4 ms·

Anyone who has jacked up a car at one wheel and tried to open a door knows that flexing is very real.

throwaway0a5e 5y ago
> Anyone who has jacked up a car at one wheel and tried to open a door knows that flexing is very real. Have you tried doing that to anything other than a 1960s convertible? My 90s junk handles that just fine (and they're not particularly rigid cars). Matter of fact I did it yesterday afternoon to change rear pads. Generally speaking you need to get a floppy vehicle really bound up (think 80s Jeep Cherokee or minivan off road) in order to have issues with doors and even then it's usually rear hatch only. OEMs specially try to avoid having bodies that flex enough to be noticeable to consumers, let alone to the point of doors not opening. Heck, I'd be surprised if you can even design a car to pass modern roof strength requirements without also making it stiff enough to have the doors open and close regardless of how bound up it is. (Pickup tailgates are another thing since the bed is open top and bolted to a frame designed to flex somewhat and even then being able to open the tailgate with two tires off the ground is not unheard of)
- dekhn 5y ago
  When I gave a friend a ride in my 2001 Miata, the very first thing he said was 'huh, you have a rigid frame, if I'd done that turn in my old MG, you could see the frame flexing'
  - jacquesm 5y ago
    Old MG is bodypanels over chassis, a Miata is a unibody. Totally different construction.
blagie 5y ago
Work is force times distance. How tough your car (or anything else) is depends on: 1) How much force it takes to flex it -- the spring constant 2) How far it will flex before it breaks Multiply the two together (or specifically, 1/2 kd^2 where d is how far it will bend before it breaks, k is the spring constant, and 1/2 kd is the average force you're applying), and you get how much energy it takes to break it. *Everything* flexes. Rigid things just flex less for the same force. Things which break when flexed just a little bit are called brittle.

> Anyone who has jacked up a car at one wheel and tried to open a door knows that flexing is very real. Have you tried doing that to anything other than a 1960s convertible? My 90s junk handles that just fine (and they're not particularly rigid cars). Matter of fact I did it yesterday afternoon to change rear pads. Generally speaking you need to get a floppy vehicle really bound up (think 80s Jeep Cherokee or minivan off road) in order to have issues with doors and even then it's usually rear hatch only. OEMs specially try to avoid having bodies that flex enough to be noticeable to consumers, let alone to the point of doors not opening. Heck, I'd be surprised if you can even design a car to pass modern roof strength requirements without also making it stiff enough to have the doors open and close regardless of how bound up it is. (Pickup tailgates are another thing since the bed is open top and bolted to a frame designed to flex somewhat and even then being able to open the tailgate with two tires off the ground is not unheard of)

dekhn 5y ago
When I gave a friend a ride in my 2001 Miata, the very first thing he said was 'huh, you have a rigid frame, if I'd done that turn in my old MG, you could see the frame flexing'
- jacquesm 5y ago
  Old MG is bodypanels over chassis, a Miata is a unibody. Totally different construction.

blagie 5y ago

Work is force times distance. How tough your car (or anything else) is depends on: 1) How much force it takes to flex it -- the spring constant 2) How far it will flex before it breaks Multiply the two together (or specifically, 1/2 kd^2 where d is how far it will bend before it breaks, k is the spring constant, and 1/2 kd is the average force you're applying), and you get how much energy it takes to break it. *Everything* flexes. Rigid things just flex less for the same force. Things which break when flexed just a little bit are called brittle.