The rapid and cyclic deformation behavior of rigid polymer foams
The existing theoretical models of the structure of open cell and closed cell foams'are presented and evaluated. It will have particular regard to the estimates of the strength and elastic modulus underlying simplifying assumptions. It is shown that the basis of the calculation of the compressive strength so far, down failure by bending or buckling of the bars or walls is not usually met. The limits of using the stability criteria for the strength assessments are given. The existing model concepts are developed by applying the finite element method to the elastic deformation behavior of an idealized cell shape with variable mass density of the rods, nodes, and cell walls. This allows the real foam structure are largely approximated. The calculated elastic moduli show good agreement with experimental values of PU and PVC foams.
For dynamic studies on crosslinked and uncrosslinked PVC rigid foams train under-pressure and shear load, a measurement and evaluation method is developed based on analysis of hysteresis loops. As characteristics of the material fatigue, the strain range, the amount of the strain ratio, the damping factor, the loss of work, the slope of the middle curves of the hysteresis loops and the number of cycles to failure are considered.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Open cell, closed cell, rigid foam, PU, PVC, cyclic, rapid, creep, fatigue, rods, knots, hysteresis, damping
Institute / chair: Fakultät für Maschinenbau der Universität Karlsruhe (TH)
Technical consultant for expert services: Prof. Dr. rer. nat. Eckard Macherauch (Betreuer), Prof. Dr. rer. nat. Ottmar Vöhringer
Publication year: 1977
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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