Twoofers Only: The Mark Roberts Factual Error Thread

[Gravy]

A more interesting question is, why did Dr. Bazant, who has co-authored numerous books (one of which I've glanced at, and seems to be well written) involving both elastic and plastic theory, cherry-pick his assumptions regarding rigidity the way he did, so as to "derive" a fragility to the building that was greater than he suggested? Recall that in a subsequent paper (Bazant and Verdure), he made reference to his not-so-youthful indiscretion of a paper with Zhou. He had plenty of time to reflect on his paper with Zhou, and to publish a correction.

What did Dr. Bazant say when you pointed this out to him and asked for his response?

 

[tsig]

Sure. The impacting mass was rigid, and the other end was constrained by a rigid surface.

In Wave Motion in Elastic Solids by Karl F. Graff, p. 103, the ratio of initial impact force is given (eq. 2.4.25) for elastic-on-elastic vs. rigid-on-elastic collisions. The elastic body being impacted is a thin rod. This is:

1 / (1 + Z1/Z2).


Where Z1 is the impedance of the elastic impacting object, and Z2 is the impedance of the impacted elastic object.

Z is given by rho*A*c0, where
rho is density
A is area
c0 is the speed of sound

In the special case of the collision of rods of exactly the same dimensions and density, the impedances are equal, and thus the peak force will be 1/2 times that of the analogous rigid-on-elastic impact.


These qualitative impact of these "revelations" was made intuitively by me over 2 years ago. The above equations are from Chapter 2 of an 8 chapter book on elasticity theory. They are not "revelations", at all.

A more interesting question is, why did Dr. Bazant, who has co-authored numerous books (one of which I've glanced at, and seems to be well written) involving both elastic and plastic theory, cherry-pick his assumptions regarding rigidity the way he did, so as to "derive" a fragility to the building that was greater than he suggested? Recall that in a subsequent paper (Bazant and Verdure), he made reference to his not-so-youthful indiscretion of a paper with Zhou. He had plenty of time to reflect on his paper with Zhou, and to publish a correction.

The Newton's Bit paper - even the new and improved one - also has un-explicated assumptions of rigidity, which invalidate his analysis. (I'll have more to say on those, later, but on his threads.) Actually, I think all of the analyses along the lines of Bazant-Zhou's original paper that ignore established theory are wrong - BZ, Ross, and Newton's Bit.

This is actually a much deeper problem than you might think. If you're curious what strain vs. time would look like in a real impact, see

http://metamars.i8.com/index.html

Notice that (apparently), the compressive stress wave is "one way". I.e., the reflected wave contributions are very small. (The data is represented two separate runs abreast, so don't misinterpret.) That tells me (I'm not 100% sure) that transmittance at the base is very high, so reflected compressive waves won't add to the net stress on the rod very much. Remember how these sorts of considerations were ignored by Manuel Garcia?


You might also ask yourself the question of why other JREF'ers, who have a technical background, did not bother to disabuse you of your mistaken notions of whether or not and how you mis-applied a mathematically correct solution to a physical problem.


Well, you're wrong. My question to you regarding a drop of all of 1 mm should have been a clue that something was amiss in your reasoning. To amuse yourself, why don't you call the professors whose results you quoted, and ask them the 1 mm question?


It's ok. I just checked, and it records about 15 pounds over my true weight when I first step on it. I don't really know the details of how it works, but I don't believe that constraints in "acquiring data points" have anything to do with not showing more than +15 pounds.

Try jumping on it.

 

[Belz...]

You had to read the whole thing. .

I did. That's why I didn't want you to remind me.

 

[Lurker]

Let's get real and suggest you have a whole bunch of friends holding the dumbbell.

Something occurs, and for some reason they are effected in a way that makes it impossible for them to maintain holding it up.

One by one they let go while struggling to maintain support.

The dumbbell gradually dips and topples to the ground completely missing your head.

Isn't reality wonderful?

MM

Hey, I was just attempting to illustrate the formula for impact, which was questioned recently by another poster. Seems your side is the one questioning reality when they question a formula that was derived many, many years ago.

Anyway, your analogy is flawed. The piledriver could not miss the building directly below it. If you think so, please advise what side force you think would contribute enough force to do so. Use f=ma where m is the mass of the piledriver and a would be the accelleration to move it to the side without hitting the structure below in the time that it fell one or two stories. Good luck.

