Notch Strain Analysis of Crossbore Geometry

Many high-pressure components have intersecting bore geometries, such as fluid end module of fracture pumps. Imposition of compressive residual stresses at crossbore intersections can extend the fatigue life, thus approaches such as autofrettage are typically used. Understanding the stress–strain response during autofrettage in the crossbore is critical for fatigue life estimation and design. Crossbore geometry is frequently complex and no closed-form analytical solution is available for prediction of residual stresses. As such, numerical methods like FEA are frequently used. Applying FEA to complicated geometries requires extensive parametric studies which are computationally expensive and time consuming, thus notch strain analysis methods are promising. Elastoplastic stress–strain responses due to varying internal pressures in a crossbore geometry were evaluated using FEA and notch strain analysis formulas including both Neuber and Glinka approaches. To define the theoretical elastic stress concentration factor based on ratios between maximum Mises or hoop stress and pressure or nominal stress four different values were calculated and imported into the notch strain analysis formulas. It was observed that the results of Glinka approach match better to the FEA results particularly by applying the ratio between maximum Mises stress and nominal stress as elastic stress concentration factor.