Modelling laser-material processing using the smooth particle hydrodynamics method

Zhong, Zhihao 2026. Modelling laser-material processing using the smooth particle hydrodynamics method. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Laser-material processing has increasingly been regarded as a promising technology due to its unique advantages, including its contactless nature, high flexibility, and capability for material manipulation with micrometre resolution. To understand the underlying physical phenomena and optimise processing parameters, numerical modelling and simulation are an important and practical approaches. Most of the existing numerical models of laser-material processing rely on mesh-based methods, such as the finite element and the finite volume methods. Although these approaches can achieve high-fidelity results, they may not be well-suited for simulating processes that involve free surface flow, multiple phase interfaces, and large deformations. In contrast, Smooth Particle Hydrodynamics (SPH), a mesh-free and Lagrangian-based method, offers distinct advantages for modelling such complex behaviours. Nevertheless, the potential of SPH modelling for laser-material processing has not yet been fully explored, and SPH-based simulations in this field remain at a relatively early stage of development. Consequently, this PhD study aims to make contributions in this field by pursuing two main research objectives. The first objective is to develop 2D and 3D weakly compressible SPH (WCSPH) solvers for laser-material processing based on the existing open-source ‘SPHysics’, incorporating the key thermal and fluid dynamic phenomena involved in these processes. Enhanced numerical approaches and corresponding correction schemes were developed and integrated into the framework to mitigate potential numerical errors, particularly associated with truncated kernel support. Furthermore, a 2D geometry-based scheme for modelling surface tension was developed, and its accuracy was evaluated through comparisons with conventional SPH formulations. To enable numerical investigations of wider underlying physical phenomena, a solidification model based on modified cellular automaton rules was also proposed to simulate solidification microstructure in a fully mesh-free computational domain. Moreover, prior to performing laser-material processing simulations, a series of numerical validations were systematically carried out to verify the accuracy of the implemented thermal and fluid dynamics models, thereby ensuring the reliability of the developed 2D and 3D SPH solvers. The second objective involves applying the developed SPH framework to simulate and model specific areas of laser-material processing, namely laser ablation, laser texturing, laser polishing and laser powder bed fusion. These laser applications either lack SPH-based numerical studies or represent areas where existing SPH models require further improvement to achieve higher accuracy and deeper investigation. In the conducted simulations of laser-material processing, the temporal evolutions of the irradiated workpiece were presented, and the underlying physical phenomena, along with the resulting outcomes, were analysed. Furthermore, the predicted temperature related outcomes (such as temperature distribution, melt depth, and ablation depth) and thermo-fluid responses (such as laser-produced surface topography and surface roughness) were validated against experimental data reported in the literature. The generally good agreement observed between the SPH simulations and the published experimental data indicates that the developed SPH-based models can produce reason outcomes. Accordingly, they can be considered as potential tools for the research community to further analyse the physical phenomena and optimise processing parameters in laser-material processing.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Engineering
Uncontrolled Keywords:	1. Smooth Particle Hydrodynamics 2. Laser-material processing 3. Numerical modelling 4. Melt pool dynamics
Date of First Compliant Deposit:	8 July 2026
Last Modified:	09 Jul 2026 09:20
URI:	https://orca.cardiff.ac.uk/id/eprint/188071

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