Joint identification of blade-root joints in typical bladed-disk assemblies is not possible with the classic decoupling methods due to inaccessibility of interface degrees-of-freedom. In a recent study, an attempt was made to identify such a joint by an expansion based decoupling strategy called System Equivalent Model Mixing (SEMM). The expanded sub-models of the connected substructures and their assembly can be influenced by the measurement errors and the discrepancies between the numerical and experimental sub-models. Therefore, the accuracy of the identified joint is compromised. In this work, we investigate some key factors to improve the expanded sub-models through a new measurement campaign on the unconstrained substructures and the assembly. These factors are i) expansion error, ii) interface type, and iii) singular value filtering. The resulting identified joint properties are validated by recoupling the joint with the respective substructures. It is shown that, by controlling these factors, the joint identification can be highly improved
