Vs BMW F10 5er vs Mercedes Benz W212 E-Klasse Body Rigidity

[Ultimate Car Guy]

This exercise is performed using publicly available information:

1. The E39 5er has torsional rigidity of approximately 24,000 nm per degree:

Torque - Google Books

2. The E60 5er has roughly the same rigidity as explained by the car's project director, Dr Walter Wohnig.

3. The F10 5er has a rigidity that is a 55% improvement on its predecessor:

"The positive properties of the steel used allow an increase in mean body strength and stiffness by 55 percent over the former model."

The New 6th Generation BMW 5 Series (F10) Unveiled - Bimmerfest - BMW Forums

4. Therefore, the F10 has a rigidity of approximately 37,500 nm x (1 + 55%)




The W212 E-Klasse has a torsional rigidity of approximately 29,000 nm. This was released in the Euro Car Body Awards in 2009. Plus i've confirmed this with a colleague of mine who consults Daimler.

 

[Wolfgang]

Euro Carbody Award 2009 press release claims slightly more? 29,920 Nm/°


First place at the EuroCarBody Award 2009 goes to the new E-class from Mercedes-Benz

This year, receiving 38.08 of max. 50 points, the highest vote of all benchmarked contestants, the new e-class from Mercedes-Benz won 1st place and was awarded the worldwide most prestigious prize for innovative car body engineering, the EuroCarBody Award.



Persuaded with an innovative car body production concept and high customer value: The presentation team of the new e-class; Dr. Jörg Langner, Heiko Kellermann and Stefan Tritschler (f.l.t.r.) achieved the first place at the EuroCarBody Awards 2009.

The new Mercedes E-class proved to be the technological highlight at this year’s EuroCarBody. The presentation by Heiko Kellermann, Dr. Jörg Langner and Stefan Tritschler took top prize. After a neck-and-neck race with eventual runners-up Jaguar, the team from Stuttgart secured first place in the benchmark for intelligent engineering and a more conservative material approach. Thus, first place at this year’s event went to a steel body weighing 492 kg and offering a torsional stiffness of 29,920 Nm/°. The engineering team had to overcome the challenges presented by the design features of the E-Class, for example the side lines and lights, especially in regard to the pressed parts. The customer value, which was particularly highly acclaimed, resides in an elaborate safety concept and a series of measures that enhance ride comfort and manoeuvrability. This is the third time the Swabian car maker has taken first place in the world's most important car body construction competition, following the victory of the E Class’s predecessor in 2002 and the S-Class’s victory in 2005.

Automotive Circle International

 

[klier]

We really need a new thread for this?

 

[deity]

It doesnt matter how strong your body is if you're performing poorly in the crash tests. The standards by which the tests are graded are much higher than looking at photos and using it as conclusive evidence...

 

[Ultimate Car Guy]

It doesnt matter how strong your body is if you're performing poorly in the crash tests. The standards by which the tests are graded are much higher than looking at photos and using it as conclusive evidence...

How can receiving a 5 star safety rating (which both the 5er and the E-Klasse achieved) be classified as "performing poorly in crash tests"?

 

[K-A]

Oh boy, here we go again. I'll sit back and take in any of the new information shown/put out, this time.

 

[Sunny]

Thanks to UCG and Wolfgang for posting credible data and not bs and conjecture. I have added the figures to this thread - The list: Torsional Rigidity

Some more figures from the torque book UGC linked -

Bentley Azure - 18000Nm/deg
Mercedes SL (R230) - 15800Nm/deg
Jaguar XK - 16000Nm/deg

Couple more numbers -

E70 X5 - 28000Nm/deg
E30 M3 - 23000Nm/deg Source - BMW Z4M Still Under Consideration

 

[deity]

How can receiving a 5 star safety rating (which both the 5er and the E-Klasse achieved) be classified as "performing poorly in crash tests"?

For arguments sake, relatively.

 

[K-A]

Roof Strength:

Model------------------Curb weight (lb)------------Peak force (lb)----------Strength-to-weight ratio
Mercedes E class 2-door
2010-11 models-----------------3,736---------------------20,852----------------------5.58

Mercedes E class 4-door
2010-11 models-----------------3,880---------------------20,961---------------------5.40

Volvo S80
2007-11 models-----------------3,756---------------------15,989---------------------4.26

BMW 5 series
2011 models---------------------3,803---------------------15,364---------------------4.04

Mercedes GLK
2010-11 models-----------------4,157---------------------26,647---------------------6.41

Volvo XC60
2010-11 models-----------------4,172---------------------21,828---------------------5.23

Audi Q5
2009-11 models-----------------4,237---------------------18,684---------------------4.41

Mercedes C class
2008-11 models-----------------3,510---------------------18,826---------------------5.36

Audi A4
2009-11 models-----------------3,523---------------------16,197---------------------4.60

Source: IIHS

 

[Sunny]

Oh, whoops, this must be "bs and conjecture", right?

