Mechanics of Advanced Materials Research Group
The Mechanics of Advanced Materials (MOAM) Research Group carries out multi-disciplinary research into the response of advanced engineering and bio-materials to various types of external loading and environmental conditions, using a combination of analytical, numerical and experimental techniques.
Our analysis of deformation processes, damage evolution as well as failure initiation and development allows us to predict the properties, performance, reliability and structural integrity of modern materials and the components and structures made from them.
Among the materials we are currently working with are composites and nanocomposites, polymers and adhesives, steels and alloys, metallic glasses, biomaterials, materials for microelectronics, sports materials, ceramics and ceramic coatings, polymeric foams and non-woven fabrics.
Main research areas:
- Computational mechanics and micromechanics of microstructured materials
- Multi-scale analysis of damage and failure evolution in advanced engineering materials and biomaterials
- Effect of in-service loading and environmental conditions on performance of components and structures
- Analysis of material’s behaviour in modern technological processes
- Effect of microstructure on effective properties and performance of advanced engineering materials
- Mechanics of advanced materials under vibro-impact loading
- Dynamic deformation and fracture of advanced materials
Visit the Mechanics of Advanced Materials Research Group website for more information.
This project is funded mutually by EPSRC UK and Department of Science and Technology, Government of India and involves Loughborough University, University of Oxford, IISc Bangalore, IIT Delhi, IIT Guwahati and industrial partners in India and UK. A transition to the next step in high-value manufacturing in the 21st century requires the development of innovative processes to (i) reduce cycle times and costs so that productivity and higher profitability are maximised, and (ii) enhance performance and quality whilst reducing environmental impact. To achieve this, the required development and intensification of modern manufacturing necessitates a broader use of higher temperatures, forces, deformations and loading rates. In practice, the development and application of modelling and simulation tools are the only practical way, in which these challenges will be met, particularly for new transformative manufacturing processes. The project will deliver the tools required to address advanced manufacturing research challenges in high-value manufacturing processes.
This EPSRC-funded project is implemented jointly with the University of Southampton and Imperial College London. The aim of this research is to investigate a physical process of oxidation damage at a crack tip and the associated crack-growth behaviour for nickel-based alloys used in gas turbines, For the first time, it provides a direct insight into the oxidation-embrittlement phenomenon at a crack tip. The work will ultimately lead to elucidation of a physically-based link between oxidation damage and crack growth for fatigue design and allow life prediction of nickel-alloy components. The research will generate unique and practically-useful data and predictive models which can be quickly exploited through our committed industrial collaborators including Alstom, NASA, E.On and dstl. The research has a direct impact on power-generation and gas-turbine propulsion systems.
Trans-Atlantic Micromechanics Evolving Research "Materials containing inhomogeneities of diverse physical properties, shapes and orientations
The project, funded by the EC, is based on collaboration with Aberystwyth University, UK; Politechnika Rzeszowska im Lukasiewicza, Poland; Université de Lorraine, France; Universita degli Studi di Trento, Italy; V.N. Bakul Institute for Superhard Materials of the Ukrainian National Academy of Sciences, Ukraine; Belarusian State University, Minsk, Belarus; Yanka Kupala State University of Grodno, Belarus; New Mexico State University, USA and Saint Petersburg State University, Russia. The project focuses on mechanical properties of materials with realistic - heterogeneous and anisotropic - microstructures that contain inhomogeneities of various shapes, orientations and physical properties. An important feature of such microstructures, that complicates their analysis but has a profound impact on their overall behaviour, is their irregular character. The main aim for MoAM is to develop multi-scale modelling tools for heterogeneous materials with complex microstructures, such as composites and bone tissues.
Vibro-Impact Machines Based on Parametric Resonance: Concepts, mathematical modelling, experimental verification and implementation
The aim of this EU-funded project is to enhance the potential and output of vibrating machines and decrease their ecological footprint by implementation of parametric resonance (PR). Academic and industrial researchers from the UK, Poland, Israel and the Ukraine participate in this multi-disciplinary project. The contribution of MoAM RG is development of advanced modelling tools for analysis of initiation and propagation of cracks in components exposed to multiple impacting (impact fatigue); non-linear dynamics of cracked components; numerical simulation of various types of screens for their optimisation. The enhancement of vibro-cutting/drilling tools via the development of the underpinning theory and application of the PR principle is another objective.
