Back Clinic Collision & Injury Dynamics Therapeutic Team. The mathematical principles of collision physics are complex and unique for each accident. However, they can be simplified, as many of the forces involved are so small that for practical purposes, they are insignificant. Importantly, these principles often support the position of the patient and their doctor.
Car accidents can be devastating! Many people suffer through the agony and pain car accidents cause their bodies, and many times they have no idea of what to do. People will go to the emergency room and be prescribed medication and sent home. The hospital does not realize that these people are still in pain and often can’t work for days after their accident.
That’s where I come in, and I make sure the patient receives a thorough evaluation to determine how much damage was done to them after their collision. Then I will treat the patient according to what they need to get back to the quality of life they enjoyed before their car accident. So if you’ve been in a motor vehicle collision and don’t know what to do, please give us a call today at 915-850-0900. I’ll make sure you get the care you deserve.
In the last two writings we explored how low speed collisions can have substantial energy transfers with minimal (if any) damage. Here we will discuss the myth of “no damage = no injury” from a vehicle appearance / design point of view and how it relates to injury in a collision.
So as to get into this subject, we need a little history lesson first. With vehicle style being the topic of focus, the industry exploded after World War II. The jet age influenced bumpers, headlights and taillight’s fins. Something else happened too, for the first time in the automobile’s history, vehicles were more than “around town” horse-less buggies; the power of their engines and speeds potential dawned a whole new arena — security. In the 1960’s vehicle aesthetics began to compromise with safety. Automotive designers started to consider topics like; occupant restraints structural integrity, and crash worthiness.
The industry faced slow growth and change into the 1980’s, each revision or change did bring with it progress and progress but not enough at any one time to be a huge leap forward. The changes which were necessary, were too experimental, too cost prohibitive, or just too market risky. Then in the 1980’s a revolution in business started to take hold — the computer. The personal computer allowed for design changes to be done with efficiency. Once plugged in and switched on the days spend calculating double function and variables became complicated than a few clicks.
The computer made it possible for car manufacturers to reduce years of conventional design and research practices into only a month or two and at the same time it allowed for much more cost effective experimentation and new process development.
No Vehicle Damage Doesn’t Guarantee No Injuries
Now that We’ve completed history 101 let Us discuss the topic of Stage – “no damage = no injury”
Vehicle layout, as an approach or concept, has undergone a considerable overhaul in recent years. The change has influenced the use of bumper covers. The long standing tradition in design is to make them of a alloy and to put the outside or separate from the body. (Consider all those classics in “American Graffiti”). The bumper was designed to function as a compliment to the vehicle’s appearance. The safety perspective was non-existent with respect as they were no longer than a sacrificial lamb to save the body.
In the early 1970’s federal mandates designed to make vehicles safer forced the producers to engineer larger and much more structurally sound designs. The most noted changes where the moving of bumper away from the body itself to an essential part of the car’s body. This “afterthought” look borrowed from the truck world was the standard until the late 1980’s. Three things changed in the 1980’s: First, bumpers began to move to behind urethane bumper covers in usage.
This gave a look to vehicles and assisted with aerodynamics. Because aesthetics were no more part of the equation, bumpers became stronger and included the use of energy absorbing material between the bumper structure and the bumper cover. Finally, automotive paints had also advanced, including the ability to resist cracking & flaking, and paint had become elastic.
These changes also had another positive side effect; because of the elastic properties of urethane and the paint, minor collisions, even those which damaged the bumper behind them, no longer seemed as serious. Often times a bumper cover needed more than some paint and prep, where past designs necessitated changing the bumper.
The largest change between older design and the new one, is the inherent elasticity of the new bumper covers. These covers can, and do, rebound into the design they have been formed in and the use of paint that is elastic means the paint is likely to rebound as well. The assessment of speed from damage is currently poorer while signs of impact are evident. Obviously when a steel bumper is distorted it remains that way leaving no room for underestimation.
Notice how we have not discussed these design changes have gained energy transfer; and this isn’t any mistake. There are no groundbreaking points. Changes in vehicle design is not going to ease violation of laws of physics. All these design changes is make the energy transfer in a low speed crash less costly and less apparent.
Evaluating Vehicle Damage
However, there are Just demonstrable measures that can be taken to assess the effects of energy transfer in no apparent damage collisions:
Remove the cover of the bumper and inspect the materials below the “skin” of the bumper for internal damage
Check the angle of the passenger seat. The factory at a angle and when the occupant is thrown backwards, often the seat angle changes rendering evidence of force transfer sets seats
Have the swivel tested with a laser apparatus most repair shops use to make sure the frame of the car is “plumb.” Even a 1-degree variation will be evident and often the chassis gets distorted and that requires energy transfer.
