Development of a Method for Predictively Simulating Penetration of a Low Speed Impactor into a Weak Cohesionless Soil

Since the horrific attacks on September 11th 2001, the United States government and research community have been focused on how to better protect US assets across the Globe. This push for safety led the research community to develop ?F2656-07 Standard Test Method for Vehicle Crash Testing of Perimeter Barriers? in 2007 which standardized the method of validating a perimeter security barrier?s ability to withstand an impact from an attacking vehicle. Many of these security barriers rely on weak cohesionless soils to stop attacking vehicles. Designers currently rely heavily on hand calculations and engineering judgment when sizing these installations. This simplified analysis is generally used because of the complex nature of these soils under impact. These soils could be simulated in advanced finite element simulations; however, traditional modeling techniques will not allow for the simulation of these complex behaviors.

Due to the complex nature of these simulations, new modeling techniques need to be evaluated and their use needed to be perfected. From this, a new method for creating a predictive simulation of a low speed impactor into a weak cohesionless soil was generated. This paper presents the development of a method by which a predictive simulation was created using only standard soil tests parameters. This paper also presents measured data from physical impact tests utilized to validate the method by which the simulation was generated. Next, the paper gives a detailed comparison of the results of the physical testing and the simulated impacts. The paper finally gives a summary of where the method is successful and where it needs improvement.

The resulting methodology developed in this paper defines a reasonable process for creating a predictive simulation of a rigid impactor penetrating weak cohesionless sands. This finding is validated by a reasonable correlation between the measured and simulated impact penetrations. This paper also highlights the high variability of measured penetrations when testing with these soil materials.