On the use of strain gages in dynamic fracture

Strain gages are the most commonly used type of strain sensors because of the fact that they are easy to use and relatively inexpensive. The application of strain gages to investigate propagating cracks in homogeneous materials, composites and bi-material interfaces is discussed in this chapter. A brief review on strain gage instrumentation and data acquisition is provided at the outset. The importance of using appropriate gage location and gage orientation relative to the crack path in obtaining reliable measurement of the fracture parameters is highlighted. The theory and analysis procedure for obtaining the crack speed and stress intensity factor are discussed for each type of material. Typical results, available from existing literature, are also presented