# 3 Component-based TPA

A fundamentally different class of TPA methods is that of component-based TPA. Using classical TPA, the interface forces between two subsystems will reflect the dynamics of both subsystems (source and receiver) and are therefore not transferable to an assembly with a different receiver. For this reason, classical TPA cannot be efficiently used to assess subsystem modifications, as one would need to conduct a new operational test for every change in design. This is a well-known drawback for applying classic TPA methods in the early phase of NVH design, where changes to source and receiver are still likely to be made.

Component-based TPA remedies this problem by characterizing the source excitation with a set of Blocked Forces $$\mathbf{f}_{\mathrm{2}}^{\mathrm{bl}}$$ that are an inherent property of the active component itself, independent of the receiver it is attached to. This framework facilitates testing of the active component in a broader set of test environments (e.g. in the full vehicle or on a test bench), as the dynamics of the receiving component will not influence the Blocked Forces. As the Blocked Forces are only a function of the active component itself, we denote this family of TPA as component-based.

Again, different variants can be defined according to how $$\mathbf{f}_{\mathrm{2}}^{\mathrm{bl}}$$ is obtained from operational tests. Three of them are listed here: