Coupling EPIC to LS-DYNA for Simulation of Blast-Structure-Fragmentation Interaction

2010 ◽  
Author(s):  
David L. Littlefield ◽  
Kenneth C. Walls ◽  
Kent T. Danielson
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
General Purpose ◽  
Structural Deformation ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Finite Element Code ◽  
Simulation Framework

In this work we have coupled the EPIC code to the LS-DYNA code to provide a high-fidelity simulation framework for simulation of blast-structure-fragmentation interaction. The coupled code exploits the strengths of the two original codes: EPIC, which has special algorithms and models for weapons effects analysis, and LS-DYNA, which is a general purpose finite element code for modeling large-scale structural deformation. Example problems are shown which illustrate the advantages of this approach.

A Study on Fundamental Mechanisms of Warp and Recoil in Hemming

2000 ◽  
Vol 123 (4) ◽  
pp. 436-441 ◽  
Author(s):  
Guohua Zhang ◽  
Xin Wu ◽  
S. Jack Hu
Keyword(s):  
Finite Element ◽  
Process Parameters ◽  
Flat Surface ◽  
General Purpose ◽  
Straight Edge ◽  
Finite Element Code

In this paper, the occurrence of recoil and surface warp during the flat surface-straight edge hemming process is investigated. A general-purpose finite element code ABAQUS/Standard is used to simulate the hemming operations. Reverse bending and springback are the fundamental mechanisms that cause surface warp and recoil. Recoil and warp are not independent. One parameter, final equivalent warp, is used to represent both. Pre-hemming target ending position is proposed based on the minimization of the final equivalent warp. The influence of the geometrical and process parameters on recoil and warp are also discussed.

Finite Element Simulations of Joints Used in the Automotive Industry

Manufacturing ◽  
2002 ◽  
Author(s):  
Rishikesh Bhalerao ◽  
Brad Heers ◽  
Mark Bohm ◽  
Marc Schrank
Keyword(s):  
Finite Element ◽  
Best Practices ◽  
Automotive Industry ◽  
Functional Performance ◽  
Effective Means ◽  
General Purpose ◽  
Vehicle Body ◽  
Finite Element Code ◽  
Automotive Applications ◽  
Modeling Techniques

Finite element-based simulations of vehicle body systems are an effective means of optimizing a design. However, body systems often consist of components from a variety of sources. Hence, accurate modeling requires a robust set of analysis functionality for joining such components. Joints—such as welds, bolts, rivets, clinches, and adhesives—present unique challenges to the analyst. Despite the critical influence joints have on functional performance, there is little information on best practices for modeling such connections. This paper presents a survey of some of the approaches available in ABAQUS, a general-purpose commercial finite element code, and discusses various applications of these techniques through a series of case studies. While the modeling techniques discussed in this paper have been motivated largely by automotive applications, they are also applicable to other areas such as aerospace structures.

Efficient Uncertainty Quantification in Structural Dynamic Analysis Using Two-Level Gaussian Processes

2015 ◽  
Author(s):  
Kai Zhou ◽  
Pei Cao ◽  
Jiong Tang
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Uncertainty Quantification ◽  
Large Scale ◽  
Computational Cost ◽  
Response Prediction ◽  
Element Model ◽  
High Fidelity ◽  
Structural Dynamic ◽  
Rapid Sampling

Uncertainty quantification is an important aspect in structural dynamic analysis. Since practical structures are complex and oftentimes need to be characterized by large-scale finite element models, component mode synthesis (CMS) method is widely adopted for order-reduced modeling. Even with the model order-reduction, the computational cost for uncertainty quantification can still be prohibitive. In this research, we utilize a two-level Gaussian process emulation to achieve rapid sampling and response prediction under uncertainty, in which the low- and high-fidelity data extracted from CMS and full-scale finite element model are incorporated in an integral manner. The possible bias of low-fidelity data is then corrected through high-fidelity data. For the purpose of reducing the emulation runs, we further employ Bayesian inference approach to calibrate the order-reduced model in a probabilistic manner conditioned on multiple predicted response distributions of concern. Case studies are carried out to validate the effectiveness of proposed methodology.

A Fluid-Structure Coupling Method for Rotor Blade Unrunning Design

2013 ◽  
Author(s):  
Hui Yang ◽  
Yun Zheng
Keyword(s):  
Finite Element ◽  
Rotor Blade ◽  
Large Scale ◽  
Structural Deformation ◽  
Convergence Criterion ◽  
Blade Profile ◽  
Structural Dynamic ◽  
Mode Superposition ◽  
Blade Shape ◽  
Nonlinear Aerodynamic

This paper reports a numerical method for the design of a unrunning blade with the consideration of both nonlinear aerodynamic and centrifugal forces. Accurate prediction of blade manufacture shape in turbomachinery is crucial for performance, efficiency and aeroelastic stability. An iterative procedure starting from a given blade running shape is developed to predict the manufacture blade shape. The model is based on a three-dimensional (3D) unsteady nonlinear Navier-Stokes Computational Fluid Dynamics (CFD) solver and the mode superposition structural dynamic theory in conjunction with a finite element structural model for the rotor blade. The manufacture profile of the blade (“Cold” blade) is estimated from the running blade shape (“Hot” blade). ANSYS finite element code is used to compute the deflection of the cold blade due to centrifugal loads. A finite volume based 3D nonlinear CFD code, coupled with a mode superposition structural dynamic modal method, is employed to determine the blade deflection due to unsteady aerodynamic loading. The difference between the computed blade profile and the targeted hot blade shape is used to predict a new cold blade for the next iteration if the convergence criterion is not met. The method is applied to predict the manufacture blade shape of a large-scale propfan and a NASA rotor 67 fan. The predicted blade profile and the twist angle of the blade at various spans are presented. The results show that improvements of the manufacture blade profile can be made by including proper nonlinear aerodynamic effect on the blade deflection in the numerical model. The results also illustrate that aerodynamic nonlinear effects on structural deformation should be included for a better cold blade design.

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.

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