 

[Lurker]

Sure. The impacting mass was rigid, and the other end was constrained by a rigid surface.

In Wave Motion in Elastic Solids by Karl F. Graff, p. 103, the ratio of initial impact force is given (eq. 2.4.25) for elastic-on-elastic vs. rigid-on-elastic collisions. The elastic body being impacted is a thin rod. This is:

1 / (1 + Z1/Z2).


Where Z1 is the impedance of the elastic impacting object, and Z2 is the impedance of the impacted elastic object.

Z is given by rho*A*c0, where
rho is density
A is area
c0 is the speed of sound

In the special case of the collision of rods of exactly the same dimensions and density, the impedances are equal, and thus the peak force will be 1/2 times that of the analogous rigid-on-elastic impact.

Hmm, it seems you are comparing a rigid/elastic vs a elastic/elastic impact. Sorry, you have a formula for comaprison there. A problem I see with your formula the way you are trying to use it is if we apply it to two billiard balls. I know you like intuition so will start with that. Two billiard balls the same size and density. I hit one and it hits a stationary ball. The stationary ball then rolls away at the same speed as the one I hit. Yet your odd formula would have only HALF the force transferred from one ball to the other. We intuitively know that is NOT true.

So where is your formula wrong? First off, I see no way your units will work out for you. you have a dimensionless equation. No big deal cause it is defined as a ratio but where is the rest of the formula that you apply this ratio to? Second, your impact is essentailly acting in space. No gravity acting on it. You see, the reason the impact formula I provided is correct and accurate is because it has gravity in it which is the reason the force has increased so much. I don't see gravity in your equation at all.

Sorry, it is clear you are totally misapplying your equation.

These qualitative impact of these "revelations" was made intuitively by me over 2 years ago. The above equations are from Chapter 2 of an 8 chapter book on elasticity theory. They are not "revelations", at all.

Be careful how you apply an equation you find in a book. Still, I am impressed you found that equation.

Well, you're wrong. My question to you regarding a drop of all of 1 mm should have been a clue that something was amiss in your reasoning. To amuse yourself, why don't you call the professors whose results you quoted, and ask them the 1 mm question?

I provided the equation and the verbiage. It is your responsibility to show it is wrong. The equation you countered with is clearly wrong since it does not include a gravity term.

It's ok. I just checked, and it records about 15 pounds over my true weight when I first step on it. I don't really know the details of how it works, but I don't believe that constraints in "acquiring data points" have anything to do with not showing more than +15 pounds.

Step on? that is not impacting your total weight then is it? Plus your scale probably cannot handle the spike, which would disappear VERY quickly.

 

[metamars]

Hmm, it seems you are comparing a rigid/elastic vs a elastic/elastic impact. Sorry, you have a formula for comaprison there. A problem I see with your formula the way you are trying to use it is if we apply it to two billiard balls. I know you like intuition so will start with that. Two billiard balls the same size and density. I hit one and it hits a stationary ball. The stationary ball then rolls away at the same speed as the one I hit. Yet your odd formula would have only HALF the force transferred from one ball to the other. We intuitively know that is NOT true.

Incorrect. Ignoring rotation, and whatever other effects may fall out from a collision of two spheres vs. rods, a similar formula in this scenario would simply say that the peak force experienced by the ball that got hit by another, real ball, is only 1/2 the peak force it would have experienced if it had gotten hit by a rigid ball of the same mass, size, and speed.

In reality, there's no such thing as a (perfectly) rigid ball. Correct?

Also, just to dot my i's wrt my former post, if you calculate the impacted rod problem assuming the rod is resting on a rigid base, you are implicitly assuming that no energy is being transmitted through the rod/base juncture. A rigid base can't flex, it can't transmit vibrational energy, and it can't displace, either, and thus absorb energy via momentum transfer.

Which is not consistent with the experimental work of Gul, et. al. , at least insofar as I can gather.

So where is your formula wrong? First off, I see no way your units will work out for you. you have a dimensionless equation. No big deal cause it is defined as a ratio but where is the rest of the formula that you apply this ratio to?

I don't have my book with me, but if you want to see the full formula, it's essentially

Fmax(elastic impactor) / Fmax(rigid impactor) = 1 / (1 + Z1/Z2).

It's a Dover book, so you can be a proud owner for just a few bucks!

