With the increasing development of techniques that utilize high-pressure shear in multiple fields, constructing a proper interpretation of strain and stress in rotational anvil apparatuses is becoming more and more urgent. A macro strain analysis in a rotational anvil apparatus that generates high pressure and shear was performed based on a polycrystal strain spatial distribution. Based on the strain, macro stress components were retrieved. Three analytical methods suitable for various application purposes are presented that can be used to conduct stress/strain analysis of a sample under pressure and shear: a sample center fitting method that obtains macro strain components from the refinement of d-spacing azimuth angle distribution, a six-point graphical method that calculates macro strain components from graphical strain distribution, and a four-point graphical method that determines the components directly from a diffraction image. This study also discusses and verifies the validity of and comparison between the methods through experimental data. The present work is expected to provide a foundation for further experimental studies of shear at pressures and expand the field of high-pressure sciences.

In the resolution of the large divergence between pressure calculated by way of axial stress components from elastic constants and pressure determined by an equation of state, a 2nd order pressure dependency of elastic constants is introduced. Incorporating results from the equation of state and ultrasonic measurements in the literature, we determined the pressure dependency of x-ray elastic constants of gold and established functions for the calculation of macro-stress components from its macro-strain counterparts. The precision of stress components through these functions is estimated to be at 1% level. The determination of stress components, including crucial shear components, through analysis of an x-ray diffraction image, is demonstrated.