GPU Parallelization is the Perfect Match with the Discrete Particle Method for Blast Analysis

Transcription

1 GPU Parallelization is the Perfect Match with the Discrete Particle Method for Blast Analysis Wayne L. Mindle, Ph.D. 1 Lars Olovsson, Ph.D. 2 1 CertaSIM, LLC and 2 IMPETUS Afea AB GTC 2015 March 17-20, 2015 San Jose, CA

2 Blast Analysis What is Blast Analysis? IEDs (Improvised Explosive Device) Buried Surface Laid Land Mines Conventional Devices Air Blast Impact on Buildings

3 Modeling Soil Soil Properties Type of soil Rock, Sand, Clay Combination of all 3 Moisture Content Density Constitutive Model Equation of State (EOS) Photos from

4 Conventional Method for Modeling Blast Scenario ALE Solver Eulerian Solver for Soil and HE Langrangian Solver (Finite Element) for the structure

5 Discrete Particle Method (DPM) - HE & Air One Particle represents ~ molecules Molecules Particles Kinetic Molecular Theory for Gas Average distance between Particles is large compared to the particle size* Equilibrium exists* Molecules obey Newton s Law Molecular collision is perfectly elastic (*Not valid for HE requires modification) Cylinder Test to Calibrate the HE Detonation Point V () R t Air modeled with same approach as HE

6 Discrete Particle Method (DPM) - Soil Soil Model Normal Spring Constant Tangential Spring Constant Normal Damper Rigid particles Inter particle contact for both friction and damping Grain size distribution, friction, damping and contact stiffness are adapted to match a given EOS Soil is packed using a unit cell with periodic boundaries which means there are no gaps between cells Soil Calibration L L HE Soil Soil Density* Friction Coefficient between soil and the structure* Spring Stiffness between soil particles Friction Coefficient between soil particles Damping Coefficient between soil particles Soil Particle Radius *Determined with standard soil tests Soil Unit Cell Soil Domain Remaining parameters are calibrated for a specific soil by simulating a blast test and optimizing the values to match the measured Maximum Impulse.

7 Discrete Particle Method (DPM) Soil is automatically filled around any object placed in the soil domain. Soil and HE must be able to accurately follow the contours of the structure that it impacts in order to correctly account for the dynamic loading.

8 Discrete Particle Method (DPM) - Example Influence of an Embedded Object in the Soil

9 Discrete Particle Method (DPM) - Example

10 Discrete Particle Method (DPM) - Example Particle Interaction with an Embedded Object

11 Experimental Results for Mine Blast Loading Mine Blast Loading: Experiments and Simulations* C.E. Anderson, Jr., T. Behner, C.E. Weiss, S. Chocron, R.P. Bigger SwRI Report /011 April 2010 Prepared for US Army RDECOM-TARDEC *Simulation results in this study used the Eulerian Solver CTH with runtimes of 96 hours Flat Plate V Degrees V Degrees V90

12 Discrete Particle Method (DPM) - Results

13 Discrete Particle Method (DPM) - Results Test ID Soil Moisture Content IMPETUS Afea Results Maximum Velocity (m/sec) Relative Error from Average Target Maximum Velocity Within Test Scatter Runtime (mins) V % % YES 19 V % % YES 20 V % % YES 20 V % % YES 20 V % % YES 18 V % % YES 17

14 Run time in Minutes Discrete Particle Method (DPM) GPU Performance Flat Plate Buried Mine Test ID V Millions of Particles

15 RDECOM-TARDEC Generic Vehicle Hull The Generic Vehicle Hull is a real structure that has been blast tested. Tests include physical Hybrid III Dummies, similar to what is used in car crash tests, to understand the potential affect of the blast load and to evaluate blast mitigation technologies.

16 RDECOM-TARDEC Generic Vehicle Hull

17 RDECOM-TARDEC Generic Vehicle Hull

18 RDECOM-TARDEC Generic Vehicle Hull Simulation includes the IMPETUS-Afea Hybrid III 50 th Percentile Dummy Model

19 Acknowledgment Many unclassified studies from past researchers have utilized fictitious vehicle geometry due to the non-availability of realistic information. Due to the sensitive nature of the work performed by the Department of Defense, data generated from testing military vehicles is usually classified, making it difficult to share data in the public domain. In order to increase the operational relevance of studies performed by the wider scientific community, the US Army Tank Automotive Research, Development and Engineering Center (RDECOM-TARDEC) has fabricated a generic vehicle hull to help evaluate blast mitigation technologies, and also shared an FEA model of the same for purposes of this research.

20 RDECOM-TARDEC Generic Vehicle Hull The simulations were performed using the IMPETUS Afea Solver which is the only commercially available Nonlinear Explicit Transient Dynamic Solver that takes full advantage of GPU Technology for parallel processing. 4 million discrete particles were used to model the Soil and HE. Runtime on a workstation using one K40 GPU 12 hours for a 20 ms simulation.

21 GPU Functionality Discrete Particle (Soil and Air Blast) Runs on both CPU and GPU GPU acceleration about 10x At this point in time using more than 1 GPU for a single job has no benefit but allows for larger models to be run. The Tesla K40 GPU with 12 GB of memory Eliminates the need to use more than 1 GPU per analysis for current problems that have been run.

22 Contact Info Wayne L. Mindle, Ph.D CertaSIM, LLC Lars Olovsson, Ph.D. IMPETUS Afea AB