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Phase field predictions of microscopic fracture and R-curve behaviour of fibre-reinforced composites

Emilio Martínez Pañeda's picture

Dear iMechanicians,

I hope that the following work is of interest to you. We combine the phase field method with cohesive zone modelling to predict the fracture behaviour of fibre-reinforced composites across scales.

Wei Tan & Emilio Martínez-Pañeda. Phase field predictions of microscopic fracture and R-curve behaviour of fibre-reinforced composites. Composites Science and Technology 202, 108539 (2021)
https://www.sciencedirect.com/science/article/pii/S0266353820323290

We present a computational framework to explore the effect of microstructure and constituent properties upon the fracture toughness of fibre-reinforced polymer composites. To capture microscopic matrix cracking and fibre-matrix debonding, the framework couples a phase field fracture method and a cohesive zone model in the context of the finite element method. Virtual single-notched three point bending tests on fibre reinforced composites are conducted. The actual microstructure of the composite is simulated by an embedded cell in the fracture process zone, while the remaining area is homogenised to be an anisotropic elastic solid. A detailed comparison of the predicted results with experimental observations reveals that it is possible to accurately capture the crack path, interface debonding and load versus displacement response. The sensitivity of the crack growth resistance curve (R-curve) to the matrix fracture toughness and the fibre-matrix interface properties is determined. The influence of porosity upon the R-curve of fibre-reinforced composites is also explored, revealing a higher crack growth resistance with increasing void volume fraction. These results shed light into microscopic fracture mechanisms and set the basis for efficient design of high fracture toughness composites.

 

Comments

Hi, Prof. Emilio, very interesting and inspiring work!

I have 2 questions regrading on the modelling details for this work.

First of all, to capture the arbitrary crack trajectories you used the Phase field method in this paper. I'm very curious about how you implemented this method. Did you use the ABAQUS's built-in XFEM technique? If so, did you combine XFEM with the user subroutine UDMGINI? If not, which user subroutine did you employ?

Secondly, from the model presented in this work, I assume the voids were introduced and distributed in matrix by python/C++?... etc.. In terms of the size and distribution of voids, were they determined from experimental results? For instance, 80% of void's diameters were in range of 1 µm and 40% of voids were located on edges based on experimental results.  Or they were generated by some random algorithms?

Appreciate your kind guidance and elaboration!

 

 

Emilio Martínez Pañeda's picture

Dear Qiongyu, many thanks for your interest and kind words.

Regarding your questions:
1) Phase field fracture and X-FEM are two different methodologies. There are several ways of implementing phase field fracture into ABAQUS using user subroutines. Usually, one would use a user element (UEL) one. I have provided all my phase field codes on my website: www.imperial.ac.uk/mechanics-materials/codes/ and I will upload another one in the following days. They come with examples and documentation, so that you should be able to easily use them. But don't hesitate to drop me an e-mail if you have any questions.
2) The voids were introduced using a python script. They were randomly generated to reach a given void fraction. The size is inspired by the experimental literature, although a very broad range of void sizes has been reported. 

I hope this clarifies things. 
Kind regards,
Emilio

Can't thank you enough Prof. Pañeda​!

 

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