# Equations for bending steel in a car crash?

• I
I wanted to know what formula's do I need to figure how much force is required to make a dent in a car. I am then placing a bumper guard made up of carbon fiber, and wanted to know what equation do I need to use to figure out how much force is required to make a dent with the carbon fiber bumper guard.

Simon Bridge
Homework Helper
1. you want the body panels, especially the bumper, to crumple ... that is what saves you in a crash: an undentable car would be a death trap.
2. it's very complicated ... there are no standards.
3. even quite gentle collisions or crushes can easily produce many times the minimum force needed to dent the metal.
https://plastics-car.com/Todays-Automobiles/Automotive-Safety/Physics-in-the-Crumple-Zone-2.html

You can get an idea by looking up "sheet metal bending force" ... force to bend sheet metal.
Extrapolate for the panel geometry of the bits you want to protect.

Chestermiller
Mentor
Consult the literature on bending beams and plates, and also the literature on quantitative yield criteria of metals. Look up von mises and Tresca yield criteria.

marcusl