Pre-Analysis & Start-Up

Pre-Analysis

In the pre-analysis step, we review the:

• Mathematical model
• Numerical solution strategy
• Hand calculations of expected results

Total Deformation

The first back-of-the envelope calculation that we will make is for the total deformation of the crank under the specified applied load. A list of different cantilevered beam loading cases along with their closed-form maximum deflections formulas can be accessed on this website. Because our beam is loaded at the second hole instead of at the tip, our loading is best represented by the case 2 presented (i.e for a cantilevered beam with a concentrated load, P, at any point). The appropriate formula for the maximum deflection is therefore

...

We now have all variables needed to find the maximum deflection. Using the equations above, we estimate the maximum deflection to be 0.039 inches.

{latex}$\sigma_x${latex}

along the height of the cross-section

Now we wish to do hand-calculations to predict the stress in the x-component across the height of the cross-section at the thinnest part of the crank (i.e the middle). Because

{latex}$\sigma_x${latex}

is linear along the height of the cross-section, and because from symmetry, the value at the top of the cross-section is the same as the value at the bottom of the cross-section, one can simply calculate the

{latex}$\sigma_x${latex}

at the top to compare with ANSYS. This value is the only real unknown because stress at other heights are directly dependent on that value and can be found quite easily by interpolation. So let's calculate

{latex}$\sigma_x${latex}

at the top of the cross section. Dividing the minimum height found above by two, we find the coordinate of this point to be (3.345", 0.306") with the origin at the left hole center.

...

The following video shows how to launch ANSYS Workbench and choose the appropriate analysis system (which, under the hood, sets the governing equations that one will be solving). The video also shows how to add a new material to the material list for this project. We'll later assign our material to the model in the Physics Setup step.

<iframe width="600" height="338" src="//www.youtube.com/embed/GqxfyBzfAeY?rel=0" frameborder="0" allowfullscreen></iframe>

...

Go to all ANSYS Learning Modules