Firehole Products
Partner Products
"Firehole offers one of the most impressive and unique methods of composite evaluation we've seen - Helius:MCT™ - a product that lets us see exactly how composites perform under extreme loads. Tools like this allow us to maximize performance and optimize weight while still maintaining safety margins."
Mark Bishop
Senior Design Engineer
Farr Yacht Design
"A simple, robust and predictive simulation tool, able to accurately identify the failure and the post-failure behavior of general composite structure was an analyst's dream until now. The innovative Firehole multi-scale approach provides an outstanding value to our customers because of its proven effectiveness and sound physical basis."
Simone Ragionieri,
SmartCAE General Manager
"Helius:MCT provides a unique and powerful analysis toolset. The integration with ABAQUS is seamless and user-friendly. The increased resolution of material failure mechanisms results in the ability to more efficiently optimize composite structures."
Christopher T. Key
Applied Technologies Group,
Hi-Test Laboratories, Inc.
Products 
Multiscale Analysis for Woven Composites
A key functionality of Helius:MCT is multiscale analysis for woven composites. 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, 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. 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.
Comparison of load-displacement curves predicted using finite element analysis with experiment [7].
The graph shows a quantitative comparison of the load-displacement curves from model results, with experimental results reported by Ahn et al. [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.