Hysteresis measurements on bead foams: Creation of a model to simulate the mid strain in dynamic fatique
Bead foams consist of many foamed beads welded together. One advantage of bead foams is, it is comparatively simple to produce light weight parts with complex geometry. The density of these parts can be varied within a wide range, whereby the mechanical properties can be specifically adapted to the particular application.
Expanded polypropylene (EPP), as a partially crystalline bead foam, and expandable polystyrene (EPS), as an amorphous bead foam, are currently the most important construction materials and are often subjected to static loads. Bead foams, however, are increasingly pressing for application areas where dynamic stress situations prevail over a long period of time. Examples are shock absorbers, roof rails and arm rests made from EPP in the car.
The particular morphology of the bead foam is a challenge for the prediction of the mechanical properties under dynamic load. Bead foams consist of a complex network of welded beads and cavities (so-called gussel). The mechanical properties of the molded part are also determined by the individual properties of the foamed beads but also by the welding of the beads. Individual beads consist of cell walls and struts that can buckle, bend or even break under dynamic loading. Enclosed gas thereby also influences the stiffness of the bead as a function of the degree of deformation as well as the deformation rate.
The aim of this work is, for EPS and EPP with same densities, the acquisition of the hysteresis curves under fatigue loading with varying mid-stresses and amplitudes and Finding suitable phenomenological models for the prediction of the changes in the midstrain.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Dynamic fatigue, Bead foam, Hysteresis measurement, Simulation of mid-strain
Institute / chair: Fakultät für Ingenieurwissenschaften der Universität Bayreuth
Technical consultant for expert services: Professor Dr.-Ing. Volker Altstädt, Professor Dr.-Ing. Maik Gude
Publication year: 2019
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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