Second, your impact is essentailly acting in space. No gravity acting on it. You see, the reason the impact formula I provided is correct and accurate is because it has gravity in it which is the reason the force has increased so much. I don't see gravity in your equation at all.
Sorry, it is clear you are totally misapplying your equation.

I am using the equation to show you that BZ's approach is misleading, as is your own argument, due to assumptions of rigidity. In particular, it is misleading in a direction contrary to his conclusion and yours. I.e., the assumption of rigidity in the special case of two impacting rods "in air" results in overestimating the maximum impact force by a factor of 2. In a WTC scenario, I see absolutely no reason why a similar result would not ensue, but the exact quantitative details remain to be worked out. I wasn't claiming to have worked them out.

A full analytic treatment, involving not only non-rigid impacting masses but also "rods" (i.e., columns) that are constrained in the horizontal plane every h (modelling the stabilizing effects of floor trusses), would require a numerical solution via finite-difference methods. (So says an applied mathematician cousin of mine, who has studied elastic theories on a graduate level.)


Can you give even one rational reason why doing an analysis in a graviational field, with aphysical, rigid bodies would still not effect the analysis in the manner I indicate? What effect to you think the presence of gravity would make wrt maximal elastic vs. rigid impacting force? Would it exactly cancel it? Make an elastic impact even more 'forceful' than a rigid impact?

Do tell. And remember that the speed of sound in steel is about 5K m/s, vs. an impact speed of ~8.5 m/s.

Be careful how you apply an equation you find in a book. Still, I am impressed you found that equation.

A-h-h-h, you would be well advised to follow your own advice.

I provided the equation and the verbiage. It is your responsibility to show it is wrong. The equation you countered with is clearly wrong since it does not include a gravity term.

I have no reason to think that the equation you quote is wrong mathematically. It is not my "responsibility" to show you anything.

The "equation I countered with" is also mathematically correct. The real question is, what is the relevance of "my" equation in showing you the physical deficiencies of "your" equation?

Since you have written:

I can list those (assumptions) that are in the book.

when are you going to do this? Were you telling the truth when you wrote this?

Doing so would be a good exercise for you, since you have muddled physical reality and math.

Step on? that is not impacting your total weight then is it? Plus your scale probably cannot handle the spike, which would disappear VERY quickly.

Hmmm. I suppose that depends on the details of how I stepped on it. A better experiment would be to drop a 20 lb weight on it from 1 mm. The scale screen doesn't seem to update all that quickly - a few times per second. It's conceivable, though, that the first reading significantly averages out it's peak value with subsequent, lesser ones to arrive at the displayed reading, thus obscuring it.

If such is the case, the experiment wouldn't prove anything.

 

[metamars]

What did Dr. Bazant say when you pointed this out to him and asked for his response?

I've never contacted Bazant. At one point, on the physorg thread, NEU-FONZE/Apollo20 had either offered to present questions to Bazant or I had asked about this (I really can't remember which one it was.) However, NBA playoffs were in the offing, and one has to keep some things in life sacred!

By this time, both Greening and Benson, two of Bazant's authors, are aware of many of the complaints I've had of the BZ paper. Its not their responsibility to convey them, but I'm assuming that that's happened in some way, shape or form.

In any event, a full rebuttal to Bazant will require a quantitative analysis using established theory, along with some computer work (see my prior post). I have also hoped that ae911truth members would be so inclined, and I could just sit back and watch the big boys work it out, but alas, this hasn't happened, yet.

 

[DGM]

I've never contacted Bazant. At one point, on the physorg thread, NEU-FONZE/Apollo20 had either offered to present questions to Bazant or I had asked about this (I really can't remember which one it was.) However, NBA playoffs were in the offing, and one has to keep some things in life sacred!

By this time, both Greening and Benson, two of Bazant's authors, are aware of many of the complaints I've had of the BZ paper. Its not their responsibility to convey them, but I'm assuming that that's happened in some way, shape or form.

In any event, a full rebuttal to Bazant will require a quantitative analysis using established theory, along with some computer work (see my prior post). I have also hoped that ae911truth members would be so inclined, and I could just sit back and watch the big boys work it out, but alas, this hasn't happened, yet.

Do you really think anyone at ae911truth is qualified? No really, think about what you've seen from them so far.

