Response of sandwiches undergoing static and blast pulse loading with tailoring optimization and stitching

C0 Layerwise Model with Fixed Degrees of Freedom and Variable In- and Out-of-Plane Kinematics by Strain Energy Updating Technique

“…Previous studies (see, e.g., [53,[55][56][57][58]71]) have proven that the OM model is able to accurately and efficiently treat local geometry, loading and material variations. In particular, a successful application to adhesively bonded joints was presented in [71] that demonstrated its capability of satisfying the quite complex stress-boundary conditions at the end of the overlap.…”

“…As a further application, laminates incorporating curvilinear paths of fibers are considered. The sample cases presented in [56] and [58] using the OM model, which were obtained as the result of an optimization process aimed at finding the orientation at any point that minimizes the out-of-plane stresses at the critical interfaces, while maximizing the bending stiffness, are retaken in order to show the effectiveness of the equivalent EM model also in this case of practical interest.…”

“…Applications to test cases (see, e.g., [53,[55][56][57][58]71]) have proven that the present model can be used elsewhere, no special models being required for treating local geometry, loading and material variations. An applications to bonded joints having already been presented in [71], in the numerical applications a sample case with clamped edges (Tessler, Di Sciuva and Gherlone [72]) will be considered in order to show how non-classical boundary conditions can be easily satisfied.…”

“…As a consequence, an always correct representation of the strain energy is obtained, from which accurate stresses are predicted directly from constitutive equations. Because the enforcement of the physical constraints is satisfied without increasing the number of unknowns, accurate results are obtained with a computational effort not considerably larger than for equivalent single-layer models, thus considerably lower than for the available discrete-layer and high-order layerwise models, as shown in [55][56][57][58][59] and also by the results reported hereafter, where the processing time by the present model is compared to that by the first-order shear deformation theory-FSDPT. In many sample cases [43,[51][52][53][54][55][56], a successful application to variable stiffness composites was shown, which proven the progressively refined "adaptive" zigzag models based on enforcement of physical conditions suited to find solutions in closed form of static and dynamic cases.…”

“…Because the transverse normal stress has a significant bearing for keeping equilibrium when temperature gradients across the thickness cause thermal stresses and when describing the core's crushing behavior of sandwiches, Icardi and coworkers [43,[51][52][53][54][55][56][57][58][59] incorporated into zigzag models a variable kinematic representation of displacements across the thickness that can adapt to the variation of solutions, where a progressively refined description of the piecewise variation of the transverse displacement was also considered. Accordingly, the representation can be refined like with discrete layer models, though the functional d.o.f.…”