Powders by design for additive manufacture through multi-scale simulations

Lead Research Organisation: University of Strathclyde
Department Name: Mechanical and Aerospace Engineering


The selective laser melting process is a promising large-scale additive manufacturing (or 3D printing) technique that allows for rapid production of prototypes, and lately for weight-sensitive/multi-functional parts at small volumes, with almost arbitrary complexity. The process builds the final parts layer-upon-layer by going through three main stages during each cycle: (1) deposition of a layer of fine powder (with a typical grain size of approximately 0.03 mm) on a fabrication surface to form a thin bed of powder, which is only marginally thicker than the average grain size; (2) a laser beam then melts the powder bed at specific locations, based on a 3D computer model of the final product; (3) the powder grains then fuse at those locations after cooling and solidifying to produce a layer of the final product.

In general, the selective laser melting process and additive manufacturing provide several advantages compared to conventional manufacturing techniques, such as greater design freedom, mass customisation and personalisation of products, production of complex geometries to improve performance and reduce labour costs, decreased wastage of precious materials, and new business models and supply chains. However, several challenges also exist. For example, a lack of understanding of the impact of powder grain shape on the underlying physical processes has forced the industry to require the majority of individual powder grains to be spherical. Such a stringent requirement increases the cost of powder (raw material), which consequently increases the production cost and hinders the development of new processes and the introduction of new materials. To address this issue, high-quality research software for process simulation is required to complement experiments and to enable new scientific discoveries and innovations.

The present research programme addresses this technological need by providing a novel computational package capable of modelling various complex physical phenomena underlying the selective laser melting process. To achieve this, high-performance computing will be used to track the motion of individual grains in the system, their interaction with a laser beam, and their phase changes. This computational package will then be used to uncover the complex impact of powder grain shapes on the absorption and scattering of a laser beam within the bed and the following rapid melting process. Furthermore, it is hypothesised that elongated or satellite-spherical particles with small inclusions on their surfaces (grain shapes which are commonly present in powders and are generally considered undesirable) can, in fact, improve the process if their number densities are carefully selected. This hypothesis will be tested here for the first time, which can greatly reduce the cost of raw materials for selective laser melting, which results in wider adoption of this enabling technology.

Planned Impact

This project will enable a step change in our ability to quantify the impact of particle shape on the selective laser melting (SLM) process by developing a novel computational tool, which will be seamlessly integrated into the framework of an open-source software suite. The impact of this work is far-reaching in the areas of economy, knowledge, people, and society.

The new powder optimisation concept allows the industry to substantially reduce powder cost (raw material), and consequently to reduce the cost of final parts through relatively cheap computer experiments. The newly developed software will provide a useful tool for technology users to improve current processes and to develop new additive manufacturing (AM) concepts, through reliable simulations and by avoiding expensive trial-and-error builds. This impact will materialise by (1) organising a final 2-day workshop; (2) developing a set of standards for modelling requirement and validation procedures for the SLM process; and (3) development of a project website.

Scientists and engineers concerned with granular flows, multiphase fluid dynamics, manufacturing, and aerospace will benefit from the new multi-scale computational package to model similar physical phenomena and engineering processes. To reach a wide-ranging audience, the scientific findings will be presented at prominent scientific conferences and in appropriate journals, a CPD course will be developed, and the software package will be released based on a combination of Academic and GNU Licenses.

This project will contribute to the training and education of UK engineers with the necessary multidisciplinary knowledge and skills to develop future infrastructures. This impact will be realised through incorporation of the findings in undergraduate and post-graduate courses at the University of Strathclyde and training of a highly skilled research associate.

Through this project, the PI will engage with the general public to explain the advantages, and more importantly, the challenges of AM and how the technology can impact people's lives through mass personalisation, on-demand manufacturing, and contribution to environmental protection by reducing wastage of precious materials. The PI will (1) communicate the scientific findings through the project website to general audiences; (2) participate in Images of Research competition; and (3) arrange out-reach activities to engage the general public and school children.


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Description Initial investigations were carried out which confirm the impact of laser radiation pressure on the dynamics of powder grains in Laser Additive Manufacturing (LAM). This provides evidence for one of the hypotheses laid out in the research proposal and justifies the use of high-fidelity computer simulations for a better understanding of LAM processes and to increase their technology readiness level (TRL).
Exploitation Route This award was transferred to the University of Edinburgh EP/T009128/2.
While active, a Route-to-Impact project was completed in collaboration with the Advanced Forming Research Centre (UK HVM Catapult) to use the laser modelling software developed during the current submission period for assessing laser-powder interaction in their Laser Metal Deposition (LMD) process. It is believed that the software tools that are being developed will be adopted by LAM device manufacturers as well as users including AFRC.
Sectors Aerospace

