Engineers: Help me understand the energy imparted to Massa's head

Sorry for adding another thread regarding Massa's qualifying accident, and let me say that my family is praying for his fast recovery and return to the F60 cockpit.

What are the estimated amounts of energy/force involved in this accident given 1) Barichello's car was nearly 4 seconds ahead of Massa around the time of impact (how much energy did the spring have when it left the car and how much energy did it lose over the 4 sec?), 2) mass of the spring was about 800 gm (how much energy was stored in that spring bouncing around in front of the Ferrari?) 3) Massa's estimated speed at impact whatever it was 4) how much energy was lost by the spring when it struck the Ferrari's nose then the left-upper cockpit fairing prior to striking the left side of his face? I would assume negligible loss of energy in the spring due to air resistance. There are probably other factors I am forgetting.

I would like to understand how much force the front of his helmet/shield endured from impact. Equivalent to a full sledge hammer strike to the face, or how much more? What would be a comparable analogy to him fracturing his skull and face through the helmet? What would the stress limits for his racing helmet (SA2005 or campatible)?

_-Joe

 

A sh1tload....

from an engineer.

 

tough and complex question...

Energy = mass x velocity^2.

but both the spinng and massa were moving

Force is also complex...

Force = mass x acceleration
acceleration = change in velocity = speed / sec ^2

problem is that the impact time is miniscule... 1/10 sec?... 1/100th sec?... 1/1000 sec?

the difference between 1/10 and 1/100 sec is 100X more force.

as impact time goes to 0... force goes to infinity...

The force will be massively higher than a hit with a sledge hammer.

 

BBC says he was doing 162 mph at time of impact.

 

Simon, I am looking for some numbers. Reasonable estimates will suffice. How can the time of impact be calculated given the speed of Massa's head and the estimated speed at elasticity of the spring traveling at X(= Barrichello's car speed - speed lost over the 4 sec prior to impact)? I wonder how much energy the spring had at impact, i.e. kinetic energy 1/2 mv2 + potential energy inherent to it's character as a partially loaded spring.

What king of energy values can these helmets endure before failure?

- Joe

 

Impact with the spring or impact with the wall? I would imagine the 162 mph was his speed when the spring hit his helmet.

 

that was impact with the spring.

The wall was approximately 125 mph.

 

If the Ferrari was doing 160+ I estimate the spring to be doing at least 40+ mph, so just as an estimate a impact speed of 200+ mph and thats just a real rough estimate form a layman...? thats real scary!

 

How did you arrive at the spring traveling ~40mph?

If the 0.8 kg spring were just floating in space (v=0) and Mass's head were traveling at 162 mph (or 72.42 m/s) then were are talking almost 2100 joules of kinetic energy (1/2 mv^2). Obviously this neglects the speed of the spring itself (40 mph or something) and other parameters. So what does that amount of energy impart on Massa's helmet and subsequently, his face in terms of every day forces that I can understand?

(I already understand that it's a sh!tload)

 

too many assumptions for me to be accurate.

if you assume the spring was still moving 40mph and massa 160mph impact speed of 120
at 120 mph a car travels about 176 feet per second or 2112 inches/sec

assume the helmet deformed 1 inch (spreading out the impact time) to approx .00047 sec (1/2 a thousandth!)

1mph = 1.61 kph
120 mph = 193 kph = 193,000 m/hr = 53.6 m/sec

f=ma= mv/s^2= 0.8kg x 53.6 m/s / (0.00047)^2 = 42.9/0.0000002= 214,500,000 newtons

remember, this is hugely inaccurate, but the force is HUGE!

(and hugely dependent on impact time)

 

These are similar calculations and measurements NASA had to do in their analysis of the Columbia orbiter failure.

Simon, I'm only trying to comprehend the forces involved that destroyed the helmet (and face/skull), so some estimation is OK (after all we're not trying re-design the helmet or space shuttle wing).

What kind of everyday forces equate with those involved in the impact that fractured his face through the best racing helmet available?

- Joe

 

1 newton = 0.225 pounds of force
214,500,000/0.225 = 953333333 pounds of force.

Damn.

 

Wow! Does it really work out to be that much? I would think with forces like that that spring would have driven right though the head and the headrest behind him.

With all due respect, the math is not working out for me, but I admit I may be entirely wrong.

 

Was the spring travelling forward or backward on the track? I want to say it was travelling forward, as it would have initially bounced forward with nearly the speed of Barichello's car, unless something projected it backwards? If your estimate of ~40mph backwards (giving it a ~200mph speed relative to Massa's car), it would have had to been projected backwards with such a force as to negate the speed of Barichello's car, and then some.

Had the spring been travelling forward 40 mph, it would have been a speed of "only" 120mph relative to Massa's car.

 

Not only is the force hugely dependent on impact time, but isn't it also dependent on the rigidity or elasticity of the spring as well?

 

This would be my expectation as well. Being that it was a spring with some amount of load on it from bouncing around at speed (160 mph-x) for up to 4 seconds before hitting Massa.

 

None

That calculation assumes that, after the collision, the spring would be moving at the same speed and direction as Massa -- it (thankfully -- if I can use that word for this tragic event) was a more glancing blow. If it had been a straight on hit, it would've passed completely thru like a cannon projectile (so the stopping in 1" estimate is much too short), but these forces have no "everyday" equivalent -- 214 MN is like the weight of a large Naval Ship so even if 100~1000 less, it's still like the weight of a locomotive.

 

Lets just be thankfull it hit the shell of his helmet and not full in the vizor, that doesent even need thinking about...Its bad enough it appears to have hit the vizor rim which may be the weakest part of the helmet shell anyway, Senna's helmet impact with his own front wheel was similar...

 

Is there a design flaw on the Brawn car that would make the spring more likely to come off or could this have happened to anyone?

 

The Brawn's rear damper appears to have broken which allowed the spring to become free, I am very surprized this part wasent contained within the bodywork after it failed as it is mounted on the top of the gearbox...But any car with a similar set up would have had the same problem depending on the design of the body.

This should be a safety thought, any part failieur on a car (not due to accident) should be able to be contained by its bodywork and not fall to the track, Motorcycle fairings have to do this as well as retaining leaking fluids?

 

I don't know, I only went from Simon's calculations. Seems extraordinary high BUT it was for only 0.00047 of a second, contrary to I dont know, about .5 of a second when being hit by a sledgehammer?

 

Florian (Farout) Maybe a help with this one..

 

Unfortunately I can't. As said before here in this thread, there are too many variables. Every calculation has to be based on assumptions, and the range of plausible numbers we can assume is so big that the spread of the results would render them meaningless.

 

Helmet must have dissipated part of energy, I think car took part of it IIRC. Still, ICP wouldn't have gone bat**** until after a moment or 2, hence brakes, but not moving once wall hit. Tire wall was NBD compared to the point impact, energy dissipated over large area. I need to look up latest Snell #'s for helmets, but this was way over their envelope. Someone quoted a Glasgow somewhere (not called a Glasgow in report), but PB coma and lightening up to "talk to family" not very realistic. Hope otherwise, but been there done that. What does the numbers we're seeing work out to in G? 30?40? more?

 

I'm no engineer, but I would imagine the spring had dissipated a lot of its energy/momentum from hitting the ground, slowing it down considerably. Which made the impact at or around 100mph with a solid metal object. Ouch.