Bimetallic Solar Tracker

Passive Mechanical Intelligence • Coiled Bimetal Strip • btHingeConstraint • Thermal Expansion • No Motors

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Sun Position

Sun Elevation (°) 45

Sun Azimuth (°) 0

Sun Intensity 1.0

Animate Sun Arc

Day Speed 1.0

Bimetal Strip

Strip Length 2.5

Strip Width 0.4

Segments 10

Coil Turns 2.0

Material Properties

α₁ (High CTE) ×10⁻⁶ 23

α₂ (Low CTE) ×10⁻⁶ 11

Spring Stiffness 40

Damping 0.5

Solar Panel

Panel Width 3.0

Panel Height 2.0

Panel Mass 2.0

Thermal

Ambient Temp (°C) 20

Solar Heating Factor 80

Cooling Rate 0.02

Show Bimetal Strip

Heat-Map Colors

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Bimetallic Solar Tracker — 3D

Temp: 20°C • Tilt: 0° • Efficiency: 0% • Sun El: 45°

Tilt & Efficiency vs Time

Tracker State

COOL — NEUTRAL

Strip Temperature

°C

Panel Tilt Angle

0.0

degrees

Solar Efficiency

% of max

ΔT (Strip − Ambient)

0.0

°C

Thermal Profile

Cold

Hot

α₁ (High CTE)	—
α₂ (Low CTE)	—
Δα	—
Strip Segments	—
Coil Turns	—
Panel Size	—
Sun Elevation	—
Sun Azimuth	—
Ambient	—

Physics

Bimetallic Principle: Two metals with different thermal expansion coefficients (α₁, α₂) are bonded together. When heated, the high-α layer expands more, causing the strip to curl.

Curvature: κ = 6(α₁ − α₂)·ΔT·(1+m)² / [h·(3(1+m)² + (1+m·n)(m² + 1/(m·n)))]
where m = thickness ratio, n = Young's modulus ratio, h = total thickness

Solar Heating: T_strip = T_ambient + H·I·cos(θ_incidence)·(1 − e^{−t/τ})
where H = heating factor, I = intensity, θ = angle between sun and panel normal

Passive Tracking: As the sun moves, different parts of the strip heat unevenly → differential curl → the panel tilts toward the sun with no motors or electronics.

Ammo.js: btHingeConstraint with angular motor. Torque = k_spring · Δα · ΔT · coil_turns. The constraint axis is perpendicular to the sun direction.

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