RESULTS ON POST #75: FEA Analysis on Fender/Cowl Brace - Page 4

Boostpimp · 01-22-2008, 06:25 PM

I'm thankful that you guys are on this forum...this is what makes our forum great...Keep up the good work...and keep that research coming!

***Turbineguy*** · 01-22-2008, 06:27 PM

Quote:

Originally Posted by Boostpimp

I'm thankful that you guys are on this forum...this is what makes our forum great...Keep up the good work...and keep that research coming!

100% agree with this. Excellent work. Makes me realize how not smart I are though.

MGizzle · 01-22-2008, 06:28 PM

That buckling feature is cool man. Looks tight. My brace uses about 60mm between holes and is 350mm long. Pulled them out of you know where

I don't have any dimensions yet from anybody and am just waiting for the braces from TiC to come to measure them.

The brace I modeled is 3mm thick and is structural steel. Steels usually have about the same young's modulus since that doesn't change with alloying differences hence I just used any steel. The Rib is about 10mm thick.

I think your model shows exactly what happens to the brace when you place a moment on it. It buckles in the middle and as sone as it even gets close to that your brace is worthless. It will go sideways and be useless.

I am going to give our FEA guru a call tomorrow to see if I can refine the model with some actual bolts etc. There is a "bolt" feature in ANSYS but I couldn't figure it out at work today.

How come you have no hot spots around the "bolt mounting" area in your model?? How did you model your load and constraints??

mtskibum16 · 01-22-2008, 06:53 PM

That is not a stress plot. It is a displacement plot to show buckling. The stress plot of this brace (not analyzing buckling) shows stress concentration around the bolt holes and also at the cutout radius at the top left of the brace.

I constrained the left two bolt holes in all directions and then applied a vertical force to the right two bolt holes. For buckling, I also added a constraint to the area around the bolt holes showing that the brace is on a flat surface. I thought this would help define the buckling motion.

MGizzle · 01-23-2008, 04:19 AM

Hmmmm... I am just surprised that you don't get the max displacement around the bolt holes where you applied the loads. Did you constrain those somehow as well?? Must be the buckling feature constraining something.

Anyhow, if I send you an IGES file of the braces when I get them will you be able to use them in your CAD software??

mtskibum16 · 01-23-2008, 09:33 AM

Yeah. I could run them. That's why it is important to test for buckle. Sometimes the part will buckle rather than displace at the location of the load.

STi_1212 · 01-23-2008, 02:23 PM

From someone studying in their 3rd year of mech eng. this thread is very interesting. I myself have used solidworks and cosmos but not to the extent you guys are working at. Keep up the awesome work guys!

paranoid56 · 01-24-2008, 08:11 AM

wow, lots of good info on here. would you be up for another brace for testing? (a paranoid fab brace) just let me know your addy and i can get some out for testing asap.
I love this stuff

keep up the great work.

mtskibum16 · 01-24-2008, 08:18 AM

Quote:

Originally Posted by paranoid56

wow, lots of good info on here. would you be up for another brace for testing? (a paranoid fab brace) just let me know your addy and i can get some out for testing asap.
I love this stuff

keep up the great work.

I could run some testing if you would like. PM me if you want to send one out.

MGizzle · 01-24-2008, 08:19 AM

Tx for the offer man. I will let you know once I figure out what we want to do with the braces as far as "physical" testing goes. If that goes well I'll hit you up.

MGizzle · 01-24-2008, 10:23 AM

I just got TiC's braces with the stock ones. Thank you to Turninconcepts again. Anyhow, I will come by work Saturday to try and measure as much as I can on the CMM and hopefully I can get a model within a week or so.

I will post plenty of pictures as well so be patient. Mtskibum16, let me know when you get the Paranoid ones so that we can maybe come up with a physical test together and run it the same way so that we can compare the different designs properly. As soon as I get the CAD model I will send you an IGES file so that you can mess around with it too.

MGizzle · 01-26-2008, 09:14 AM

So, Saturday it is. I measured the Tic braces since the stock ones are impossible to CMM due to their 1.5mm thickness. Anyhow, I will model the stock ones later too.

