Inventor General Discussion

Inventor General Discussion

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highflight109
Posts: 3
Registered: ‎12-01-2011
Message 1 of 6 (373 Views)

G-Forces in Stress Analysis

373 Views, 5 Replies
01-06-2014 03:34 PM

Hello, 

 

I am trying to properly stress test a steel aircraft fuselage. I can easily model the estimated weight of the pilot, copilot, etc as loads on the airframe. However, when it comes to simulating a high-G situation, (a load factor of around 7.5 times the force of gravity), I am not sure what to do. On one hand, I can simply multiply the loads on the airframe by the load factor and see if the frame can take it. In most cases, it performs very poorly, (safety factor less than 1). However, if I model all the loads under normal conditions, (normal pilot weight, etc.), then add a gravity load equal to 7.5 G, the airframe performs well. Yet I am not sure if the loads on the airframe, (such as pilot weight), are being adjusted along with the increased gravitational load. 

 

My question is, what is the best way to accurately simulate real world loading for high-G situations? I would a appreciate an experienced opinion on this matter. 

*Expert Elite*
blair
Posts: 4,440
Registered: ‎11-13-2006
Message 2 of 6 (339 Views)

Re: G-Forces in Stress Analysis

01-06-2014 09:42 PM in reply to: highflight109

Apply your Gravity (apple icon) along with it's direction vector and change gravity from it's default 1g to the the desired G

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Member
highflight109
Posts: 3
Registered: ‎12-01-2011
Message 3 of 6 (318 Views)

Re: G-Forces in Stress Analysis

01-07-2014 07:25 AM in reply to: blair

Thank you for your swift response! Just to clarify, so I do not need to increase my applied loads, (which are in place of component weights such as the pilot,copilot, etc.)? 

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cwhetten
Posts: 1,090
Registered: ‎09-03-2008
Message 4 of 6 (308 Views)

Re: G-Forces in Stress Analysis

01-07-2014 08:22 AM in reply to: highflight109

Hi and welcome to the forum!

 

Increasing the acceleration of gravity in Inventor simulation will only increase the body load of the elements in your model.  It does not also increase external loads of other types.  If you have external forces applied that represent weights, Inventor doesn't know that those are supposed to represent weights.  You will have to increase the magnitude of those loads accordingly.

 

Cameron Whetten
Inventor 2014

Member
highflight109
Posts: 3
Registered: ‎12-01-2011
Message 5 of 6 (300 Views)

Re: G-Forces in Stress Analysis

01-07-2014 09:21 AM in reply to: cwhetten

Ah ha! I worried that was the case. I will be sure to change both the loads and the gravity vector. Thank you for your response!

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rmerlob
Posts: 135
Registered: ‎10-21-2011
Message 6 of 6 (283 Views)

Re: G-Forces in Stress Analysis

01-07-2014 04:19 PM in reply to: highflight109

I you ever need to do more complex scenarios (ie gravity and acceleration in different directions) I think you should read into the ´´Body Load´´ type load I think this is the actual intended aplication for it.

 

Sorry I cant give some real insight since I´ve only toyed around with it.

 

RM

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