UNIVERSITY OF ENGINEERING & TECHNOLOGY
PROJECT REPORT OF
MECHANICS OF MATERIAL
COURSE TITLE:
MtE-222L: MECHANICS OF MATERIAL
SEMESTER:
TH
BS-4
SUBMITTED BY:
MUNEEB FAYYAZ
21PWMCT0793
HUZAIFA HAIDER
21PWMCT0776
AQSA INAM
21PWMCT0787
SUBMITTED TO:
PROF. DR FARID KHAN
DEPARTMENT OF MECHATRONICS ENGINEERING
Table of Contents
ABSTRACT: ......................................................................................................................................... 3
A
INTRODUCTION: ....................................................................................................................... 3
OBJECTIVES: ...................................................................................................................................... 3
B
LITERATURE REVIEW: ........................................................................................................... 3
WEIGHT MACHINE: ............................................................................................................................ 3
TYPES OF WEIGHT MACHINE: ..................................................................................................... 4
C
MAIN COMPONENTS:............................................................................................................... 6
BLOCK DIAGRAM: ............................................................................................................................ 9
D
APPROACH AND METHODOLOGY: ................................................................................... 10
a.
HARDWARE: ............................................................................................................................. 10
i.
DESIGN OF THE LOAD CELL:.............................................................................................. 10
ii.
SOLIDWORKS SIMULATION: .............................................................................................. 10
iii.
FABRICATION OF THE BEAM: ........................................................................................ 12
b.
CIRCUIT DESIGNING: ............................................................................................................ 14
c.
PROGRAMMING: ..................................................................................................................... 17
PROJECT IMAGE:............................................................................................................................ 19
RISKS AND DIFFICULTIES: .......................................................................................................... 19
BUDGET: ............................................................................................................................................ 19
REFERENCES: .................................................................................................................................. 20
PROJECT TITLE
WEIGHT MACHINE OF BEAM LOAD CELL
ABSTRACT:
Beam load cell weight machines are widely used in various industries for accurate and
precise weight measurement applications. These machines employ the principle of strain
gauges mounted on a beam to convert the applied force into an electrical signal, which is then
used to determine the weight of an object or load. This abstract provides an overview of beam
load cell weight machines, highlighting their working principle, key components, advantages,
and applications.
A INTRODUCTION:
The beam load cell weight machine consists of one or more load cells strategically positioned
beneath a weighing platform or structure. As a load is applied to the platform, the load cell
deforms proportionally, generating a measurable electrical output. This output is then
converted into weight readings that can be displayed on a digital screen or integrated into a
computer system for data analysis and processing.
Beam load cell weight machines play a crucial role in weight measurement applications
across various industries. These machines utilize the principle of strain gauges mounted on a
beam to convert applied force into an electrical signal, enabling accurate and precise weight
readings.
OBJECTIVES:
•
•
•
•
To demonstrate the working of a load cell.
To design a weight machine that should provide accurate and precise measurements of the
measured weight.
The weight machine should be robust and able to withstand regular use without losing its
accuracy or performance.
The weight machine should have a user-friendly interface that is easy to understand and operate.
B LITERATURE REVIEW:
WEIGHT MACHINE:
Beam load cell weight machines are widely used in various industries for accurate and
precise weight measurement applications. These machines employ the principle of strain
gauges mounted on a beam to convert the applied force into an electrical signal, which is then
used to determine the weight of an object or load.
PURPOSE:
The purpose of a beam load cell weight machine is to accurately and precisely measure the
weight or applied force of an object or load. These machines are designed to provide reliable
weight measurements in various industries and applications. The primary purpose of a beam
load cell weight machine can be summarized as follow:
ACCURATE WEIGHT MEASUREMENT:
The main purpose of a beam load cell weight machine is to provide accurate and precise
weight measurements. By utilizing strain gauges mounted on a beam, these machines can
convert the applied force into an electrical signal, which is then processed to determine the
weight of the load with high accuracy.
QUALITY CONTROL:
Beam load cell weight machines play a crucial role in quality control processes across
industries. They are used to ensure that products meet specified weight requirements,
enabling manufacturers to maintain consistency, reliability, and compliance with regulations.
These machines help identify any variations in weight that may indicate defects or
inconsistencies in production.
