Mechanical Engineering Design - Dissertation
Material Point Method in simulating impact and explosion. Suprvisor Dr. Henry Tan
In this project we apply the Material Point Method to simulate impact and explosion. Material Point Method was adopted at the US Department of Energy’s Centre for the Simulation of Accidental Fires and Explosions. It is designed with the robust ability to handle large deformation, penetration, material separation, fracture, fragmentation, and interactions with fluids and chemical reactions. Tan and Nairn (2002) further developed the Hierarchical Adaptive Material Point Method for multi-scale simulations with different resolutions. Use this method we will study the damage evolution in energetic materials, and structure responses to high speed impacts.
Design Optimisation and Structural Reliability. Suprvisor Dr. K. Davey
Design optimisation involves: the selection of a set of variables to describe the design alternatives; the selection of objectives (criteria), expressed in terms of the design variables, which are to be minimised (or maximised); the determination of a set of constraints, expressed in terms of the design variables, which must be satisfied by any acceptable design; and the determination of a set of values for the design variables which minimise (or maximise) the objectives, whilst satisfying all the constraints. The focus of this project is on the determination of constraints and the role reliability analysis has on the determination of the constraints. Measures of structural reliability can be deterministic (factor of safety, load factor, partial factor) or probabilistic (normal, lognormal, Gumbel, Frechet, Weibull, Gamma). Simple structural designs are to be assessed in combination with the many possible methods of defining the constraints in a design space. Distributions can be visualised with the aid of Mathematica and/or Matlab.
Dynamic response of nuclear waste container subjected to drop loading. Suprvisor Dr Qingming Li
It is necessary to ensure the safety of nuclear waste container during transportation. IAEA has set criteria for the potential impact threats during transportation. Student on this project will establish a FE model using ABAQUS or LS-DYNA for a standard nuclear waste container and conduct numerical simulations on several drop tests. Response and/or damage of the container will be identified based on numerical results and analyses. The energy distribution in the nuclear waste will be predicted, based on which the possible release rate can be estimated.
Liquid Drop Model to Obtain Mechanical Properties of Cancer Cells. Suprvisor Dr. Teresa Alonso-Rasgado
Continuum models are used to model living organisms such as cells. These types of models consider the cell as comprising materials with continuum properties and consequently are concerned with the biomechanical response of the cell as a whole. Initially, continuum models were developed to study blood cells. The mechanical properties of cells are important as potentially, it may be possible to indirectly relate these properties to the health and structure of the cell. This would open up a number of useful applications, for example in clinical diagnostics and even in the therapy of certain types of diseases, including cancers. The aim of this project is to develop a continuum model for a prostate cancer cell. Liquid drop models are one particular variation of the continuum viscoelastic approach. The student will be required to select the most appropriate liquid drop model for the application. Commercial finite element software will be used (basic instruction in the use of ABAQUS will be provided if required).
Dynamic crushing of honeycombs. Suprvisor Dr Zhenmin Zou
Honeycombs are often proposed to be used for impact energy absorption purposes. Experimental studies in the literature reveal that the dynamic crushing of a honeycomb material is quite different from its quasi-static counterpart. One of the most distinctive features is the enhanced stress required to crush the material. The crushing stress increases with the increase of the impact velocity. In this project, the dynamic crushing process of a chain of honeycombs will be simulated using commercial finite element code ABAQUS. The aim of this project is to investigate the mechanism for the increase in crushing stress and energy absorption of cellular materials under dynamic loading condition and to validate a simple one-dimensional analytical model developed in the literature.
Concealed Weapon Detection using Acoustic and Ultrasonic Waves. Suprvisor Dr S O Oyadiji
Although the possession, carrying and use of firearms are criminal offences in the UK, there has been an increase in the number of firearms offences. Related to this is the number of brutal attacks committed with knives. Consequently there is the need for the development of techniques to detect concealed weapons, whether firearms or knives, in public places. For metallic weapons, the metal detectors commonly used for security checks at airports and high security public buildings can be used. However, the citing of metal detector portals in open spaces such as city centres and town squares will not be effective as criminals will simply avoid such places. There is therefore the need for the development of techniques that can be deployed remotely. The aim of this project is to develop a technique based on the use of acoustic and ultrasonic waves for detecting concealed weapons at standoff distances. The project is linked to a sponsored research project.
Distinguish the support looseness and crack in a cantilever beam based on the vibration response. Suprvisor Dr Jyoti K. Sinha
The study involves Finite element (FE) modelling of a cantilever beam. In the FE model, a crack and the looseness in the support have to be introduced one by one to begin with and then introduction of both faults simultaneously. The vibration responses need to be calculated for the known applied force for each case and their results should be compared both in time and frequency domain to bring out the possible feature to distinguish these two faults. The study requires programming skill in MATLAB and little knowledge of structural dynamics.
Stiffness of Stitched FRP Laminate Structures. Suprvisor Dr Jack Wu
Stitched fibre-reinforced plastics layered structures have been widely used where through-the-thickness properties are important. The stiffness of such a composite structure is the main concern of this project. In current stiffness analysis, most analytical models, from classical laminate theory (CLT) to various high order plate/shell theories, can only take a few elastic constants of a layer into account, and hence no predictions can be made for transverse moduli, E33, G13 and Poisson's ratios. The project is to program a developed analytical model for the stiffness of an orthotropic stitched laminate structure based on 3-D iso-strain/ iso-stress assumption. All elastic stiffness can be estimated numerically. The program would be able to be applied to a generalized laminated structure such as 3-D woven fabrics and layered foundations in geotechnics.
Geometrical and mechanical modelling of textile composites. Suprvisor Dr S. Li
Fibre reinforced composites are often made from textile fabrics and preforms nowadays. Prediction of the mechanical properties of these composites is still at rather immature state of development. There are a number of difficult issues associated with this. Lack of mathematical models for the description of the complicated geometries involved is one of them. Having obtained a geometric representation of the fabric, the next challenge will be the characterisation of the composite so that the effective properties can be predicted. The proposed project will look into the modelling of such microstructures. Effective way of characterising the behaviour of the composite made of such fabric reinforcements will be explored.