Dielectric elastomers Maxwell stress, electric field

The induced Maxwell stress (ctm) can be related to the applied electric field ( ) and the dielectric constant of the elastomer... 

It is important to point out that as the electrostatic problem must be solved in all space R, whenever an electric field exists outside the dielectric an associated Maxwell stress can be defined (see next Section). Therefore, equilibrium at the external boundary of the elastomer must be understood in terms of the jump between the stresses at the two sides (Bertoldi and Gei 2011). 

In one of the first papers dealing with dielectric elastomers, Pelrine et al. (1998) proposed a widely used model to analyze stresses and strains in a thin elastomeric membrane subjected to a transverse electric field. The notion of Maxwell s pressure Pel = eE is well known among the EAP research community. How does this concept match with the theory developed here This can be easily explained recalling that fire stress measure adopted by Pelrine et al. (1998) corresponds to our and their model is valid only for incompressible materials. 

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