Dynamic Response of Complex Structural Intersections Using Hybrid Methods

1999 ◽  
Vol 66 (3) ◽  
pp. 653-659 ◽  
Author(s):  
P. J. Halliday ◽  
K. Grosh
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Lagrange Multipliers ◽  
Variational Formulation ◽  
Hybrid Methods ◽  
Finite Element Code ◽  
Reduced Order ◽  
Complex Structural ◽  
Continuous Problem

A novel application of Lagrange multipliers to couple domains modeled independently with linear elastodynamic and reduced-order theories is presented herein. This method is developed from a variational formulation of the continuous problem and is easily implemented within a finite element code. Applications include, but are not limited to, modeling of inhomogeneities such as joints, cracks, holes, and welds within a frame-like structure. Results from this method compare well with a full elastodynamic discretization and existing methods for modeling such problems.

Postbuckling Analysis of Variable Stiffness Composite Panels Using a Finite Element Based Perturbation Method

2009 ◽  
Author(s):  
T. Rahman ◽  
S. T. IJsselmuiden ◽  
M. M. Abdalla ◽  
E. L. Jansen
Keyword(s):  
Finite Element ◽  
Perturbation Method ◽  
Variable Stiffness ◽  
General Purpose ◽  
Reduced Order Model ◽  
Finite Element Code ◽  
Order Model ◽  
Reduced Order ◽  
Quick Estimate ◽  
Optimization Loop

In earlier research the authors optimized variable stiffness panels for maximum buckling load, using lamination parameters. The aim of the present research is to analyze those optimized panels in the postbuckling regime so that further improvement can be achieved in the future with respect to its postbuckling performance. Because the incremental-iterative nonlinear analysis in the postbuckling regime is not feasible within an optimization loop a finite element based perturbation method (Koiter type) is used to compute postbuckling coefficients, which are in turn used to make a quick estimate of the postbuckling stiffness of the panel and to establish a reduced order model. The proposed perturbation method has been implemented in a general purpose finite element code. In the present work the postbuckling analysis of variable stiffness panels carried out using the reduced order model is presented and the potential of the approach for incorporation within the optimization process is demonstrated.

Numerical Simulation of Blast Loadings on a Thick-Walled Cylindrical Vessel

2007 ◽  
Author(s):  
Guide Deng ◽  
Ping Xu ◽  
Jinyang Zheng ◽  
Yongjun Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Dynamic Response ◽  
Rigid Wall ◽  
Cylindrical Vessel ◽  
Finite Element Code ◽  
Explicit Finite Element ◽  
Shell Deformation ◽  
Blast Loadings ◽  
Good Agreement

Determining blast loadings on an explosion containment vessel (ECV) is the foundation to design the ECV. Explosion of TNT centrally located in a thick-walled cylindrical vessel and its impact on the cylinder was simulated using the explicit finite element code LS-DYNA. Blast loadings on the cylinder computed are in good agreement with the corresponding experimental results. Then wall thickness and yield stress of the cylinder were changed in the following simulation to investigate effect of shell deformation on blast loadings. It is revealed that shell deformation during the primary pulses of blast loadings is so slight that it has little influence on the blast loadings. Though the deformation may increase greatly after the primary pulses, the dynamic response of an ECV is mainly affected by the primary pulses. Therefore, decoupled analyses are appropriate, in which the shell of an ECV is treated as a rigid wall when determining blast loadings on it.

Analysis of the Dynamic Response of Underground Structures under Internal Explosion

2011 ◽  
Vol 255-260 ◽  
pp. 1681-1686
Author(s):  
Peng Fei Ning ◽  
De Gao Tang
Keyword(s):  
Finite Element ◽  
Cylindrical Shell ◽  
Dynamic Response ◽  
Analytic Solution ◽  
Underground Structure ◽  
Finite Element Code ◽  
Underground Structures ◽  
Underground Blast ◽  
Internal Explosion ◽  
Different Thickness

Analytic solution for the dynamic response of underground structure is generally based on the theory of cylindrical shell. The underground structure constructed to resist internal blast is not suitable to be treated as cylindrical shell structure and is difficult to get analytic solution. In this paper, finite element code LS-DYNA is employed to calculate the dynamic response of underground blast-resistant structures exposed to internal blast. Two structures with different thickness buried in four types of surrounding rocks are calculated, and the influence of the surrounding rocks to the dynamic response of underground blast-resistant structures is analyzed.

Dynamic Modeling of Synchronous Belt-Drives Using an Explicit Finite Element Code

2005 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Michael J. Leamy
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Fixed Number ◽  
Friction Model ◽  
Rigid Bodies ◽  
Finite Element Code ◽  
Tooth Contact ◽  
Friction Forces ◽  
Normal Contact ◽  
Explicit Finite Element

A time-accurate explicit time-integration finite element code is used to simulate the dynamic response of synchronous belts-drives. The belt is modeled using beam or truss elements. The sprockets are modeled as cylindrical rigid bodies. Normal contact between the belt and a sprocket is modeled using the penalty technique and friction is modeled using an asperity-based approximate Coulomb friction model. The belt teeth/grooves are assumed to be located at the belt nodes (every fixed number of belt nodes). The nodes in-between teeth are subjected to the normal contact and tangential friction forces. The belt and sprocket teeth are assumed to be trapezoidal. The equivalent belt-sprocket tooth stiffness and damping coefficients in the normal tooth contact direction are used to calculate a normal tooth contact force at the belt teeth nodes. The tooth contact model also includes the effect of the tooth engagement tolerance. For validation purposes, a two-sprocket drive is modeled and a comparison is made between tooth loads predicted by the finite element model and experimental data available in the literature. Reasonable agreement between the simulation and experimental results is found of the drive’s tooth loads. Also, the dynamic response of a hybrid sprocket – flat pulley belt-drive is studied.

Geometrically nonlinear static and dynamic analysis of CNT reinforced laminated composite plates: A finite element study

2021 ◽  
pp. 095440622110089
Author(s):  
Balakrishna Adhikari ◽  
BN Singh
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Dynamic Response ◽  
Integration Scheme ◽  
Static And Dynamic Analysis ◽  
Finite Element Study ◽  
Nonlinear Eigenvalues ◽  
Nonlinear Static ◽  
The Impact ◽  
Element Study

In this paper, a finite element study is conducted using the Green Lagrange strain field based on vonKarman assumptions for the geometric nonlinear static and dynamic response of the laminated functionally graded CNT reinforced (FG-CNTRC) composite plate. The governing equations for determining the nonlinear static and dynamic behavior of the FG-CNTRC plate are derived using the Lagrange equation of motion based on Reddy's higher order theory. Using the direct iteration technique, the nonlinear eigenvalues for analyzing the free vibration response are obtained and the nonlinear dynamic responses of the FG-CNTRC plate are encapsulated based on the nonlinear Newmark integration scheme. The impact of the amplitude of vibration on mode switching phenomena and the consequence of the duration of the pulse on the free vibration regime of the plate are outlined. Also, the effect of time dependent loads is studied on the normal stresses of the plate. Furthermore, the impact on the nonlinear static and dynamic response of the laminated FG-CNTRC plate of various parameters such as span-thickness ratio (b/h ratio), aspect ratio (a/b ratio), different edge constraints, CNT fiber gradation, etc. are also studied.

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