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Analyzing the Performance of the Same Axle Using SolidWorks COSMOSXpress

SolidWorks offers a handy utility that can be used to quickly determine if and how a trebuchet axle,

or other load-bearing component will perform when stressed. COSMOSXpress can help answer

questions like:

x Will the axle fail or break?

x How will it deform or bend?

x Can the axle dimensions be reduced and still support the applied loads?

COSMOSXpress is also a great tool that can be used to verify the answers you calculated using the

flexural formula.

The icon for the COSMOSXpress utility can be found on the upper level of the SolidWorks toolbar.

Using COSMOSXpress is easy

and self explanatory:

1. Sketch and extrude the

axle on the front plane

with the dimensions:

r = 0.118", L = 4".

2. Click on the

COSMOSXpress Icon.

3. Choose

Options/English

4. Choose Next/Steel/304

and

Apply the material.

5. Choose

Next, read the

statement and choose

Next again.

6. Select the round face on

each end. This is a

restraint set. You have

essentially supported the

axle on each end.

Click

Next.

7. Read the statement about force and pressure, select Next, and select the Force radio button.

8. Select the outside of the axle to add the

Load Set. Click Next.

9. Click Normal to a Reference Plane radio button. Click on the Top Plane Specify 7.7 lbs.

for the force value. Click

Next and Click Next again.

10. Click the

Yes radio button to accept the default settings.

11. Click

Next and click Run. COSMOSXpress will calculate the lowest factor of safety. A

factor of safety greater than 1 indicates the part will handle the design loads. Note:

COSMOSXpress will usually yield a higher factor of safety than you will obtain using the

flexural formula. This is due to the fact that the flexural formula assumes a worse case, center

loading of the axle. This concentrates the force on the weakest part of the axle (Center span).

COSMOSXpress on the other hand assumes a load that is equally distributed across the span.

In actual practice, the real loading on a trebuchet axle is likely somewhere between the two

values.

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