An optimisation approach towards locking-free isotropic shell elements

A new reinforcement measure with no-fire operation is presented, which is very suitable for space trusses which are located in gas stations. A finite element model (FEM) is presented with shell elements and multipoint constraint elements. With this FEM, nonlinear analyses are carried out. Analytical results show that integral failure of reinforced pipe is caused by yielding of original pipe inside. So it is not necessary to reinforce original pipe using steel pipe bonded outside with high yield strength. With the increase of length of bonded pipe outside, loading according to elastic stage and ultimate bearing loading increase, it is clear that the length of bonded pipe outside is an important factor which influences the bearing capacity.

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Study of CRFP Shell Structures under Dynamic Loading in Shock Tube Setup

Journal of Structures ◽

10.1155/2014/487809 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

H. A. Khawaja ◽

T. A. Bertelsen ◽

R. Andreassen ◽

M. Moatamedi

Keyword(s):

Shock Tube ◽

Dynamic Loading ◽

Test System ◽

Shell Structures ◽

Fiber Reinforced Polymers ◽

Carbon Fiber Reinforced Polymers ◽

Reinforced Polymers ◽

Isotropic Shell ◽

Flexural Response ◽

Good Agreement

The paper gives the study of the response of carbon fiber reinforced polymers (CRFP) quasi-isotropic shell structures under the influence of dynamic loading. The quasi-isotropic CRFP shell specimens are fabricated using Multipreg E720 laminates. These laminates are laid in such a way that shell structure has equal strength and mechanical properties in the two-dimensional (2D) plane and hence can be regarded as quasi-isotropic. In this study, the dynamic loading is generated using shock waves in a shock tube experimental setup. The strain and pressure data is collected from the experiments. Additional tests are carried out using Material Test System (MTS) for both tensile and flexural response of CRFP. Results obtained from experiments are compared with numerical simulations using ANSYS Multiphysics 14.0 finite element method (FEM) package. The numerical simulation and experimental results are found to be in good agreement.

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Modeling Thin Conductive Sheets Using Shell Elements in Magnetoquasistatic Field Simulations

IEEE Transactions on Magnetics ◽

10.1109/tmag.2009.2012601 ◽

2009 ◽

Vol 45 (3) ◽

pp. 1292-1295 ◽

Cited By ~ 8

Author(s):

S. Koch ◽

J. Trommler ◽

H. De Gersem ◽

T. Weiland

Keyword(s):

Shell Elements

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Application of the Radial Return Method to Compute Stress Increments From Mroz’s Hardening Rule

Journal of Engineering Materials and Technology ◽

10.1115/1.1395022 ◽

2000 ◽

Vol 123 (4) ◽

pp. 398-402 ◽

Cited By ~ 4

Author(s):

Sing C. Tang ◽

Z. Cedric Xia ◽

Feng Ren

Keyword(s):

Metal Forming ◽

Computing Time ◽

Isotropic Hardening ◽

Stress Increment ◽

Anisotropic Hardening ◽

Forming Process ◽

Shell Elements ◽

Hardening Rule ◽

Metal Forming Process ◽

Return Method

It is well known in the literature that the isotropic hardening rule in plasticity is not realistic for handling plastic deformation in a simulation of a full sheet-metal forming process including springback. An anisotropic hardening rule proposed by Mroz is more realistic. For an accurate computation of the stress increment for a given strain increment by using Mroz’s rule, the conventional subinterval integration takes excessive computing time. This paper proposes the radial return method to compute such stress increment for saving computing time. Two numerical examples show the efficiency of the proposed method. Even for a sheet model with more than 10,000 thin shell elements, the radial return method takes only 40 percent of the overall computing time by the subinterval integration.

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Some new results and current challenges in the finite element analysis of shells

Acta Numerica ◽

10.1017/s0962492901000034 ◽

2001 ◽

Vol 10 ◽

pp. 215-250 ◽

Cited By ~ 7

Author(s):

Dominique Chapelle

Keyword(s):

Finite Element ◽

Shell Theory ◽

Shell Structures ◽

Engineering Practice ◽

Element Analysis ◽

Shell Elements ◽

Shell Models ◽

The Finite Element Analysis ◽

Shell Finite Element ◽

Mathematical Analyses

This article, a companion to the article by Philippe G. Ciarlet on the mathematical modelling of shells also in this issue of Acta Numerica, focuses on numerical issues raised by the analysis of shells.Finite element procedures are widely used in engineering practice to analyse the behaviour of shell structures. However, the concept of ‘shell finite element’ is still somewhat fuzzy, as it may correspond to very different ideas and techniques in various actual implementations. In particular, a significant distinction can be made between shell elements that are obtained via the discretization of shell models, and shell elements – such as the general shell elements – derived from 3D formulations using some kinematic assumptions, without the use of any shell theory. Our first objective in this paper is to give a unified perspective of these two families of shell elements. This is expected to be very useful as it paves the way for further thorough mathematical analyses of shell elements. A particularly important motivation for this is the understanding and treatment of the deficiencies associated with the analysis of thin shells (among which is the locking phenomenon). We then survey these deficiencies, in the framework of the asymptotic behaviour of shell models. We conclude the article by giving some detailed guidelines to numerically assess the performance of shell finite elements when faced with these pathological phenomena, which is essential for the design of improved procedures.

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BLOOD FLOW SIMULATION USING SPH METHOD IN LS-DYNA, ANALYSIS OF ADVANTAGES AND DISADVANTAGES

10.46793/iccbi21.255t ◽

2021 ◽

Author(s):

Marko Topalovic ◽

◽

Aleksandar Nikolic ◽

Miroslav Zivkovic

Keyword(s):

Blood Flow ◽

Flow Simulation ◽

Fem Analysis ◽

Sph Method ◽

Shell Elements ◽

Advantages And Disadvantages ◽

Fluid Analysis ◽

Eulerian Formulation ◽

Mesh Free ◽

Modelling Methodology

The purpose of this research was to investigate the possibility of blood flow modelling in LS-DYNA using its SPH solver and SPH-FEM coupling. SPH and FEM methods are both based on the continuum mechanics, and SPH uses Lagrangian material framework, while FEM can use both Lagrangian for solid, and Eulerian formulation for fluid analysis. SPH implementation is mesh-free giving it the capability to model very large deformations without mesh distortions. However, this comes at a high computational price, so the number of SPH particles needs to be significantly lower in comparison to the number of FEM elements in the Eulerian analysis of the same fluid domain. In the case of combined SPH-FEM analysis, the blood vessel wall is modelled with FEM shell elements, while the blood inside is modelled with SPH particles. The contact between the two is done using nodes to surface algorithm, while if we use the SPH only, there is no need for the specific contact definition. The Lagrangian framework of the SPH method means that we need to generate particles at one end, and to destroy them on the other, in order to generate a continuous fluid flow. To do this we used activation and deactivation planes, which is a solution implemented in the commercial LS-Dyna SPH solver. In the results section of the paper, the velocity field of blood obtained by implementation of described modelling methodology is shown. SPH-FEM coupling offers greater possibilities to study the effects of wall deformations, tracking of movement of solid particle inclusion, or mixing two different fluids, but it requires elaborate contact definition, and prolonged analysis time in comparison to the FEM CFD analysis.

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