This document discusses a new non-destructive testing method for measuring residual stress using a vibrometer and pulse generator. It explains that elastic energy transmitted from the pulse generator remains constant for a given metal hardness, causing an elastic volumetric deformation that can be measured. The document establishes that the elastic energy is equal to the integral of half the volume times the elastic modulus times displacement, and also equal to the integral of half the mass times acceleration times displacement. It then states that the residual stress value, with the elastic energy held constant, depends on changes in the elastic modulus and inversely on displacement, allowing residual stress to be determined by measuring the proportional variation in vibration acceleration.

1. Residual stress theory measurement new NDT.
Preface:
The equipment consists of a vibrometer and a pulse generator at constant energy.
The elastic energy transmitted from the pulse generator at constant energy, on the
surface of the metal, variable with the hardness of the metal itself. This elastic energy,
however, remains unchanged at each corresponding hardness.
The pulse of force from origin to an elastic deformation volumetric equal to:
Ee = ∫ ½ Vol. K dx.
Vol = Volumetric deformation
K = Elastic module reaction volumetric.
dx = Displacement.
At the same time gives a transverse vibration forced with energy equal to:
Ev = ∫ ½ m a dx
m = inertial mass
a = acceleration of vibration.
therefore
Ee = ∫ ½ Vol. K dx = Ev = ∫ ½ m a dx = constant
The value of residual stress, (with the elastic energy invariable), depends on the
change from the module K values and inversely from dx. (other values are fixed
( π, D, ρ).
The variation of K therefore corresponds to a proportional variation of:
a (acceleration of vibration).
p.i.Ennio Curto
with Sadt.cn collaboration