 

[metamars]

Two billiard balls the same size and density. I hit one and it hits a stationary ball. The stationary ball then rolls away at the same speed as the one I hit.

BTW, Goldsmith solves the problem of two elastic collinear rods undergoing collision in Impact: The Theory and Physical Behaviour of Colliding Solids. Like the billiard balls, the rods exchange momentum (at least when they are of equal length).

 

[cmcaulif]

metamars, I think you should contact Dr. Bazant directly, I have emailed him with questions and got a response within hours.

I suspect that assumptions of rigidity would make little difference if it is only a factor of 2 we are talking about, due to dynamic snapthrough or limit point stability, similar to the maxwell construction from Seffen.

This is treated in any book on dynamic stability of structures, Bazant and Cedolin wrote one called Stability of Structures: Elastic, Inelastic, Fracture, and Damage Theories and there is a helpful section on snapthrough in Dynamic Stability of Structures by Wei-Chau Xie.

Essentially infinitesimal changes in loading can cause finite changes in deflection due to the fact that the structure will be unstable at certain points on the curve. There are load deflection diagrams in Bazant and Verdure, calculated for a story, and these were used to find a mean crushing force.

So if a non rigid body would not deliver a load greater than the snapthrough load (you can also ask Bazant what load he calculated) then you might have something.

 

[metamars]

metamars, I think you should contact Dr. Bazant directly, I have emailed him with questions and got a response within hours.

Maybe someday. If you feel motivated enough to do so now, and post the answer(s), feel free.

I suspect that assumptions of rigidity would make little difference if it is only a factor of 2 we are talking about, due to dynamic snapthrough or limit point stability, similar to the maxwell construction from Seffen.

I know nothing about dynamic snapthrough. I took a course dynamical systems many moons ago, so I have a hazy remembrance of stable limit cycles, but frankly don't know if this is the same as "limit point stability".

Thus, I am in no position to evaluate theory regarding same, though in order for me to have faith in it, I'd have to see some sort of experimental verification.

This is treated in any book on dynamic stability of structures, Bazant and Cedolin wrote one called Stability of Structures: Elastic, Inelastic, Fracture, and Damage Theories and there is a helpful section on snapthrough in Dynamic Stability of Structures by Wei-Chau Xie.

Essentially infinitesimal changes in loading can cause finite changes in deflection due to the fact that the structure will be unstable at certain points on the curve. There are load deflection diagrams in Bazant and Verdure, calculated for a story, and these were used to find a mean crushing force.

I actually bought this book a couple months ago or so. It's the one I referred to. I would be interested in learning more about this subject, but it it just isn't a priority right now.

I note with some amusement, though, that when I talked with my mathematician cousin last Thanksgiving, I noted that some of the papers on column buckling that I've seen involve Liapunov functions. He told me "Lyapunov functions are BS". I didn't take this as gospel truth, but note that Bazant/Cedolin covers Liapunov theorems (p. 182).

The only point of mentioning this (beside amusement) is that perhaps what my cousin meant is that Liapunov theory is not very insightful for physical systems, in his experience. However, he normally studies things like fluid flows, not collapsing steel.

So if a non rigid body would not deliver a load greater than the snapthrough load (you can also ask Bazant what load he calculated) then you might have something.

Can you summarize for us whatever experimental evidence exists for theoretical calculations of "snapthrough" load? Evidence via computer simulation that had been previously validated against real physical columns and rods would also be of interest.

 

[uk_dave]

However, NBA playoffs were in the offing, and one has to keep some things in life sacred!

Oh!! I love it! Absolute 'truther' - "Nevermind relatives of those I believe were killed by an 'inside job' on 9-11, the proof will have to wait, there's a game on!"

Too funny. Yet another 'truther' who doesn't really care about the events he is debating, just wants to score a few points in an online debate.

 

[Gravy]

I've never contacted Bazant. At one point, on the physorg thread, NEU-FONZE/Apollo20 had either offered to present questions to Bazant or I had asked about this (I really can't remember which one it was.) However, NBA playoffs were in the offing, and one has to keep some things in life sacred!

I expected nothing more.

By this time, both Greening and Benson, two of Bazant's authors, are aware of many of the complaints I've had of the BZ paper. Its not their responsibility to convey them, but I'm assuming that that's happened in some way, shape or form.

Since it's not their responsibility to convey your concerns, your assumption is not logical.

