Asymptotic boundary conditions for axisymmetric finite element electrostatic analysis

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.

Download Full-text

Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

Applied Sciences ◽

10.3390/app11041482 ◽

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.

Download Full-text

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

Sensors ◽

10.3390/s21041388 ◽

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.

Download Full-text

Understanding the critical role of boundary conditions in meso-scale finite element simulation of braided composites

Advanced Composites and Hybrid Materials ◽

10.1007/s42114-021-00284-3 ◽

2021 ◽

Author(s):

Zhenqiang Zhao ◽

Peng Liu ◽

Haoyuan Dang ◽

Yang Chen ◽

Chao Zhang ◽

...

Keyword(s):

Finite Element ◽

Boundary Conditions ◽

Finite Element Simulation ◽

Critical Role ◽

Braided Composites ◽

Element Simulation ◽

Meso Scale

Download Full-text

Numerical Solution of Nonlinear Schrödinger Equation with Neumann Boundary Conditions Using Quintic B-Spline Galerkin Method

Symmetry ◽

10.3390/sym11040469 ◽

2019 ◽

Vol 11 (4) ◽

pp. 469 ◽

Cited By ~ 2

Author(s):

Azhar Iqbal ◽

Nur Nadiah Abd Hamid ◽

Ahmad Izani Md. Ismail

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Boundary Conditions ◽

Numerical Solution ◽

Neumann Boundary ◽

Neumann Boundary Conditions ◽

Spline Method ◽

Galerkin Finite Element Method ◽

Galerkin Finite Element ◽

B Spline

This paper is concerned with the numerical solution of the nonlinear Schrödinger (NLS) equation with Neumann boundary conditions by quintic B-spline Galerkin finite element method as the shape and weight functions over the finite domain. The Galerkin B-spline method is more efficient and simpler than the general Galerkin finite element method. For the Galerkin B-spline method, the Crank Nicolson and finite difference schemes are applied for nodal parameters and for time integration. Two numerical problems are discussed to demonstrate the accuracy and feasibility of the proposed method. The error norms L 2 , L ∞ and conservation laws I 1 , I 2 are calculated to check the accuracy and feasibility of the method. The results of the scheme are compared with previously obtained approximate solutions and are found to be in good agreement.

Download Full-text