Stress measurement by electrical means

THE ADVENT of electric strain gauges¹ suitable for the measurement of mechanical performance on a strength basis not only has widened the field of the electrical engineer with regard to equipment and techniques but gradually has imposed upon him a responsibility to the aeronautical or mechanical engineer in his role as interpreter. For if the designer turns to electric strain gauges (and by this is meant herein the bonded wire gauge,² unless otherwise stated) for verification of his work, it is only natural for him eventually to leave the whole problem of gauge operation and data analysis to the electrical engineer. It is essential that both the man who measures and the man to whom the measurements are reported clearly understand the scope of their separate responsibilities. Otherwise there may exist a gap which will destroy the accuracy necessary to the honest affirmation or negation of the design. Accordingly, the authors here endeavor to present the strength evaluation problem broadly enough for one working in a relatively narrow element of it to appreciate the requirements of the whole, while emphasizing the electrical aspects primarily and keeping always in sharp focus the prime requisite, accuracy.