This focus area develops a Smoothed Particle Hydrodynamics (SPH)–based computational framework to study crack initiation and propagation in ductile, brittle, and composite materials under high-velocity impact. Cracks evolve using a pseudo-spring analogy that links SPH particles; these springs weaken and break based on damage accumulation, allowing cracks to form and propagate dynamically without artificial enrichment or particle-splitting. The framework effectively captures shear plugging, fragmentation, and conoid fracture patterns in impacted plates, and its predictions show strong agreement with experimental observations.

Figure: Failure in metallic and ceramic plates due to projectile impact

Relevant Papers:

• Islam, M.R.I., Chakraborty, S., Shaw, A. and Reid, S., "A Computational Model for Failure of Ductile Material Under Impact", International Journal of Impact Engineering, 108, 334-347, 2017. (doi)
• Chakraborty, S., Islam, M.R.I., Shaw, A. Ramachandra L.S. and Reid, S.R., "A Computational Framework for Modelling Impact Induced Damage in Ceramic and Ceramic-Metal Composite Structures", Composite Structures, 164, 263-276, 2017. (doi)

This research focuses on bridging atomistic and continuum scales to understand fracture and plasticity from a fundamental perspective. A sequential multiscale method couples molecular dynamics (MD) simulations with SPH to accurately simulate material behaviour under stress. MD provides the nonlinear stress-strain response and equation of state, which are directly embedded into the SPH solver. This ensures that continuum-scale predictions retain fidelity to atomic-level mechanisms, particularly for materials like graphene under various notch orientations and loading conditions.

Figure: Multigrained graphene sheets, stress-strain response, and crack propagation in different notch orientations.

Relevant Papers:

• Islam, M.R.I., Ganesh, K.V. and Patra, P.K., "On the Equivalence of Eulerian Smoothed Particle Hydrodynamics, Total Lagrangian Smoothed Particle Hydrodynamics and Molecular Dynamics Simulations for Solids", Computer Methods in Applied Mechanics and Engineering, 391, 114591, 2022. (doi)
• Bhattacharyya, S., Islam, M.R.I. and Patra, P.K., "Multiscale modelling of fracture in graphene sheets", Theoretical and Applied Fracture Mechanics, 122, 103617, 2022. (doi)

This area addresses the dynamic interaction between deformable structures and fluid forces, particularly under high-speed or underwater conditions. A fully coupled SPH framework models both fluid and structural phases—fluid using weakly compressible SPH and solids using a pseudo-spring SPH model. The δ-SPH formulation improves pressure accuracy, while fracture in the solid phase is handled via spring failure based on a threshold damage indicator. The framework effectively simulates large deformations, crack propagation, and fracture dynamics, with validation against benchmark experiments.

Figure: Deformation of elastic structures under hydrodynamic loading.

Relevant Paper:

• Islam, M.R.I., "SPH-based framework for modelling fluid-structure interaction problems with finite deformation and fracturing", Ocean Engineering, 294, 116722, 2024. (doi)