Tuesday  |  Salon 11  |  04:40 PM–05:00 PM

#15706, A Comparison of Dynamic Mechanical Analysis (DMA) Experimentation and Post-Processing Analysis Techniques for Polymeric Foams

Dynamic Mechanical Analysis (DMA) is a technique to characterize viscoelastic materials. Traditionally, an oscillatory force is applied to a material, where the tendency for the material to flow (viscosity) and stiffness can be measured across time, temperature, or frequency. This technique commonly assumes the material under investigation remains under small deformation, within in the linear regime. In this work, however, soft polymeric foams are investigated outside of the linear regime at large deformation. Large deformation understanding is required for the materials of interest for two reasons. Firstly, it is expected that there will be large material strains in applications associated with the material of interest. These polymeric foams are used in a variety of applications such as military helmet padding that undergo blunt and blast impacts. Secondly, the polymeric foam acts as a low pass filter, preventing clean data acquisition at higher frequencies when only exciting at small deformation. To analyze the nonlinear output from these experiments, three post processing algorithms are compared. Specifically, displacement, energy, and Fourier transform techniques are examined (for the same set of experimental data) and their inherent benefits and drawbacks are discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding also provided by Office of Naval Research N00014-18-1-2494 (Dr. Tim Bentley, Grant #402067). LLNL-ABS-840397

Moira Foster   Lawrence Livermore National Laboratory
Mark Herynk   Lawrence Livermore National Laboratory
Leslie Lamberson   Colorado School of Mines