Loss of stability of dynamically loaded ideal cylindrical shell welded to saddle support

Abstract

The article deals with the loss of stability of a cylindrical shell at dynamic transverse load. A typical practical example of this kind of construction is a road tank welded to saddle supports. All known domestic or foreign standards or recommendations for thin-walled shell structures such as ČSN 690010 [1], EN 13445-3 [2], EN 1993-1-6 [3], AD-Merkblätt [4], DIN 18800 [5], ASMECode [6], European recommendation ECCS 2008 [7] etc., provide the solution of stability of thin-walled shell structures for static load only. However, the situation of the traffic vehicles like road tanks is more complex because, in the vast majority of cases, these are loaded dynamically. Within this article, computational FEM analysis of the dynamically loaded cylindrical shell has been applied on a geometrically reduced model, which will later be more suitable for experimental verification. The cylindrical shell is firmly attached to the single saddle support through which both static and dynamic reaction forces are transmitted. The saddle support embracing angle takes values 2 = 60°/90°/120° in accord with the demand of the standards and recommendations mentioned above. At first, the loss of stability of the statically loaded cylindrical shell has been analysed. Both geometric and material nonlinearities have been taken into consideration. The geometric nonlinearity describes the loss of stability while material nonlinearity describes the limit state of elastic-plastic carrying capacity. The resulting phenomenon is a nonlinear stability snap-through of the saddle support into the cylindrical shell in the elastic-plastic field due to the static load. At second, the dynamic analysis of the same problem follows. The initial load velocity is selected in the range of 1 to 15 msec-1. The upper limit of the initial velocity corresponds to the maximum possible piston speed of the hydraulic pulsator installed at Education and Research Center in Transport (ERCT) of the Faculty of Transport Engineering, University Pardubice. The hydraulic pulsator will be used for the planned experimental testing designed based on the analysis results presented in this article. At the end of the article, the static and dynamic load capacities of the computational model have been compared and then conclusions have been made based on this outcome.