The Element menu

Figure 1. The Element
commands

The commands listed under the Stress and Strain menus are used to visualize the complete stress and strain fields over the cross-section of a beam, respectively. In contrast, the commands under the Element menu list detailed information about one single element. To exercise the commands of the Element menu, the following steps must be completed first.

  1. Load the case you want to run and perform the finite element analysis, and
  2. Select a loading case.

Once these steps are completed, you are ready to select a single element of the model and obtain detailed information about this specific element. Select the menu Element, to reveal the options shown in fig. 1.

Select a single element (Element→Select element)

Command Element→Select element is used to select one specific element of the model. Invoke the Select element command to enter the element selection mode, see fig. 1. Once in the element selection mode, use the mouse left button to select the desired element, see fig. 2 that shows the selected element highlighted in blue. Note the following.

  • Once an element has been selected, the element selection mode is cancelled. To select another element, invoke the Select element command again and select another element.
  • An element must be selected to access to remaining commands of the Element menu.
Figure 1. Invoking the Element→Select elementFigure 2. Selecting a single element
command for a Rectangular sectionof the Rectangular section

List stress tensor for one element (Element→Element stresses)

Once an element of the model has been selected, the six components of the stress tensor at the middle point of the element can be listed by invoking the Element→Element stresses command. Figure 1 shows the list of these stress components at the middle point of one element of the IH60 section.

The stress tensor comprises six stress components, which can be divided into two groups.

  1. The out-of-plane stress components. The axial stress component, σ11, the two transverse shear stress components, τ12 and τ13.
  2. The in-plane stress components. The two in-plane direct stress components σ22 and σ33, and the in-plane shear stress component τ23.

The usual sign conventions are used for these various stress components. Note that in Euler-Bernoulli or Timoshenko beam theory, the in-plane stress components are assumed to vanish, i.e., σ22 ≈ 0, σ33 ≈ 0, and τ23 ≈ 0.

Figure 1. Listing the stress components at the middle Figure 2. Listing the strain components at the middle
of one element of the IH60 section of one element of the IH60 section

List strain tensor for one element (Element→Element strains)

Once an element of the model has been selected, the six components of the strain tensor at the middle point of the element can be listed by invoking the Element→Element strains command. Figure 2 shows the list of these strain components at the middle point of one element of the IH60 section.

The strain field comprises six strain components, which can be divided into two groups.

  1. The out-of-plane strain components. The axial strain component, ε11, the two transverse shear strain components, γ12 and γ13.
  2. The in-plane strain components. The two in-plane direct strain components ε22 and ε33, and the in-plane shear strain component γ23.

The usual sign conventions are used for these various strain components. Note that in Euler-Bernoulli beam theory, all strain components are assumed to vanish, except for the axial strain component, ε11, which is assumed to vary linearly over the cross-section. Timoshenko beam theory relaxes these assumptions by allowing non-vanishing values for the two transverse shear strain components, γ12 and γ13, that are uniformly distributed over the cross-section.