Define a Static Perturbation Step

Define a static perturbation step consisting of three load cases.

A load case is a combination of loads. You can define multiple loads and combine them in various arrangements to create permutations of load cases. A load case analysis is generally more efficient than the equivalent multiple step analysis because it uses the principle of linear superposition.

In this example, you create three load cases that represent the different load configurations that occur during the typical usage of the excavator. You use the results of this load case analysis to define the fatigue loading history.

  1. From the Procedures section of the action bar, click Static Perturbation Step .
  2. Accept all the default settings for the static perturbation step, and click OK.
  3. From the Boundary Conditions section of the action bar, click Hinge .
  4. Define a hinge restraint on the first pair of bearing faces, as shown below.



  5. Similarly, define another hinge restraint on the second pair of bearing faces, as shown below.



  6. Restrain the sideways motion of the bucket.
    1. From the Boundary Conditions section of the action bar, click Fixed Displacement .
    2. Select the face shown below as the Support.



    3. From the Translation options, select X.
  7. Create the first load set.
    1. From the Loads section of the action bar, click Load Set , and name it Left.
      The app creates the load set and displays it in the context selector.
      Tip: You can use the context selector to switch between load sets.
    2. From the Loads section of the action bar, click Force .
    3. From the Support options, select Connection .
    4. Click the coupling named left.
    5. Enter a unit force of -1 N in the Force Y field. Leave the other force components set to zero.
    The app displays a green arrow, as shown below, that indicates the location and direction of the force.

  8. Similarly, create the remaining load sets.
    1. Create a load set named Mid with a load identical to that used in the previous load step, but use the coupling mid as the support.
    2. Create another load set named Right with a load identical to that used in the other load steps, using the coupling right as the support.
  9. Use the context selector to switch from the load set back to the static perturbation step.
  10. Create the load cases.
    1. From the Loads section of the action bar, click Load Case .
    2. From the Load Case editor, click Use load sets.
    3. In the Add Load Sets dialog box, select Left, specify a scale factor of 120,000, and click OK.
    4. Similarly, create two load cases for the load sets Mid and Right.