Vibration Analysis of Flint Blade Specimens for Submerged Stone Age Analysis

The characterization of submerged Stone Age sites remains an important concern for the archaeology community. Stone tools such as flint blades and flakes represent the most commonly found material in the submerged old coast lines. Because these tools are known to be highly sound-producing materials, acoustic methods are expected to be efficient techniques for their characterization. In this study, a 3D Finite Element Model is developed to study the vibrational behavior of flint blade specimens in a submerged condition. This numerical model is applied to realistic 3D-scanned samples of flint blades to investigate their resonance frequencies and mode shapes. The technique of removing the flakes by hitting the flint core, also known as the “knapping process”, is analyzed in this work. The obtained results show that the fundamental frequencies for these samples are smaller than 20 KHz. Due to their complex-curved shapes, the vibration modes are difficult to predict. However, a parametric study is carried out to show the effect of the flint sample’s curvature on the resonance frequencies. The presented study also shows that in most cases, during the knapping process, the amplitude of the first harmonic peak is greater than the fundamental peak value and often occurs at frequencies close to 20 KHz. This later result suggests that the high sound pitch produced during the knapping process is likely to be linked to the structural behavior and response of flint materials. This study contributes to the general project of unlocking the mechanisms behind the sound produced by stone tools.