XRD Integral Method Determination of the Triaxial Residual Stress Field

Finish machining of structural ceramics can produce residual stresses, and subsurface defects (SSD) acting as stress concentrators, in the near-surface material. Residual stresses and SSD produced by machining affect the mechanical properties of ceramic components. In this context, it is essential that the residual stresses be properly quantified in ceramics, in order to establish suitable machining parameters. Residual stress measurement techniques have been developed, with varying results, for determining the residual stresses in ceramics. XRD is the most suitable method for determining machining stresses in ceramics due to the method's high resolution and ability to characterize the macro and micro- residual stresses. A novel XRD method will be developed for nondestructive measurement of residual stress depth distributions resulting from machining. The proposed integral method provides a stable solution of the subsurface residual stress profile, and has been successfully applied in mechanical residual stress measurements. Feasibility of the proposed method will be demonstrated on beta silicon nitride and metallic aluminum coupons for comparison to standard layer removal methods. The x-ray elastic constants for beta silicon nitride will also be determined.