Magneti Marelli Powertrain S.p.A. is a well known company which designs and realizes high technology parts for automotive field, and in particular drive by wire throttle bodies, nowadays very often made by technical polymers.
In some cases, only body itself is made by plastic, while other parts of the same assembly are still in metallic material – for example butterfly itself.
In such cases, very important temperature variations like those that are normal in a under-a-hood environment, can have a big impact on components’ design, manly because it’s mandatory to find the best compromise between low clearance and absolute certainty of avoiding the risk of jamming; obviously different materials coupled together have different coefficient of thermal expansion, so different expansions.
In this scenario, Magneti Marelli Powertrain S.p.A. performs a coupled simulation, in which all part involved in thermal changes are meshed (for example body, butterfly and shaft) and linked together by means of constraint equations.
Performed analysis is a temperature step one, after which the post-processing phase is usually very time consuming (generally creating a path of nodes where displacements can be get, exporting the same data via text file, creation of diagrams with external programs).
This way of working is actually very precise, and gives all the info needed by the designer, but it can be even too much at very early stages: very often it could be enough to have a “go-no go” answer.
For this reason we decided to implement contact elements making them work in a way different than normal: in fact we were only interested in their capacity of giving as a result the amount of penetration or gap.
With a tricky solution, this was done and the whole activity has been a success. |