Defence and Marine

Digital/Communication/Information Technologies (including Software)


including Industrial Biotechology

Title Automatic image analysis of Angle of Repose test 
Description Enables us to automatically extract the static Angle of Repose from the experimental rig and the images taken from the test results. 
Type Of Material Computer model/algorithm 
Year Produced 2021 
Provided To Others? No  
Impact Contribution to the overall goal of the project to create digital twins of powders in AM and use powder characterisation data in high-fidelity AM process modelling. 
Title Digital twin for Angle of Repose (AoR) test 
Description A Python code to sample the space of Discrete Element Method (DEM) parameters using a Latin Hypercube sampling strategy and automatically prepare DEM simulations corresponding to AoR experimental test rig. Reduced orders models are then created automatically and the best parameters are found through an optimisation strategy. 
Type Of Material Computer model/algorithm 
Year Produced 2021 
Provided To Others? No  
Impact Enabled us to create a digital twin of Inconel 718 powder used for additive manufacture of parts for aerospace industries. The digital twin of the powder is imported to our DEM simulations which provides an accurate high-fidelity simulator of the spreading process in additive manufacture using Inconel 718. This process simulator is used for process optimisation, determination of the best powder characteristics and design optimisation of AM devices. 
Title Particle force-chain detection and analysis 
Description Based on the 3D particle contact force data obtained from DEM simulations, this C++ code uses advanced techniques including principal orthogonal decomposition to detect the force chains and to visualise them. 
Type Of Material Data analysis technique 
Year Produced 2021 
Provided To Others? No  
Impact Analysis of the simulation data to better understand the spreading simulation, contribution to the overall objectives of the project. 
Title Supplementary Material for: "Analysis of Radiation Pressure and Aerodynamic Forces Acting on Powder Grains in PBAM." 
Description The PDF file contains detailed information about the correlations and methods used to produce the data. All the data is made available in OriginPro format in a file named RadPressure_PowTec_AllDataGraphs. All columns are labeled and after opening, it should be straight forward to identify the data for each curve. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://pureportal.strath.ac.uk/en/datasets/f76ef4e9-8272-42d7-bf0f-4e3a4402abb5
Description Addition of Mie theory solver to The multi-platform lattice Boltzmann code (MPLB) for particle-EM wave interaction simulations 
Organisation Daresbury Laboratory
Country United Kingdom 
Sector Private 
PI Contribution Mie theory code has been developed within the multi-platform lattice Boltzmann code (MPLB) by using the oxford parallel library for structured mesh solvers (OPS) platform. This allows for modelling of particle interaction with electromagnetic fields in multiphase or granular systems.
Collaborator Contribution 1. Participation in project meetings and general communication and dissemination of the results through the industry network of the Hartree Centre and UKCOMES (Prof David Emerson, one day per year, and Dr Jianping Meng two days per year) 2. Providing technical support on the development of DL_MESO_LBE (Dr Chrysovalantis Tsinginos and Dr Jianping Meng, two hours per week.)
Impact Open-source software to be released (link provided)
Start Year 2021
Title ML-GLMT 
Description A multi-precision and object-oriented library for the calculation of internal and scattered electric and magnetic fields as well as various cross-sections resulting from the interaction of light beams (monochromatic) with small particles. The library is written using advanced C++17 features which allow the user to arbitrarily choose the required precision at compile time. The library is being actively developed and currently, Gaussian beams, as well as planar waves, can be modelled with no restriction on the particle diameter to wavelength ratio. Dependencies are Boost and Eigen libraries. For multi-precision support GMP, MPFR and MPC libraries are required. 
Type Of Technology Software 
Year Produced 2021 
Open Source License? Yes  
Impact Used in a Route-to-Impact project with Advanced Forming Research Centre, one of the UK's high-value manufacturing centres, to assess powder-laser interaction in their laser metal deposition process. 
Description Particles 2021 Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A research presentation entitled "Particle-scale Simulation of Powder Spreading in the Presence of Gas in Additive Manufacturing" was provided in the VII International Conference on Particle-Based Methods (PARTICLES 2021) organised on 4-6 October 2021, in Hamburg, Germany. Research on powder characterisation, digital twinning and spreading in AM was presented to a group of researchers, postgraduate students, academics and industrial practitioners.
Year(s) Of Engagement Activity 2021
URL https://congress.cimne.com/Particles2021/frontal/Objectives.asp
Description UK-China International Particle Technology Forum (Invited) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Research presentation entitled "Simulation of Powder-Based Additive Manufacturing Processes" provided in the UK-China International Particle Technology Forum 8 (PTF8) on 9-13 July 2021, in Dali, China. Research on powder characterisation, digital twinning and laser-powder interaction was presented to a group of researchers, postgraduate students, academics and industrial practitioners.
Year(s) Of Engagement Activity 2021
URL http://ptf8.csp.org.cn/?bust=1646736276505&sid=1842&mid=479&v=100