جستجوی مقالات مرتبط با کلیدواژه "square section" در نشریات گروه "مکانیک"

Tube bending is widely used in the aerospace and automotive industries. Of the main difficulties of this process are wrinkling, rupture and incomplete filling of the die. If the ratio of the bend radius to tube diameter (R/D) in the bending process is between 1 and 1.5, the bending cannot be performed by conventional methods. Therefore, it is important to develop a new technique in this respect. In this study, at first, closed-end seamless tubes were produced by multistage deep drawing and ironing processes. Then, the proposed hydroforming process of square cross-section tubes with the ratio of R/D=1 has been examined experimentally and by FEM. It is illustrated that the square cross section tubes with low R/D can successfully be produced by the developed technique. In addition, the effect of internal fluid pressure and die bend angle on the thickness distribution of the inner, outer and lateral walls of the bending area has been investigated. It is shown that with increasing the pressure, the thickness of the inner, outer and lateral tube walls increases. The reduction in the thickness is much greater for the external wall. The tube in the R / D = 1 was formed with multi of bending angles. The results exhibit with increasing the bending angle, the pressure of forming was decreased.

The behavior and modeling of circular concrete sections confined by Fiber Reinforced Polymer (FRP) wraps have been recently studied extensively while non-circular sections have received much less attention. This study focuses on FRP-confined specimens with square sections under axial loading. A fuzzy logic based model is developed to predict the compressive strength of the FRP-confined square sections. The explicit formation of the proposed fuzzy model for the compressive strength of FRP-confined concrete is presented as a function of the section width، corner radius، compressive strength of unconfined concrete، thickness of FRP sheets، tensile strength and elastic modulus of FRP materials. The results indicated that the accuracy of the proposed fuzzy model is quite satisfactory as compared to a large database containing experimental results of 182 specimens assembled from the open literature. Moreover، the proposed fuzzy model is compared with the existing nine models developed by various researchers and is found to be more accurate.