Granular Science LabMechanical Engineering Department

New Jersey Institute of Technology

Aleksandr SpiridonovDecember 2, 2011

Granular Science- Study of behavior of granular materials

- Increasing research interest in the subject over the past few decades

- Granular material is a medium composed of smaller solid particles, like sand, grain, or powder

- Granular column is a common industrial application of granular science to granular containers, such as grain silos

- In 1895, Janssen developed a theory to predict the force on the bottom, however, his theory is based on assumptions which are known to not be true

- Theory also does not work for certain conditions, such as the presence of a weight applied to the top of the column

Grain Silo

(http://understandinggov.org/tag/grain-bin-accidents/)

Experimental Set-Up

- Existing systems use a vertical stage with a scale mounted on top- Force of the granular column is transmitted to the scale via a

piston- As the column starts moving down, friction is activated at the

walls and the force on the piston decreases

Scale

VerticalStage

Piston

Granular Medium

Direction of Travel

Weight / Overload(if any)

Proposed Apparatus

Piston

Shaft

Shaft Guide

ACMELeadscrew

Load Cell

GearedStepperMotor

TimingBelt

VerticalStage

Cylindrical Containerwith Granular Material

Proposed mechanical system:

-Based on previous experimental systems-Material is loaded in the cylinder and pushes down on the piston-A shaft transfers force to a beam load cell mounted on a vertical stage-The vertical stage is translated up and down by ACME leadscrews-A geared stepper motor is linked to pulleys on the leadscrews, allowing for very slow speeds required in this experiment

Proposed Apparatus (Cont’d)

Proposed electrical system:

-Arduino based controls, allowing use of publicly available code libraries resulting in reduced development time-Robust user interface allowing maintenance and calibration tasks-Two methods of data extraction: SDcard and serial connection to a computer

ADC

M Driver

Micro-controller(Arduino)

UserInterface

Data Storage and

Serial Interface

Load Cell Amplifier

Motor

Project ScheduleProject is to be developed as part of the ME408 course

(Mechanical Engineering Design Capstone)

Phase 1 Phase 2 Phase 3 Phase 4

Electrical Design and Prototyping

Mechanical Design and Analysis

Construction and Testing

Validation

- Design and testing of individual electrical systems (force measurement, motor control, user interface, data and communication)- Phase concludes with an integrated design composed of individual systems

- Design of the mechanical systems and structure- Analysis of components for longevity and stability of the system- Determination of power requirements

- Assembly of the apparatus- Fine tuning of mechanical fits- Testing and debugging of all routines

- Multiple experiments to recreate data from similar experiments and computer simulations

Project Budget

Total cost estimated at $1600

-Major mechanical and electrical components have been compiled into a Bill of Materials and prices were quoted from suppliers such as McMaster-Carr and Digi-Key. Total cost of components in the BOM is approximately $900, including taxes.

-Structural components (not included in the BOM) are estimated at $200.

-Machining costs for modification of raw materials and commercial components is approximated at $200 - $300

-The total cost of the project also includes $200 allowance for miscelaneous and unforeseen expenses

Qualifications

Aleksandr Spiridonov-BS/MS Mechanical Engineering candidate at NJIT, minor in Applied Mathematics-Planning to pursue a future Ph.D. in Mechanical Engineering-Industrial and academic experience

- 1.5 years of mechanical design engineering experience at Dialight Corporation- 1 year research experience at NJIT’s Granular Science Lab

-Multidisciplinary knowledge- Mechanical design- Electrical and circuit design- Programming

- C/C++, FORTRAN, MATLAB- Physical computing

- Scientific computing and numerical methods

As part of the ME408 course, additional members will be added to the team based on their qualifications

Summary

Granular science is an expanding research field and its applications cover many multibillion dollar industries such as the pharmaceutical, agricultural, and mining industries.

The granular column is a commonly studied case in granular science because of its immediate application in granular containers, such as grain silos. These case studies help scientists and engineers understand force transmission inside the column and predict the forces acting on the structure of the containers.

The proposed project will help validate the results of Granular Science Lab’s computer simulations.

Questions and Answers

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References

[1] Arroyo-Cetto, D., Pulos, G., Zenit, R., Jiménez-Zapata, M. A., & Wassgren, C. R. (2003). Compaction force in a confined granular column. Physical Review E - Statistical, Nonlinear and Soft Matter Physics, 68(5 Pt 1), 051301. Retrieved from http://link.aps.org/doi/10.1103/PhysRevE.68.051301

[2] Bratberg, I., Måløy, K., & Hansen, A. (2005). Validity of the Janssen law in narrow granular columns. The European physical journal E Soft matter, 18(3), 245-52. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/16231076

[3] Janssen, H.A. Versuche über Getreidedruck in Silozellen, Zeitschr. d. Vereines deutscher Ingenieure 39, 1045 (1895)

[4] Vanel, L., & Clement, E. (1999). Pressure screening and fluctuations at the bottom of a granular column. Stress The International Journal on the Biology of Stress,533(3), 525-533. Springer. Retrieved from http://www.springerlink.com/index/TVYLFRHE3L8711KQ.pdf

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