Volume 17, Issue 7 (9-2017)
Abstract
This research presents the study on mechanical buckling of thick-walled cylindrical shell made of functionally graded materials with ring supported under uniform axial and lateral loads. The mechanical properties of shell are variable along the thickness direction. First the governing equations on the buckling of the FGM cylindrical shell supported with ring are established based on third-order shear deformation theory. Then the governing characteristic equations were employed, using energy method and by applying the Ritz technique. In the following with solving characteristic equations, the critical load buckling of the FGM thick-walled cylindrical shell supported with axial and lateral loads are calculated. The boundary conditions represented by end conditions of the FGM shell are the following: clamped-clamped and free-free. To verify the validity of the proposed analytical method the results of this research are compared with the results came from using the finite element software. Finally, the effects of the different parameters such as thickness variations, boundary conditions, loading conditions and geometrical parameters of shell and ring on the buckling behavior of FGM thick-walled cylindrical shell are investigated. The results showed that by increasing the FGM volume fraction power in the shell structure, the critical buckling load increases and the location of the ring support has the significant effect on the critical buckling load. The results presented can be used as an important benchmark for researchers to validate their numerical and analytical methods.
Volume 25, Issue 6 (11-2023)
Abstract
One way of developing sustainable agriculture is to increase crop Water Productivity (WP). In drought conditions, cultivation management should result in reducing water consumption as well as lowering the negative impacts on crop yield and quality. This experiment was conducted to determine the influence of irrigation levels (full and deficit irrigation, providing 100 and 75% of the irrigation water requirement, respectively) and soil water retaining materials (organic fertilizer, superabsorbent at depths of 30 and 40 cm, superabsorbent mixed with soil, band application of superabsorbent, plastic installation at depths of 30 and 40 cm and control) on WP, leaf Relative Water Content (RWC), Electrolyte Leakage (EL), photosynthetic pigments, yield and yield components of wheat during the growing seasons of 2017 and 2018. The deficit irrigation caused an increase in WP and EL and decreased yield, yield components, RWC, and photosynthetic pigments, while the soil water retaining materials improved these properties. The average yields in the organic fertilizer treatment and installation of plastic at a depth of 40 cm were 9.55 and 8.76 tons ha-1, respectively. The highest WP (1.89 kg m-3) was observed in the organic fertilizer treatment. Application of cow manure and installation of plastic membrane did not have significant effect on wheat properties in the two water conditions. Overall, utilizing organic fertilizer and nylon membranes under deficit irrigation, improved wheat characteristics and WP. However, to reach a comprehensive conclusion, it is necessary to evaluate these treatments for several consecutive years with different soil and water conditions.