BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Vít Průša (Mathematical Institute\, Faculty of Mathematics and Physics\, Charles University) DTSTART:20241002T070000Z DTEND:20241002T080000Z DTSTAMP:20260422T122225Z UID:MathMAC/14 DESCRIPTION:Title: Negative thoughts on negative mass\nby Vít Průša (Mathematical Ins titute\, Faculty of Mathematics and Physics\, Charles University) as part of Modelling of materials - theory\, model reduction and efficient numeric al methods (UNCE MathMAC)\n\n\nAbstract\nThe concept of effective mass is frequently used for simplification of complex models. It i claimed that in the case of wave transmission analysis of some metamaterials the correspo nding effective mass can be frequency dependent\, negative and it may not even be a scalar quantity. These findings have even led some authors to su ggest that Newton's second law needs to be modified within the context of classical continuum mechanics. While there is nothing wrong with the mathe matical procedures used to reach these conclusions\, the accompanying phys ical interpretation thereof is absurd. We show that the puzzling concept o f negative mass can be easily eliminated provided that we model the corres ponding metamaterials using an effective constitutive relation. The effect ive constitutive relation is a rate-type constitutive relation\, and the s imple models we study give a clue how to design a non-trivial effective ra te-type constitutive relation that is conservative\, that is\, possessing an associated conserved energy depending on the force/stress and its time derivatives. In short\, the rate-type constitutive relations obtained in o ur study might be seen as a revival of hypoelastic materials.\n LOCATION:https://researchseminars.org/talk/MathMAC/14/ END:VEVENT END:VCALENDAR