An analytical solution was used for obtaining the maximum allowable heat flux in symmetric composite laminates containing a quasi-square cutout with different stacking sequences subjected to uniform heat flux. The Tsai-Hill criterion was used to assess the maximum allowable heat flux of the laminate. The analytical solution was obtained based on the thermoelasticity theory and the Lekhnitskii’s method. Furthermore, by employing a suitable mapping function, the solution of symmetric laminates with a circular cutout was extended to the quasi-square cutout. The quasi-square cutout was studied in a symmetric laminate made of Glass/epoxy with different stacking sequences of [0/90]S, [45/-45]S , [30/-30]S. The results showed that the maximum allowable heat flux experienced in perforated plates can be improved by considering the appropriate stacking sequence and the optimal values of the cutout parameters. According to the results, the best cutout geometry was not always a circle, as in some cases by choosing the appropriate values of bluntness parameter, cutout orientation, heat flux angle, cutout aspect ratio and laminate stacking sequence, a non-circular cutout provided higher maximum allowable heat flux value for a perforated plate than a circular cutout. تفاصيل المقالة

In this study, the effects of impact angle and impactor geometry were investigated on the impact behavior of aluminum honeycombs experimentally and numerically. The high-velocity impact tests were carried out using a gas-gun test machine with flat, spherical and conical-head impactors and impact angles of 0°, 15° and 30° at different incident velocities ranging from 55.8 to 150.5 m/s. The numerical models were developed in LS-Dyna finite element code and well validated against the experimental results. The results showed that the impact behavior of honeycombs is considerably dependent on the impactor head geometry and the impact angle. The honeycomb panel impacted by the conical projectile experienced the highest absorbed energy and ballistic limit velocity. Moreover, it was found out that increasing the impact angle increased the absorbed energy and ballistic limit velocity of honeycombs. Furthermore, different impactor head geometries resulted in different failure mechanisms in the course of impact loading. تفاصيل المقالة

Mechanical behavior of two-layer metal laminate structures under low-speed impact loading was investigated experimentally and numerically. The experimental results were just used for validation of numerical results. Then numerical modeling was used to study the behavior of metal laminates in details. The mechanical behavior of the metal laminate structures under impact loading was found to be dependent on the material substance of the layers. The metal layers were made of four common materials used in the industry. Results showed that the maximum amount of contact force and minimum amount of contact duration for the metal laminate structures with similar metal layers were obtained when the layers were made of steel. Whereas, the maximum amount of displacement and dissipated energy were achieved for the structure with lead layers. For the structures in which the first metal layer was Al-6061T6, the maximum contact force obtained when the second metal layer was made of steel; and the maximum displacement occurred when the second metal layer was made of lead. It was found that the maximum mean amount of contact force belonged to the structures with first metal layer of steel and the maximum mean amount of displacement belonged to the structures with the first metal layer of lead. The finite element analysis results were in good agreement with the experimental results and also with the other researcher’s results. تفاصيل المقالة