterizing foams and porous materials, and enhance knowledge about theirproperties for novel applications.
THE MECHANICAL PROPERTIES OF POROUS ALUMINUM USING FINITE ELEMENT METHOD SIMULATIONS AND COMPRESSION EXPERIMENTS
- Max Larner, Lilian P. Dávila
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1580 / 2013
- Published online by Cambridge University Press:
- 06 June 2013, mrss13-1580-bbb09-05
- Print publication:
- 2013
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Lightweight porous metallic materials are generally created through specialized processing techniques. Their unique structure gives these materials interesting properties which allow them to be used in diverse structural and insulation applications. In particular, highly porous Al structures (Al foams) have been used in aircraft components and sound insulation; however due to the difficulty in processing and random nature of the foams, they are not well understood and thus they have not yet been utilized to their full potential. The objective of this project was to determine whether a relationship exists between the relative density (porous density/bulk density) and the mechanical properties of porous Al structures. For this purpose, a combination of computer simulations and experiments was pursued to better understand possible relationships. A Finite Element Method (FEM)-based software, COMSOL Multiphysics 4.3, was used to model the structure and to simulate the mechanical behavior of porous Al structures under compressive loads ranging from 1-100 MPa. From these simulated structures, the maximum von Mises stress, volumetric strain, and other properties were calculated. These simulation results were compared against data from compression experiments performed using the Instron Universal Testing Machine (IUTM) on porous Al specimens created via a computernumerically-controlled (CNC) mill. CES EduPack software, a materials design program, was also used to estimate the mechanical properties of porous Al and open cell foams for values not available experimentally, and for comparison purposes. This program allowed for accurate prediction of the mechanical properties for a given percent density foam, and also provided a baseline for the solid Al samples tested. The main results from experiments were that the Young’s moduli (E) for porous Al samples (55.8% relative density) were 15.9-16.6 GPa depending on pore diameter, which is in good agreement with the CES EduPack predictions; while the compressive strengths (σc) were 155-185 MPa, higher than those predicted by CES EduPack. The results from the FEM simulations using 3D models (55.8% relative density) revealed the onset of yielding at 13.5-14.0 MPa, which correlates well with CES EduPack data. Overall results indicated that a combination of experiments and FEM simulations can be used to calculate structure-property relationships and to predict yielding and failure, which may help in the pursuit of simulation-based design of metallic foams. In the future, more robust modeling and simulation techniques will be explored, as well as investigating closed cell Al foams and different porous geometries (nm to micron). This study can help to improve the current methods of characterizing porous materials and enhance knowledge about their properties for alternative energy applications, while promoting their design through integrated approaches.
Enhancing Materials Research Through Innovative 3D Environments and Interactive Manuals for Data Visualization and Analysis
- Claudia Flores, Teenie Matlock, Lilian P. Dávila
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1472 / 2012
- Published online by Cambridge University Press:
- 11 July 2012, mrss12-1472-zz01-03
- Print publication:
- 2012
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Spatial intelligence plays an important role in the success of nanoscience students specific to their visual ability to perceive structures in three dimensions. The NSF-funded IDEAS project makes use of a unique interactive 3D visualization system, based on immersive environment technology, for research and learning in Materials Science and Engineering (MSE) at UC Merced. In order to determine the effectiveness of the immersive system on nanoscience learning, a pilot project was conducted with undergraduate students, which showed the success of immersive systems in the science learning process. Overall, the immersive environment provided complete control in the construction and analysis of carbon-based nanostructure models. Results also showed the 3D visualization system benefited students with low spatial abilities. To facilitate a better understanding of the structure and properties of nanostructures, the IDEAS project has recently been expanded to allow accelerated simulations for materials research. It is important to integrate these new applications into undergraduate level courses in order to strengthen materials science education, recruit and retain future students, and to adapt modern technologies for future materials science educators. The expansion of the IDEAS project relies on the flexibility of this system to serve as a research tool as well as an innovative resource for science education. To adapt the 3D visualization and computing system and help engage students early in engineering research, our research group gathered practical technical documentation geared towards education of science users, based on both Cognitive Science and MSE Education (MSE-Ed) research. The work presented here involves developing educational resources through the design of audio-visual manuals for effective nanoscience learning. The manuals are being created using commercial software to produce interactive electronic books (ebooks). During the planning of the audio-visual manuals, we discovered that it is imperative to provide adequate educational tools as well as efficient guiding principles for the large number of visual, inductive, and active learners in general engineering education. This interdisciplinary project combines fundamental concepts from materials science and cognitive science, particularly project-based learning and active processing, while considering the concepts of overloading, and the unreliability of natural language, among other topics. This investigation will serve society by enhancing materials science research and education, as well as influencing engineering, chemistry, computer science and cognitive science fields, among others.
The Emergence of Immersive Low-Cost 3D Virtual Reality Environments for Interactive Learning in Materials Science and Engineering
- Benjamin N. Doblack, Claudia Flores, Teenie Matlock, Lilian P. Dávila
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1320 / 2011
- Published online by Cambridge University Press:
- 25 March 2011, mrsf10-1320-xx04-01
- Print publication:
- 2011
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Materials science is an interdisciplinary field that examines the structure-property relationships in matter for its applications to many areas of science and engineering. Providing a means for intuitive development of understanding of these relationships by young learners and university undergraduates alike is critical. The effectiveness of an immersive low-cost 3D virtual reality (VR) environment was evaluated during a pilot study sponsored by the Center of Integrated Nanomechanical Systems (COINS) program. The 3D VR environment involves the use of a specialized display, sensors, computers, and immersive visual technology equipment. In collaboration with Cognitive Science investigators, our research focused on understanding the impact of the 3D VR environment on the visual ability to perceive structures in three dimensions and on quantifying the learning of COINS participants. The premise was to measure the learning of undergraduate participants in activities designed to evaluate the quality of the learning environment. Our investigation consisted of three stages in which participants learned about carbon nanotubes (CNTs) via traditional methods, physical models and virtual models. Traditional methods (2D projection graphs) were not appealing to participants and did not facilitate depth perception. Physical (ball-and-stick) models motivated participants by allowing interactivity but bond distance/angle measurements were tedious. Virtual models (3D models) offered complete manipulation, real-time measurements and the capability of mimicking realistic atomic forces (attractive/repulsive), giving the user a better insight into the structure of CNTs compared to previous methods. While immersive environments offer virtual models with some of the same benefits of physical models, it is the extended features (e.g. accurate distance representation, computer simulations capability and analysis tools for further investigations) that suggest such environments as effective learning tools for materials science education. Preliminary data analysis suggests that highly accurate perception of a molecular structure is facilitated by the use of immersive environments in which the operator may manipulate and measure important intrinsic information about the structure. Moreover, computer simulations of materials are of great scientific interest for technological progress. We are presently working on the development of the immersive 3D VR environment to perform atomistic simulations to enable scientists to perform accelerated calculations to solve problems with performance enhancements over conventional methods. Another important value in the immersive 3D VR environment lies in its expanded use for multi-disciplinary research, influencing structure-dependent applications, science learning, and design of nanodevices in fields such as materials science, chemistry, engineering, cognitive science, nanotechnology, and computer science among others.