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Phd in Numerical Simulation of Particle Stress and Fracture using FEMDEM: Application to Process Catalysts, Imperial College UK

Johnson Matthey CASE/EPSRC PhD Studentship Award

Industrial and Scientific Context: Currently Johnson Matthey (JM) manufactures a wide range of particulate catalysts (pellets, extrudates, granules) used in packed bed or tubular reactors. Improved understanding of the mechanical stresses to which these particles or pellets are subjected during initial filling/loading and while in service as solid grains that form the skeleton of the particulate catalyst would be beneficial to developments in catalyst shape and specification. Catalysts specifications are typically based on a simple uni-axial compression test ("crush strength"). This test, while assuring consistency of product does not adequately represent the conditions within a reactor where the catalyst particles are locally subjected to very different stresses.

The Department of Earth Science and Engineering at Imperial College has developed a 3D code based on the combined Finite-Discrete Element Method (FEMDEM), see These codes allow not only particle flows to be simulated for moving particles (the DEM part) but they also allow detailed stress calculations to be undertaken on any complex particle shapes and complex structures (such as packed beds) by meshing the interior of the solid (the FEM part). This code therefore offers the prospect in the long term of simulating stresses during catalyst loading and in service. This capability would promote the ability to more realistically test catalyst mechanical strength and in the development/innovation of new catalyst shapes for many applications as well as develop more appropriate strength tests.

This studentship links JM’s future needs with Imperial’s excellence award winning AMCG research group. Implementing fracture in the 3D multi-body FEMDEM code that is capable of capturing packing processes with great accuracy is still very much a "work in progress" and this project will develop and validate certain aspects of the code that are relevant to JM's interests. For example, the research will reveal how force and stress chains form within packed beds or packed tubes and how different pellet shapes and strengths contribute to improved catalyst performance indicators. The code has the capability and the project has the scope for new pellet designs to be investigated.

The student will also have a unique opportunity to work at JM’s laboratories on pellet preparation as well as strength and fracture studies to validate existing 2D models and support the development and validation of the 3D fracture models. The aim would be to compare laboratory measurements at JM with the equivalent FEMDEM models to examine particle stresses and fractures e.g. in a system with a small number of particles in a tubular container. 

For further information please see our website: The project is funded by EPSRC and JMTC who require candidates to be UK/EU. Minimum Stipend for 2012 - 2013 is £16,000 per annum. Application forms and instructions to send CVs, references etc can be obtained from our website:

( or from Ms Samantha Delamaine (E-mail:, Tel: +44 (0) 207 594 7339). Further information about the project can be obtained from John-Paul Latham ( Interviews are planned for September and applications are accepted until the post is filled.

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