The scope of our information is limited to chiropractic and spinal injuries and conditions. To discuss options on the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .�
Additional Topics: Weakened Ligaments After Whiplash
Whiplash is a commonly reported injury after an individual has been involved in an automobile accident. During an auto accident, the sheer force of the impact often causes the head and neck of the victim to jerk abruptly, back-and-forth, causing damage to the complex structures surrounding the cervical spine. Chiropractic care is a safe and effective, alternative treatment option utilized to help decrease the symptoms of whiplash.
In the prior writing we explored the criteria for vehicle integrity. In this writing we’ll expand on conservation of momentum. You’re encouraged to do so when you haven’t read the previous article.
Expanding on Conservation of Momentum
Remember we previously said, “The momentum moving into a collision could be accounted for at the outcome” when we discussed the concept of conservation of momentum. Here we will introduce the formula and walk through its parts; we have to comprehend this in order to explore each other influence.
The full formula:
Let�s walk through this, on the left side of the equation we have which is the weight of the first vehicle before the collision multiplied by which is the velocity (in feet per second) of the first vehicle before the collision. is the weight of the second vehicle before the collision times which is the velocity (in feet per second) of the second vehicle before the collision. On the right side of the equation we have which is the weight of the first vehicle after the collision multiplied by which is the velocity (in feet per second) of the first vehicle after the collision. is the weight of the second vehicle after the collision times which is the velocity (in feet per second) of the second vehicle after the collision.
Ok, I know this looks very intricate and the explanation is not jumping off the page so let’s write with a bit more ease of comprehension. Let us take the National Highway Transportation Safety Administration (NHTSA) standards for testing and place two of the identical mass vehicles in this. Let us use a 2012 Toyota Corolla, and we will say the other is blue and one is red because we need two of them.
Red Corolla * 5 mph + Blue Corolla * 0 mph = Red Corolla * 0 mph + Blue Corolla * 5 mph
The 2012 Toyota Corolla has a curb weight of 2,734 pounds, substituted in the formula it looks like this:
Now when we do the math to show the conservation of momentum we end up with the following:
20,094.9 + 0 = 0 + 20,094.9
20,094.9 = 20,094.9
Momentum conserved
Now we have proved the concept so we are going to apply it to a collision involving two different vehicles. We will substitute the 2012 red Toyota Corolla for a 2012 red Chevrolet Tahoe. The 2012 Chevrolet Tahoe weighs 5,448 lbs. Now the formula looks like this:
Red Tahoe * 5 mph + Blue Corolla * 0 mph = Red Tahoe * 0 mph + Blue Corolla * 9.96 mph
Now when we do the math to show the conservation of momentum we end up with the following:
40,042.8 + 0 = 0 + 40,042.8[1]
40,042.8 = 40,042.8
Momentum conserved
Three significant points can be observed in this protest.
First, when testing is done notice the change in rate at the Tahoe is 5 mph (5 to 0). This is less than the rates used by the Insurance Institute and we would expect the Tahoe to have minimal damage and no structural deformation.
The second point to note is the change in speed the Corolla experiences, 9.96 mph (0 to 9.96). This change in speed is four times the original.
Conclusion
Finally, neither vehicle exceeds the speed of 10 mph, which the automobile manufactures and insurance institute for highway safety often consider threshold for injury. This confirms that cars can easily deform and residents become injured in low speed crashes once you begin to check out the conservation of energy (momentum) and coefficient of forces moved to the target car.
The scope of our information is limited to chiropractic and spinal injuries and conditions. To discuss options on the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .� References
Edmunds.com. (2012). 2012 Chevrolet Tahoe Specifications. Retrieved from Edmunds.com: www.edmunds.com
Edmunds.com. (2012). 2012 Toyota Corolla Sedan Specifications. Retrieved from Edmunds.com: www.edmunds.com
Brault J., Wheeler J., Gunter S., Brault E., (1998) Clinical Response of Human Subjects to Rear End Automobile Collisions. Archives of Physical Medicine and Rehabilitation, 72-80.
Additional Topics: Weakened Ligaments After Whiplash
Whiplash is a commonly reported injury after an individual has been involved in an automobile accident. During an auto accident, the sheer force of the impact often causes the head and neck of the victim to jerk abruptly, back-and-forth, causing damage to the complex structures surrounding the cervical spine. Chiropractic care is a safe and effective, alternative treatment option utilized to help decrease the symptoms of whiplash.
There are many factors that play a role in the dynamics of collisions. These include vehicle design and type, speeds, angles of approach, kinetic & potential energy, momentum, acceleration factor, friction… the list is quite long. There are a few constants in which we are curious. These constants are the building blocks of the planet and they make the world of collisions quantifiable and predictable.
Within this two-part series we will explore the factors which have the most influence in low speed collisions and how these factors are associated with injury. Note: nothing about these writings is inclusive, there is too much material to explore in depth. The objective of these writings is to present the concepts.
