High-Strength Steel Component Inspection for Sustained Stresses Using Magnetic Property Sensing

A method for nondestructive measurement, characterization, and mapping of sustained stresses in high-strength steel components, using magnetic stress gages (MSG), is proposed. The goal is to provide a nondestructive inspection (NDI) tool for locating specific areas within the components, where high tensile sustained stresses exist making them susceptible to environmentally assisted cracking. This NDI tool will take advantage of the unique capabilities of model-based stress gages such as scanning MWM-Array sensors. In Phase I, JENTEK will perform measurements with the MSG sensors on two types of coupons (in the Base Effort) and on component samples (in the Option Effort) to determine feasibility of measuring the state and magnitude of sustained stresses in primary aircraft structure steel components. JENTEK will perform measurements in two modes: stationary and scanning, in two orientations. In the stationary mode, we will measure on a coupon to demonstrate sensitivity to various levels of sustained stresses and to determine the correlation between the magnetic permeability and stresses for the selected material. In the scanning mode, we will generate maps revealing the residual stress distribution. This latter mode is to be used ultimately on actual rotorcraft components, particularly at the locations where high tensile sustained stresses are likely.