A TESTING METHOD ON THE ATTENUATION OF STRESS WAVES IN LOOSE POROUS MEDIA AND ITS APPLICATION TO CORAL SAND

Stress waves exhibit excellent attenuation characteristics when propagating in loose porous media, which is commonly used for wave mitigation in protection engineering. In order to accurately measure the stress wave attenuation effect of loose porous media, a new method to quantitatively study the attenuation of one-dimensional strain waves in loose porous media by an improving SHPB device was presented. The proposed method is suitable for loose porous media that is independent of or insensitive to strain rate within the range of strain rate of impact load (about 1-10² s^-1). Based on the fitting transmission coefficient T₂, the true peak stress at both ends of the specimen could be calculated by three waves (incident wave, reflected wave and transmitted wave) in the bars. Other key parameters, such as the elastic wave velocity, the peak stress velocity and the rise time of the stress wave at both end of the specimen, can also be tested by the method. By using the new testing method, the stress wave attenuation in dry coral sand was tested. Parametric analysis shows that the error of the fitting transmission coefficient of T₂ was less than 2.83%, indicating satisfactory reliability and practicability of the proposed method.