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Author Topic: Questions regarding Ultimate vs Limit load factors  (Read 15651 times)

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Questions regarding Ultimate vs Limit load factors
« on: November 05, 2008, 01:16:32 PM »
In the beam sizing using Standalone feature of Hypersizer, say one chooses several isotropic materials and concepts. Then he sizes the component of interest. I assume the weight reported for the beam is still in lb/in^2 similar to the unit used for panel. Right? Is this weight per unit cross sectional area of the beam?

Would you also please comment on the following statements?

1) The material that results in the lightest weight will be shown with a blue dot next to it.

2) To view the resulted optimal concept among those initially chosen, we need to use Graphics button. Right? Doing so, I noticed if you have changed something and saved the analysis and run that again, the optimal concept doesn't necessarily gets updated and seems like it is a safe bet to reset the view each time.

3) Say one already has entered ultimate load factors directly into HyperSizer. Then to get only the Ultimate MOS check involved in sizing process, one needs to first specify Limit load factor=Ultimate load factor=1 in "Design to Loads" section. Then he needs to go to "Failure" section and toggle off the limit MS column and then analyze. The last part (i.e., toggling off the MOS) results in neglecting the limit MOS calculation totally in the sizing process. This is especially important in sizing metallic parts where just specifying limit load factor=ultimate load factor=1 doesn't mean that your ultimate load factors dictate the sizing process (for metals yield and ultimate strength allowables are used). Right?

Phil

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Re: Questions regarding Ultimate vs Limit load factors
« Reply #1 on: November 05, 2008, 01:17:03 PM »
Beam unit weights are lb/ft, that is weight per running length of beam. You can hover your mouse over any field on the sizing form and a tooltip will show you the units for that field.

1. Correct

2. Yes, refreshing is a good idea. We have some known sync issues between the sizing form and the graphics and we are working on this.

3. Your description is correct. Often, if the loads coming in are ultimate, we will put in a limit factor of 0.6667 and that way you can still analyze/size for limit loads. For metallics, yield properties are used for all limit analyses and ultimate properties are used for ultimate analyses.

Also see:

http://hypersizer.com/faq/index.php?topic=113.0
« Last Edit: November 05, 2008, 01:20:13 PM by Phil »