EFFECTS OF EXTERNAL FORCES (TRANSIENT AND PERMANENT).

Investigations are reported in the reactions of an oscillating piezoid to the application of external forces and torques. Further cases of superimposed tensile and compressive force fields were set up in AT-cut plates, involving the combining of stress doublet and triplet sets, using a newly designed and more precise positioning arrangement. The superposition studies were extended to some of the numerous additional azimuthal cases more readily obtainable by the use of circular piezoids with tensile fields. Progress was made in attacking the problem of transient effects caused by sudden changes in stress. Experiments are reported on half-inch plates resonating in fundamental and third and fifth overtone modes and on larger plates. By applying nonlinear theory an analysis comparable to that in the last previous report, but with psi equal to 90 degrees rather than 0 degree, is carried out and tested for fit with experimental results.