Analysis of failure loads and optimal design of composite lattice cylinder under axial compression

Incremental auxetic response of composite lattices under isotropic prestress

“…(29)- (30), when the the dimensionless prestress variable �/ � ranges in the interval [0,1]. As we already noticed, we indeed focus our attention on lattices subject to equal biaxial tension, on considering that compressed lattices may suffer anticipated failure due to buckling [13,14]. We use the acronyms 'Hard1&2', 'Soft1&2', 'Hard1/Soft2' and 'Soft1/Hard2' to respectively denote the lattices that employ ABS for the rods of Type 1 and 2, NJF for the rods of Type 1 and 2, ABS for the rods of Type 1 and NJF for the rods of Type 2, and NJF for the rods of Type 1 and ABS for the rods of Type 2.…”

“…and it is immediate to verify that it results (12) where ∘ denotes the scalar axial force carried by the −th rod in the prestressed configuration. According to the constitutive equation (5), such a quantity is given by (13) By making use of Eqn. (4) into Eqn.…”

Improving the mass efficiency of a composite launch vehicle head fairing with a sandwich structure

“…Work [18] tackles issues on the optimization of cylindrical sheaths, homogeneous and heterogeneous in thickness, forming an irregular periodic structure. However, the results given were obtained only under the action of isolated axial compression.…”

“…Choosing a scheme of reinforcement and the thickness of bearing sheaths for a head fairing requires an analysis of their weight effectiveness. It is known [11,13,[16][17][18][19][20] that the reinforcement scheme of bearing sheaths significantly affects the shell's carrying capacity. At the same time, incompatible estimated cases of loading the articles such as a launch-vehicle head fairing considerably complicate the choice of the optimal reinforcement scheme for bearing shells for the entire spectrum of external loads.…”

“…At the same time, incompatible estimated cases of loading the articles such as a launch-vehicle head fairing considerably complicate the choice of the optimal reinforcement scheme for bearing shells for the entire spectrum of external loads. There are not enough studies into the optimal structures of reinforcement of sheaths made from polymeric composite materials exposed to combined loading, and they are almost missing for incompatible cases [11,13,[16][17][18][19][20]. In this regard, below is the analysis of results from the optimization of a composite cylindrical sheath with various reinforcement schemes, reported in [32] and further developed in [33].…”