John Herman
New member
Looks good to me. 
Your opinion please.
- Thread starter gsbaker
- Start date
Z3_GoCar
New member
Mohr's theory states that the largest pricipal stress will be used to predict failure. I assume you're going to force normalize your graph to compress it down to one line. Also, for directional purposes I'd suppose you'd use the same directions used to define vehicle centered coordinates, i.e. x-left, y-fore, z-down and mx-pitch, my-roll, mz-yaw.
James
X and Y axes are reversed in this convention. Like you, I initially assumed the opposite.
We will force normalize the graphs, yes. (I assume you are referring to resolving axial and shear loads to a value normal to the principle direction.) That's the question we are facing, i.e. different audiences may appreciate some but not all representations of performance, so we will probably layer the data somehow.
Personally, what I really want to get to is the point where we can compare the principal unit stress applied to the unit strength of bone, which is ~135MPa for a healthy 30-40 year old. This will tell us how close a particular design is to fracture for a given hit, and can be used as a basis for predicting the level of impact protection a design can offer--70Gs, 100Gs, 150Gs, etc. This is the kind of data people are looking for.
We probably won't publish this detailed level of data for some time. It relies on certain assumptions about the bone geometry and the mix between cortical and cancellous bone (different strengths) at the head-neck junction that needs to be confirmed. We'll take a SWAG at it in house (can't resist), but to publish it without verifying it helps no one.
At a minimum we will publish the raw load numbers.
Jim,
Is this what you had in mind:
?
Titled for a bunch of biogeeks, these are the principal loads in the coronal plane. For normal people, that means the combined effect of neck tension, bending and shear in the up-down/left-right plane.
I know, I know, there should be no fixed plane associated with the true principal load, but we don't want to give away too much too soon.
Seriously, aside from titles, does anyone see any fundamental problem with this?
TIA
Hi Gregg,
I'd suggest embedding some explanatory text right with the chart graphic. Then, when the inevitable out-of-context spread around the internet happens, there will be some hope that the viewer gets a sense of what the graphic is trying the show, the significance, etc.
cheers,
bruce
I'd suggest embedding some explanatory text right with the chart graphic. Then, when the inevitable out-of-context spread around the internet happens, there will be some hope that the viewer gets a sense of what the graphic is trying the show, the significance, etc.
cheers,
bruce
Jim,
Is this what you had in mind:
?
Titled for a bunch of biogeeks, these are the principal loads in the coronal plane. For normal people, that means the combined effect of neck tension, bending and shear in the up-down/left-right plane.
I know, I know, there should be no fixed plane associated with the true principal load, but we don't want to give away too much too soon.
Seriously, aside from titles, does anyone see any fundamental problem with this?
TIA
[/b]
Thanks Bruce. Good point.
There is much about this graph we don't like. It is fine for illustrating a point to a technical audience so there are no qualms about it's scientific merit. But we are very concerned that it may be misleading/misinterpreted. To do this properly one would calculate these loads for all planes and present the highest for each design. Unfortunately, we don't have that much data.
We will probably pull it from the Web but use it in the presentation
There is much about this graph we don't like. It is fine for illustrating a point to a technical audience so there are no qualms about it's scientific merit. But we are very concerned that it may be misleading/misinterpreted. To do this properly one would calculate these loads for all planes and present the highest for each design. Unfortunately, we don't have that much data.
We will probably pull it from the Web but use it in the presentation
http://www.isaacdirect.com/html/OtherPages/TestGraphs.html
This is very rough, but we promised you guys on the A-Team first look. We'll flesh it out with explanations and such, but until we do we will not link to it on our site and ask that you not spread this around--no real damage if you do, but we'd prefer not getting swamped with silly questions simply because someone doesn't get it.
Speaking of "getting it", we will probably trim this back significantly, or at least separate it into dummies, normal people and nerds categories. We'd greatly appreciate your input in that regard.
Without a summary measure you have to be pretty up on this subject to put these loads in perspective. As it is, what is shown is a subset of what was presented at SAE. Do yourself and SAE a favor and get a copy of the paper for a more complete understanding of these test procedures.
