Spaceframe versus monocoque

[hermanchauw]

I notice that different types of cars have different types of chassis. In general i find that high performance off-road vehicles use spaceframe chassis. And ashphalt racing cars in recent days use monocoque chassis or monocoque with spacefame reinforcing in the form of rollcage or something else. And high-load bearing vehicles like trucks use ladderframe chassis.

I also noticed that in nature, monocoque (exoskeleton) are usually found in small creatures, the largest is much smaller than creatures with endoskeleton, whereas spaceframe (endoskeleton) are usually found in larger creatures, and the largest weighs tons.

And also in building construction, there are some engineers choosing spaceframe structure over monocoque in large and tall buildings, eg statue of Liberty, Eiffel Tower.

Question is: what are the advantages and disadvantages of the different types of chassis?

[replicant_008]

A spaceframe is relatively easy to engineer, assemble (got a MIG welder or brazing torch around anywhere), repair and to get stiffness where you need it (just put in some heavier gauge bar or tube). It is also flexible in that you can relocate mounting points etc without a whole lot of changes.

Ladder frames are good for trucks as they are usually fairly strong, but very heavy. For trucks and SUVs, using a ladder frame also allows you to have the body mounted onto the chassis which with bushings improve the NVH. It also allows more suspension travel but as the chassis typically runs under the entire vehicle it ends up being quite high after attaching the body.

Monocoques suit passenger vehicles as the body work becomes a structural member. It allows a tighter body to be built that can be lighter than a ladder frame and the panel finish better than a spaceframe type arrangement where the panels are unstressed.

[911GT2]

Monocoques use the entire body to stiffen the car.

It was invented during the Porsche 917 era when the regulations on spaceframes were so stiff that it was the only logical choice to make the body the load carrying member.

[Hudson]

Okay...maybe you folks can be a bit more specific for me...

Define:

Spaceframe
Monocoque
Unibody

Give specifics that make them different from each other and what similarities do they have?

[flylwsi]

unibody and monocoque are basically the same thing...

i know there's bigger differences... but...

spaceframe would be if you took the body off a nascar racer. it's a tube framed car. the body doesn't do anything for structure.

a monocoque would be something like an f1 car, where everything is bolted to the "body" or tub.

our regular cars are unibody... meaning one piece... the subframes are mounted to the unibody.