Novel measurements of material properties at high rates of strain using speckle metrology

Abstract

The application of speckle metrology to high strain rate materials characterisation, through the use of appropriate high-speed photography, provides an exciting opportunity for measurements to be performed on materials, and in loading configurations, which were not previously possible. In particular, a full understanding of the mechanical properties of inhomogeneous materials such as composites, geological and biological materials at high strain rates, requires more data than has previously been provided by the split Hopkinson pressure bar, which only gives a measure of average specimen response. Following from a separate paper by Siviour and Grantham describing the application of speckle metrology to the Hopkinson bar, this paper discusses recent experiments in which this application was used to make previously unobtainable measurements of specimen response. Results are presented from experiments performed on a polymer bonded explosive simulant and long polymer rods. These experiments were designed to evaluate the technique in a number of different configurations, as well as providing useful experimental data on these materials. In addition, we revisit the use of speckle metrology in the high strain rate Brazilian test.

Local Deformation and Failure Mechanisms of Polymer Bonded Energetic Materials Subjected to High Strain Rate Loading

“…Optical methods, such as photoelasticity, digital speckle radiography, laser induced fluorescent speckle photography, and digital image correlation have been used in the past to understand the failure and fracture mechanics of PBXs subjected to dynamic loading [1][2][3][4][5][6][7]. Most of these studies are at macroscale and have provided much insight into the continuum scale high strain rate behavior of PBXs [2][3][4][5][6][7][8][9][10]. However, these experiments are inadequate to understand the local deformation mechanisms in highly heterogeneous PBX materials.…”

Fracture Behaviour Investigation into a Polymer‐Bonded Explosive

“…He corroborated the validity and practicability of the Brazilian test for energetic materials. Grantham [9] and Siviour [10] examined the use of speckle metrology to specimens during dynamic Brazilian test. In addition, Liu et al.…”

Advanced phase shifting algorithms: development and evaluation

“…Metrology, as the science of measurement concerning both the theoretical and practical aspects, is critical in all industrial branches and enables faster and more accurate manufacturing with a higher standard and cheaper cost. Among different metrology techniques, the optical metrology [1][2][3][4][5][6][7][8][9][10] which concerns measurement with light is playing a significant role in various application fields including the semiconductor manufacturing [11][12][13][14][15][16], the mechanical engineering [17][18][19][20], the optical shop testing [21][22][23][24][25], the material engineering [26][27][28][29][30][31], the bio-engineer [32][33][34][35][36][37], etc. The interferometry based techniques [38][39][40][41][42][43][44][45]…”