A constitutive model for active–passive transition of muscle fibers

• Published in: International journal of non-linear mechanics 2012-03, Vol.47 (2), p.377-387
• Main Authors: Paetsch, C., Trimmer, B.A., Dorfmann, A.
• Format: Article
• Language: English
• Subjects: Active tension; Energy of formation; Energy use; Fibers; Finite deformations; Mathematical analysis; Mathematical models; Muscles; Phenomenological models; Strain; Three dimensional
• ISSN: 0020-7462; 1878-5638
• DOI: 10.1016/j.ijnonlinmec.2011.09.024

In this paper, we examine the transition of striated muscles between active and passive states. New experimental data of a muscle performing such a transition are provided, allowing for a new model to be developed to capture this mechanical behavior. Specifically, a strain energy function is formulated using the theory of transient networks, introducing an intermediate, stress-free configuration for the active muscle fibers. Additionally, energy dissipation occurring during the unloading is accounted for by specifying a pseudo-energy function. The general three-dimensional case is specialized to uniaxial deformation for comparison with test data, from which material parameters are determined. Finally, numerical results are presented, demonstrating the model's ability to capture the mechanical behavior with changing stimulus. ► New experimental data show the transition from the passive to the active state in a Manduca muscle under uniaxial extension. ► The data show that the active muscle, in the reference configuration, is no longer stress-free. ► The constitutive model accounts for multiple stress-free reference configurations, for the change in mechanical behavior under stimulus and for energy dissipation during unloading.