Research On The Local Buckling Strength Of Chimney With Cutouts

Thin-walled cylindrical shells have been widely used in engineering structures very early because of their efficient load carrying capacity and beautiful appearance.But it is also found that there are considerable differences between experimental studies and theoretical analysis on the strength of the shells under axial compression,especially when the diameter-to-thickness ratio is large.As a result,this paper researched typical kinds of initial geometrical imperfections due to their enormous effect to the cylindrical shells.Besides,it is necessary to equip cutouts on the shells sometimes,but there are few researches on the buckling strength of these holes reinforced shells.Above all,the buckling behavior of shells under axial compression with large diameter-to-thickness ratio was investigated in this paper,the details are as follows:?1?Firstly,the general finite element software ANSYS was used to establish the model.The shell181 elements were adopted for the shells,the solid45 elements were adopted for the rigid loading plates,and conta 175 and targe170 elements were used for contact simulation.The factors of element mesh,mechanical properties of the materials,boundary conditions and loading method were also considered.The finite-element modeling technique developed in the present paper was validated by the experimental and numerical results familiar to this study.?2?It is always very complicated of initial geometrical imperfections distribution.As a result,this paper investigated the eigenvalue buckling analysis model,the axisymmetric Rotter imperfection model and the local imperfection model which are typical and representative.Plenty different parameter analyses were explored,and this paper compared each parameter after obtained the influence law.?3?This paper introduced the design methods relative to the strength of axial compression shells,which include Code for design of chimneys in China,Code for design of chimneys in Japan,Australia Standard in Steel Structures 4100 and The Eurocode 3Standard.Plenty of experimental results were also collected.The results based on different design codes were compared with the experimental results and the finite-element results separately,and the discrepancy among them were checked then.Regression analyses were presented according to the data of finite-element results,and mathematical expressions were created later.The limit amplitude of initial geometrical imperfections were suggested after the comparison of the experimental results and regression formula results.?4?The buckling behavior influence of each parameter to the axial compressed holes reinforced cylindrical shells by inner tube was studied.The main influencing parameters are as follows:length-to-diameter ratio?L/D?of the shells,location ratio?L₀/L?of the cutout,diameter-to-thickness ratio?D/t?of the shells,length ratio?l_w/d?of the inner tube,cutout size ratio?d/D?and thickness ratio?t_w/t?of inner tube.Regression analyses were presented according to the data of finite-element results,the proposed formula for calculating the strengh of axial compressed and holes reinforced cylindrical shells by inner tube was obtained by using multiple regression method finally.