Modal analysis comparison and performance analysis of conventional and isogrid surface barrel

The firearms adventure, which started with the discovery of gunpowder, continues its technological development at full speed today. Considering the importance of precision and efficiency studies in firearms, detailed studies are carried out on the barrel section where kinetic energy is added to the bullet core. Vibration occurs in the barrel section due to explosion energy. This vibration impairs shooting sensitivity and accuracy on the target. In this study, by using the barrel of a conventional AR-15 automatic rifle with a weight of 763 g, by applying a grid (isogrid) surface with the nTopology program, as a result of topological optimization, the barrel was 699 g. reached weight. Modal analysis was performed in the Ansys program for both barrels. It is aimed to increase structural rigidity by increasing the mode frequencies. At the same time, the barrel with a grid surface was verified by checking the structural strength with the ANSYS Workbench LS-Dyna program. As a result of the modal analysis, it was seen that there was a decrease in modal frequency only in the fifth, sixth and eighth modes for the first eleven modes, and an increase in different percentages was observed for the other modes. According to the internal ballistic pressure-time graph in the conventional barrel, it was seen that there was a stress of 856.91 MPa in the structural analysis performed in the Workbench LS-Dyna program at the time step with the highest pressure. In the barrel with a gridded surface, a stress of 811.38 MPa was observed, resulting in a stress reduction of 5.31 percent. In line with these results, it was observed that the target sensitivity and accuracy of the barrel with a grid surface applied increased.