Bellow are some pictures of the TiC vs. Stock braces and couple sheets with most of the dimensions needed to draw the TiC brace into CAD. The Square bar is 0.75'' bar and 1/4'' plates welded to it. HOpefully I will get to draw them up next week.

http://i214.photobucket.com/albums/c...5/P1261824.jpg
http://i214.photobucket.com/albums/c...5/P1261825.jpg
http://i214.photobucket.com/albums/c...5/P1261819.jpg
http://i214.photobucket.com/albums/c...5/P1261823.jpg
http://i214.photobucket.com/albums/c...5/P1261822.jpg

At the same time, I am machining a set up to load these braces. I will fix them in vehicle position to a fixture and then we will pull straight up on them with an Instron machine at different loads. This way we can compare deflection of stock braces vs. the TiC ones and see how the data corelates to the FEA model. If it correlates good than we can model any other type of brace and compare them to each other. I will run the fully powdercoated TiC braces to see if the powder coat will effect stiffness until it starts giving up. It is pretty thick hence I think it will have some influence until it starts shearing off.

Oh, and as a surprise I got these in my office today as well

http://i214.photobucket.com/albums/c...5/P1261827.jpg

Hopefully I will have some spring rate "k" plots on these bad boys soon to verify the spring rates.

Later.

4banger · 01-26-2008, 09:38 AM

This thread makes me wish I had majored in mechanical engineering.

mtskibum16 · 01-27-2008, 09:02 AM

Quote:

Originally Posted by MGizzle

Mtskibum16, let me know when you get the Paranoid ones so that we can maybe come up with a physical test together and run it the same way so that we can compare the different designs properly. As soon as I get the CAD model I will send you an IGES file so that you can mess around with it too.

I have no means of doing a physical test, so maybe it would be better to have paranoid send you his brace.

MGizzle · 01-27-2008, 11:00 AM

Hmmm....well let us wait until I test the TiC and stock ones. If I can get the FEA to correlate than we don't need to brake the Paranoid ones.

01-22-2008, 06:25 PM	#46
Boostpimp Grassroots STI Racer Car: 04 WRB/G STi Fav Mod: Sz49 + Meth Location: South Carolina Posts: 538 Join Date: Jun 2004 Trader Rating: (2)	Re: FEA Analysis on Fender/Cowl Brace I'm thankful that you guys are on this forum...this is what makes our forum great...Keep up the good work...and keep that research coming! This ad is not endorsed by this member. Please register or login to hide this ad.

01-22-2008, 06:28 PM	#48
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace That buckling feature is cool man. Looks tight. My brace uses about 60mm between holes and is 350mm long. Pulled them out of you know where I don't have any dimensions yet from anybody and am just waiting for the braces from TiC to come to measure them. The brace I modeled is 3mm thick and is structural steel. Steels usually have about the same young's modulus since that doesn't change with alloying differences hence I just used any steel. The Rib is about 10mm thick. I think your model shows exactly what happens to the brace when you place a moment on it. It buckles in the middle and as sone as it even gets close to that your brace is worthless. It will go sideways and be useless. I am going to give our FEA guru a call tomorrow to see if I can refine the model with some actual bolts etc. There is a "bolt" feature in ANSYS but I couldn't figure it out at work today. How come you have no hot spots around the "bolt mounting" area in your model?? How did you model your load and constraints??

01-22-2008, 06:53 PM	#49
mtskibum16 Professional STI Driver Car: 05 Subaru WRX STi Location: Montana Posts: 461 Join Date: May 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace That is not a stress plot. It is a displacement plot to show buckling. The stress plot of this brace (not analyzing buckling) shows stress concentration around the bolt holes and also at the cutout radius at the top left of the brace. I constrained the left two bolt holes in all directions and then applied a vertical force to the right two bolt holes. For buckling, I also added a constraint to the area around the bolt holes showing that the brace is on a flat surface. I thought this would help define the buckling motion.

01-23-2008, 04:19 AM	#50
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace Hmmmm... I am just surprised that you don't get the max displacement around the bolt holes where you applied the loads. Did you constrain those somehow as well?? Must be the buckling feature constraining something. Anyhow, if I send you an IGES file of the braces when I get them will you be able to use them in your CAD software??

