#video on colloidal crystal #materials (#metamaterials like opal), just an #interview with Sharon Glotzer of UMich
on 02024-12-04#video about #optics microlens arrays as a “key to our sci-fi future”. Nanometer-sized pillars on a silicon wafer; company is Metalenz. Video (by "Freethink") is pretty clueless and gives no real information about #metamaterials except that they can do polarization imaging. Lots of talking-head filler. #Plonk
on 02024-09-17code for #deep-learning of #truss #metamaterials
on 02022-02-09#deep-learning of #truss #metamaterials to instantly generate designs with a given anisotropic #stiffness tensor. #CC-BY
on 02022-02-09#pdf #paper on #mechanical #flexure #metamaterials
on 02016-10-04This 2008 #paper on “Design for additive manufacturing of cellular structures” has the best diagram I’ve ever seen of the octet truss (aka fcc crystal structure). They’re doing #topology-optimization of #metamaterials using “particle swarm optimization”, which I hadn’t heard of before, but apparently it’s a cooperative variant of genetic algorithms. They’re apparently doing this to optimize “morphing airfoils”, but their final results are not very impressive.
on 02016-09-22#metamaterials (“mesostructures”) via #3D-printing in order to achieve customized and graded elasticity. Still, they seem to just be replacing struts with coils, mostly, although there are some other #flexures mentioned. #manufacturing
on 02016-09-22#PDF #paper on using multi-objective #topology-optimization for #metamaterials (“finite periodic structures”) for things like stiff heatsinks (solid #heat-exchangers). Cool pictures. #toread
on 02016-09-205-page #pdf #paper about negative-refractive-index #metamaterials and superlenses and so on.
on 02015-11-16interesting stuff about waves propagating through strongly nonlinear #metamaterials (with negative #stiffness, actually very similar to the negative-stiffness structures being sold now to isolate turntables).
on 02015-08-14Dennis Kochmann’s #metamaterials lab at #Caltech, which participated in the work on giant-#stiffness barium-titanate/tin composite. (Did Sofia work in his lab? She was analyzing perovskite behavior under stress when I met her.) Huge list of publications on giant-stiffness materials.
on 02015-08-14Jaglinski, Kochmann, Stone, and Lakes 2007. A giant-#stiffness metamaterial of 10% barium titanate particles dispersed in a tin matrix with a Young's modulus of several TPa, greater than that of diamond at 1TPa, and more than an order of magnitude greater than that of the components (100 and 50 GPa); but only within a critical temperature range of about 58–59°. “The constraint [of the expansion of the inclusions by the matrix] stabilizes the negative bulk modulus (inverse compressibility) of the inclusions. This negative modulus arises from stored elastic energy in the inclusions, in contrast to periodic composite #metamaterials that exhibit negative refraction by inertial resonant effects.” Also note that this doesn’t help with shear (e.g. torsion) stiffness, and that their materials decayed after thermal (and load?) cycling, though they suggest that using a stronger matrix would help.
on 02015-08-14This is the actual Nicolaou and Motter 2012 paper on negative-#stiffness #metamaterials. They allude to giant-stiffness metamaterials in one of their references.
on 02015-08-14Another #abstract from Nature Materials on negative-compressibility or negative-#stiffness #metamaterials.
on 02015-08-14#Abstract of “Mechanical #metamaterials with negative compressibility transitions” (i.e. negative #stiffness, although they contrast it in figure 1). This is Nicolaou and Motter 2012.
on 02015-08-14this #paper about muscle myosin folding mentions “negative #stiffness at the point where all cross-bridges collectively flip... Similar mechanical behavior has been recently artificially engineered in #metamaterials by drawing on the #Braess paradox ... the mean-field type coupling in such materials is achieved via parallel connections with multiple shared links.” The references given are Cohen & Horowitz 1991 (the paper with the springs and strings) and Nicolaou and Motter 2012 in “Nat Mater”, which I guess is “Mechanical metamaterials with negative compressibility transitions” in Nature Materials.
on 02015-08-14I wonder if #Braess’s Paradox is applicable to negative-#stiffness #metamaterials? Braess’s original formulation was, "an extension of the road network may cause a redistribution of the traffic that results in longer individual running times”, but I’m pretty sure I’ve seen this in the form of a mobile that hangs higher after you cut a thread in it.
on 02015-08-14Very brief negative-#TCE #metamaterials introduction.
on 02015-08-12A #popsci explanation of negative-#stiffness #metamaterials or structures, with an #interview.
on 02015-08-12A #paper on negative-#stiffness #metamaterials (“structures”) through “constrained bistable structures” #3D printed in nylon with #SLS. The figures are at the end. Related to #Merkle’s buckling-spring #mechanical logic.
on 02015-08-12A company promoting negative-#stiffness #metamaterials (or “mechanisms”) for #vibration isolation, replacing air tables.
on 02015-08-12“By incorporating constituents of negative #stiffness [elasticity] in structures and composites, one can attain extremely high values of mechanical damping, stiffness considered as a viscoelastic modulus, of thermal expansion, or of other physical properties. Negative stiffness is of itself usually unstable but can be stabilized by incorporation in heterogeneous structures or composites.” #metamaterials #bibliography
on 02015-08-12A short, clear-seeming #paper about #metamaterials with tunable #TCE. #toread
on 02015-08-12Roderic Lakes’s #bibliography on composite #metamaterials that can have either negative or colossal thermal coefficients of expansion (#TCE) even if their components don’t. This is potentially useful for making nanometrically-precise #flexures without resorting to exotic materials like #Invar or maybe even metals.
on 02015-08-12