Experimental Determination of Cohesive Zone Models for Epoxy Composites
- 494 Downloads
In this work, a new test set-up was applied in order to determine cohesive zone models experimentally. A high speed camera in combination with a digital image correlation system was used to record the local displacements enabling the detailed determination of crack opening values. The J-Integral method was used to calculate the cohesive stresses. The analyzed materials were composites made of glass fiber reinforced epoxy resin layers. Two different specimen geometries and the difference between warp and weft of the glass fiber mats were analyzed. As the specimen geometry didn’t have a significant influence, the difference between warp and weft, regarded by the loading direction, lead to considerably different cohesive zone laws. The initial part, the linear increase to a maximum stress, was very similar, while the damage evolution was either exponential or bilinear in shape. In future work, the derived cohesive zone models will be used to perform finite element simulations on laboratory specimens and on component scale. Thus, by comparison to the measurement result, the cohesive zone models can be evaluated.
KeywordsFracture mechanics Cohesive zone model Digital image correlation J-Integral method Epoxy composite
The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the Kplus-program of the Austrian Ministry of Traffic, Innovation and Technology with contributions by the Institute of Material Science and Testing of Plastics, University of Leoben and AT&S GmbH. The PCCL is funded by the Austrian Government and the State Governments of Styria and Upper Austria.
- 9.Li VC, Ward RJ (1989) A novel testing technique for post-peak tensile behaviour of cementitious materials. In: Mihashi et al (eds) Fracture toughness and fracture energy. Balkema, Rotterdam, pp 183–195Google Scholar
- 12.Rice JR (1968) A path independent integral and the approximate analysis of strain concentration by notches and cracks. J Appl Mech 35:379–386Google Scholar
- 14.Turner CE (1980) The ubiquitous η factor. Fract Mech, 12th conference, ASTM-STP 700:314–337Google Scholar
- 15.Towers OL (1985) Tests for fracture toughness and fatigue assessment: a compilation of stress intensity, compliance, and elastic η factors. The Welding Institute, AbingtonGoogle Scholar