Conservation of Momentum & Auto Accidents
In this writing the subject of exploration is conservation of momentum and how it relates to low speed collisions and bodily injury of the occupant. Conservation of momentum is built on Sir Isaac Newton’s third law. Newton’s third law says “For every action there’s an equal and opposite reaction”.
In the interest of exploring conservation of momentum in a simple format, we aren’t likely to investigate and explain the history and physics of momentum; for this conversation, we’ll concentrate on the relationship to crash dynamics. It is momentum to speed collisions’ relationship that helps enlighten and is the causal factor of the injuries people who have held tight to the argument that is deceptive that no damage = no injuries.
While there is a formula and derivation, neither is needed just yet. For now, we’ll simply use the concept as follows: The momentum going into a collision can be accounted for in the outcome or the energy going in to the accident, must be accounted for at the end of the incident and that and what was exposed to and/or absorbed that energy.
Let’s apply some perspective to this notion with the following example.
Let us say we are standing at around a pool table and we are going to try the winning shot of the eight ball into a corner pocket. Following the cue ball is struck, we have and another. After the cue ball strikes the ball, then it stops moving and the eight ball begins moving. In this scenario the cue ball before the collision’s momentum is the same as the momentum of the eight ball after the collision[1]. The eight ball rolls to the corner pocket.
The transfer is extremely efficient due in part to the fact that neither pool balls can deform. Some of the energy would be used to perform this and less if either pool ball could deform. The National Highway Transportation Highway Safety Administration (NHTSA) mandates minimum performance standards for passenger vehicle bumpers. Vehicle bumpers are tested with 2.5 mph (3.7 fps)[2] impact equipment that has the same mass as the test vehicle. The test vehicle is struck with its brakes disengaged and the transmission in neutral. There’s no offset between the automobile and the barrier.
Performance Standards for Vehicle Safety
The NHTSA outlines acceptable damage to your vehicle’s various systems after the tests. Successful completion of these tests mandate operation of systems that are particular. The factory adjustment of the vehicle’s braking, steering, and suspension must be unaltered. In other terms, in order for a vehicle to pass these tests it canhave no change in its structure. If changes did occur the system that is braking, steering, and suspension would be out of factory adjustment.
The NHTSA isn’t alone in low rate bumper testing. The Insurance Institute for Highway Safety (IIHS) also conducts low rate bumper tests. The IIHS’s test rates are conducted at 6 mph (8.8 fps)[3] and the goal is to determine which vehicles have the least damage and therefore cost the least to repair. The vehicle ratings are proportional to the estimated cost of repair. The more costly the repair, the lower the rating.
While the vehicles used in the IIHS testing all show signs of contact with the barrier, none of the vehicles suffer harm which deforms the structure of the vehicle. Don’t have any change in its structure affecting the system, steering, and suspension, just as with the NHTSA the vehicles tested by the IIHS.
The lack of change in the structure (deformation) drives a test vehicle to accept the momentum transfer in the testing equipment. Further, the test vehicle is free to move after being destroyed. This testing scenario is like that of the cue ball and eight ball.
If a vehicle doesn’t deform during a low speed collision, then it will experience a change in speed (or velocity) very quickly; Consequently, the occupant(s) also experience this exact same change in speed. The key factor in these examples is that the mass of testing equipment and their vehicles involved, but what happens when the masses change?
Conclusion
When the mass of one vehicle changes the momentum also changes, the more mass the more momentum the vehicle can bring to the event and the greater the injury potential to the occupant. There are many complicating factors that now must be considered regarding injuries beyond the Laws of Momentum when determining trauma like the height, weight, muscle mass, occupant position, kind of seat belt used, etc.. However, the first step is to decide if there was enough energy as an initiating factor in low speed crashes to cause those injuries and to overcome no crash = no injury misconceptions and have a health expert in low speed injuries confirm relationship.
In the next installment, part II, we’ll discuss this in detail and it will necessary for the later subject of occupant injuries.
The scope of our information is limited to chiropractic and spinal injuries and conditions. To discuss options on the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .�
REFERENCES:
Insurance Institute for Highway Safety. (2010, September). Bumper Test Protocol. Retrieved from Insurance Institute for Highway Safety: www.iihs.org
National Highway Transportation Safety Administration. (2011, October 1). 49 CFR 581 – BUMPER STANDARD. Retrieved from U.S. Government Publishing Office: www.gpo.gov
Additional Topics: Weakened Ligaments After Whiplash
Whiplash is a commonly reported injury after an individual has been involved in an automobile accident. During an auto accident, the sheer force of the impact often causes the head and neck of the victim to jerk abruptly, back-and-forth, causing damage to the complex structures surrounding the cervical spine. Chiropractic care is a safe and effective, alternative treatment option utilized to help decrease the symptoms of whiplash.
IFM's Find A Practitioner tool is the largest referral network in Functional Medicine, created to help patients locate Functional Medicine practitioners anywhere in the world. IFM Certified Practitioners are listed first in the search results, given their extensive education in Functional Medicine