Ultrasonically assisted machining (UAM) is a unique hybrid machining process where the cutting tool is made to vibrate at high frequencies (> 20 kHz) with low amplitudes (10-20 microns) in a preferred direction during the machining process. UAM, which is typically carried out without the need for coolants or lubricants, has been shown to possess significant advantages in machining of intractable alloys and heterogeneous composites. This has emanated from decades of pioneering research carried out at Loughborough University. UAM demonstrated significantly improved machinability of Ti- and Ni-allys with increased material removal rates, reduced tool wear and improved structural integrity of the machined component. New hybrid techniques, e.g. Hot Ultrasonically Assisted Turning, were suggested and successfully implemented. Researchers of MoAM were the world-first in developing 2D and 3D finite-element models of these techniques.
The project, implemented in partnership with The Hadley Group, aims to develop a finite-element-based numerical scheme to assess reusability of sheet metal parts without melting. It is intended to address the main issues regarding sheet metal forming with an emphasis on assessments of formability and measures of multi-stage forming. This effort aims to open a window to cold or warm recycling rather than melting in order to evaluate the possibility of augmentation a new life cycle to sheet metals at the end of the primary one. Within this research, formability of pre-deformed sheets is characterized and possibility of re-forming processes and necessary after treatments are investigated. To verify the proposed numerical scheme, several practical case studies will be conducted.
Deformation, damage and fracture processes demonstrate specific features in materials loaded dynamically. Non-trivial spatio-temporal realisation of these processes becomes even more complex in microstructured materials, both artificial (composites) and natural (bones). MoAM undertakes a broad programme of research into dynamic deformation and fracture of a broad spectrum of materials, using a combination of microstructural studies, experimental tests and advanced numerical simulations. In a case of fibre-reinforced laminates exposed to wide range of loading velocities – from low, characteristic to sports application, to high as in blast and impact loading, the Group collaborates i.a. with the University of Rhode Island, USA and IIT Bombay, India.
This project aims to develop a multi-scale constitutive model to describe plastic deformation for high-temperature materials and apply the model to study crack-tip deformation and short crack growth. Interaction between dislocations and material microstructure is the major source for heterogeneous plasticity and internal stress concentration, leading to initiation and growth of short cracks. To physically simulate the material’s plasticity behaviour, a three-dimensional discrete-dislocation-dynamics (DDD) approach is developed to study the interaction between dislocations and material microstructures based on experimental results. The DDD model will be interfaced with viscoplasticity and crystal-plasticity models, and further applied to investigate the role of dislocation dynamics in depicting short-crack growth, with validation against experimental measurements and characterisation. The research will provide scientific guidance and support for industries to gain a maximum life in service through the optimisation of operation conditions and material microstructures.
This project aims to develop continuum-mechanics-based finite-element models to analyse a mechanical behaviour of graphene-reinforced nanocomposites (GRNC), including their deformation and damage. The developed numerical models will offer a practical approach for design and optimisation of GRNC structures. The experimental part of the project focuses on characterisation of global (macroscopic) mechanical properties (elastic, plastic and damage) of a system consisting of a single-layer graphene and a substrate (matrix) material The numerical part aims at development of a numerical model to simulate mechanical performance of single-layer graphene with implementing its anisotropic elastic-plastic and damage properties.
Bulk metallic glasses (BMGs) are an emerging class of advanced engineering meta-materials, with many desirable and unique properties. Unlike crystalline materials, BMGs lack orientational long-range order that leads to unusual structural properties and non-conventional deformation mechanisms. BMGs are microscopically homogeneous and isotropic with high strength and elasticity demonstrating enhanced plasticity at small scales. Additionally, deformation is observed to occur inhomogeneously through plastic strains concentrated in localized shear bands. With these experimental observations and the current and future industrial applications, understanding the mechanics of BMG is essential to the development of multi-scale models with predictive. The project advances the technique of continuum modelling of BMGs by accounting for their fundamental physical behaviour both from a theoretical point of view as well as respective numerical aspects.
Composite materials offer excellent strength-to-weight ratio, damage tolerance, fatigue and corrosion resistance, making them good candidates for replacement of conventional materials for structural applications. As a result, advanced composite materials make about 50% of the structural weight of Boeing 787 and Airbus A350XWB. Generally, parts made of composites are produced to a near-net shape, but additional machining operations are often required to facilitate component assembly. To this end, cutting edge state-of-the art modelling capabilities are being developed to address the challenge in predicting component damage post-machining. The developed models were calibrated with some benchmark experiments followed by an exhaustive validation study with several industry-relevant test conditions. The model has been shown to accurately characterise damage patterns at hole entry and exit. The project is implemented in collaboration with the MTC and AMRC and their industrial partners.
