DEPARTMENT OF Agricultural and
Biosystems Engineering
Name: Reca S. Bautista
Program and Year Level: BSABE-III
Instructor: Engr. Philip Donald C. Sanchez, MSc.
Course Code/Section: ABE 106/DEN1
Date Submitted: November 4, 2020
Score/Date:
Frictional Properties of Agricultural and Biological Materials: Measurement of the Angle of
Repose of Rice and Corn (Rough and Milled) Grains
Activity Report No. 1
I- Introduction
Engineering properties are useful in the design and operation of equipment in the
field of agricultural processing. In farm machinery, these properties are useful for
development and design. These engineering properties are physical, mechanical, frictional,
rheological, aero and hydrodynamic, electrical, and optical properties. And in this activity,
we will talk more about the frictional property.
Frictional properties such as angle of repose and coefficient of friction are important
in designing storage bins, conveyors, forage harvesters, etc. Angle of repose is used for
characterization of the bulk of particulate foods such as seeds, grains, flours, grits, and fruits.
For this activity, we will be using different kinds of grains.
The angle of repose of granular materials is relevant in various applications of
science and engineering, such as sedimentology, geomorphology, hydraulic, and chemical
engineering. It can be used in the descriptions of initial motion of sediment grains and
sediment transport process, and in the investigations of bank stability, riprap protection, and
reservoir sediment removal.
In the field of agriculture, angle of repose is widely used especially in designing and
dimensioning of silos, tanks, hoppers and bunkers to determine the capacity and required volume of
the stored and transported seeds, wheat, rice, flour, etc. That’s why it is very essential to study
frictional properties and other properties in engineering.
DEPARTMENT OF Agricultural and
Biosystems Engineering
II- Objectives
The objectives of this activity are the following:
1. Measure the angle of repose of the select agricultural materials.
a. Milled Rice
b. Rough Rice
c. Milled Corn
d. Shelled Corn
2. Measure the angle of repose using the following methods:
a. Funnel Method
b. Tilting Box Method
c. Revolving Cylinder Method
3. Solve the angle of repose using the formula
Θ=tan-1( )
Formula 1.
Θ=tan-1( )
Formula 2.
III- Materials and Methods
This section includes three parts, namely: apparatus, procedure, and calculations.
Apparatus:
DEPARTMENT OF Agricultural and
Biosystems Engineering
APPARATUS
SET-UP EXPERIMENT
1. Funnel- this will be used to make
the material flow and form a cone.
2. Tilting box- this maybe either flat
surface wood or a galvanized steel.
This will used to make the
materials slide.
3. Revolving Cylinder- the material is
placed within the cylinder and
rotated at fixed speed.
Table1. Apparatus and Set-Up Experiment
Procedure:
1. Funnelling Method (Milled Rice, Rough Rice, Shelled Corn, Milled Corn)
i.
Set up your experiment place. Funnel is the tool for this method.
ii.
Place the material at the top of the funnel.
iii.
The material will flow through the funnel and as the material forms a cone it
grows, so slowly raise the funnel up.
iv.
When done, measure the height of the formed cone material and draw a circle
around it to measure the radius.
v.
When measuring the radius, I made three estimations for each material
DEPARTMENT OF Agricultural and
Biosystems Engineering
2. Tilting Box Method (Milled Rice, Rough Rice, Shelled Corn, Milled Corn)
Use either wood or galvanized steel for this method. Place the material in the box.
Tilt the box and only stop when the material slides. Measure the height and the base.
I made three observations for each material.
3. Revolving Cylinder (Milled Rice, Rough Rice, Shelled Corn, Milled Corn)
In this method, three observations were also made for each material.
The material is placed inside the cylinder and rotated it. Once done, measure the
base and the height.
Calculations:
To obtain the angle of repose for each method, three observations were made. See Table2,
Table3, Table4 for the data. The desired to be measured angle of repose were shown in
Figure1, Figure2, Figure3.
