force measurement instruments for students in mechanical engineering

1. Chapter 3
Force Torque and Strain
Measurement
Subject code: 2141901
Class: B.E 4th Semester
Marks 15%
Chapter 03
Prepared By:
Asst. Professor Chauhan Hemant
Apollo Institute of Engineering And Technology
Ahmedabad Gujarat 1

2. Force Measurement Methods (Imp)
 Balancing the unknown force against known
gravitational force Mass. Scales and Balances
 Applying an Unknown Force to an Elastic member
(spring, beam, cantilever, ring etc)
 Translating the Force into a Fluid pressure and
measuring the Hydraulic and Pneumatic Load Cell
 Balancing the force Against a Magnetic Force
Developed By Interaction of Magnetic Coil.
2

3. Scales and Balance
Equal Arm Beam Balance Scale
3

4. Scales and Balance
Un-Equal Arm Beam Balance Scale
4

5. Scales and Balance
Pendulum Scale
5

6. Elastic Measurement
Proving Ring
6

7. Elastic Measurement
Proving Ring
7

8. Elastic Measurement
Proving Ring
 Large Forces measurement for 2KN to 2MN
 Working in Compressive and Tensile Force
 Capable of Reading a wide Range of forces
 Good Accuracy
 High Output Signals Produced
8

9. Hydraulic Load Cell
9

10. Load Cell
Hydraulic Load Cell
 Large Forces measurement for up to 2.5MN
with Accuracy of 0.1% in Full load Condition.
 Working in Compressive Force
10

11. Load Cell
Strain gauge Load Cell
11

12. Load Cell
Strain gauge Load Cell
The Bending Moment developed in the
Beam is Proportional to the Applied
Force.
Cantilever beam Deflects and Strain Gauge
will Measure the Strain Produced.
12

13. Load Cell
Piezoelectric Load Cell
Piezoelectric Load Cell
13

14. Measurement of Shaft Power
Dynamometer
1. Absorption type Dynamometer
1. Prony Brake Dynamometer
2. Rope Brake Dynamometer
3. Eddy Current Dynamometer
4. Hydraulic Type Dynamometer
2. Transmission Type Dynamometer
1. Belt Transmission Dynamometer
2. Torsion Transmission Dynamometer
3. Driving Type Dynamometer
14

15. Measurement of Shaft Power
Prony Brake Dynamometer
15

16. Measurement of Shaft Power
Prony Brake Dynamometer Advantages
Simple In construction
Easy to Operate
Suitable for small Power
Prony Brake Dynamometer Disadvantages
Oscillations Produced in uneven Torque
With the time Blocks Wear out and Friction Less
Produced
Heat Generated During the Process
16

17. Measurement of Shaft Power
17

18. Measurement of Shaft Power
Prony Brake Dynamometer
18

19. Measurement of Shaft Power
Rope Brake Dynamometer
Rope Brake Dynamometer
19

20. Measurement of Shaft Power
Rope Brake Dynamometer
20

21. Measurement of Shaft Power
Eddy Current Dynamometer
21

22. Measurement of Shaft Power
Eddy Current Dynamometer
22

23. Measurement of Shaft Power
Eddy Current Dynamometer
Working on Principle That Power Loss produced on
Account of Eddy Current when rotating conductor
cuts across magnetic Flux.
Toothed Steel Rotor fixed on Engine Shaft
Existing Coil is Fitted on Inner Surface of Stator
◦ Used to 250Kw and up to 6000 RPM
◦ Good Control
◦ Small Size for Given Capacity
23

24. Measurement of Strain
Types of Strain Gauges
1. Mechanical Strain Gauges
2. Optical Strain Gauges
3. Electrical Strain Gauges
1. Electrical Resistance Gauge
A. Bounded type
i. Rosette Gauge
ii. Flat type Gauge
iii. Wrap Around type
24

25. Measurement of Strain
25

26. Measurement of Strain
26

27. Measurement of Strain
Rosette gauge
A Set of Multiple Strain gauges in which More
than one strain gauges bonded to the same
supporting Material in Relative Position Known
as Rosette
27