I said you had one figure and one image right. Does your memory not last more than a day? Rest, yes was "bs and conjecture".

 

[Mr. Mercedes]

Are we even sure body rigidity and torsional rigidity are the same thing? They sound like completely different concepts to me.

 

[K-A]

I stated that I have a few points: Roof Strength Stats, Side Impact Photo's, and an Award that support my belief that the E-Class has a stronger body. Not to mention W212 HSS % figures (no notation on the F10's, so I'll guess that the W212's is higher, but I have no proof), and some safety cage movement detected in the F10's wheel and pedal NCAP figures.

 

[K-A]

Are we even sure body rigidity and torsional rigidity are the same thing? They sound like completely different concepts to me.

This is what I was saying. I feel that torsional rigidity is more related to the CHASSIS strength, which I believe the F10 has more of. My belief, based on what I can gather, is that the body rigidity, which is what we see from the Crash Test data (the IIHS Pictures, roof Strength Stats, etc.), and what the EuroBody Award appears to focus on, is what I believe the W212 has over the F10, based on the information at hand.

 

[Sunny]

Are we even sure body rigidity and torsional rigidity are the same thing? They sound like completely different concepts to me.

Rigidity is a structure or body's resistance to deform or flex when subjected to a force. Now the force it self can be of different types - torsional force being one of them, others being shear, axial - which again can be tensile or compression. So yes, torsional rigidity is only one component of a body's rigidity, which again can be along the different axis it can be applied. Which is why said long back only a first class moron would claim one body or the other is more rigid based on few figures, when it would probably take zillion measurements to fully define a body's rigidity.

and some safety cage movement detected in the F10's wheel and pedal NCAP figures.

Steering wheel and pedal are not part of safety cage nor attached rigidly to it.

This is what I was saying. I feel that torsional rigidity is more related to the CHASSIS strength

Wrong again, for cars with monocoque construction, chassis and body are pretty much the same. In fact the chassis is same as "body-in-white".

 

[K-A]

If the steering wheel and pedals are "moved", then that means that the hard points behind them have "moved" (safety cage). Unless it's an issue with how sturdily they've screwed in, moving from the force/g's of the impact.

My "guess" is based on various hard and telling evidence that I have, however, not absolutely conclusive evidence. This evidence I've posted, hard facts, photo/visual and statistical form.

Chassis strength is not completely related to the strength of the body on top of it. In terms of torsional and overall rigidity, they are very much related and work off of each other, however, the strength of the safety cage has little to nothing to do with the chassis "floor" of the car. If you slam into the side of a car, or a car rolls over, the chassis strength isn't going to help it as much as the body strength (various elements which make up the "body"/ steels and steel strength/thickness/etc. used throughout). Hence why my analyzation leads me to believe that the 5's chassis' is stronger than the E's, but the E has may have a stronger body (using roof strength and side structural strength photo's/statistics).

 

[Sunny]

^What is "chassis" according to you? Just curious.

 

[K-A]

The bones/structure, the "floor", etc.

However, this isn't directly equated with the safety cage, and the materials used in the safety cage and throughout the body. GM cars are perfect examples. Many of them (Unibodies) have chassis' spread throughout a decade of use, and all the different cars using them will vary in terms of frame stiffness when involved in stress-tests (accidents), rollovers, etc.

If car A (ex: F10) has more chassis strength and higher torsional rigidity than car B (ex: W212), it doesn't mean that car A will hold up better if each car was tossed down a cliff (i.e, putting stress tests on roof, side, front, rear frame/safety cage structural elements).

 

[Sunny]

The bones/structure, the "floor", etc.

What is "bones"? I never heard that term being used to describe a car's chassis, so care to illuminate what you exactly mean? or by chassis you mean the floor and the bracing on the floor?

What is this? Just the chassis or something more?

 

[Ultimate Car Guy]

The bones/structure, the "floor", etc.

However, this isn't directly equated with the safety cage, and the materials used in the safety cage and throughout the body. GM cars are perfect examples. Many of them (Unibodies) have chassis' spread throughout a decade of use, and all the different cars using them will vary in terms of frame stiffness when involved in stress-tests (accidents), rollovers, etc.

If car A (ex: F10) has more chassis strength and higher torsional rigidity than car B (ex: W212), it doesn't mean that car A will hold up better if each car was tossed down a cliff (i.e, putting stress tests on roof, side, front, rear frame/safety cage structural elements).

K-A, i think you've managed to confuse yourself. In a monocoque body construction, the "body" and "chassis" are one and the same. Hence the "mono".

 

[Giannis]

On an effort not to lock this thread as well (as it started with hard facts and numbers) I will clean it from anything that has the potential to derail this thread and ruin it like the other one.

I am kindly asking you to avoid any personal attacks and no matter what your opinion for the other members is, to be as polite as possible.

Thank you!