Modeling of the Strain Rate Dependent Material Behavior of 3D-Textile Composites with Production and Operational Defects

Abstract

This paper concerned with modeling of the strain rate dependent material behavior of 3D-textile composites with simultaneous consideration of production and operational (e.g. pores or fatigue damage) defects. Therefore an additive model in the sense of continuum damage mechanics was introduced. For the model validation extensive experimental tests on glass non-crimp fabrics reinforced epoxy (GF-NCF/EP) composites are performed. The focus is put on the influence of production and fatigue related pre-damage under subsequent highly-dynamic tensile loading. The theoretical studies shows a good coincidence with the experimentally results

Influence of voids and impact damage on the fatigue behaviour of large scale composites

“…The comparison of coupon tests with multiaxial tests on stringer stiffened panels showed the behaviour of internal damages as voids or impacts have already been studied thoroughly on the coupon level [6][7][8][9][10][11][12][13][14][15][16]. However, a final verification on its influence on the level of panels is necessary, as further influencing factors by specific panel geometry and design (stiffeners) have to be considered.…”

“…However, the influence of the aforementioned defects when embedded in a composite panel cannot totally be predicted. Thus, the authors collaborated in a joint research project on the topic of glass fibre non-crimp fabric reinforced epoxy composites covering the range from coupons to large scale specimens [7][8][9][10][11][12][13][14][15][16].…”

“…The catastrophic failure starts from one of the delaminations caused by large accumulated voids. More detailed results on the influence of defects in the aforementioned material regarding its structural behaviour have been published [11][12][13][14][15][16].…”

Adjunctive Damage Model to Describe the Interaction of Different Defect Types in Textile Composites on the Strain-Rate-Dependent Material Behaviour

“…NCF-composites can be compromised by defects that arise during manufacture, like voids [3,4] and fibre misalignments [5][6][7]. However, defects can also occur during product use, such as fatigue [8][9][10] or impact [11][12][13]-induced cracks (further on referred to as service-related defects).…”

“…Investigations on the influence of voids on the strain-rate-dependent material behaviour of FRP have been presented by the author in [28]. The first approaches for modelling the strain-rate-dependent deformation behaviour have been published for glass-fibrereinforced thermoplastics [10,48,49] and thermosets [8,50,51]. Potentially existing defects due to previous damage caused by service loads are only considered in [10].…”