01-23-2008, 09:33 AM	#51
mtskibum16 Professional STI Driver Car: 05 Subaru WRX STi Location: Montana Posts: 461 Join Date: May 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace Yeah. I could run them. That's why it is important to test for buckle. Sometimes the part will buckle rather than displace at the location of the load.

01-23-2008, 02:23 PM	#52
STi_1212 Grassroots STI Racer Location: Toronto, Ontario Posts: 520 Join Date: Jun 2006 Trader Rating: (0)	Re: FEA Analysis on Fender/Cowl Brace From someone studying in their 3rd year of mech eng. this thread is very interesting. I myself have used solidworks and cosmos but not to the extent you guys are working at. Keep up the awesome work guys!

01-24-2008, 08:11 AM	#53
paranoid56 Amateur STI Driver Car: 06 WRX wagon Fav Mod: green wheels Location: Santa Barbara, CA Posts: 27 Join Date: Nov 2006 Trader Rating: (0)	Re: FEA Analysis on Fender/Cowl Brace wow, lots of good info on here. would you be up for another brace for testing? (a paranoid fab brace) just let me know your addy and i can get some out for testing asap. I love this stuff keep up the great work.

01-24-2008, 08:19 AM	#55
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace Tx for the offer man. I will let you know once I figure out what we want to do with the braces as far as "physical" testing goes. If that goes well I'll hit you up.

01-24-2008, 10:23 AM	#56
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace I just got TiC's braces with the stock ones. Thank you to Turninconcepts again. Anyhow, I will come by work Saturday to try and measure as much as I can on the CMM and hopefully I can get a model within a week or so. I will post plenty of pictures as well so be patient. Mtskibum16, let me know when you get the Paranoid ones so that we can maybe come up with a physical test together and run it the same way so that we can compare the different designs properly. As soon as I get the CAD model I will send you an IGES file so that you can mess around with it too.

01-26-2008, 09:14 AM	#57
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace So, Saturday it is. I measured the Tic braces since the stock ones are impossible to CMM due to their 1.5mm thickness. Anyhow, I will model the stock ones later too. Bellow are some pictures of the TiC vs. Stock braces and couple sheets with most of the dimensions needed to draw the TiC brace into CAD. The Square bar is 0.75'' bar and 1/4'' plates welded to it. HOpefully I will get to draw them up next week. http://i214.photobucket.com/albums/c...5/P1261824.jpg http://i214.photobucket.com/albums/c...5/P1261825.jpg http://i214.photobucket.com/albums/c...5/P1261819.jpg http://i214.photobucket.com/albums/c...5/P1261823.jpg http://i214.photobucket.com/albums/c...5/P1261822.jpg At the same time, I am machining a set up to load these braces. I will fix them in vehicle position to a fixture and then we will pull straight up on them with an Instron machine at different loads. This way we can compare deflection of stock braces vs. the TiC ones and see how the data corelates to the FEA model. If it correlates good than we can model any other type of brace and compare them to each other. I will run the fully powdercoated TiC braces to see if the powder coat will effect stiffness until it starts giving up. It is pretty thick hence I think it will have some influence until it starts shearing off. Oh, and as a surprise I got these in my office today as well http://i214.photobucket.com/albums/c...5/P1261827.jpg Hopefully I will have some spring rate "k" plots on these bad boys soon to verify the spring rates. Later.

01-26-2008, 09:38 AM	#58
4banger Professional STI Racer Car: 05 WRB STi Fav Mod: TiC AST's - 7/6K Location: Chesapeake, VA Posts: 625 Join Date: Feb 2005 Trader Rating: (3)	Re: FEA Analysis on Fender/Cowl Brace This thread makes me wish I had majored in mechanical engineering.

01-27-2008, 11:00 AM	#60
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	Re: FEA Analysis on Fender/Cowl Brace Hmmm....well let us wait until I test the TiC and stock ones. If I can get the FEA to correlate than we don't need to brake the Paranoid ones. This ad is not endorsed by this member. Please register or login to hide this ad.