High-strain rate compressive behavior of Douglas fir and glubam

Understanding the high-strain rate compressive behavior and related energy absorption performances of Douglas fir and glubam is crucial for the application of these materials under impact/blast loading. To this aim, quasi-static tests using a universal testing machine and dynamic tests using an expressly-designed aluminum Split-Hopkinson Pressure Bar (SHPB) apparatus were performed. A total of 90 specimens of Douglas fir and two types of glubam were tested to characterize the quasi-static and high-strain rate compressive characteristics covering a large range of strain rates from 2.2×10-3s-1 to around 1×103s-1. Two different directions were studied: along the fiber (longitudinal) and across the fiber (transverse). The compressive stress-strain curves were analytically described through two uniaxial phenomenological models taken from the literature. Using the fitted parameters of the phenomenological models, it is provided an original definition of the Dynamic Increase Factor (DIF). Finally, energy absorption performances are investigated. The results of this investigation show that Douglas fir and glubam are strain rate sensitive and this sensitivity highly depends on the loading direction