L7: Strain Measurement Flashcards
What are three instruments that can be used for monitoring strain
- Electrical Resistance Strain Gauges (ERS gauges)
- Demec Gauge (Extensometer)
- Vibrating Wire Gauges
How do Electrical Resistance Strain Gauges (ERS Gauges) measure strain
How does the Wheatstone Bridge circuit work in an Electrical Resistance Strain Gauge (ERS gauge)
How does a Demec Gauge (Extensometer) measure strain
How does a Vibrating Wire Gauge measure strain
How can you find the direct normal strain on an inclined plane
How can you find the shear strains on an inclined plane
How can these shear stresses and strains be related to each other
How can a Mohr Circle showing τxy with γxy/2
How can you find the Principal Strains, ε1 and ε2, and Maximum Shear Strain, γmax, using the geometry of the Mohr Circle for normal strain vs shear strain
How can Shear Strains be found directly in practice
It can be difficult to measure shear strain directly in practice. Therefore, if the principal directions are not known, it is normal to use a strain gauge rosette to monitor the normal strains in 3 or more independant directions.
There are various rosette configurations - normally 3 strain gauges are oriented at angles of 0, 90 and either 45 or 60 degrees.