Funnel Method:
Milled Corn
Shelled Corn
Milled Rice
Rough Rice
Figure1. Funneling Method
Observation 1
Material
Observation 2
Observation 3
Height
(in)
Base (in)
Height
(in)
Base (in)
Milled Corn
2
6.9
2
7
2
6.9
Shelled Corn
1.5
8.5
1.5
8.2
1.5
8.7
Milled Rice
1.9
7.3
1.9
7
1.9
6.9
Rough Rice
2.9
8.7
2.9
9.5
2.9
8.9
Table2. Funnel Method Observations
Height
(in)
Base (in)
DEPARTMENT OF Agricultural and
Biosystems Engineering
Angle of Repose: tan-1(
Milled Corn: θ= tan-1(
Milled Rice:
θ= tan-1(
Tilting Box Method:
Milled Corn
)= 29.99º
Shelled Corn: θ= tan-1(
= 28.26º
Rough Rice:
Shelled Corn
= 19.50º
θ= tan-1=(
)= 32.71º
Milled Rice
Rough Rice
Figure2. Tilting Box Method
Observation 1
Material
Observation 2
Observation 3
Height
(in)
Base (in)
Height
(in)
Base (in)
Height
(in)
Base (in)
Milled Corn
4.5
7.5
4.1
7.6
4.9
7.8
Shelled Corn
3.1
8
3
7.9
3.6
8
Milled Rice
3.5
7.5
3.5
7.9
4
7.4
Rough Rice
5
7.5
4.6
7.6
4.1
7.8
Table3. Tilting Box Method Observations
Angle of Repose:
θ= tan-1(
Milled Corn: θ= tan-1(
= 30.53º
Shelled Corn:
θ= tan-1(
= 22.06º
θ= tan-1(
= 25.78º
Rough Rice:
θ= tan-1(
= 30.92º
Milled Rice:
DEPARTMENT OF Agricultural and
Biosystems Engineering
Revolving Cylinder Method:
Milled Corn
Shelled Corn
Milled Rice
Rough Rice
Figure3. Revolving Cylinder Method
Observation 1
Material
Observation 2
Observation 3
Height
(in)
Base (in)
Height
(in)
Base (in)
Height
(in)
Base (in)
Milled Corn
1.5
3
1.7
3
1.9
3.3
Shelled Corn
1.3
3.3
1.1
3.2
1.2
3.3
Milled Rice
1.3
2.3
1
2.5
1
2.3
Rough Rice
2.3
3.7
1.9
3.5
2.5
3.9
Table4. Revolving Cylinder Method Observations
Angle of Repose:
θ= tan-1(
Milled Corn: θ= tan-1(
= 28.74º
Shelled Corn:
θ= tan-1(
= 20.15º
θ= tan-1(
= 24.9º
Rough Rice:
θ= tan-1(
= 31.08º
Milled Rice:
DEPARTMENT OF Agricultural and
Biosystems Engineering
IV- Results and Data Analysis (Results and Discussions)
Average height and base of Table5, Table6, Table7 were obtained from the observed data.
Funnel Method:
Material
Average Height (in)
Average Base (in)
Angle of Repose
Milled Corn
Shelled Corn
Milled Rice
Rough Rice
2
1.5
1.9
2.9
6.93
8.47
7.07
9.03
29.99º
19.50º
28.26º
32.71º
Table5. Funnel Method Results
Tilting Box Method:
Material
Average Height (in)
Average Base (in)
Angle of Repose
Milled Corn
Shelled Corn
Milled Rice
Rough Rice
4.5
3.23
3.67
4.57
7.63
7.97
7.6
7.63
30.53º
22.06º
25.78º
30.92º
Table6. Tilting Box Method Results
Revolving Cylinder Method:
Material
Average Height (in)
Average Base (in)
Angle of Repose
Milled Corn
Shelled Corn
Milled Rice
Rough Rice
1.7
1.2
1.1
2.23
3.1
3.27
2.37
3.7
28.74º
20.15º
24.9º
31.08º
Table7. Revolving Cylinder Method Results
V- Summary and Conclusions
As I compare the results, the angle of repose of each method is not the same but quite
close to each other, this means that the level of accuracy of the obtained data is good. It is
necessary and good to make different observations for each method to obtain more accurate
results and to avoid possible errors. In this activity, among the four materials, rough rice has
the highest angle of repose and the lowest is shelled corn. The laboratory experience is
challenging, especially in the revolving cylinder method but fun. Each material has different
angle of repose.