NEW METHODOLOGY FOR SIMULATING FRAGMENTATION MUNITIONS

Transcription

1 NEW METHODOLOGY FOR SIMULATING FRAGMENTATION MUNITIONS V. Gold, E. Baker *, K. Ng and J. Hirlinger U.S. Army, TACOM-ARDEC, Picatinny Arsenal, NJ *Presented By: Dr. Ernest L. Baker

2 Report Documentation Page Report Date 09Apr2001 Report Type N/A Dates Covered (from... to) - Title and Subtitle New Methodology for Simulating Fragmentation Munitions Contract Number Grant Number Program Element Number Author(s) Gold, V; Baker, E; Ng, K.; Hirlinger, J. Proect Number Task Number Work Unit Number Performing Organization Name(s) and Address(es) U.S. Army, TACOM-ARDEC, Picatinny Arsenal, NJ Sponsoring/Monitoring Agency Name(s) and Address(es) NDIA (National Defense Industrial Association) 211 Wilson Blvd, STE. 400 Arlington, VA Performing Organization Report Number Sponsor/Monitor s Acronym(s) Sponsor/Monitor s Report Number(s) Distribution/Availability Statement Approved for public release, distribution unlimited Supplementary Notes Proceedings from the 36th Annual Gun & Ammunition Symposium & Exhibition 9-12 April 2001 Sponsored by NDIA Abstract Subect Terms Report Classification unclassified Classification of Abstract unclassified Classification of this page unclassified Limitation of Abstract UU Number of Pages 16

3 Outline Introduction Background Modeling Methodology Natural Fragmentation Preformed Fragmentation Conclusions

4 Introduction TACOM-ARDEC Warheads Long history of warheads design Technology development Application Fragmentation Ammunition Requirements ALACV, OCSW, OICW, M203 upgrade Lightweight ammunition Lethal fragmentation, various approaches

5 Background Natural Fragmentation Limited lethality due to poor size distribution Good structural characteristics (G load) Preformed and Scored Fragmentation High lethality potential Reduced structural integrity, efficiency issues Combined Fragmentation Natural AND preformed/scored fragmentation Multiple materials (eg: steel and tungsten) Maintain structural integrity where required, use preformed/scored fragmentation elsewhere Require new modeling methodology

6 Modeling Methodology Warhead Mechanics (early time) Arbitrary Lagrangian/Eulerian High Rate Continuum Modeling: CALE (LLNL) finite difference program Velocity and Mass Distributions Fragmentation Modeling Hybrid Analytical and Empirical Approach Natural Fragmentation: Mott based model Preformed/Scored Fragmentation: Experimentally based size distribution

7 Natural Fragmentation: CALE Explosive R Hardened steel shell t=0 msec, V/V 0 =1 z Copper shaped charge liner t=8 msec, V/V 0 =3 Steel fragments v r Q Copper et t=20 msec, V/V 0 =14

8 0.4 Fragmentation Modeling Natural Fragmentation: CALE 0.3 5msec, V/V 0»1.8 10msec, V/V 0»4.3 20msec, V/V 0» msec, V/V 0»31.9 Experimental Data Mass, m/m exp q, degrees

9 Natural Fragmentation: CALE CALE-MOTT analyses, t=20msec Experimental Data CALE-MOTT analyses, t=8msec Velocity, cm/m s q, degrees

10 Natural Fragmentation: Mott Stress Release Wave B 1 A 1 A 1 Fracture R (R i,z i ) v Dq B 1 Region Under Plastic Expansion r Region Stress Relieved A 2 B 2 q R i z B 2 A 2

11 ( ) 2 1/ 0 = m e N m N µ 3 2 3/ 2 = F V r P γ ρ µ m N µ = 0 Fragment Size Distribution: Total Number of Fragments: g is a statiscally based material dependant constant Fragmentation Modeling Natural Fragmentation: Mott

12 Natural Fragmentation: Mott 2.0 Normalized number of fragments, N/N exp Experimental Data CALE-MOTT analyses, t=20ms, g =30 CALE-MOTT analyses, t=8ms, g=30 CALE-MOTT analyses, t=8ms, g=12 CALE-MOTT analyses, t=8ms, g=5 g calibration g=12 final value, V/V0=3 (t=8ms) Normalized fragment mass m/m

13 1.25 Fragmentation Modeling Natural Fragmentation: Mott CALE-MOTT analyses, N 0, t=8msec Experimental Data Number of fragments, N/N exp g=12 final value, V/V0=3 (t=8ms) Q, degrees

14 Preformed Fragmentation: CALE Explosive R Steel shell t=0msec, V/V 0 =1 Copper shaped charge liner z t=20msec, V/V 0 =4 Steel fragments v r Q Copper et t=30msec, V/V 0 =6.8

15 Fragmentation Modeling Preformed Fragmentation: CALE t=10msec t=20msec t=30msec Velocity, cm/m s Liner/Jet Case q, degrees

16 Preformed Fragmentation: Analysis Preformed, 2m 0 = 3grains, t=10msec, V/V 0 = Number of fragments Q, degrees

17 Summary New Fragmentation Simulation Capability Natural Fragmentation Preformed and Scored Fragmentation Combined Fragmentation Required new modeling methodology Natural/Scored/Preformed, multiple materials Currently being applied on the ALACV program