Helius:MCT™ Multiscale Analysis for Woven Composites
One of the primary features introduced by Helius:MCT 3.0 is woven composite functionality.
This permits the finite element user to model woven composite structures using the
same progressive failure methodology that has been successfully used for unidirectional
composite structures [1-4].
This is accomplished using what is known as three-constituent multicontinuum theory
(MCT) [5, 6]. This approach allows volume average constituent (fiber and matrix)
stresses to be extracted from homogenized composite stresses so that failure of
each constituent can be evaluated. If any failure is detected, the elastic properties
of the failed constituent are degraded and, correspondingly, the composite elastic
properties are appropriately degraded. As with unidirectional composites, this approach
is very computationally efficient, and the proprietary intelligent discrete softening
(IDS) method is used to ensure robust convergence.
Technology Demonstration
As an example of the capabilities of the woven composite functionality of Helius:MCT
3.0, we present results from a finite element progressive failure analysis of a
pin-loaded coupon in tension. Using geometries and material properties reported
by Ahn et al. [7], we modeled three different geometries of a pin-loaded coupon,
labeled ED10, WD20, and WD25. The composite laminate was a combination of woven
laminae and unidirectional laminae; all were carbon/epoxy. A tensile load was applied
via a pin in the hole of the coupon.
Composite failure states predicted by finite element analysis using Abaqus and Helius:MCT
3.0. Images on the left correspond to a failure state with matrix failure only.
Images on the right correspond to predictions of fiber failure in one or both tows
of the woven composite.
Our analysis predicted three different failure modes: shear out (ED10), net tension
(WD20), and bearing (WD25). Here we show the predicted failures in the coupons at
two different times: the images on the left correspond to a time when only fiber
failure is present, while the images on the right show fiber failure. The modes
shown in the images on the right are exactly the failure modes reported by Ahn et
al. for each coupon. The colors correspond to the failure states that are captured
in our progressive failure analysis. Not only does our analyses predict the correct
mode of failure, they also accurately capture the load-displacement behavior of
the coupons.
The graph shows a quantitative comparison of the load-displacement curves from model
results, with experimental results reported by Ahn et al. [7].
Comparison of load-displacement curves predicted using finite element analysis with experiment [7].
For the WD20 and WD25 coupons, the ultimate loads and displacements are in excellent
agreement with experimental values. The ED10 fails earlier than the experimental
results, both in displacement and load, but the results are still satisfying, given
that only standard test data was used and the exact nature of the contact conditions
was not known.
References
- [1] J. Mayes and A. Hansen, "A comparison of multicontinuum theory based failure
simulation with experimental results," Composites Science and Technology, vol.
64, Mar. 2004, pp. 517-527.
- [2] J.S. Mayes and A.C. Hansen, "Composite laminate failure analysis using
multicontinuum theory," Composites Science and Technology, vol. 64, Mar. 2004,
pp. 379-394.
- [3] E. Nelson, A. Hansen, and J. Mayes, "Failure analysis of composite laminates
subjected to hydrostatic stresses: A multicontinuum approach," Accepted as
part of the Second Worldwide Failure Exercise, 2009.
- [4] J. Mayes and A. Hansen, "Multicontinuum failure analysis of composite structural
laminates," Mechanics of Composite Material Structures, vol. 8, 2001, pp. 249-262.
- [5] C. Key, R. Six, and A. Hansen, "A three-constituent multicontinuum theory
for woven fabric composite materials," Composites Science and Technology, vol.
63, 2003, pp. 1857-1864.
- [6] R. Fertig, "An accurate and efficient method fo constituent-based progressive
failure modeling of a woven composite," Collected Proceedings: Advances in
Composite, Cellular, and Natural Materials, Seattle, WA: TMS, 2010.
- [7] H. Ahn, J-H Kweon, and J. Choi, "Failure of unidirectional-woven composite
laminated pin-loaded joints," Journal of Reinforced Plastics and Composites,
vol. 24, 2005, pp. 735-752.