Design of a Disc BrakeTania M. Ortiz MenéndezLiza M. Cardona Gonzalez

Ramon Torres

Objectives

Design of the rotor component for a disc brake system using load analysis, stress analysis and fracture analysis system approach.

DescriptionSingle disc brake component from a brake

system compound of a master cylinder, a four piston caliper, two brake pads and the rotor.

It is supposed to produce a torsion from an input driver force of 100 lb.

How a Brake System Works

Mechanical Design

Mechanical DesignPedal force = 600 lbMaster Cylinder = 1559.4 psiCaliper Force = 78367.3 lbPads Force = 35265.3 lbRotor Torque = 437289.8 τ = 409.97 psi

Material SelectionGray Cast Iron: wear resistant, hard, good

heat absorption and dissipation. Sut = 40000 psiSuc = 150000 psi

Mechanical designKt = 2.5 (assumed)τ(corrected) = 1024.9 psi

Static Fracture Analysis (Internal Friction Theory)

σ 1 = 1024.9 psi, σ3 = -1024.9 psin = 30.81

Mechanical Design Dynamic Fracture AnalysisSe’ = 16000 psiKsurf = 1.016Ksize = 0.7296Kload = 0.59Ktemp = 1Krel (99.9%)=0.814Se = 5695 psi

Mechanical Designq = 0.8 (assumed)Kf = 2.2Ta = 437289.8 lbτa(corr) = 901.934 psiσ1 = 901.94 psi, σ3 = -901.93 psi Tm = 218644.9 lbτm(corr) = 450.98 psiσ1 = 450.98 psi, σ3 = -450.98

Mechanical DesignModified-Goodman

nf = 5.896

Mechanical DesignTm = 218644.9 lbτm(corr) = 450.98 psiσ1 = 450.98 psi, σ3 = -450.98 psinf = 5.896 (Goddman) Endurance LimitN = 99.2 x 107

ConclusionWith this project we achieved a safe, durable and

viable design for a rotor component in a disc brake system taking in consideration the forces exerted for all the components in the brake system. In our fracture analysis for the static and the dynamic approach we found that our safety factor numbers are elevated. With this we demonstrate that disc brakes do not fracture. That is because the force exerted in the disc is a compressive force. That’s why the materials used for the manufacturing of brake disc are brittle. Also for that reason we calculate a big endurance limit.

Questions

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