week 3

Strain gauge has related with load cell sensor.The strain gauge has been in use for many years and fundamental for any other sensor such as pressure sensor and etc.

 When external forces are applied to a stationary object, stress and strain are the result. Stress is defined as the object's internal resisting forces, and strain is defined as the displacement and deformation that occur.

 Strain may be compressive or tensile and is typically measured by strain gages. It was Lord Kelvin who first reported in 1856 that metallic conductors subjected to mechanical strain exhibit a change in their electrical resistance. This phenomenon was first put to practical use in the 1930s.
Figure above is define as stress and strain.

Visit a few website to get knowledgeable about strain gauge.
http://www.sensorland.com/HowPage002.html 
http://www.omega.com/literature/transactions/volume3/strain.html 
http://www.dynasen.com/html/stressstraingages.html