EPSRC supported EngD project: Thermo-Mechanical Modelling for Structural Ceramics

Fatigue fracture is one of the failure modes in engineering ceramics where crack initiates, propagates, and finally results in failure under cyclic thermal loading. The efficient prediction of fatigue crack growth helps make engineering decisions on product durability. The conventional Paris law or J-integrals are not enough to predict crack growth in complex 3D geometries such as 3D perioidic structures from additive layer manufacturing. As an alternative method, the Phase Field models have been receiving increasing attention. In this approach it is possible to model both plastic and elastic deformations with a time in microcracked ceramics. The model predictions can also be used to track weaker zones in the structure and the severity of the applied loading conditions on the product durability. There is a knowledge gap in extending the Phase Fieldd models for elasto-plastic ceramics and measuring model input parameters such as fracture toughness, separation energy, cohesive strength, fatigue parameters for such complex structures such as honeycombs. In this work,
Phase Field models will be developed to understand the durability of the microcracked systems and novel experimental techniques will be developed for measuring model parameters by utilizing facilities like high temperature bending test, Dynamic Mechanical Analyser, high-temperature impulse excitation, and nanoindentation. The model predictions will be validated on model materials under thermal shock load conditions. Similarly, these models will be used to explain the revesible grain growth and hysteresis in the elastic properties of microcracked ceramics.
This project will specifically address some of the product development and quality control needs of JM. The EngD student will work as an integral part of thermal processing group and quality control teams. JM is building an enhanced capability in this area, enabling the model driven manufacturing & design. The EngD researcher will play a key role within this team; developing bespoke measurement methods, fracture model for a given product formulations. The focus of the EngD will be the fundamental R&D needs of the group, but also being involved in trials and implementation of models in commercial environment and support different manufacturing sites in Europe. For any concern with Brexit, this position is fully paid and sponsored.

The beneficiaries of the research and training of the CDT will be UK industry, the graduates of the programme, the wider academic community, and consumers :

(i) UK industry: the formulation sector is wide and diverse, and our industry partners are world-leading in a number of areas; foods (PepsiCo, Mondelez, Unilever), HPC (P+G, Unilever), fine chemicals (Johnson Matthey, Innospec), pharma (AstraZeneca, Pfizer, Imerys) and aerospace (Rolls-Royce). All projects are cocreated with industry, and cofunded - the majority will be EngD students based in company sites. Industry will benefit in a number of ways: (i) from a supply of trained graduates in this critical area, with > 90% of graduates of the programme to date getting jobs in formulation companies, and (ii) through participation in industry-academia research projects in which students work within the company on projects of practical value, (iii) through the synergy possible between companies in different non-competitive sectors (we have current projects between Mondelez and P+G, and Johnson Matthey and Unilever resulting from CDT linkages). We will also work with Catapult Centres, including the National Formulation Centre at CPI and the MTC at Coventry, to enhance the industry relevance of the CDT and train students in modern manufacturing methods.

(ii) Graduates of the programme: students are trained in a critical area where graduates are in short supply, obtain training and experience of the issues involved in industrial and collaborative research, present their work at external and internal meetings and get good jobs (>90% within formulation companies). Many of our graduates are now reaching senior positions in industry, and one, Dr Stewart Welch of Rolls Royce, is now the representative of Rolls-Royce on our Industrial Management Committee. In the next 5 years we will build at least 50 new projects with companies, creating EngD and PhD graduates, a new generation of leaders for the formulation industries.

(iii) Wider academic community in the UK and elsewhere. We will ensure that students on the programme write papers (as many as possible with industrial co-authors) on formulation projects. This is a vital part of the CDT, as it both ensures and demonstrates the academic quality of the programme. We have published extensively in areas such as; soft solid mixing processes (Unilever, Johnson Matthey; see Hall et al., Chem.Eng. Res. Des. 91, 2156-2168, 2013); food materials for enhanced mouthfeel, low-salt and low-sugar delivery, (Pepsico, Nestle, Mondelez; such as Moakes et al RSC Advances 5, 60786-60795, 2015); design of innovative cleaning strategies (Unilever, GSK, Heineken, P+G; Food Bioprod. Proc., 93, 269-282, 2015); characterisation of domestic cleaning processes (washing machines and dishwashers) to minimise water usage (P+G; Chem.Eng Sci., 75, 14, 2012); in-vitro models for formulated product breakdown and nutrient and drug delivery in the mouth, stomach and GI tract; EngD work followed up by BBSRC and industry funding (Eur J Nutr. 55, 2377-2388, 2016); dynamics of spray driers (P+G, AIChE J 61 1804-1821 2015; Chem. Eng. Sci. 162, 284-299, 2017), and ways to reduce waste in soyamilk production (Unilever; Innovative Food Science & Emerging Technologies, 41, 47-55, 2017).

(iv) consumers: many of the companies we work with are involved in Fast Moving Consumer Goods, where research has direct consumer benefit, for example in the creation of low fat foods that have high-fat mouthfeel. In addition, the overall aim of the programme is to develop sustainable formulated products and processes; such materials will be better for the environment and consumers.