A new methodology for measuring residual stress using a modified Berkovich nano-indenter

•New nanoindenter geometry and testing procedure to measure biaxial residual stress.•Asymmetric nanoindenter to estimate principal residual stresses and directionality.•Analytical-numerical mixed methodology to measure surface biaxial residual stress.•Non-equi-biaxial residual stress determined through two or three nanoindentations.•Using residual stress and indenter orientation influence on nanoindentation curves.