Proposed piezoceramic excitation for rotational and translational structural mobility measurements

A piezoceramic excitation approach is proposed that allows for a more convenient measurement of translational and rotational structural mobility compared with current methods. Using this approach, a lightweight, compact array could be designed and attached to a structure to induce a normal force as well as bending and torsional moments. This paper focuses on verifying the ability of piezoceramic patches, when aligned in certain formations, to mimic normal force and moment excitation and allow easy measurement of translational and rotational structural mobility. The demonstration test structure is a 0.3175 cm (0.125 in.) thick, clamped-clamped 30.48 cm (12 in.) by 2.54 cm (1 in.) aluminum beam to which two 2.54 cm (1 in.) by 1.27 cm (0.5 in.) piezoceramic patches are attached. Depending on the orientation of the patches, a normal force, bending moment or torsional moment is created. Accelerometers are used to measure the mobility at the center point of the beam. This method combined with the proposed array could be placed on any point on a structure to excite the structure and measure the point structural mobility. Experimental results are compared to numerical results from a finite element program to verify the representation of the piezoceramic patches. The specific arrangements of the patches are able to excite the desired modes and agree well with the numerical model.