Thermodynamic optimisation of cold expansion of holes by means of spherical mandrelling

Abstract

The paper presents the outcomes of optimisation in the spherical mandrelling process (SM) employed for cold expansion of holes in order to create a zone of residual compression stresses around the worked holes. The multi-objective optimisation of the process is performed in two approaches: scalarisation of the vector optimisation criterion, performed by the reference approach (optimistic approach) and by an alternative (thermodynamic) approach. The vector optimisation criterion has been substituted by the generated entropy functional depending on the vector of controlling factors (process parameters). The generated entropy plays the role of a surrogate function of a feasible scalarised function, and therefore it is not necessary to scalarise the vector optimisation criterion. Optimisation is reduced to generated entropy minimisation. The effectiveness of the latter approach has been proved.