In any event, a full rebuttal to Bazant will require a quantitative analysis using established theory, along with some computer work (see my prior post).

I was referring to your claim that Bazant cherry-picked rigidity assumptions in order to deceive. I assume you have proof of that. Where can I find it?

I have also hoped that ae911truth members would be so inclined, and I could just sit back and watch the big boys work it out, but alas, this hasn't happened, yet.

That you're hoping for such a patently unlikely event, and that you think there are "big boys" in Richard Gage's group, tells me that you've never seen the ae911truth website.

 

[metamars]

I expected nothing more.

Since it's not their responsibility to convey your concerns, your assumption is not logical.

Oh, sure! And it's not logical, if I tell you repeatedly that your wife is cheating on you, or driving on the left-hand side of the road, or running naked in the city parks, for you to confront her, either, now is it? Benson and Greening are co-authors with Bazant, you know. Your 'logic' seems rather ad-hoc and self-serving, does it not?

I was referring to your claim that Bazant cherry-picked rigidity assumptions in order to deceive. I assume you have proof of that. Where can I find it?

You assume incorrectly. But if I ever come across documentation that says "I, Dr. Bazant, cherry picked rigidity assumptions deliberately, so as to deceive", I will be sure to post it. I find it hard to believe that it wasn't deliberate, but that is not the same as claiming I have proof of same, or even believing that it was.

I certainly suspect it, though, to the point that I have tentatively concluded it was so. Nevertheless, I could be wrong about that.

It isn't necessary for Bazant to have deliberately sought to deceive. I have read both Not Even Wrong and The Trouble with Physics, and am well aware of the capacity of very bright people, such as theoretical physicists, to deceive themselves


Also, in the area of the foundations of physics, in Speakable and Unspeakable in quantum mechanics by J. S. Bell

But in 1952 I saw the impossible done. It was in papers by David Bohm. Bohm showed explicitly how parameters could indeed be introduced, into nonrelativistic wave mechanics, with the help of which the indeterministic description could be transformed into a deterministic one. More importantly, in my opinion, the subjectivity of the orthodox version, the necessary reference to the 'observer,' could be eliminated.

Moreover, the essential idea was one that had been advanced already by de Broglie in 1927, in his 'pilot wave' picture.

But why then had Born not told me of this 'pilot wave'? If only to point out what was wrong with it? Why did von Neumann not consider it? More extraordinarily, why did people go on producing 'impossibility' proofs after 1952, and as recently as 1978? When even Pauli, Rosenfeld, and Heisenberg, could produce no more devastating criticism of Bohm's version than to brand it as 'metaphysical' and 'ideological'? Why is the pilot wave picture ignored in text books? Should it not be taught, not as the only way, but as an antidote to the prevailing complacency? To show that vagueness, subjectivity, and indeterminism, are not forced on us by experimental facts, but by deliberate theoretical choice?

(emphasis mine)

Nowhere does Bell say that the physicists who produced impossibility proofs for deterministic hidden-variable theories of qm, up to 26 years after they were shown to be wrong, intended to deliberately deceive anybody. Since I assume their proofs were mathematically sound, I can only assume that their physical assumptions were wrong.

That you're hoping for such a patently unlikely event, and that you think there are "big boys" in Richard Gage's group, tells me that you've never seen the ae911truth website.

It's interesting, isn't it, how many of your presumptions are wrong? It's also interesting how you don't care to address the the key issue I raise concerning the validity, or lack thereof, of Bazant's paper.

Apparently, I can expect nothing more.

 

[ref]

Still no factual errors by Mark? There's gotta be some. Let's ask the man himself. Mark, have you ever had factual errors in your 9/11 work, that you later found out being wrong and have corrected? What were they?

 

[Belz...]

Maybe someday. If you feel motivated enough to do so now, and post the answer(s), feel free.

"Well, I don't want to actually make any effort to know the truth, but thanks!"

 

[Pookster]

Oh, sure! And it's not logical, if I tell you repeatedly that your wife is cheating on you, or driving on the left-hand side of the road, or running naked in the city parks, for you to confront her, either, now is it? Benson and Greening are co-authors with Bazant, you know. Your 'logic' seems rather ad-hoc and self-serving, does it not?

Speaking of rather ad-hoc and self-serving logic, are the NBA playoffs still in the offing? Did you Tivo them or something? Just asking questions.

