Estimation of random bending strain in a beam from discrete vibration measurements

A method is presented for using vibration measurements obtained at discrete locations on a randomly excited beam to estimate the power spectral density of bending strain. The technique is intended to be applied using a scanning laser vibrometer to allow a non-contacting measurement of random bending strain over the surface of a structure. The theory behind the measurement method is presented, along with results of numerical simulations. The results indicate that the method is practical and can lead to reliable estimates.