Crash Test Dummy: Head Impact Parameter & Force Estimation

In summary: I dun think u can measure that by any measure..." but "...the solution depends a lot on what u want to measure."So, it's more of a theoretical question than an experimental one.
  • #1
Try hard
13
0
A typical car with a dummy crashed into a wall, what is a suitable parameter for the head of the crash test dummy(with and without restraints) as a function of time? and how do i estimate the forces acting on the head in the two situations? Thanks a lot :confused:
 
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  • #2
You could use impulse, you know...

[tex]
\Delta G = \int_{t_{i}}^{t_{f}} F dt
[/tex]

What do you mean by

Try hard said:
what is a suitable parameter for the head of the crash test dummy

What do you want to measure?


Cheers
Vivek
 
  • #3
I dun think u can measure that by any measure...Impulse won't do it...
Impulse wud solve it only in a case of a particle, I dun think it can be applied in this case...The solution depends a lot on what u want to measure..

I think it requires complex calculations (dun assume it right, coz most of my ideas arent!)..

Hey maverick, impulse will definitely act on the head, but whether it will be considered a conventional case needs to be examined...have you tried some calculations on it?
 
  • #4
Okay I see the problem you folks have visualizing a dynamic variable when you've used it so far only for a particle and not for an extended body. Well, the conventional definition lacks the rigour of complexity, so it would be better if I write it to express the net impulse vector of the center of mass of the extended body (in this case, it is the head). On impact, the head moves forward (sort of rotates about a "hinge" in the neck). The center of mass of the head evidently moves as well and may execute a circular arc about the fixed hinge (or a curvilinear motion...).

Assuming in this case that the mass of the head is constant (i.e. the inflow of fluids into the brain and outflow of fluids is more or less equal during impact) the calcululations, higlytoxic, are fairly straightforward IF you can take into account the mass distribution in the head.

HIGHLYTOXIC said:
I dun think u can measure that by any measure
What do you mean??

HIGHLYTOXIC said:
The solution depends a lot on what u want to measure..
Of course, it always does!

HIGHLYTOXIC said:
but whether it will be considered a conventional case needs to be examined...have you tried some calculations on it?

What do you mean by conventional case? Of course, the calculations will be complex because we're not dealing with an elementary motion of the system under consideration here...it is a kind of superposition of elementary motions leading to what is called a complex motion.


Of course, calculation of impulse or any dynamic variable in this case cannot be done by just plugging in the value under the integral and integrating as I pointed out earlier. However, you can (experimentally) determine quantities through graphs by subsequent interpolation, data point extraction and/or a least square analysis (and more generally, experimental methods).

Cheers
Vivek
 
  • #5
"I dun think u can measure that by any measure..."

Well...I was thinking whether it wud be possible to actually calculate the force on the head...Vivek, you are right when you say that the motion wud be a bit kind of circular, but it wud be translational too...But I think there are far more factors that must be taken into consideration (IMO)..Coz the hinge in the neck will also move, so will the body and the head...

However, we can find the acceleration of the centre of mass easily...
 
  • #6
Hello highlytoxic (Abhishek)

Well I didn't say that it would be circular. I said it would be sort of circular or more complex (please read my post again).

Finding the center of mass motion is also not easy my friend :redface:. It seems easy theoretically while solving problems (textbook ones) but complex superpositions of translational, vibrational and rotational motion in the bulk leads to nonidealities and you can never be accurate in an experiment anyway (the finest detail measurements too have errors for a reason more fundamental than experimental limitations: the Heisenberg Uncertainty Principle).

What we're dealing with here is experimental determination. The simplest way of thinking about it would be to get a set of finitely spaced readings of some easily measurable dynamic variable. Then you could plot it on a graph, linearize the data set or do a best fit/least square approximation using a computer and finally use approximate mathematical models to get an answer.

Cheers
Vivek
 

What is a crash test dummy?

A crash test dummy is a human-like model used to simulate the effects of a car crash on the human body. It is equipped with sensors to measure impact forces and record data during crash tests.

Why is it important to study head impact parameters and force estimation in car crashes?

Head injuries are one of the most common and serious consequences of car accidents. Studying head impact parameters and force estimation can help researchers and engineers design safer cars and improve safety measures to reduce the risk of head injuries in car crashes.

How do scientists estimate head impact parameters and forces in car crashes?

Scientists use a combination of crash test dummies, sensors, and computer simulations to estimate head impact parameters and forces in car crashes. The crash test dummy is equipped with sensors that measure acceleration, deceleration, and forces on different parts of the body, including the head. This data is then analyzed using computer simulations to estimate the forces experienced by the head during a crash.

What factors affect head impact parameters and forces in car crashes?

There are several factors that can affect head impact parameters and forces in car crashes, including the speed and angle of the crash, the size and weight of the vehicles involved, and the use of safety features such as airbags and seatbelts. Additionally, factors such as the type of road surface and weather conditions can also play a role in the severity of head injuries in a car crash.

How do scientists use the data from crash tests to improve car safety?

The data collected from crash tests is analyzed to identify patterns and trends in head impact parameters and forces. This information is then used by engineers and designers to develop and improve safety features in cars, such as airbags, seatbelts, and crumple zones. Scientists also use this data to create computer simulations that can predict the effects of different crash scenarios and help in the design of safer cars.

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