Riassunto analitico
This thesis represents the outcome of the project undertaken during the author's internship at Ferrari GeS.
The investigation discussed in this document is aimed at improving the understanding of the WT Model's aeroelasticity. In this work, this is achieved with the creation of Finite Element Method (FEM) models validated through a two-phase experimental campaign, at coupon and at component level.
In particular, this work focuses on the modeling of metal coated Rapid Prototyping parts. Polymer metallization is extensively used in WT testing as a way to add stiffness to thin parts which work as a cantilever under aerodynamic loads. However, this process has proved to be inconvenient both from a logistical and economical point of view.
The FEM model developed can be used as a tool to aid the designer's decision making process, helping him in choosing the right materials for specific model regions. This has a two-fold benefit: it improves the correlation of WT results and it limits the use of expensive materials and time consuming processes to regions where they are strictly required.
The main conclusions that could be drawn from these experimental investigations are as follows: The gain in stiffness provided by the coating is strongly related to the part's thickness, i.e. the coating is more effective when applied to very thin parts with a maximum gain of approximately 85% for parts thinner than 3mm in the best case scenario; When applied to an airfoil-like part, the chord and the cantilever length do not have an influence on the coating's stiffening effect.
Finally yet importantly, it was discovered that the coating process is characterized by significant variability, both in terms of thickness and composition. The ratio between Nickel and Copper has been observed to vary from 47 to 69%, while variation in thickness of up to 400% have been measured in two nominally identical samples. Moreover, the thickness measured in all randomly selected specimens is well below the value declared by the supplier, in a range between 15 and 50% of the nominal value.
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Abstract
This thesis represents the outcome of the project undertaken during the author's internship at Ferrari GeS.
The investigation discussed in this document is aimed at improving the understanding of the WT Model's aeroelasticity. In this work, this is achieved with the creation of Finite Element Method (FEM) models validated through a two-phase experimental campaign, at coupon and at component level.
In particular, this work focuses on the modeling of metal coated Rapid Prototyping parts. Polymer metallization is extensively used in WT testing as a way to add stiffness to thin parts which work as a cantilever under aerodynamic loads. However, this process has proved to be inconvenient both from a logistical and economical point of view.
The FEM model developed can be used as a tool to aid the designer's decision making process, helping him in choosing the right materials for specific model regions. This has a two-fold benefit: it improves the correlation of WT results and it limits the use of expensive materials and time consuming processes to regions where they are strictly required.
The main conclusions that could be drawn from these experimental investigations are as follows: The gain in stiffness provided by the coating is strongly related to the part's thickness, i.e. the coating is more effective when applied to very thin parts with a maximum gain of approximately 85% for parts thinner than 3mm in the best case scenario; When applied to an airfoil-like part, the chord and the cantilever length do not have an influence on the coating's stiffening effect.
Finally yet importantly, it was discovered that the coating process is characterized by significant variability, both in terms of thickness and composition. The ratio between Nickel and Copper has been observed to vary from 47 to 69%, while variation in thickness of up to 400% have been measured in two nominally identical samples. Moreover, the thickness measured in all randomly selected specimens is well below the value declared by the supplier, in a range between 15 and 50% of the nominal value.
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