TIA
This is very rough, but we promised you guys on the A-Team first look. We'll flesh it out with explanations and such, but until we do we will not link to it on our site and ask that you not spread this around--no real damage if you do, but we'd prefer not getting swamped with silly questions simply because someone doesn't get it.
Speaking of "getting it", we will probably trim this back significantly, or at least separate it into dummies, normal people and nerds categories. We'd greatly appreciate your input in that regard.
Without a summary measure you have to be pretty up on this subject to put these loads in perspective. As it is, what is shown is a subset of what was presented at SAE. Do yourself and SAE a favor and get a copy of the paper for a more complete understanding of these test procedures.
TIA
Greg:
This one's from a "Normal Racer" who knows he should be wearing some sort of Head and Neck Restraint Device!! On those graphs presented with a red Line in them is the red line the probable Fatality line?? Based on info presented Baseline vs. multiple H&N restraint devices, something is better than nothing, but for my use data provides me with info to make informed judgement.
This one's from a "Normal Racer" who knows he should be wearing some sort of Head and Neck Restraint Device!! On those graphs presented with a red Line in them is the red line the probable Fatality line?? Based on info presented Baseline vs. multiple H&N restraint devices, something is better than nothing, but for my use data provides me with info to make informed judgement.
Close enough for decision purposes. The polite and official lingo is "IARV", which is an acronym for injury assessment XXX value (doing this from memory without references).
Both the ISAAC and HANS bump up against the IARV on some measures, which is why it is valuable to give consideration to a broad range of measures. Keep in mind that I've spent the last couple days watching crash videos that are nothing less than rolling explosions, so the idea that you might be injured at 70Gs with modern safety gear, when you would be toast at 30Gs without it, is good to know but we need to keep things in perspective.
Yes, pay attention to the red line.
We did some slight editing of the presentation file and posted it here. Please right click and "Save as." ~6.5MB.
I think the videos are embedded in this file. Let me know if not and we will make other arrangements. You must see George White drive a Caddy into a wall at 60 mph. He broke his leg in two places.
Everyone have a safe weekend.
I think the videos are embedded in this file. Let me know if not and we will make other arrangements. You must see George White drive a Caddy into a wall at 60 mph. He broke his leg in two places.
Everyone have a safe weekend.
Hi Gary,
Let me also say thanks for being public with this and also for coming to the Waterford meeting with it Wed evening. I'm the guy who asked the "political" question.
I am not gettting videos to play in the downloaded presentation.
Also, I should have asked Wed, but just what is the White device?
Bruce Wentzel
Let me also say thanks for being public with this and also for coming to the Waterford meeting with it Wed evening. I'm the guy who asked the "political" question.
I am not gettting videos to play in the downloaded presentation.
Also, I should have asked Wed, but just what is the White device?
Bruce Wentzel
And with my answer went my credibility!Let me also say thanks for being public with this and also for coming to the Waterford meeting with it Wed evening. I'm the guy who asked the "political" question.
That was a great group; thanks for putting up with me.I was afraid of that. Apparently videos are linked to those files, not contained within. I'll get it fixed.
Remember the video of the guy crashing the Caddy into the wall? That was George "It freakin' works!" White, and you can buy an updated version in Kevlar from his operation for ~$400.
And with my answer went my credibility!
I was afraid of that. Apparently videos are linked to those files, not contained within. I'll get it fixed.
Remember the video of the guy crashing the Caddy into the wall? That was George "It freakin' works!" White, and you can buy an updated version in Kevlar from his operation for ~$400.
[/b]
You were paying attention.
I assumed the White was the same, but never saw the "nuts and bolts" of the system. Guess I'll do the research just to satisfy my curiosity.
BTW, here's a link that was posted to the Waterford site that bears on the topic:
http://news.bbc.co.uk/1/hi/england/hampshire/6217036.stm
Try the bottom of this page.
I'm nearly positive you have to link videos to PPT files, so those links will have to be reconstructed after everything is moved to your machine--or just watch them independently.
I'm nearly positive you have to link videos to PPT files, so those links will have to be reconstructed after everything is moved to your machine--or just watch them independently.
It's a rare moment.You were paying attention.
George is here.
That's amazing. Just enough force to break the bone, but not enough for soft tissue damage. That's as close as you can cut it. Wow.