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

Blast Analysis

What is Blast Analysis?

IEDs (Improvised Explosive Device)

Buried

Surface Laid

Land Mines Conventional Devices

Air Blast

Impact on Buildings

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 http://freebigpictures.com

Conventional Method for Modeling Blast Scenario ALE Solver

Eulerian Solver for Soil and HE

Langrangian Solver (Finite Element) for the structure

Detonation

Point

( )RV t

Molecules Particles

Cylinder Test to Calibrate the HE

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)

One Particle represents ~ 1015 – 1020 molecules

Discrete Particle Method (DPM) - HE & Air

Air modeled with same approach as HE

Discrete Particle Method (DPM) - Soil

Normal

Spring Constant Normal Damper

Tangential

Spring Constant

L L

HE

Soil

Soil Unit Cell Soil Domain

Soil Model

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

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

Remaining parameters are calibrated for a specific soil

by simulating a blast test and optimizing the values to

match the measured Maximum Impulse.

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.

Discrete Particle Method (DPM) - Example

Influence of an Embedded Object in the Soil

Discrete Particle Method (DPM) - Example

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

Experimental Results for Mine Blast Loading

Flat Plate

V180 120 Degrees

V120 90 Degrees

V90

Mine Blast Loading: Experiments and Simulations* C.E. Anderson, Jr., T. Behner, C.E. Weiss, S. Chocron, R.P. Bigger

SwRI® Report 18.12544/011

April 2010

Prepared for US Army RDECOM-TARDEC

*Simulation results in this study used the Eulerian Solver CTH with runtimes of 96 hours

Discrete Particle Method (DPM) - Results

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)

V180-07-30 7% 5.52 1.3% YES 19

V180-07-20 7% 6.52 -12% YES 20

V120-07-25 7% 4.03 5.7% YES 20

V090-07-25 7% 2.56 -2.7% YES 20

V180-14-20 14% 7.03 -2.1% YES 18

V180-21-20 21% 7.62 -9.0% YES 17

Discrete Particle Method (DPM) – GPU Performance

Millions of Particles

Run t

ime in M

inute

s

Flat Plate Buried Mine

Test ID V180-20-7

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.

RDECOM-TARDEC Generic Vehicle Hull

RDECOM-TARDEC Generic Vehicle Hull

RDECOM-TARDEC Generic Vehicle Hull

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

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.

Acknowledgment

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.

RDECOM-TARDEC Generic Vehicle Hull

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.

Contact Info

Wayne L. Mindle, Ph.D CertaSIM, LLC

www.certasim.com

wayne@certasim.com

Lars Olovsson, Ph.D. IMPETUS Afea AB

www.impetus-afea.com

lars@impetus.no