Rollover Risk: Will a Car Tip Over if Centre of Gravity Changes?

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Discussion Overview

The discussion centers around the question of whether a car will roll over if there is a change in its center of gravity (CG). Participants explore various scenarios involving the dynamics of vehicles, particularly focusing on how changes in CG can affect rollover risk during different maneuvers and conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that a car may roll over if there is a change in CG, but the extent of the change and its location are critical factors.
  • One participant describes a scenario involving a pickup truck loaded with steel I beams, arguing that this could significantly alter the CG height and location, potentially leading to rollover during sharp turns if the load shifts.
  • Another participant notes that if the CG rises during a high-speed turn, the risk of rollover increases, while a lower or inward-moving CG may reduce that risk.
  • A different perspective introduces the equivalence principle, suggesting that during acceleration, the effective gravitational direction changes, which could influence rollover risk if the line from the CG extends outside the wheelbase.

Areas of Agreement / Disagreement

Participants express varying opinions on the conditions under which a car may roll over due to changes in CG. There is no consensus on a definitive answer, as multiple competing views and scenarios are presented.

Contextual Notes

Limitations include the dependence on specific conditions such as vehicle speed, load distribution, and the nature of the turn being executed. The discussion does not resolve the complexities involved in calculating rollover risk based on CG changes.

varunsangani
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Will a car roll over if there is a change in centre of gravity?
 
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varunsangani said:
Will a car roll over if there is a change in centre of gravity?

Possibly. Depends on how much of a change and where it occurred.

CS
 
Last edited:
probably so
imagine a pick up truck with load of steel I beams, stacked above the pick up bed..this changes the center of gravity height AND possibly the center line location from the Roll Centers front and rear...does it not?
.now imagine what happens when the truck makes a sharp right turn and the tie straps used to secure the I beams suddenly breaks..the weight shifts to one side ( as does the center of gravity height and location from the vehicle center line...as does the distance from the vehicles Roll centers and makes for a much longer lever to act about the RC..this could bottom out the springs on that side of the truck and by doing this..effectively do away with any form of working suspension and now we have an overloaded Go Cart not able to handle the sprung weight and the result is lifting the wheels on the opposite ..given enuff speed and sharp enuff cornering...hang on and hope your are belted in ..tight..
 
Sounds like a good Matlab project.
 
varunsangani said:
Will a car roll over if there is a change in centre of gravity?

It all depends on how the center of gravity changes, and what the car is doing at the time. If the CG gets higher in a flat high speed turn, the car might roll over; but if the CG gets lower or moves towards the center of the curve, it's doubtful the car will roll. if the car is stationary, it will only roll over if the CG moves outside the box defined by it's 4 wheels.

Are you trying to manipulate a car's CG?
 
varunsangani said:
Will a car roll over if there is a change in centre of gravity?

Hi varunsangani! :smile:

When a car accelerates (relative to the road), the equivalence principle means that an observer in the car can regard the car as stationary, provided he regards there as being an equal fictional gravitational acceleration.

Add that horizontal fictional gravitational acceleration to the vertical real gravitational acceleration, g, to get a total effective acceleration on the "stationary" car.

The direction of that will not be vertical, and the car will roll over if the line in that direction, from the centre of mass, goes outside the wheelbase. The higher the centre of mass, the further that line will go.
 

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