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Failure on microscale of epoxy resin and composites - limits of continuum mechanical analysis on micro- and nanoscale

  • The problems of the limits of continuum mechanics are shown on some examples. The fiber-matrix debonding and subsequent crack propagation in fiber reinforced composites is studied. While Finite Element Analyses predict clear crack surfaces, either following the interface or bridging to the neighbouring fiber forming planes, the actual surfaces are very cliffy. Due to the much larger fracture surfaces and the completely different stress states on the cliffy fracture surfaces the continuum mechanical prediction is far from the actual local behaviour. The phenomenon of local high stresses which re much higher than the macroscopically measured strength of the material is also encountered in general fracture mechanics. The scale dependency of materials is shown on indentation tests conducted on different scales. From a continuum mechanical point of view it makes no difference if the indentation test is performed on a nano-, micro- or macroscale, because it is a matter of self-similarity.The problems of the limits of continuum mechanics are shown on some examples. The fiber-matrix debonding and subsequent crack propagation in fiber reinforced composites is studied. While Finite Element Analyses predict clear crack surfaces, either following the interface or bridging to the neighbouring fiber forming planes, the actual surfaces are very cliffy. Due to the much larger fracture surfaces and the completely different stress states on the cliffy fracture surfaces the continuum mechanical prediction is far from the actual local behaviour. The phenomenon of local high stresses which re much higher than the macroscopically measured strength of the material is also encountered in general fracture mechanics. The scale dependency of materials is shown on indentation tests conducted on different scales. From a continuum mechanical point of view it makes no difference if the indentation test is performed on a nano-, micro- or macroscale, because it is a matter of self-similarity. However, in nano- or microindentation tests on a pure polymer using e.g. a Berkovic indentor, the extremely high stress concentrations arising at the indentor tip are domination more or less the whole region around the indentor. In case of a macroscopical test, this zone covers only a small part of the material loaded by the indentor. Accordingly, the results of the different test cannot be scaled up.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Christian Marotzke
Koautoren/innen:Titus Feldmann
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:5 Werkstofftechnik
5 Werkstofftechnik / 5.0 Abteilungsleitung und andere
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:continuum mechanics; epoxy resin; fracture mechanics; large deformations; plasticity
Themenfelder/Aktivitätsfelder der BAM:Material
Veranstaltung:Second International Symposium on Directions in Damage and Durability of Composite Materials
Veranstaltungsort:Venedig, Italy
Beginndatum der Veranstaltung:18.06.2016
Enddatum der Veranstaltung:20.06.2016
Verfügbarkeit des Volltexts:Volltext-PDF im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:18.10.2016
Referierte Publikation:Nein