Evaluation of Under-body Blast Response to Loading from Alternative Terra-Medium Environments

Principal Investigator

• David Littlefield, University of Alabama at Birmingham (UAB)

Faculty/Staff

• Gerald Pekmezi, Shannon Lisenbee, UAB

Students

• TBA, UAB

Government

• TBA, US Army GVSC

Project began Q4 2022.

Modeling of under-body blast loading presents many challenges for simulation. One of the most significant challenges is proper accounting for the terra-medium propelled by the blast wave when an explosive detonation occurs. There have been significant advances over the last two decades in developing models for response of soils when subjected to blast and ground shock scenarios. Many of these models excel at predicting the behavior of different types of homogeneous soils in blast simulations. However, realistic terrain environments contain other materials, such as water, rocks and gravel, which must be properly taken into account in order to make accurate predictions of vehicle under-body response. The response of a combined terra-medium containing soil, water and rocks/gravel in particular is a challenging problem, since modeling the water and soil is more readily adaptable to an Eulerian or mixed Eulerian-Lagrangian (ALE, CEL) computational approach, whereas motion of the gravel/rocks is better characterized using a mesh-free approach such as Lagrangian particles, i.e. discrete elements. Likewise, the loading by highly saturated soils, mud, or even water alone, presents considerable challenges for simulation.

The goal of this research project is to implement a coupling of the proven ALE/CEL methods with the widely used Discrete Element particle method, which will serve to improve computational models that include hard, coarse aggregates in addition to the softer particulate media. Toward that goal, four distinct supporting objectives are identified. Development of an ALE/CEL-to-DEM algorithm is the initial goal, which will produce a module that can start with ALE/CEL model and feed all the relevant geometry and parameters to the Discrete Element code. Next comes the development of the different DEM-to- ALE/CEL algorithms, which will complete the coupling loop for each code by updating the forces/kinematics in the ALE/CEL code from the result of the DEM step(s). With the coupling loop complete, attention will turn to optimization and calibration, consisting of tuning the parameters that control the separate codes as well as the coupling details. Finally, in the evaluation and prediction step, myriad simulations will be carried out to evaluate the performance of the coupling with the different codes.

The proposed effort will result in improvements to the modeling and simulation of ground vehicle design and operation, in this case, operation under adverse conditions resulting from extreme loadings.

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