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Localizing Implicit Gradient Damage Based Modelling of Quasi-brittle Failure with Non-planar Cracks

B. Kaçmaz ∗ , İ. Özdemir

İzmir Institute of Technology, Faculty of Engineering, Department of Civil Engineering 35430, Urla İzmir, Turkey

∗ kacmabek@gmail.com

Keywords: quasi-brittle failure, damage mechanics, localizing implicit gradient damage Localizing implicit gradient damage (LIGD) is a gradient extended model which is equipped with a decreasing internal length scale with damage evolution, [1]. The model is thermodynami cally consistent and resolves the well-known problems of conventional implicit gradient damage (CIGD) model such as artificial diffusion of damage and erroneous predictions of failure initiation and propagation directions. So far, the effectiveness of the model has been demonstrated for two-dimensional quasi-brittle and three-dimensional ductile failure predictions with flat fracture surfaces. It is the aim of this contribution to assess the predictive capabilities of the model for three-dimensional quasi-brittle failures with non-planar cracks. To this end, localizing implicit gra dient model is embedded within a tetrahedral element formulation and implemented in commercial finite element package Abaqus through user element (UEL) subroutine. Skew notched prismatic and cylindrical torsion tests are modeled and capabilities of the model are assessed in terms of reaction force-displacement curves as well as the resulting crack surfaces, [2, 3]. Comparison of LIGD and CIGD predictions suggest that LIGD is superior than CIGD. Furthermore, as far as capturing the experimental results is concerned, it performs as good as other alternative modeling frameworks, e.g., mixed finite element formulations. References [1] Poh, L., Sun, G. (2017). Localizing gradient damage model with decreasing interactions, International Journal for Numerical Methods in Engineering, 110, 503–522. [2] D. Brokenshire, D. (1996) A study of torsion fracture tests, PhD Thesis, Cardiff University, United Kingdom. [3] Jefferson, A., Bennett, T., Hee, S. (2004) Three dimensional finite element simulations of fracture tests using the craft concrete model, Computers and Concrete 1 (3), 261–284.

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