tailieunhanh - Stability analysis of cylindrical shells subjected to complex loads

The paper deals with stability analysis of shell on the basis FEM via Castem 2000. The numerical results of stability problems of cylinders subjected to different loads as compress load, pressure, concentrated and combined loads are compared with analytical result and give a good agreement. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 23, 2001, No4 (247 - 256) - STABILITY ANALYSIS OF CYLINDRICAL SHELLS SUBJECTED TO COMPLEX LOADS NGO HUONG NHU Institute of Mechanics 264 Doi Can, Hanoi, Vietnam ABSTRACT. The paper deals with stability analysis of shell on the basis FEM via Castem 2000. The numerical results of stability problems of cylinders subjected to different loads as compress load, pressure, concentrated and combined loads are compared with analytical result and give a good agreement. The influence of changing radius of the cylindrical shell on the unstable forms and the influence of angles of fibers on unstable behaviour of laminated composite shell are considered . Numerical results and corresponding programs by languages Gibian given in the paper to realize software Castem 2000 can be applied in the design and in the stability analysis of the shell with more complex conditions. 1. General equations and solutions for the stability problem The system of equations for the stability problem of shell with small deflections [1] is () () where w is a function of deflection and rp is a stress function. In the Cartesian coordinates, we have: q 8 2w ) fJ2w f:J2w = - h ( Px fJx2 + Py fJy2 + 2s fJxfJy and the system of equations can be reduced into an eight-order equation: D h v sw + 4 E fJ w R2 fJx4 2 (fJ w) (8 w) ( fJ w ) + Px \74 fJx2 +Py \74 fJy2 + 2s\74 fJxfJy 2 2 = 0. () a. Circular cylindrical shell subjected to axial compressed distributed in plane force p In this case the values Py = O; s = 0, the minimum possible critical stress has the form [1]: () 247 -* h when v = then P = R. b. Circular cylindrical shell subjected to pressure q. In this case the values Px = O; Py =/= O; s = 0, the minimum possible critical pressure is: (R) (Rh) for the middle cylinder and 3D E (h)3 q= R = ( _ v R for the long cylinder. q = L 3 4 1 2) () () c. Circular cylindrical shell subjected to a .