JEC COMPOSITES MAGAZINE - Issue #108 - October 2016 - 54

TECHNOLOGY simulation

a)
b)

Fig. 3: U-shaped beam test case: a) selected stress component in the third
direction; b) lifetime prediction result with model implemented in ESI's Virtual
Performance Solution

Material and composite lay-up
Multi-layered flatbed weft-knitted glass fibre/polypropylene composites made from three-dimensional textile reinforcements developed
by the Institute of Textile Machinery and High Performance Material
Technology (ITM) at TU Dresden ([4]) were considered. The textile
architecture and composite lay-up are shown in Figure 2.
The following tests were conducted to identify the material properties:
static tensile tests in different directions (longitudinal, transverse and
bias) and tensile-tensile fatigue tests with a load ratio R=0.1. Optical
microscope observations were also carried out. Several elastic properties were determined using analytical and numerical homogenization
methods (through-thickness elastic modulus and out-of-plane shear
modulus). The material properties are listed in Table 1, where subscripts 1, 2, and 3 stand for the warp, weft and thickness directions,
respectively.

Test case: simulating the lifetime of a composite structure
A U-shaped beam was selected as the test case for a composite structure simulation. The stress component in the third direction and the
lifetime prediction result are shown in Figure 3. The following boundary conditions were applied: pinned condition at both ends and cyclic
load along the line at the top surface. These boundary conditions result in a remarkable stress concentration in the middle of the structure
and a slight increase of stress at the end tips which bring out a finite life
of this structure.
Figure 4 shows a comparison of simulation and experimental data for
a six-ply composite laminate subjected to cyclic load in the warp direction. The model slightly underestimates the lifetime in the 102-103
cycles range, which is explained by the inclusion of static strength into
the data and by the presence of extensive inelastic deformations in this
range. However, it provides a safe design of the composite material.
The lifetime estimation is within the scatter band at a 10-90% probability of survival.

Conclusion
Static and fatigue modelling of composite structures was developed
by progressive damage simulation at the level of the equivalent (or

jec composites magazine / No108 October 2016

Fig. 4: Comparison
of test data with
simulation results
(VPS) for a six-ply
composite laminate
under a tension-tension cyclic load in the
warp direction

homogenized) ply and direct post-treatment analysis, respectively.
The progressive damage mechanisms can be modelled successfully
by taking into account the degradation of the material properties at
the mesoscopic scale. The implemented models, used in VPS (ESI's
Virtual Performance Solution software), showed a robust and considerably straightforward development procedure leading to the lifetime
estimation of structural components made from composite materials.
Verified on a simple test case, these proved their capacity for further
industrial development.
More information:
www.esi-group.com/software-solutions/
virtual-performance/virtual-performance-solution
http://tpcim.mines-douai.fr/
dmytro.vasiukov@mines-douai.fr
Acknowledgement
The research leading to these results received funding from the
European Union's Seventh Framework Programme FP7 under grant
agreement no.263159-1 (FP7 large-scale integrating collaborative project entitled "One-shot manufacturing on a large scale of 3D upgraded
panels and stiffeners for lightweight thermoplastic textile composite
structures" MAPICC 3D).
References
[1] Kaddour A.S., Hinton M.J. Maturity of 3D Failure Criteria for
Fibre-Reinforced Composites: Comparison Between Theories and
Experiments: Part B of WWFE-II. J Comp Mats 2013;47:925-66.
[2] Van Paepegem W. Fatigue models for woven textile composites
laminates. In: Valter C., Lomov S. V., editors. Fatigue Text. Compos.,
Woodhead Publishing Series in Composites Science and Engineering;
2015, p. 295-325.
[3] Virtual Performance Solution. Solver Notes Manual, ESI Group,
Paris, France. 2013.
[4] Cherif C., Krzywinski S., Diestel O., Schulz C., Lin H., Klug P., et al.
Development of a process chain for the realization of multilayer weft
knitted fabrics showing complex 2D/3D geometries for composite
applications. Text Res J 2012;82:1195-210.
[5] Thieme M., Böhm R., Gude M., Hufenbach W. Probabilistic failure
simulation of glass fibre reinforced weft-knitted thermoplastics. Compos Sci Technol 2014;90:25-31. doi:10.1016/j.compscitech.2013.10.011.

http://www.esi-group.com/software-solutions/vitual-performance/vitual-performance-solution http://tpcim.mines-douai.fr/

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #108 - October 2016