Fragment and particle size distribution of impacted ceramic tiles E. Carton, J. Weerheijm, C. Ditzhuijzen, I. Tuinman, D. Mevec TNO, section Explosions, Ballistics and Protection, P.O. Box 45, 228AA Rijswijk, The Netherlands

Outline of talk Introduction Low velocity tile impact High velocity tile impact Fragment size distribution (Aerosol) particle size distribution Conclusion Preview: Dynamic crack recording at 1 MFPS Future APP for Virtual Ballistic Laboratory (V i /V out, V 50, etc.)

Introduction Main effect on ceramic impact: multiple cracking What cracks do form and when? What surface area is created? Fragments Aerosol particles

Dynamic cracking of impacted ceramics Elastic response + surface damage Herzian stress distribution Ring cracks at strike face Cone cracking Low impact velocity on thin tiles or high velocity impact on thick tiles SiC tile (6 71 m/s steel sphere impact

Fragment and particle size distribution Tile in closed box Particle size analysers 0.01 to 10 micron Seaves 32 micron to 7 mm

Particle size analyser Measures concentration of particles in air (particles/cm 3 ) Separates particle sizes Registrates number of particles of a range of particle sizes

Particle size analyser Electrical Low Pressure Impactor (ELPI) Measures concentration of particles in air (particles/cm 3 ) Separates particle sizes Registrates number of particles of a range of particle sizes

Ballistic testing on ceramic tiles Armor grade Alumina and SiC (6 to 15 mm tile thickness) m/s

Fragment size distribution Fragment size distribution of 12 mm Alumina tiles Sieve fractions (> 10 micron) Assuming particle shape; volume and area distribution calculated

Fragment size distribution Fragment size distribution of 9 mm Alumina tiles Sieve fractions (> 10 micron)

(Aerosol) particle size distribution Alumina SiC

SEM images of SiC particles stage 6 and 2 (ELPI)

SEM images of Alumina particles Stage 2 (ELPI)

(Aerosol) particle size distribution

Conclusions Cone crack occurs due to elastic response of tile (projectile largely overmatched): Surface damage (circular cracks) Herzian stress distribution Cone crack formation Dynamic fracturing of thin tiles at high impact velocities (target overmatched): Radial cracks, failure wave, transverse cracks, fragment flow Fragment and (aerosol) particle size distribution measured Very small particles (<< grain size) are formed for armor grade ceramics (down into the nanometer range) Total surface area created < 1 m 2 (5-20 J/m 2 )

Normal tile impact: Crack shadowgraphy

Dynamic crack visualization using high speed shadowgraphy 1 Mfps

TNO-APP: Virtual Ballistic Laboratory Bullet + Velocity + Material + Thickness 400 m/s 500 m/s 600 m/s 700 m/s 800 m/s 900 m/s 5 mm 10 mm 15 mm 20 mm 25 mm 30 mm 35 mm User selects input parameters TNO model calculates outcome User obtains results (V residual ) Virtual Ballistic Laboratory

TNO-APP: Virtual Ballistic Laboratory Soon on your mobile phone? Interested? Send mail to: Penetration Residual velocity: 253 m/s 400 m/s 500 m/s 600 m/s 700 m/s 800 m/s 900 m/s 5 mm 10 mm 15 mm 20 mm 25 mm 30 mm 35 mm User selects input parameters TNO model calculates outcome User obtains results (V residual ) Virtual Ballistic Laboratory