The project, carried out in partnership with Ford and High Speed Sustainable Manufacturing Institute, UK, aims to employ benefits of finite-element analysis to simulate machining of hardened valve seat in internal combustion engines in order to improve accuracy of the dimensions generated with machining and tool life. A parametric finite element model will be developed to analyse the entire machining system to simulate its mechanical performance, with a focus on thermo-mechanical material behaviour and vibration response. Toll life will be improved based on the developed advanced multi-physics models.
Bones are the principal structural components of a skeleton; they play unique roles in the body, providing its shape maintenance, protection of internal organs and transmission of forces. Ultimately, their structural integrity is vital for the quality of life. Unfortunately, bones can only sustain loads until a certain limit, beyond which they fail. Understanding deformation and fracture behaviours of bones are necessary for prevention and diagnosis of trauma; this can be achieved by utilizing both experimental techniques and numerical simulations. Generally, most of bone fractures occur in long bones consisting typically of cortical bone tissue. Therefore, in this project, experimental studies and numerical simulations of deformation and fracture processes in cortical bone tissue are considered. An experimental programme is conducted to characterise mechanical properties of cortical bone tissue in order to gain basic understanding of spatial variability and anisotropy of its mechanical properties and its link to an underlying microstructure.
Restoration of human functional activity has been a drive for many centuries dating back to early Egyptian and Greek civilizations. These interventions would often take the form of a prosthesis made from various materials - depending upon the body part. Technology has progressed to using newer materials enabling lighter devices and more realistic appearances. Current state-of-the-art research is looking at the integration of robotics, electrical components, temperature, pressure sensors etc. The field of tissue engineering has progressed significantly with various relevant tissues now able to be “fabricated” in vitro. The areas of study of this project include biological and chemical interfaces, loading and performance, materials, manufacturing, design and integration. MoAM focuses on the loading and performance aspects in the development of a smart-prosthetic lower limb.
Cardiovascular diseases affect millions of people world-wide and often lead to life-threatening heart attacks and strokes, which are treated largely by implanting stents. In this project, advanced computational and experimental mechanics is used to study a biomechanical behaviour of metallic and biodegradable polymer stents. Effects of cell design, material choice and drug elution coating on stent behaviour are studied using computational models. Degradation of biopolymers and its effect on the mechanical properties of next-generation biodegradable stents are investigated using experimental methods. A clinical impact of stenting, which causes the disruption of blood flow, in-sent restenosis, stable and unstable angina and acute thrombosis, is investigated through solid-fluid interaction approach. This research is of great interest to, and impact on, both clinical researchers and bioengineers to gain a scientific understanding of stent biomechanics and its interaction with the dynamics of blood flow and mechanics of vascular walls.
Bacterial cellulose (BC) is an organic compound produced from certain types of bacteria. Unlike plant cellulose, bacterial cellulose has unique characteristics, such as high purity, strength, moldability and water-holding ability. While bacterial cellulose is produced in nature on a limited scale, various laboratories are currently investigating methods to enhance cellulose growth on a large-scale with specific properties. This, in turn, can allow producing cellulose with unique mechanical properties for applications in various fields of science including biotechnology, biomedical, and material science. In this project, a full set of its mechanical properties will be obtained using various experimental setups including uniaxial tension, compression, nanoindentation and creep tests. In addition, advanced finite-element models will also be developed in order to investigate the adequacy of BC as an artificial 3D scaffold for tissue-engineered tendons.
A long-standing collaboration with the Nonwovens Cooperative Research Center, Raleigh, NC, USA deals with analysis of deformation behaviour, damage and fracture of thermally bonded nonwoven materials. A broad range of materials – in terms of density, type of fibres and manufacturing processes have been studied, using a combination of mechanical tests on single fibres and fabric samples, X-ray micro computed tomography and advanced numerical (finite-element) models. For the latter, apart of continuum approaches, a discontinuous-continuous scheme was developed based on a parametric modelling technique. It allows direct introduction of multiple fibres into simulations, based on experimentally acquired orientation distribution function together with account for manufacturing parameters (bond pattern, basis weight, etc.).
MoAM have studied various microelectronics-specific mechanical problems that arise mostly due to continuous miniaturisation of devices. As a result, grain-level mechanisms of deformation and fracture gain increased importance in assessment of reliability of microelectronic devices under various loading and environmental conditions. A typical example is lead-free solder, with a single bump in a chip containing one (or few) grains. The group also studies indium joints at cryogenic temperature, thermo- and electro-migration in small –sized solders and damage in MEMS using multi-scale computational tools as well as various experimental mechanical tests.