Friction Coefficient for Brake Pads: Validity of F=2x(UN) Equation?

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SUMMARY

The discussion centers on the validity of the equation F=2x(UN) for calculating the friction coefficient of brake pads. The user tests the friction by pulling a brake disc between two clamped brake pads, measuring the maximum force required for slipping. The consensus is that while both equations F=UxN and F=2x(UN) are referenced, the latter is applicable when both brake pads exert identical forces and coefficients of friction. The scenario changes if one pad is frictionless, leading to F=1x(UN) for the functional pad.

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  • Understanding of basic physics principles, particularly friction.
  • Familiarity with the concepts of normal force (N) and friction coefficient (U).
  • Experience with load cell measurement techniques.
  • Knowledge of brake system mechanics and their operational principles.
NEXT STEPS
  • Research the derivation and applications of the friction equation F=UxN.
  • Explore the impact of varying normal forces on friction coefficients in brake systems.
  • Investigate load cell calibration methods for accurate force measurements.
  • Study the effects of different materials on friction coefficients in braking applications.
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Mechanical engineers, automotive technicians, and researchers focused on brake system design and performance optimization.

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I've been trying to figure out the friction coefficient of some brake pads. My test fixture only allows me to pull (F2) a brake disc between two brake pads clamped around the disc with a force F1. I then measure with a load cell the maximum force required for the brake disc to slip.

My question is simply, will the basic equation F=UxN be valid, or is it correct to assume that F= 2x(UN) in this scenario assuming F1 and U is identical for both brake pads?

I've been googling the topic and my impression is that both equations are used.
 

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Should be F=2 x (UN). Imagine replacing one of the pads with a frictionless pad and then you'd get F = 1 x (UN) for the one pad with friction.
 

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