INVENTORY MANAGEMENT:
In logistics and warehousing operations, beam load cell weight machines are employed for
efficient inventory management. By accurately measuring the weight of goods and materials,
these machines enable precise tracking and recording of stock levels, ensuring accurate
inventory control and efficient supply chain management.
MATERIAL HANDLING:
Beam load cell weight machines are utilized in material handling equipment, such as
conveyor belts and forklifts, to determine the weight of goods being transported. This
information helps optimize load capacities, prevent overloading, and ensure safe and efficient
material handling processes.
RESEARCH AND DEVELOPMENT:
Beam load cell weight machines are also used in research and development settings,
particularly in scientific laboratories and engineering facilities. They enable precise weight
measurements for experiments, testing, and prototyping purposes, supporting the
development and validation of new products and technologies.
TYPES OF WEIGHT MACHINE:
There are several types of weight machines available to cater to different weight
measurement needs. From beam load cell weight machines for industrial applications to
digital weighing scales for household use, each type of weight machine utilizes specific
technologies and mechanisms to ensure accurate and precise weight readings. The selection
of the appropriate weight machine depends on factors such as the application, weight
capacity, accuracy requirements, and environmental conditions. Some of the most commonly
used weight machines are discussed below:
BEAM LOAD CELL WEIGHT MACHINE:
Beam load cell weight machines are widely used in industrial and commercial settings. They
employ the principle of strain gauges mounted on a beam or cantilever to measure the
bending or deflection caused by the applied load. The strain gauges convert this mechanical
stress into an electrical signal, which is then processed to determine the weight. Beam load
cell weight machines are known for their accuracy, durability, and suitability for heavy-load
applications.
PLATFORM SCALES:
Platform scales, also known as floor scales, consist of a large weighing platform on which the
load is placed. These scales typically use load cells or hydraulic sensors beneath the platform
to measure the weight. Platform scales come in various sizes and weight capacities, making
them suitable for weighing large and heavy objects. They find applications in industries such
as logistics, manufacturing, and agriculture.
COMPRESSION LOAD CELL WEIGHT MACHINES:
Compression load cell weight machines are designed to measure the weight or force applied
in a compression or downward direction. These machines utilize load cells that are
specifically designed to measure compressive forces. Compression load cell weight machines
are commonly used in applications such as material testing, force monitoring, and industrial
weighing where the load is applied in a vertical direction.
TENSION LOAD CELL WEIGHT MACHINE:
Tension load cell weight machines are used to measure the weight or force applied in a
tension or upward direction. These machines employ load cells that are engineered to
measure tensile forces. Tension load cell weight machines are frequently used in applications
such as crane scales, hanging scales, and force testing where the load is suspended or pulled
upward.
DIGITAL WEIGHT SCALES:
Digital weighing scales have become ubiquitous in household and commercial settings. These
scales utilize strain gauge load cells or piezoelectric sensors to measure the weight. Digital
weighing scales offer precise and instant weight readings and often come with additional
features such as weight conversion, tare function, and memory storage. They are commonly
used in kitchens, bathrooms, fitness centers, and retail stores.
C MAIN COMPONENTS:
1. LOAD CELL
A load cell is a transducer that converts force into measurable electrical output. Although
there are many varieties of force sensors, strain gauge load cells are the most commonly
used type.
Fig 1: Load cell
2. STRAIN GAUGES
A strain gauge is a device that measures the change in electrical resistance when a force is
applied. It converts force, pressure, tension, weight, etc., into a change in electrical
resistance which can then be measured. When external forces are applied to a stationary
object, stress and strain are the results.
Fig 2: Strain gauge
3. HX711 AMPLIFIER:
The HX711 amplifier is a widely used integrated circuit (IC) designed specifically for
amplifying and converting small electrical signals from load cells or strain gauges into
measurable digital data. It serves as a critical component in precision weighing
applications, where accurate and reliable measurements are required.
The HX711 amplifier is typically interfaced with microcontrollers, such as Arduino or
Raspberry Pi, through a simple two-wire communication protocol (usually SPI or I2C).
This allows for seamless integration into various electronic systems, enabling users to
easily access and process the converted data.
Fig 3: HX711 Load cell amplifier
4. LCD DISPLAY:
The term LCD stands for liquid crystal display. The 16x2 LCD display is a widely used
alphanumeric display module that consists of 16 columns and 2 rows, hence the name
"16x2." It utilizes liquid crystal technology to display characters, numbers, symbols, and
basic graphical elements, providing a simple and effective means of visual feedback in
electronic projects.
