Innovative and Integrated Technologies for the Development of Aeronautical Components
The scope of this study was to determine and validate a more efficient simulation procedure for the design phase of Al-Si alloy components for the aeronautical industry. The study combines the simulation of the manufacturing process with that of the component’s structural behavior to create a better predictive tool that is able to analyze the component’s behavior over its life cycle. The study concludes that the detailed knowledge of the manufacturing process at its different stages, from casting to heat treatment and machining, and scale factors can be virtually implemented to find the optimal manufacturing process for the component’s reliability. This study was carried out by a team comprised of EnginSoft senior engineers and the Oeffevi foundry with the collaboration of AVIO and the University of Padua, Italy.
The Object of this Integrated Chain Study
The object of the study was a gearbox Casing Angle V2500. The part was selected for this study because its simple geometry and well-known productive cycle offer an ideal reference point for further analysis. Two specimens of the component were sand cast in A357 alloy. The first casting was examined as-cast whilst the second was put through an artificial aging heat treatment in accordance with AVIO regulations. Three thermocouples, included in the cast, surveyed the temperature evolution during the heat treatment with particular attention to the quenching phase. The results were then compared to those obtained from the integrated simulation of the design chain.
The Integrated Design Chain Approach
Close-up of two sampling areas location: stress-strain curve from experimental tensile test and comparison with simulation results. Good correlation for the ultimate tensile strength can be observed for most sampling areas (within 5% tolerance).
The development of a virtual prototype should integrate the simulation carried out using the casting process simulation tool and the numerical response, based on FEM code, of the component at in-service conditions.
The main need for this integrated simulation approach is that a component’s material microstructure, including micro- and macro-defects, is often the reason for an earlier than expected in-service failure of the component.
In the specific case of Al-Si alloys, the mechanical properties are determined by the ?-Al phase properties, by the grain size, by the eutectic silicon characteristics, as well as by the presence of secondary and inter-metallic phases. Generally speaking, a component characterized by a fine microstructure, with no brittle phases, presents better mechanical properties if compared to a component with a coarse structure, high SDAS values and with the presence of acicular eutectic silicon crystals.
(a) the high shrinkage rate value highlights the risk of acceptable micro-porosity in a specific location
(b) the same micro-porosity location as previously identified by Avio quality control.
A wholesome representation of the component’s mechanical properties along the manufacturing process chain, both at the macro- (residual stresses, local mechanical properties, casting defects) and micro- level (morphology, phase types, SDAS values, grain size), is the starting block for reliable structural design. The simulation process carried out for this particular study is outlined in the figures above.
What did the Integrated Virtual Simulation of the Component’s Design Chain Achieve?
The results of the integrated virtual simulation analysis concurred with those of the experimental tests carried out on the actual physical component specimens. It was concluded that the integrated design chain methods used in the simulation could be successfully reused on new products to predict the same type of defects that were identified in this study.