High-Performance Composite Chocolate Julian Dean, Katrin Thomson, Lisa Hollands, Joanna Bates, Melvyn Carter, Colin Freeman, Plato Kapranos and Russell Goodall Abstract The performance of any engineering component depends on and is limited by the properties of the material from which it is fabricated. It is crucial for engineering students to understand these material properties, interpret them and select the right material for the right application. In this article we present a new method to engage students with the material selection process. In a competition-based practical, first year undergraduate students, design, cost and cast composite chocolate samples to maximise a particular performance criterion. The same activity could be adapted for any level of education to introduce the subject of materials properties and their effects on the material chosen for specific applications. Introduction With a near limitless range of materials available the selection of the ‘best’ material for a particular job is not easy. Fortunately, materials scientists have developed formally defined procedures to identify the best selection in a quantifiable way. Efficient material selections balance not only factors such as the material properties important for the application, but also additional aspects such as environmental impact and cost. In order to decide which materials will be the best for the application, we need to find a compromise between the material properties and these other factors which is done by combining them into a single performance index. In a very simple case the requirement could be to create a material that requires a large amount of energy to break, that is toughness, at the lowest possible cost. This can be expressed as a performance index of Performance index = toughness / Cost Equation (1) In the modern world, some of the toughest materials are composite as shown in table 1 highlighting the relative cost and the associated performance index. Composites are made from multiple materials with the aim of combining their desirable properties. They are formed by using a “matrix”, normally a cheaper and lightweight material, to surround and bind together a “reinforcement” material made of fibres or particles which are generally stiffer, stronger and more expensive. Composite materials exist in nature; one example is wood, where starch fibres are bound together by a matrix of lignin. Man-made composites include concrete and plastic reinforced materials such as fibreglass (GFRP) and carbon fibre reinforced plastics (CFRP). These materials are used extensively in the building industry, aerospace and civil engineering.