Blocked force determination on plate structures using an offset interface

Blocked force determination is an alternative to the more routine method of inverse force determination using classical transfer path analysis. One advantage of determining blocked forces is that there is no need for the source to be detached or isolated from the system. Results are, in theory, valid so long as blocked forces are determined at the interface between the source and receiver system under the assumption that the interface is well defined. Another advantage is that calculated blocked forces are appropriate when modifications are made on the receiver side of the interface. This insures that the blocked forces are suitable for utilization in analysis models where receiver system modifications are considered. Difficulties in using the approach arise when interface locations are difficult to instrument. This paper demonstrates that blocked forces may also be determined along a continuous interface offset from bolted connections or isolators making the method more convenient to use. This offset interface strategy is demonstrated for plate structures using both simulation and measurement. Recommendations are made for selecting the number of forces and blocked force locations along this offset interface.