 

[Pookster]

Oh, sure! And it's not logical, if I tell you repeatedly that your wife is cheating on you, or driving on the left-hand side of the road, or running naked in the city parks, for you to confront her, either, now is it? Benson and Greening are co-authors with Bazant, you know. Your 'logic' seems rather ad-hoc and self-serving, does it not?

Also, the matter of credibility comes into play. History plays into that as well. If someone known for making wild unsubstantiated claims were to tell me my husband was running naked in the streets, well I'd probably just let that person take that up with him. I'd have more important things to do ... like watching the NBA playoffs. Just sayin'

 

[Lurker]

Incorrect. Ignoring rotation, and whatever other effects may fall out from a collision of two spheres vs. rods, a similar formula in this scenario would simply say that the peak force experienced by the ball that got hit by another, real ball, is only 1/2 the peak force it would have experienced if it had gotten hit by a rigid ball of the same mass, size, and speed.

Do you know the difference between a rigid body and an elastic body?

I don't have my book with me, but if you want to see the full formula, it's essentially

Fmax(elastic impactor) / Fmax(rigid impactor) = 1 / (1 + Z1/Z2).

I am using the equation to show you that BZ's approach is misleading, as is your own argument, due to assumptions of rigidity. In particular, it is misleading in a direction contrary to his conclusion and yours. I.e., the assumption of rigidity in the special case of two impacting rods "in air" results in overestimating the maximum impact force by a factor of 2. In a WTC scenario, I see absolutely no reason why a similar result would not ensue, but the exact quantitative details remain to be worked out. I wasn't claiming to have worked them out.

I don't know about Bazant's approach. I thought you were trying to assail my formula for impact. Since you are not, I will bow out as it has gone beyond my expertise but if you feel comfortable, carry on.

A-h-h-h, you would be well advised to follow your own advice.

The difference between us being that I actually studied from teh book that I took that formula from. I actually studied the very chapter and formula in class. Meanwhile, you did take your formula from a book which I doubt you took the class in. The danger being you are misapplying a formula. My point was about impact.

I have no reason to think that the equation you quote is wrong mathematically. It is not my "responsibility" to show you anything.

The "equation I countered with" is also mathematically correct. The real question is, what is the relevance of "my" equation in showing you the physical deficiencies of "your" equation?

I am not arguing whether the equation is sound, but whether it is applicable. By YOUR equation, if a body is moving at a constant velocity of 100000000 m/s or whether it is moving at 1 m/s makes no difference in the force transferred. Does that sound right to you?

No, it is clear you are applying the formula in a way not intended.

when are you going to do this? Were you telling the truth when you wrote this?

I was waiting for your big reveal on why the impact formula was wrong.

Hmmm. I suppose that depends on the details of how I stepped on it. A better experiment would be to drop a 20 lb weight on it from 1 mm. The scale screen doesn't seem to update all that quickly - a few times per second. It's conceivable, though, that the first reading significantly averages out it's peak value with subsequent, lesser ones to arrive at the displayed reading, thus obscuring it.

If such is the case, the experiment wouldn't prove anything.

Glad we have established that your scale is insufficient to the task.

 

[Lurker]

BTW, Goldsmith solves the problem of two elastic collinear rods undergoing collision in Impact: The Theory and Physical Behaviour of Colliding Solids. Like the billiard balls, the rods exchange momentum (at least when they are of equal length).

I am sure they do, which contradicts the equation you provided earlier. Anyway, how about the problem that actually relates to the WTC collapse where the impact is in the vertical direction where gravity needs to be considered? Surely you agree that you have two forces acting here:

1. The gravity pulling the piledriver down onto the lower section
2. The force from velocity

As you can see, both are considered in Shigley's equation.

Metamars, try this simple experiment. Hold a rather hefty book like a dictionary or college textbook. Extend your arm out all the way. Hold hte book in your extended hand. Feel the weight of it. Now, lift it an inch or so and drop it onto your extended hand. Note how your arm lowers a bit when the book impacts. Next, try again but drop the book from higher up. Note again how your arm swings even further. Your arm swings further when impacted with the book because the force has risen dramatically. This illustrates the equation I provided.

If you question it, what is your estimate of the additional force from impact versus static load and how you arrived at the estimate. Thanks!