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In this paper, an innovative flexible sandwich structure is introduced which can be used in shape changing (morphing) aircrafts that adapt their external shape to different flight conditions. First, different ideas for achieving smart aircraft in the literature is briefly reviewed and then characteristics of the new deformable sandwich structure as well as its different features in comparison to other proposed structures are described. Moreover, fabrication details of deformable and load bearable sandwich panel are explained. In an aircraft with variable camber wings, deformable sections can be supposed as a cantilever beam. As a result some specimens of new deformable sandwich structure are constructed and then tested as end-loaded beams. Since the numerical study of the new proposed structure requires an understanding of the mechanical behavior of components used, a comprehensive study about the mechanical behavior of individual components of structure is conducted. According to the observation of broken samples, a distribution of cavities resulting from the manufacturing process is supposed in one type of model to obtain more accurate numerical results. Finally, another example is analyzed with the same assumptions and it is shown that in the second example, the numerical results are close to the experimental data.

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Skeletal muscles simulation remains a controversial topic as a result of its complex anatomical structure and mechanical characteristics such as nonlinear material properties and loading conditions. Most of the current models in the literature for describing the constitutive equations of skeletal muscles are based on Hill's one-dimensional, three element model. In this paper a 3D constitutive model which is based on the hyper elastic behavior of skeletal muscle and energy function has been presented. By using the derivatives of such energy function for defining the Second Piola and Cauchy stresses, we able to describe the inactive behavior of skeleton muscles. The applied constitutive equations are an efficient generalization of Hamphury's model for the inactive behavior of skeletal muscle. In this paper using a 3D model, different modes of deformations of skeletal muscle such as simple tension, biaxial and shear tests has been investigated and material properties constants for each modes of deformation has been optimized by Genetic algorithm. Finally the results of the model simulations of each mode are compared with those obtained from experimental tests. Also, the model results are compared with the ones from two well- known hyper elastic Ogden and Mooney-Rivilin models in order to show the priority of the new developed 3D model to those aforementioned models has been shown.