DETERMINATION OF THE DEFORMATION DEPENDENT STIFFNESS OF FIBER REINFORCED MEMBRANES |
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| R. Reihsner, R. J. Beer , M. Gingerl, H. Millesi |
- Abstract:
- Some manufacturing processes of fiber reinforced soft membranes do not provide knowledge neither about the density nor about the orientation of the fairly random distributed fibers. As a consequence, the result of these processes is often an anisotropic membrane with an unknown, in general inhomogeneous, stiffness distribution.
In case of soft membranes both the distribution of the stiffness and the degree of anisotropy are in addition a function of the state of deformation. This leads in general to non-linear constitutive laws. For soft membranes which can only bear membran stresses parallel to its center plane it is evident that only correspondingly small (from the theoretical point of view infinitesimal small) deformation steps can be described using the generalized Hooke’s law. This incremental procedure of the experiments is equivalent to the application of Henky’s definition of strain by which the actual given strain results using a simple integration procedure. For the determination of the in general 6 independent coefficients of the generalized Hooke’s law the results of 6 independent deformation steps are needed.
From experience with such kind of membranes, especially with biomechanical experiments with skin, it is known that all quantities have a considerable wide range of scattering. Therefore, a sufficient high number of measurements are necessary allowing the application of the methods of least mean square fits. This method has to be applied two times. First, to determine the stresses in each procedure with respect to an applied coordinate system, and second, for the coefficients of Hooke’s law. - Keywords:
- Keywords : mathematical modelling, anisoptropy, inhomogeneous structures, biomechanics
- Download:
- IMEKO-WC-2000-TC13-P342.pdf
- DOI:
- -
- Event details
- Event name:
- XVI IMEKO World Congress
- Title:
Measurement - Supports Science - Improves Technology - Protects Environment ... and Provides Employment - Now and in the Future
- Place:
- Vienna, AUSTRIA
- Time:
- 25 September 2000 - 28 September 2000