Discrete element simulations are employed to study the influence of static friction on the mechanical response of assemblies of nonbonded semiflexible fibers during cycles of isostatic compressions and releases. Hysteresis is evidenced during the cycles and is related to the sensitivity of the frictional contacts on normal forces. Nonzero frictions are shown to decrease both the packing density and caging number but do not affect the critical exponents that characterize the pressure and bulk and shear moduli. Assemblies of frictionless fibers are found fragile in the sense that they resist isostatic compressions but have a zero shear modulus at all densities.
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http://dx.doi.org/10.1103/PhysRevE.80.016115 | DOI Listing |
Materials (Basel)
August 2024
J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX 77840, USA.
ACS Omega
July 2024
Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States.
Efficient carbon capture requires engineered porous systems that selectively capture CO and have low energy regeneration pathways. Porous liquids (PLs), solvent-based systems containing permanent porosity through the incorporation of a porous host, increase the CO adsorption capacity. A proposed mechanism of PL regeneration is the application of isostatic pressure in which the dissolved nanoporous host is compressed to alter the stability of gases in the internal pore.
View Article and Find Full Text PDFMaterials (Basel)
April 2024
Department of Mechanical Engineering, École de Technologie Supérieure, Montreal, QC H3C 1K3, Canada.
This study applies numerical and experimental techniques to investigate the effect of process parameters on the density, structure and mechanical properties of pure tungsten specimens fabricated by laser powder bed fusion. A numerical model based on the simplified analysis of a thermal field generated in the powder bed by a moving laser source was used to calculate the melt pool dimensions, predict the density of printed parts and build a cost-effective plan of experiments. Specimens printed using a laser power of 188 W, a scanning speed of 188 mm/s, a hatching space of 80 µm and a layer thickness of 30 µm showed a maximum printed density of 93.
View Article and Find Full Text PDFPhys Rev E
March 2024
Graduate Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut 06520, USA.
Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that the attractive systems quenched to temperatures below the glass transition T≪T_{g} and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions.
View Article and Find Full Text PDFMaterials (Basel)
February 2024
College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
In this work, a new use of mixed Ti-6Al-4V powder, consisting of the retained powder after screening for additive manufacturing and the recycled powder after multiple printing, has been exploited. The powder mixture has been hot-isostatically-pressed (HIPed) at 930 °C/120 MPa for 3 h to reach full density. The hot deformation behavior of the as-HIPed powder compacts were investigated through isothermal compression tests, kinetic analyses, and hot processing maps.
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