Riassunto analitico
When considering thick composites' carbon fiber laminates, especially in high performance applications like Formula 1, one of the main things that can come up to our mind are stock-blocks used for the production of inserts. For stock-block we usually mean a large plate made of a composite material, with a thickness that can arrive even at several centimeters, from which we can CNC machine smaller blocks: the inserts. An insert is a solid part which is embedded in the lamination process for the production of carbon fiber components, that allows to locally enhance the strength and the stiffness of a laminate. Inserts are applied in several points of a Formula 1 car, mainly where we need to introduce high loads in the structure of a composite component guaranteeing a high level of structural performance, or where we have the connection between several components, like for example where the suspensions are coupled with the chassis. The problem of thick laminates is Delamination, hence the separation of the layers that constitute our component. Delamination in stock-block inserts can happens in two ways: either during the proper working operation of the component, hence when the car is running and it's subjected to unpredictable load cases, or during the production of the component itself, consequently to the thermal cycles that characterize the curing process. The latter option is deeply analyzed in this thesis, trying to find a correlation between some Finite Elements models and the experimental tests. First an analysis of different prepregs that can be used in stock-block production is performed, highlighting the main properties that affects the delamination phenomenon. Consequently FEM simulations were carried out in parallel to experimental tests trying to evaluate the effect of many external parameters, like the geometry of the insert and the temperature reached in the curing cycle. Above all, the main objective was to find a correlation between the digital and the real world, allowing us to understand why delamination is happening during the production process of the component and finally to stipulate a list of rules and recommendations to be adopted in order to avoid the above mentioned phenomenon.
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