DYNAMIC MODULUS TESTING for PROTECTIVE TEXTILES FILIZ AVSAR LAWSON-HEMPHILL (USA) LAWSON - HEMPHILL LAWSON - HEMPHILL Smart Quality Control Smart Quality Control PROTECTIVE TEXTILES BASIS OF BALLISTIC PREVENTION Protective textiles, especially the ones that are used in Ballistic Prevention need to stop the projectile flight in the shortest distance possible. For that, high modulus (very high strength and low elasticity) materials needed. Earlier: Silk and Nylon 6.6 used 1970’s: Aramids and ultra high modulus PE (UHMPE) Kevlar by Dupont and Twaron by Teijin Aramid Dyneema by DSM and Spectra by Honeywell The basis of the ballistic prevention is to extract maximum energy from the incoming projectile. Absorption of kinetic energy of the projectile is related to: 1- Wave propagation (transversely and longitudinally) 2- Frictional Energy Dissipation When selecting a fiber for the ballistic protection, the dominating selection parameter is the WAVE PROPAGATION VELOCITY. This parameter determines the speed of spreading the energy on ballistic impact. -1 1 3 5 7 9 11 13 15 0 20 40 60 80 100 120 140 160 Specific Energy Absortion (index) Sonic Velocity (1000 m/s) Aramid, Bal.grade. Aramid , Reg.grade S-glass Dyneema SK65 Dyneema SK75 Dyneema S 76 K Polyamide Wave Propagation DYNAMIC MODULUS TESTING with DMT Lawson- Hemphill Dynamic Modulus Tester, DMT is designed to measure the Sonic Velocity, c through materials. DMT can be used to test yarns as well as strips of almost any materials with these options: 1- DMT Fiber Scanner Option for YARN testing 2- DMT Planar Mount Option for MATERIAL testing Lawson-Hemphill Dynamic Modulus Tester, DMT Steel Wire (c=5.06km/sec) Paraaramid (c=7.23km/sec) UHMPE (c=7.59km/sec) Nylon Tirecord (c=3.63km/sec) DMT Operation Principle PULSE RECEIVER PULSE RECEIVER PULSE TRANSMITTER PULSE TRANSMITTER TIMING CIRCUIT TIMING CIRCUIT METER SAMPLE Receive Transducer Transmit Transducer Turn Off Turn On QC for OTHER TECHNICAL TEXTILES Transportation Textiles Medical Textiles Geotextiles Contact information LAWSON-HEMPHILL A TMl Group Company 1658 GAR Highway, Unit 6 Swansea, MA 02720-USA Tel: + 1 508 679 5364 Fax: + 1 508 679 5396 www.testingmachines.com www.lawsonhemphill.com The biggest growth areas for Technical textiles are transport Textiles, followed by Geotextiles, Protective Textiles and Medical Textiles. Below are some examples of instruments for Quality Control of Technical Textiles by Lawson-Hemphill. Force & Shrinkage Tester Textured Yarn Tester Artificial heart valve Tirecord Hot Draw Force Tester POY PES Draw Force Results VELOCITY OF THE WAVE PROPAGATION SONIC VELOCITY of STEEL WIRE Sonic Velocity of Steel Wire as measured by Lawson- Hemphill Dynamic Modulus Tester, DMT is shown below. Steel Wire Density = 7800kg/m 3 Young’s Modulus =c 2 * r Young’s Modulus =c 2 * r Young’s Modulus = 5060 * 7.8 * 10 2 3 Young’s Modulus = 5060 * 7.8 * 10 2 3 Young’s Modulus = 2 * 10 Pa 11 Young’s Modulus = 2 * 10 Pa 11 Sonic Velocity (5.06km/sec) 0 50 100 150 200 250 0 100 200 300 400 500 Transit Time (microsec) Separation (cm) Velocity of the wave propagation, c is: 1- Directly proportional to the square root of the modulus 2- Inversely proportional to the square root of the fiber density Velocity of the propagation for Aramids is ~8km/sec Velocity of the propagation for Nylon is ~2km/sec Up to 4 times the volume of the aramid fiber can be involved in the wave propagation and energy dissipation. Young’s Modulus C= r