on the derivation of passive 3d material parameters from 1d stress–strain data of hydrostats

the present paper offers a novel equivalent-pressure approach to the derivation of isotropic passive muscle parameters from 1d stress–strain data sets. the approach aims specifically at the identification of material parameters in hydrostats, in which case the equivalent-force approach that is common for skeletal muscle generates suboptimal results. instead, an equivalent-pressure hypothesis is formulated which provides more adequate boundary conditions for the concluding curve-fitting procedure. the choice of an appropriate constitutive description is decisive for the quality of the deduced parameter sets. here, a yeoh material law is chosen for the model of a squid tentacle. parameters derived by both, equivalent-force and equivalent-pressure algorithms, are compared, illustrating the applicability limits of either. they are implemented in a finite element model of the tentacle. a prey-capture strike is simulated and compared to data from literature. the hydrostat-specific interpretation of the equivalent-pressure hypothesis is shown to match the reference very well.