A microstructure image-based numerical model for predicting the fracture toughness of alumina trihydrate (ATH) filled poly(methyl methacrylate) (PMMA) composites


Particulate reinforced polymeric materials are a class of materials which appear in numerous applications in our lives, such as in automotive parts, building materials and various consumer products. On a macroscopic level they appear as continuous materials but when examined on a smaller scale, the particulate reinforcement dispersed into the continuous polymeric matrix marks the crucial link between structure and mechanical performance.

The particles can have a wide size and shape distribution; they may be well dispersed in the polymeric matrix or agglomerated into localised regions. They could be well or poorly bonded to the continuous polymeric matrix. In addition, their relative amount by volume and the contrast in their properties in comparison to those of the matrix can greatly affect the composite’s bulk response.

We have developed a modelling methodology which considers all these parameters and provides accurate predictions of the composite’s bulk response, hence providing a powerful design tool for optimising the performance of these materials in their respective applications. In our study, we use microstructural images of such a composite – Alumina trihydrate filled poly(methyl methacrylate) – and we feed these into a Finite Element model of a representative material volume.

Our model is capable of simulating several failure micro-mechanisms and not only predicts well the modulus and the strength of the composite but also gives accurate estimates for the fracture toughness of the composite using a novel and simple approach, as a function of particle volume fraction and particle size. The estimation of the fracture toughness in particular from models has been a long-standing gap in the composites literature. For example, the model is able to predict the effect of crack arrest caused by larger particles associated with higher toughness, and the agglomeration of small particles leading to matrix cracking associated with lower toughness.

This work enables material manufacturers to cost effectively develop tougher, hence safer and more durable, particulate composites.

Authors: Ruoyu Zhang, Idris K. Mohammed, Ambrose C. Taylor, Maria N.Charalambides

Published in: Composites Part B: Engineering, Volume 232, 1 March 2022, 109632