Finite element formulations for exterior problems: application to hybrid methods, non-reflecting boundary conditions, and infinite elements

1997 ◽  
Vol 40 (15) ◽  
pp. 2791-2805 ◽  
Author(s):  
Isaac Harari ◽  
Paul E. Barbone ◽  
Joshua M. Montgomery
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Hybrid Methods ◽  
Exterior Problems ◽  
Infinite Elements ◽  
Finite Element Formulations

Analysis of Partially Treated Multi-Layer Beam With Magnetorheological Fluid

2009 ◽  
Author(s):  
Vasudevan Rajamohan ◽  
Ramin Sedaghati ◽  
Subhash Rakheja
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Boundary Conditions ◽  
Fluid Layer ◽  
Transverse Displacement ◽  
Mr Fluid ◽  
Fluid Layers ◽  
Vibration Responses ◽  
Magneto Rheological ◽  
Finite Element Formulations

The vibration properties of multi-layer beam structure comprising a partial magneto-rheological (MR) fluid layer are investigated to study the influences of size and location of the fluid treatment of the beam. The governing equations for the partially-treated multi-layered MR beam were formulated in the finite element form. The validity of the proposed finite element formulations is demonstrated by comparing the simulation results with those obtained from the Ritz formulation. Two different configurations of a partially treated MR-fluid beam are considered. Simulations are performed to investigate the influences of intensity of an external magnetic field, and the location and length of the MR-fluid layers on the dynamic characteristics of the beam with different boundary conditions. The properties and vibration responses of the partially-treated multi-layer beam are then compared with those of a fully-treated beam. The results suggest that the natural frequencies and transverse displacement response of the partially-treated MR beam are strongly influenced by the location and the length of the fluid pocket, and the boundary conditions, apart from the applied magnetic field.

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

scholarly journals Shape Sensing of a Complex Aeronautical Structure with Inverse Finite Element Method

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1388
Author(s):  
Daniele Oboe ◽  
Luca Colombo ◽  
Claudio Sbarufatti ◽  
Marco Giglio
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Strain Field ◽  
Element Analysis ◽  
Inverse Finite Element Method ◽  
Shape Sensing ◽  
Definition Of ◽  
High Level ◽  
Element Method

The inverse Finite Element Method (iFEM) is receiving more attention for shape sensing due to its independence from the material properties and the external load. However, a proper definition of the model geometry with its boundary conditions is required, together with the acquisition of the structure’s strain field with optimized sensor networks. The iFEM model definition is not trivial in the case of complex structures, in particular, if sensors are not applied on the whole structure allowing just a partial definition of the input strain field. To overcome this issue, this research proposes a simplified iFEM model in which the geometrical complexity is reduced and boundary conditions are tuned with the superimposition of the effects to behave as the real structure. The procedure is assessed for a complex aeronautical structure, where the reference displacement field is first computed in a numerical framework with input strains coming from a direct finite element analysis, confirming the effectiveness of the iFEM based on a simplified geometry. Finally, the model is fed with experimentally acquired strain measurements and the performance of the method is assessed in presence of a high level of uncertainty.

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