One of the distinguishing features of the 16x2 LCD display is its simplicity in terms of
interfacing with microcontrollers and other electronic devices. It typically connects using a
parallel interface, where each character or command is sent to the display module using a set
of data lines and control signals. This makes it compatible with a wide range of
microcontrollers and allows for easy integration into various projects.
In addition to character display, the 16x2 LCD module also supports basic graphical
functions. It can display simple bar graphs, custom characters, and even limited pixel
manipulation. While it may not match the graphical capabilities of more advanced displays,
the 16x2 LCD still offers a versatile and cost-effective solution for many applications.
5. I2 C MODULE:
I2C stands for Inter-Integrated Circuit. It is a bus interface connection protocol incorporated into
devices for serial communication.
Fig 4: 16x 2 LCD display with I2 C module
6. BATTERY:
A 12V battery would be used to power the circuit of the weight machine.
Fig 5: 12v battery
7. ARDUINO NANO:
The Arduino Nano is a microcontroller-based device with 16 digital pins that can be used for
various purposes. It can be used for almost every task, from minor to massive industrial-scale
projects. It can also be used for prototyping and developing new applications. Arduino Nano
is simply a smaller version of Arduino UNO, thus both have almost the same functionalities
Fig 6: Arduino nano
BLOCK DIAGRAM:
Fig 7: Block diagram
D APPROACH AND METHODOLOGY:
a. HARDWARE:
i.
DESIGN OF THE LOAD CELL:
For this project, a cantilever beam is selected, having a length of 5cm(50mm), width of
1cm(10mm), and height of 1cm(10mm). The Solidworks design of the beam is given below.
Fig 8: Cantilever beam load cell
ii.
SOLIDWORKS SIMULATION:
The solidworks simulation of the beam was done. Keeping one of the sides of the beam fixed a load
of 50N was applied on the free end of the beam to observe the stress, strain and displacement in the
beam.
Fig 9: Stress due to 50N load
Fig 10: Displacement due to 50N load
Fig 11: Strain due to 50N load
iii.
FABRICATION OF THE BEAM:
1. MATERIAL SELECTION:
A bar of mild steel was selected for making the load cell. Considering the factors such as
material strength, and weight-bearing capacity.
2. MEASUREMENT AND MARKING:
Measure the desired length of the beam on the square bar using a measuring tape or ruler.
Make sure to mark the starting and ending points accurately. Keeping the length of the beam
as 5cm, width as 1cm, and height as 1 cm.
3. CUTTING:
Use a saw or cutting tool appropriate for the material of the square bar to cut along the
marked lines. Ensure a clean and straight cut to maintain the integrity of the beam.
Fig 12: Cutting of the bar
4. DRILLING:
After cutting the square bar to the desired length, drill the required number of holes for
creating the cavity of the beam to weaken its strength, so it can give us deflection whenever
loaded by a weight. Also drill four holes on both the ends of the beam so that it can be fixed
on a platform.
Fig 13: Drilling holes
5. FINISHING:
Smooth out any rough edges or imperfections using a grinder or file. This step helps improve
the appearance and functionality of the beam.
Fig 14: Finishing
b. CIRCUIT DESIGNING:
STRAIN GAUGES:
1. SELECTION OF STRAIN GAUGE:
Choose the appropriate type of strain gauge based on the application requirements, such as
foil strain gauges or semiconductor strain gauges.
Fig 15: Strain gauges
2. SOLDERING:
Use a proper soldering iron to attach conducting wires in order to make it work. Make sure
that the wires are properly soldered.
Fig 16: Soldered strain gauges
3. CONTINUITY CHECKING:
Check the continuity of the wires after soldering through the digital or analog multimeter.
4. MOUNT THE STRAIN GAUGES:
Attach the active strain gauges to the appropriate positions on the beam load cell. Ensure that
they are securely mounted and aligned properly. The strain gauges should be placed in a
manner that allows them to measure the bending or deflection of the load cell accurately.
Fig 17: Mounting the strain gauges
5. CONNECTION OF STRAIN GAUGES:
Connect the strain gauges to the Wheatstone bridge circuit. Each strain gauge has two leads
that need to be connected. Follow the manufacturer's instructions for proper wiring and
connections.
