Introduction to Finite Element Analysis (FEA) and element types used in FEA


This article deals with the overview of Finite Element Analysis (FEA) and types of elements used during Finite Element Analysis (FEA). Common element types used are linear, quadratic, and cubic nature. The cubic element gives a better result than quadratic and linear. Again quadratic gives a better result than linear. ANSYS software uses these types of elements during FEA. Here an attempt is made to highlight the common element types used in ANSYS software.

Introduction to Finite Element Analysis (FEA)

Finite Element Analysis uses numerical methods to solve complex problems in Mechanical as well as civil structural problems. It deals with finding out the deflections of structural members, stresses produced due to various loading coming from applications and finding the right size and shape as well as orientation to optimize the design of the structure.

Finite Element Analysis(FEA) solves the problem by dividing the problem domain into a small number of parts/cells/elements and for each element, the governing equation of problem physics is applied. A final solution is then calculated at the end by summing up the effect/solution of each element of the problem domain. The solution means deflection, stress, and strain at the desired location or points in the domain.

In FEA, the solution largely depends on element types. Each element type has its characteristics.

Basic types of elements used in Finite Element Analysis (FEA)

1D (Line element)


Mainly of three types -
  • Linear (2 Noded per side) e.g. Beam, truss
  • Quadratic (3 Noded per side) e.g. Beam
  • Cubic (4 Noded per side) e.g. Beam

The accuracy of analysis directly depends on the type of element chosen in analysis inputs. Cubic elements give better analysis compared to the quadratic element and quadratic gives a better result than the linear element.

2D (Area element)

Mainly of three types-
  • Linear (2 Noded per side) e.g. Plane stress
  • Quadratic (3 Noded per side) e.g. Plane strain
  • Cubic (4 Noded per side) e.g. Plate and shell

3D (Volume element)

Mainly of two types
  • Linear
  • Quadratic

Common element types used in ANSYS

Element type LINK1:

  • It is a 2D spar element that supports tension and compression forces in the applicationLINK1 does not support bending force- related information, Hence by LINK1 only approximate analysis is possible
  • This element has only two degrees of freedom (Displacement in X and Y direction only)
  • Example: Truss elements can be analyzed by LINK1 element

BEAM

2D elastic 3 elements:
  • This element supports compression, tension and bending capabilities during the analysis
  • 2D elastic 3 element has three degrees of freedom (Displacement in X & Y and rotation about 2 axes)
    This element defined by 2 nodes, cross-sectional area, the moment of inertia, the height and material property
  • Element height is used only in the bending and thermal stress calculations
  • The Moment of inertia in the z-direction can be neglected if large deflections are not used.

3D beam element

Element name: Beam 4
  • This element supports uniaxial compression, tension, and bending capabilities.
  • It has six degrees of freedom, three in displacement in X, Y, Z direction and the remaining six in rotation about the same X, Y, Z-axis.
  • Inputs required to define completely this element are the cross-sectional area, the moment of inertia, the thickness along with all directions and shear and strain deflections.

Element Type: Shell

Element name: Elastic 4 node 63
  • This element supports both membrane and bending capabilities.
  • Both in-plane and normal loads are permitted for this element type in particular applications
  • It has six degrees of freedom, three in displacement in X, Y, Z direction and remaining six in rotation about the same axis.

Element Type: Solid/Brick

  • Element name: Brick 8node 45
  • This element is used to do Finite element analysis of 3D or solid objects


Comments

Guest Author: Gruhalakhsmi02 Jan 2020

I am learning ANSYS APDL. I have a doubt in ANSYS A element type.

Author: Umesh05 Mar 2021 Member Level: Diamond   Points : 6

The author has presented the article in a nice technical language. I would like to explain it in a simple language so that beginners in this area can understand the basic idea behind FEA.

Finite element analysis is a mathematical technique of simulating any physical phenomenon. In structural engineering, it has a great scope for finding the weak spots in a particular structure or shape and using advanced computer methods for distinguishing the strength of the design at different points. Finite element analysis is used in many areas though primarily it is used in designing.

In some complex situations sometimes, we have information about the limited points only and in that case, the design or structure is made by extrapolation of these points. Linear is the easiest extrapolation but will be away from the desired design so it is advisable to use polynomial extrapolations for which robust mathematical programming or codes are to be in place.



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