Dynamic behavior of brittle geological materials under high strain rates

Extreme events like impacts of meteorites on the Earth's crust represent an important field of research in geoscience. The probability of occurrence of such events contrasts with the enormous damage potential for infrastructures, life and environment. A way to model the impact cratering process and define measures to minimize the damage derived from these happenings is by means of numerical analysis. Hence, the knowledge of the material behavior is essential to study the effects from such a loading scenario. With this aim, an adequate material model is required where the dynamic behavior of the impacted material is represented as realistic as possible. Solid geological materials like quartzite and granite are characterized by a high brittleness, resulting in low fracture energy, and an abrupt failure if the ultimate strength is reached. The failure is characterized by the initiation of cracks due to exceedance of the tensile strength under both the compressive and the tensile loading. The behavior of such material under quasi-static loading has been already well characterized, but the dynamic behavior has been rarely investigated until now. Within this context, the paper focuses on the experimental characterization of four brittle geological solid materials under impact loading in Hopkinson-Bar spallation tests. The analysis encompasses the determination of the tensile properties as well as the comparison between the quasi-static and dynamic behavior (Dynamic Increase Factors, DIF).