# What is quadratic triangular element?

## What is quadratic triangular element?

The quadratic triangular element is a two-dimensional finite element with both local and global coordinates. It is characterized by quadratic shape functions. This element can be used for plane stress or plane strain problems in elasticity. It is also called the linear strain triangle.

How many nodes have a triangle element?

three nodes
A linear triangular element is a two-dimensional finite element that has three nodes and three sides shown in Fig. 6.8. It has three vertices and the nodes have coordinates (x1, y1) , (x2, y2) , (x3, y3) in global Cartesian coordinate system.

Why shape functions are used in FEM?

The shape function is the function which interpolates the solution between the discrete values obtained at the mesh nodes. In this work linear shape functions are used. For three-dimensional finite element simulations it is convenient to discretize the simulation domain using tetrahedrons, as depicted in Figure 4.1.

### What is the shape of a tetrahedral element’s face?

In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners.

Why is the triangular element stiffer?

Triangular Finite Elements are stiffer in bending problems because they have constant strain across the element. This simply makes it impossible for an FE solver to calculate the bending response properly… unless a lot of TRI elements are used!

How many nodes are there in tetrahedron elements?

The 10-node tetrahedron element is a quadratic element. Compared with the linear tetrahedron element (4-nodal) developed earlier, six additional nodes are added at the middle of the edges of the element.

## What are shape functions?

Shape functions are used to determine the value of state variable at any point of element based on values of state variable on three nodes. From: Finite Element Analysis Applications, 2018.

Why do we use tetrahedron?

Tetrahedral elements can fit better complex geometry. To sum up, if your geometry is simple, the best option is to mesh it with hexahedral elements. If it is not possible (curved geometries, accute angles or similar) then go with tetrahedal but controlling the distortion of the elements.

What is the height of a tetrahedron?

Space Height The height of the tetrahedron is between the centre of the basic triangle (1) and the vertex (2). For calculations you regard the so-called support triangle (3, yellow), which is formed by one edge and two triangle heights. There is H=sqr(6)/3*a using the Pythagorean theorem.

### What can the quadratic triangular element be used for?

This element can be used for plane stress or plane strain problems in elasticity. It is also called the linear strain triangle. The quadratic triangular element has modulus of elasticity E, Poisson’s ratio v, and thickness t.

How are shape functions used for triangular elements?

The solution for each triangular element can be approached by their corresponding to be expressed using the shape functions: If the shape functions are lineal polynomials (three-node triangular element, n=3), and remembering: The element area is computed as the half of the determinant of the coordinates matrix:

How to obtain derivatives of the shape functions?

To obtain the derivatives of the shape functions: with the Jacobian matrix with a determinant From here is easy to obtain: The solution for each triangular element can be approached by their corresponding to be expressed using the shape functions: If the shape functions are lineal polynomials (three-node triangular element, n=3), and remembering:

## How many degrees of freedom does a quadratic triangle have?

It is also called the linear strain triangle. The quadratic triangular element has modulus of elasticity E, Poisson’s ratio v, and thickness t. Each quadratic triangle has six nodes with two in-plane degrees of freedom at each node as shown in Figure 12.1.