Mechanical analysis of coin striking: Application to the study of byzantine gold solidi minted in constantinople and carthage

A mechanical analysis of the forging of a coin, using an upper-bound method, is briefly presented: the geometry of the coin, simplified, consists of an axisymmetric disk with a central circular design and an outer annular legend. The energy and strain necessary to form the design are calculated and the shape of the blank then computed from the shape of the coin. This analysis is applied to numismatic problems, in the present instance considering whether mechanics is able to explain the evolution of the geometry of Byzantine gold solidi at the Mints of Carthage and Constantinople between the VIth and XIIth centuries. It is shown that, in Carthage, this evolution was aimed at saving energy, and in Constantinople, the evolution of the geometry of solidi was due to variation in the fineness of the gold.