This proposal involves mathematical modelling of the burning and degradation of mechanical properties of flame retadant glass fibre reinforced plastic laminates. At Bolton, novel flame - retardant laminates have been developed and patented during an earlier EPSRC project. These laminates contain novel flame retardant chemicals and inherently flame retardant cellulosic fibres as additives in the resin matrix or as additional fabric layer. Some laminates also contain polymer layered silicate nanocomposites with or without conventional flame retardants. The laminates show improved flame reatrdant and residual mechanical properties after fire/heat exposure compared to unmodified laminates. This proposal is a joint attempt by 'Fire and Heat Resistant Materials' group at Bolton Institute and 'Fire Engineering Research Group' at University of Manchester to numerically predict their burning and mechanical behaviour under a fire condition. The Bolton team will focus on the burning aspect and the Manchester team the burning induced degradation of mechanical properties. Results from the Bolton team will provide input of material damage and temperature information to the Manchester team so that the outcome of this project will be an integrated predictive model for combining both burning and burning-induced mechanical behaviour. A limited amount of mechanical tests at elevated temperatures will be carried out to provide data for validation of the numerical models developed.

This proposal involves mathematical modelling of the burning and degradation of mechanical properties of flame retadant glass fibre reinforced plastic laminates. At Bolton, novel flame - retardant laminates have been developed and patented during an earlier EPSRC project. These laminates contain novel flame retardant chemicals and inherently flame retardant cellulosic fibres as additives in the resin matrix or as additional fabric layer. Some laminates also contain polymer layered silicate nanocomposites with or without conventional flame retardants. The laminates show improved flame reatrdant and residual mechanical properties after fire/heat exposure compared to unmodified laminates. This proposal is a joint attempt by 'Fire and Heat Resistant Materials' group at Bolton Institute and 'Fire Engineering Research Group' at University of Manchester to numerically predict their burning and mechanical behaviour under a fire condition. The Bolton team will focus on the burning aspect and the Manchester team the burning induced degradation of mechanical properties. Results from the Bolton team will provide input of material damage and temperature information to the Manchester team so that the outcome of this project will be an integrated predictive model for combining both burning and burning-induced mechanical behaviour. A limited amount of mechanical tests at elevated temperatures will be carried out to provide data for validation of the numerical models developed.

1. To experimentally determine the strain rate sensitivity of notched, fibre reinforced composites through tensile tests 2. To develop finite element modelling techniques to predict the sub-critical damage at high strain rate 3. To observe the sub-critical damage development in notched glass fibre reinforced specimens 4. To characterise the damage process and compare results to quasi-static tests5. To compare numerical and experimental results and investigate the interaction of different damage modesNotches or holes are required in nearly all aircraft structures for fasteners, access and weight saving. The presence of such notches significantly reduce the load carrying capability of the material. This reduction affects all types of materials but in composites (e.g. carbon fibre reinforced plastic) the damage process is considerably more complex than in other engineering materials. This is because there are many different ways that a composite can fail since it is made up from layers of fibres embedded in a matrix material. The interaction of the different failure mechanisms affects the overall strength of the material, especially when there is a hole in it.In aircraft design it is necessary for the safety of the aircraft to ensure that the worst case is always considered. If for example the material was weaker when it was loaded very quickly then this would have to be taken into account in the design if it was possible that such loading could occur. High speed loading can indeed occur through impact with runway debris, birds or ballistics. Whilst the effect of high speed loading on composite materials has been extensively researched, very little is known about the effect of such loading when there is a hole in the material. This work aims to address that shortfall in knowledge to ensure safety in design.This is to be accomplished by testing different composite materials with and without holes at a variety of loading rates up to very high speed using specially designed equipment. This will generate useful data about what is happening around the hole and a better understanding of the complex damage modes which occur. Because such testing is expensive to carry out, computer models which can predict the damage are very useful. A model will be developed which will take account of the complexities of the damage and their interaction under high speed loading.

