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In this study, the forward hot dieless spinning method is employed in order to fabricate conical tubes using thick aluminum. The process is first examined numerically and then verified by an experimental work. In the numerical study, a 3-D dynamic explicit model is used to solve a common problem in the modeling of the spinning process, the tube is fixed and the roller rotates around the tube. The strain distribution in the tube at various forming passes is studied. The numerical results show that the circumferential strain distribution in different positions of the tube has a negative value whose value increases toward the free end of the tube. Besides, the results indicate that the hardness of the sample increases by about 18% due to the hot dieless spinning process and such a hardness augmentation is obvious along the thickness of the formed tube.

Light and medium protection for small naval vessels guarantees their high performance and safety during the guard duties. In this study, a protective shield fabricated from Dyneema HB25 fibers has been utilized as an add-on layer on the coast guard boat hull. Finite element analyses have been conducted using Chocron's model. Two standards of gun-fire were employed and various thicknesses of the composite layers were examined by ballistic impacts. Afterward, numerical simulations results compared with experiments and revealed a good consistency. Finally, some graphs have been presented to help designers for choosing more convenient shield based on protection and weight characteristics after judgment of vessel requirements.