جستجوی مقالات مرتبط با کلیدواژه « بار ضربه ای » در نشریات گروه « مکانیک »

Due to the increasing use of new materials, such as auxetic structures, it is necessary to investigate mechanical phenomena, such as vibration, in structures made of these types of materials. This paper examines the forced vibrations of a three-layer cylindrical shell containing inviscid fluid under shock load. All three layers are made of aluminum, and the central layer is made of a re-entrant honeycomb cell structure. Using high-order shear deformation theories (HSDT) and Hamilton’s principle, the governing equations of the system have been extracted and solved by the Galerkin weighted residual method. The outputs of the Abaqus finite element software are used to validate the results. The system is investigated with both simple and clamped support conditions. Finally, this study investigates the influence of the geometrical parameters of the shell and the auxetic structure, as well as the type, intensity, duration, and location of the load, and the effect of the fluid on the dynamic and time responses.

This paper details the experimental testing and numerical simulation of crushing performance of laminated composite tube under impact loading. Composite tube is modeled as multiple layers of shell elements and chamfered trigger is accounted for by sequentially reducing the length of the layers. The simulation is performed using a Continuum Damage Mechanic material model for representing the intralaminar behavior in which damage activates according to LaRC03-04 failure criteria and propagates according to a set of linear and bi-linear softening laws. Mesh objectivity is accounted for by incorporating crack band law and regularizing dissipated energy by element characteristic length. Interlaminar fractures are modeled using Tiebreak contact based on traction-separation law while a mesh-independent energy based method, utilizing cohesive zone length criterion, is implemented to effectively simulate the delamination. Most of the laminate properties, required for simulation, are obtained by standard tests. To validate the simulation results, impact tests are performed in drop tower machine. Specimens are made of cross-ply laminate using vacuum assisted resin transfer molding procedure and output data is filtered using channel frequency class 600. A good agreement is achieved between numerical and experimental data.