BIOMECHANICAL CHARACTERIZATION OF THE CONSTITUTIVE RELATIONSHIP FOR THE BRAINSTEM

Experimental tests using porcine brainstem samples were performed on a custom designed stress relaxation shear device. Tests were performed dynamically at strain rates over 1s (super -I), to three levels of peak strain (2.5%-7.5&). The directional dependence of the material properties was investigated by shearing both parallel and transverse to the predominant direction of the axonal fibers. Quasi-linear viscoelastic theory was used to describe the reduced relaxation response and the instantaneous elastic function. The time constants of the reduced relaxation function demonstrate no directional dependence. However, the relative magnitude of the exponential functions and the parameter representing the final limiting value are significantly different for each direction. The elastic function qualitatively demonstrates a dependence on direction. The results suggest that the brainstem is an anisotropic material. The data provides a starting point for analyzing the directionally dependent nature of brainstem material and can serve as a guide in developing new material models for finite element analysis. (A) For the covering abstract of the conference see IRRD 882980.

Language

  • English

Media Info

  • Features: References;
  • Pagination: p. 153-9

Subject/Index Terms

Filing Info

  • Accession Number: 00729428
  • Record Type: Publication
  • Source Agency: Institute for Road Safety Research, SWOV
  • ISBN: 1-56091-741-5
  • Files: ITRD
  • Created Date: Dec 26 1996 12:00AM