1. COMPOUND MAGNIFICATION SYSTEM- Berry Strain Gauge

2. COMPOUND MAGNIFICATION SYSTEM
Berry Strain gauge

3. It has Greater sensitivity
The point b is rigidly fixed to the frame .
The point c is pivoted from the frame and is integral with a lever arm d, which alone magnifies the strain about 5:1
The dial indicator permitting measurements of strain to the nearest mm with a 0.025mm micrometer.
The variations of micrometer contact pressure and seating of the conical points in holes, making the gauge length, probably reduce the accuracy to about 0.015mm

4. Tinius Olsen Extensometer

5. Tinius olsen strain gauge is a very compact and convenient instrument.
This combines lever and an indicator in which the strain in the 5cm gauge length may be read to the nearest mm micrometer.
The knife contacts acting on opposite side of the specimen, gives an average of the strain values on the two sides with only one gauge reading.
A cantilever spring acting on the specimen opposite each knife edge provides the necessary mounting force and contact pressure.

6. COMPOUND LEVER MAGNIFICATION- Porter- Lipp strain gauge

7. COMPOUND LEVER MAGNIFICATION
These type of gauges are very sensitive to any vibration that may occur in the structure under test.
The natural frequency of these gauge is rather low
The gauge length of this gauge is 25mm and magnification 300
Advantages:
Compactness
Extreme light weight

8. HUGGENBERGER EXTENSOMETER

9. The magnification may vary from 300 to 2000 depending upon the model.
The gauge length varies from 12.5 to 25 mm
Advantages:
Small size
High magnification factor

10. MAGNIFICATION BY RACK AND PINION

11. COMBINED LEVER, RACK AND PINION MAGNIFICATION