Research Projects

Fracture behaviour in composite materials is governed by a complex interplay between microstructural characteristics, the coalescence of microcracks that leads to crack nucleation, and propagation. Polymer-based composites, because of their inherent heterogeneity and rate-sensitive behaviour, offer unique opportunities to design systems with high-energy dissipation and delayed failure. They have become essential materials in advanced engineering sectors such as aerospace, marine, automotive, and civil infrastructure, primarily due to their high specific strength and stiffness, low density, and excellent fatigue and damping characteristics. Traditional strength-based failure models, which treat composites as homogeneous materials, are limited in their ability to distinguish between the diverse failure mechanisms that occur within individual constituents. These conventional criteria typically conceptualise failure as a singular event, without taking into account the explicit influence of fibre architecture, fibre distribution, or the nature of the matrix-fibre bond on the orientation and evolution of crack surfaces. As a result, such models cannot adequately capture critical phenomena such as the effect of ply thickness on transverse cracking, nor can they analytically characterise local stress states or differentiate between crack initiation and propagation processes. Recent advances in phase-field fracture modelling, including anisotropic and micromechanics-informed formulations, have enabled improved prediction of orientation-dependent crack growth. However, these models largely neglect the size effect, which becomes critical when material microstructural dimensions become comparable to the structural geometry -- such as in ultra-thin laminates or highly heterogeneous systems. The proposed research addresses this gap by introducing a microstructure-informed nonlocal phase-field model that integrates key material features such as material length scale, orientation, composition, defect morphology and residual stresses in a thermodynamically consistent micropolar continuum mechanics formulation. The research aims to establish a robust, experimentally validated simulation–testing workflow that will drive fracture prediction in polymer composites from phenomenological modelling to the first-principle-based prediction. The work plan includes four consistently interconnected components: (1) theoretical formulation of a micropolar phase-field model embedded with physically meaningful microstructural descriptors; (2) multi-scale fracture testing of pure polymers, layered systems, and particle-reinforced composites using advanced imaging (DIC, SEM) and measurement tools; (3) staged implementation and calibration of the model to simulate size effects, interfacial damage, and microcrack evolution; and (4) a tightly integrated experiment–simulation feedback loop for iterative refinement, parametric sensitivity analysis, and validation. This proposal not only addresses a fundamental gap in the mechanistic understanding of fracture in polymer composites but also establishes a predictive modelling infrastructure that is modular, scalable, and extendable. The project will yield an open-access simulation tool and validated datasets that serve as virtual experimental tools for industrial design and material qualification. In doing so, this project supports the national drive toward advanced materials innovation by enabling the design of lighter, tougher composites through rigorous scientific insight. The outcomes are relevant to high-performance applications in defence, energy, and infrastructure, while also offering opportunities for intellectual property generation and technology transfer.