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Creative Machine Design — Brazil-Nut Effect Vibrator

Year
2018
Field
Mechanical engineering
Type
Undergraduate course project

Overview

Designed and built a vibration apparatus to induce and control the Brazil-Nut Effect (BNE) and its reverse (RBNE) in granular mixtures, generating multiple continuous frequencies across a wide bandwidth.

Key points

  • Modeled BNE via granular convection with onset condition Γ ≥ 3 (a function of amplitude and frequency); BNE favors low amplitude / high frequency, RBNE favors high amplitude.
  • Two-part design: a pneumatic gear transmission with bicycle-brake friction for continuous frequency shifting, plus a 3D-printed cam striking an acrylic amplitude plate.
  • Chose acrylic for its low Young's modulus to add bending-induced vibration; six adjustable amplitude slots tune BNE vs. RBNE.
  • Results: 21 Hz (BNE, Γ 9.74), 16 Hz (RBNE, Γ 4.87), plus 11/10 Hz band; BNE achieved in 1.18 s and RBNE successful.

Figures

(a) Vibration machine — demonstration
(a) Vibration machine — demonstration
(b) Low frequency
(b) Low frequency
(c) High frequency
(c) High frequency
(d) Brazil-Nut Effect
(d) Brazil-Nut Effect
⤓ Individual report (PDF)
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