Over the past decade, a range of commercial metallic foams have been developed. These are mostly produced by the introduction of gas bubbles (e.g. hydrogen) into the melt. The bubble expansion process leads to random cellular structures, and minimisation of surface energy leads to a low nodal connectivity, with typically three to four struts per joint. The resulting mechanical properties are far from optimal due to the fact that the cell walls deform by local bending. This led to a search for open-cell microstructures which have high nodal connectivities and deform by the stretching of constituent cell members, giving a much higher stiffness and strength per unit mass. These cellular solids known as lattice materials also have potential for multifunctional applications as structural heat exchangers and shape changing structures.The principal aims of this project are to: (i) expand property space by new combinations of material and topology, (ii) model and measure the mechanical properties of lattice materials (stiffness, strength, toughness and fatigue resistance) as a function of topology, constituent material and imperfection, and (iii) explore multifunctional applications including morphing and active energy absorption capabilities. This study will lead to a fundamental pre-competitive understanding of the mechanics of lattice materials, and will provide a tool-kit for designing with lattice materials.

This proposal focuses on the impact performance of state-of-the-art composites in the form of fibre-reinforced plastics (FRPs) with through-thickness reinforcement introduced via Z-pinning. The application of composites in primary lightweight structures has been steadily growing during the last 20 years, increasing the requirement for new and advanced composites technologies. Recent examples include large civil aircraft, such as the Boeing 787 and the Airbus A350, high performance cars, such as the McLaren 650S, and civil infrastructure, such as the Mount Pleasant bridge on the M6 motorway. FRPs are made of thin layers (plies) of plastic material with embedded high stiffness and strength fibres. The plies are bonded together in a stack by applying heat and pressure in a process known as "curing". The resulting assembly is the FRP laminate. The main reasons for the increasing usage of FRPs in several engineering fields are the superior in-plane specific stiffness and strength with respect to traditional alloys and the long-term environmental durability due to the absence of corrosion. Another key advantage of FRPs is that they can be tailored to specific design loads via optimising the orientation of the reinforcing fibres across the laminate stack. FRPs are, however, prone to delamination, i.e. the progressive dis-bond of the plies through the thickness of the laminate. This is due to the fact that standard FRP laminates have no reinforcement in the through-thickness direction, so the out-of-plane mechanical properties are significantly lower than the in-plane ones. According to the US Air Force, delamination can be held responsible for 60% of structural failures in FRP components in service. Impacts are the main cause of delamination in FRP laminates with energies usually in the order of 20J, sufficient to produce multiple delaminations in FRP plates. A representative scenario for such energy level is that of a 2cm diameter stone impacting a laminate at a speed of 110 km/h. In aerospace impact scenarios can be much more severe. For example, the certification of turbofan engines requires the fan blades to be able to withstand an impact with a bird whose mass is in the order of a few kilograms at speed in excess of 300 km/h, with impact energies of thousands of Joules. Introducing through-thickness reinforcement in FRPs is a viable strategy for improving the through-thickness mechanical properties and inhibiting delamination. Z-pinning is a through-thickness reinforcement technique whereby short FRP rods are inserted in the laminate before curing. Z-pinning has been proven to be particularly effective in inhibiting delamination under quasi-static, fatigue loading and low velocity/low energy impact loading. Nonetheless, little is known regarding the performance of Z-pinned laminates withstanding high energy/high speed impacts, whose effects are governed by complex transient phenomena taking place within the bulk FRP laminates and multiple ply interfaces. Overall, these phenomena are commonly denoted as "high strain rate" effects. There is some evidence that Z-pinning is beneficial also for high-speed impacts, but this is not conclusive. The current lack of knowledge may be circumvented with overdesign and expensive large-scale structural testing, but this is not a sustainable solution in a medium to long-term scenario. This project aims to fill the knowledge gap outlined above, by combining novel experimental characterisation at high deformation rates with new modelling techniques that can be used for the design and certification of impact damage tolerant composite structures. The development of suitable modelling techniques is particularly important for industrial exploitation, since it will reduce the amount of testing required for certification of composite structures, with a significant reduction of costs and shorter lead times to mark