scholarly journals Transverse waves in nonlinearly elastic solids and the Milne—Pinney (or Ermakov) equation

2011 ◽  
Vol 16 (6) ◽  
pp. 586-593 ◽  
Author(s):  
Michel Destrade ◽  
Giuseppe Saccomandi
Author(s):  
Marina Sokolova ◽  
Yuri Astapov ◽  
Dmitrii Khristich

Dynamic methods for identifying a model of a nonlinearly elastic deformable body are considered. By the effective phase velocities of longitudinal and transverse waves propagating along and across the axis of the compressed bar, it is possible to determine five elastic constants of the second and third orders included in the model relations. Calculation formulae are obtained and an example of determining the dependence of phase velocities on the preliminary deformation for polyamide 6 is given. The influence of preliminary deformations on polar diagrams of wave velocities is investigated.


1997 ◽  
Vol 50 (11S) ◽  
pp. S93-S96 ◽  
Author(s):  
C. O. Horgan

One of the most widely used constitutive models for compressible isotropic nonlinearly elastic solids is the generalized Blatz-Ko material for foam-rubber and its various specializations. For this model, a discussion of necessary and sufficient conditions for ellipticity of the governing three-dimensional displacement equations of equilibrium is provided. When the parameter f occurring in the generalized Blatz-Ko model is in the range 0 ≤ f < 1, it is shown that ellipticity is always lost at sufficiently large stretches, while for f = 1, the equilibrium equations are globally elliptic. The implications of these results for material instabilities in a variety of physical problems are discussed.


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