Dynamic Biaxial Compression Tests Using 4 Symmetric Input Hopkinson Bars

Multiaxial dynamic loading situations occur in many industrial cases and multiaxial dynamic test development is thus a crucial issue.

To meet this challenge, a biaxial compression Hopkinson set-up with four symmetric input bars is designed.

The set-up consists of a vertical single striker, a sliding surface mechanism that transfers the impact energy to four horizontal tension bars, and four horizontal Hopkinson bars whose extremities are dynamically compressed by the previous tension bars. Strain gauges on two positions of each Hopkinson bar enable for force and displacement measurements at the bar-sample interfaces.

Simple and biaxial compression tests are carried out on cuboid and cross samples, and the sample material dynamic behavior is deduced from simple compression tests.

The displacements are also estimated using digital image correlation, which confirms the previous measurements. The consistency of the global sample behavior identified from a biaxial compression test is checked by processing numerical simulations based on the behavior determined in simple compression. The results show that the experimental device can be used to identify any behavior law in dynamic biaxial compression.