Authors: Amit Karmakar, Kikuo Kishimoto
Abstract: In this paper a transient dynamic finite element analysis is presented to study the response of centrally impacted delaminated composite pretwisted cylindrical shells. An eight noded isoparametric plate bending element is employed in the finite element formulation. Effects of transverse shear deformation and rotary inertia are included. To satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front a multipoint constraint algorithm is incorporated. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations
are solved by Newmark’s time integration algorithm. Parametric studies are performed in respect of relative size of delamination and angle of twist for graphite-epoxy composite cylindrical shallow shells subjected to low velocity normal impact.
1285
Authors: Xian Feng Wang, Feng Xing, Ming De Xue, Bing Ye Xu
Abstract: A lower-bound shakedown analysis for cylindrical shells containing defects is performed based on the static shakedown theorem in a finite element computational form. To overcome the numerical difficulties, the pseudo-temperature field is applied to a structure and the resulting thermo-elastic stress is considered as the self-equilibrium residual-stress field. The pseudo temperature is assumed as a harmonic function satisfying the uniqueness theorem, therefore the nodal temperature matrix of the whole structure can be expressed by the boundary nodal temperature matrix. The nonlinear yield condition is piece-wise linearized so that the shakedown analysis is transformed into a linear programming problem in which the strategic variable is boundary nodal temperature and objective variable is the loading multiplier. The relations of limit and shakedown pressures to geometric parameters of various defects are presented.
1680
Authors: Hui Jie Zhang, Zhi Ping Tang, He Huang
Abstract: In this paper, radial impact responses of TiNi phase transformation cylindrical shell were experimentally studied on two-directional constraint. The nominal load-displacement curve was gained by advanced SHPB; meanwhile, the deformation process of the cylindrical shell was recorded by the high speed camera (30000 fps). The effect of stress wave on the whole structure during load process was as follows: the load-displacement curve fluctuated fiercely and rose gradually in the beginning period, whose frequency was basically the same as that of the stress wave propagation in the Striker 2; After that, the load-displacement curve tended to flat, the shell structure became to be ellipse as the compression increases, and the whole unload process slowed down. Finally, the surface strain was obtained by processing the shell deformation image, and the dynamic effect of the material phase transition and phase transition hinge on the cylindrical shell was examined.
1155
Authors: Deng Wang Wang, Xue Jun Qin, Shi Ying Tang, Wen Xiang Liu
Abstract: Dynamic fracture of explosion containment vessels subjected to internal blast loads is the foundation for conducting safety assessment and failure analysis of explosion containment vessels. The experiments were carried out to investigate dynamic fracture characteristics of cylindrical steel shells subjected to internal blast loadings at the centers. The elastic-plastic response of cylindrical steel shells was conducted using nonlinear dynamic finite element analysis code LS-DYNA. The fracture mode and fracture mechanism of a cylindrical shell were specially studied through analysis of deformation, macrographs of fracture surface and elastic-plastic response. The results show that dynamical ductility deformations appear and the shear bands form when the cylindrical steel shell expands under internal blast loading. The cylindrical steel shell fractures preferentially along the shear bands due to its softening effect. The fracture mechanism is that the shear bands tear under tensile circumferential stress. The shear bands and the tensile circumferential stress dominate the final fracture mode. The fracture mode is of the ductile fracture.
245
Authors: Fu Yin Gao, Yuan Long, Chong Ji, Chang Xiao Zhang
Abstract: Experimental researches were presented on dynamic characteristics of Q235 steel cylindrical shell impacted-explosive laterally by 75g cylindrical TNT dynamite at the center.The dynamic response was obtained under different distances with different setting ways of explosive sources.By means of an explicit nonlinear dynamic finite element computer code LS-DYNA,the nonlinear dynamic response process of cylindrical shell subjected to laterally explosion loading were numerically simulated with ALE coupling method. The numerical simulation results were in good agreement with experimental data. The results provided important reference for the blast-resistant properties analysis and safety assessment of oil-gas pipes safety.
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