Abstract: A novel system for determining the magnitudes of loads on rotating helicopter components from signals remotely measured on the helicopter fuselage is characterized by a processor which decomposes the measured signals into corresponding Fourier components and extracts selected components therefrom. A programming module performs a multiplication on the respective Fourier components to correlate the measured components with corresponding determinative parameter values. The parameter values are established in a calibration process which is characterized by determination of the independent values of a measured signal set using a Jones orthogonalization process. The signals output from the coefficient programming module are provided to a multiplying resolver which receives synthesized reference sinusoids from a digital processor and generates time dependent signal components therefrom. These signals are ultimately summed in an analog summer circuit whose output signal corresponds to the desired parameter signal.

Abstract: A vibration isolator of the dynamic antiresonant type, for reducing the transmission of vibratory forces along a given line of action between two bodies having a component of vibration relative to one another along such line, includes an inertia bar driven by a crank and having its center of gravity so arranged as to allow the bar to be oriented at any angle to the line of action. This gives the isolator the capability of being designed to make it adaptable to the limitations of the space available between the vibrating bodies.

Abstract: A method and apparatus for analyzing a damped structural specimen permits undamped mobility values and modal accelerations to be determined. The specimen is excited by vibrations in conventional fashion, and both actual and modified mobility response curves or characteristics are determined from measured responses. The modified mobility curve is produced by adding to a signal representing the vibratory force applied to the specimen an artificial force signal generated electronically. The generated artificial force signal simulates the addition or subtraction of mass at the point on the specimen where responses are measured. An undamped mobility value of the damped specimen is determinable at resonant frequencies indicated by the modified mobility curve. From the undamped mobility value and the corresponding frequencies, it is possible to determine modal accelerations for the various vibratory modes of the specimen.