Error reduction of measured impact forces and their lines of action via cross sensitivity studies

Cross-Axis sensitivity of a transducer can compromise the resulting measurements. A recent development is the advent of the force and two moment load cell. We want to take these measurements and evaluate how much error is involved in the force, moment, and location measurements when cross-axis sensitivity is taken into account. Equations are developed to explicitly relate the measurement offorce and moments to structural frequency response functions (FRF), the transducer's electro-mechanical cross-sensitivity matrix and input force. Based on the equations, a cross-axis sensitivity matrix is estimated using experimentally determined force and moment data. The experimental study reveals that how the load is applied to the structure is vital to measurement accuracy; and thus, is most influential to imprecise cross-axis sensitivity results. Besides an anomaly in the measurement is observed and discussed in detail. The practice of applying a load directly through the center bolt to the transducer is based on an erroneous assumption of the rigidity of the bolt-nut-plate connection. When the load is applied through the plate, the results are improved significantly.