dynamic modulus testing for protective textiles€¦ · dynamic modulus testing for protective...

DYNAMIC MODULUS TESTING for PROTECTIVE TEXTILESFILIZ AVSAR

LAWSON-HEMPHILL (USA)LAWSON - HEMPHILLLAWSON - HEMPHILL

Smart Quality ControlSmart Quality Control

Aramid. Reg.

PROTECTIVE TEXTILES

BASIS OF BALLISTIC PREVENTION

Protective textiles, especially the ones that are used inBallistic Prevention need to stop the projectile flight in theshortest distance possible. For that, high modulus (veryhigh 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 maximumenergy 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, thedominating selection parameter is the WAVEPROPAGATION VELOCITY.

This parameter determines the speed of spreading theenergy 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)

So

nic

Ve

loc

ity

(10

00

m/s

)

Aramid, Bal.grade.

Aramid , Reg.grade S-glass

Dyneema SK65

Dyneema SK75

Dyneema S 76K

Polyamide

Wave Propagation

DYNAMIC MODULUS TESTING with DMT

Lawson- Hemphill Dynamic Modulus Tester, DMT isdesigned to measure the Sonic Velocity, c throughmaterials. DMT can be used to test yarns as well asstrips 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

PULSERECEIVER

PULSERECEIVER

PULSETRANSMITTER

PULSETRANSMITTER

TIMINGCIRCUITTIMINGCIRCUIT

METER

SAMPLE

ReceiveTransducer

TransmitTransducer

Turn Off Turn On

QC for OTHER TECHNICAL TEXTILES

Transportation Textiles

Medical Textiles

Geotextiles

Contact information

LAWSON-HEMPHILLA TMl Group Company1658 GAR Highway, Unit 6Swansea, MA 02720-USA

Tel: + 1 508 679 5364Fax: + 1 508 679 5396 www.testingmachines.com

www.lawsonhemphill.com

The biggest growth areas for Technical textiles aretransport Textiles, followed by Geotextiles, ProtectiveTextiles and Medical Textiles. Below are some examplesof instruments for Quality Control of Technical Textiles byLawson-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/m3

Young’s Modulus = c2

���Young’s Modulus = c2

���

Young’s Modulus = 5060 * 7.8 * 102 3

Young’s Modulus = 5060 * 7.8 * 102 3

Young’s Modulus = 2 * 10 Pa11

Young’s Modulus = 2 * 10 Pa11

Sonic Velocity (5.06km/sec)

0

50

100

150

200

250

0 100 200 300 400 500

Transit Time (microsec)

Sep

ara

tio

n(c

m)

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 fiberdensity

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 beinvolved in the wave propagation and energy dissipation.

Young’s ModulusC =