Fig 18: Wheat stone bridge circuit
Fig 19: Wheat stone bridge
6. APPLYING EXCITATION VOLTAGE:
Apply a stable and constant excitation voltage across the two opposite corners of the
Wheatstone bridge. This voltage serves as the power supply for the bridge circuit and is
typically in the millivolt range.
7. MEASURE OUTPUT:
Connect a voltage measuring device or a signal conditioning circuit to the remaining two
corners of the Wheatstone bridge. This is where the output voltage is measured. The output
voltage is proportional to the change in resistance of the active strain gauge, which is
influenced by the applied load on the beam load cell.
Calibrate the Wheatstone bridge by applying known loads to the beam load cell and recording
the corresponding output voltages. Use this calibration data to establish a linear relationship
between the output voltage and the applied load.
8. CONNENTING LOAD CELL TO AMPLIFIER:
Connect the output wires of the load cell to the input terminals of the amplifier circuit. And
do proper wiring and connections.
9. CONNECTING AMPLIFIER TO ARDUINO:
Wire the amplifier circuit to the appropriate pins of the Arduino. Ensure the connections are
correct, and refer to the microcontroller's documentation for the pin configuration.
10. CONNECT LCD:
Connect the LCD display to Arduino according to the specified pin connections. Utilize the
appropriate library to display weight readings and other relevant information on the LCD.
c. PROGRAMMING:
Use the programming language compatible with Arduino that is C/C++ to read the amplified
load cell signal. The Arduino code for the weight machine is given below:
Arduino code:
#include "HX711.h"
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
int dout = 4;
int sck = 5;
HX711 scale;
float units, ounces = 0;
float calibration_factor = 10.32;
int button = A0;
void setup() {
Serial.begin(115200);
pinMode(button, INPUT);
lcd.init();
// initialize the lcd
// Print a message to the LCD.
lcd.backlight();
lcd.print("Digital Balance");
scale.begin(dout, sck);
scale.set_scale();
scale.tare();
long zero_factor = scale.read_average();
Serial.print("Zero factor : ");
Serial.print(zero_factor);
}
void loop() {
if (digitalRead(button) == 0) {
scale.tare();
}
//delay(50);
scale.set_scale(calibration_factor);
Serial.print("Reading: ");
units = scale.get_units(), 10;
if (units < 500)
{
units = 0.00;
}
ounces = units * 0.035274;
Serial.print(units);
Serial.print(" grams");
Serial.print(" calibration_factor: ");
Serial.print(calibration_factor);
Serial.println();
if (Serial.available())
{
char temp = Serial.read();
if (temp == '+' || temp == 'a')
calibration_factor += 0.01;
else if (temp == '-' || temp == 'z')
calibration_factor -= 0.01;
}
delay(500);
float kg = units / 1000;
Serial.print("Grams: ");
Serial.print(units);
Serial.print(" !! KG: ");
Serial.println(kg);
lcd.setCursor(0, 1);
lcd.print("Weight:");
lcd.print(kg);
lcd.print(" KG
");
}
CALIBRATION:
Place known weights on the load cell and compare the displayed values with the actual
weights. Adjust the calibration parameters in the code if necessary to improve accuracy.
PROJECT IMAGE:
Fig 20: Project image
RISKS AND DIFFICULTIES:
•
•
•
As we have selected a mild steel bar for making the load cell, cutting and drilling holes
was difficult due to its hardness.
Soldering the strain gauges was difficult due their sensitivity and small size.
Calibration of the weight machine to accurately measure the load.
BUDGET:
Table 1: Components list
Components
Cost
Arduino nano
1200/-
HX711 Amplifier
200/-
I2C module
700/-
16x2 LCD display
500/-
Mild steel Bar
500/-
Strain gauges
Per 80/-
Wooden Base
1000/-
Total cost
5500/-
REFERENCES:
https://www.researchgate.net/publication/327471393_Development_of_an_Electronic_Weighing_Ind
icator_for_Digital_Measurement
https://circuitdigest.com/microcontroller-projects/arduino-weight-measurement-using-load-cell
https://www.techtarget.com/whatis/definition/LCD-liquid-crystal-display
https://www.theengineeringprojects.com/2018/06/introduction-to-arduino-nano.html
https://www.electronicshub.org/wheatstone-bridge/