Thermomechanical cycles in martensite energy converters

Abstract

We have studied the quantitative relationships governing the formation of thermomechanical cycles in heat engines with operational elements fabricated out of materials exhibiting the shape memory effect. With this purpose in mind, we have conducted experiments for two of the most common regimes under which materials function, namely: with a rigidly fixed amplitude of strain deformation, and for a scheme involving interconnected elements. We have plotted numerous phase diagrams in stress-strain-temperature coordinates and we have optimized such cycles in terms of their energy parameters. It has been established that the capacity of a metal to transform heat into mechanical work depends substantially on the form of the phase diagram, and this is at its maximum for sign- variable symmetric limit cycles. We undertook a theoretical calculation (and achieved positive results) of phase diagrams involving the application of structural-analytic theory insofar as this pertains to the functional properties of materials exhibiting the shape memory effect.