Materials Database Development for Ballistic Impact Modeling

1
Materials Database Development for Ballistic
Impact Modeling

• Mike Pereira
• Kelly Carney
• Bill Emmerling
• Don Altobelli
• Chip Queitzsch

2
Problem

• Lack of consistency in material modeling
  practices
• Lack of high quality set of data to develop and
  verify impact models
• Data typically assembled from a number of
  different sources
• Lack of quantitative measurements to evaluate
  model accuracy
• Limited pedigree

3
Objective

• Develop a set of data to help improve and
  validate computational impact models
• Material property data
• Ballistic impact test results
• Model inputs and results
• Initially two metallic materials will be
  considered. More will be added as the database
  evolves.

4
Initial Materials

• Ti-6Al-4V
• 0.080 in
• 0.140 in
• 0.25 in
• Al 2024-T3/T351
• 0.125 in (T3)
• 0.25 in (T351)
• 0.50 in (T351)

5
Database Contents

• Material Property Data
• Shear, compression and tension
• Different strain rates
• Different temperatures
• Ballistic Impact Test Data
• Flat plate tests
• Subcomponent tests
• Damage Characterization

6
Material Property Measurements

• Tension, shear, and compression tests will be
  done at various strain rates ranging from 10-4 to
  5x103 s-1. Tests at various elevated
  temperatures will be done at one of the strain
  rates.
• Uniaxial tension tests, uniaxial compression
  tests, and torsion tests at strain rates from
  10-4 to 2 s-1 will be done using a hydraulic
  Instron machine. Tests at strain rates from 300
  to 5000 s-1 will be done using the tension,
  compression, and torsion split Hopkinson bar
  techniques.

7
Room temperature testsAl 2024-T351
8
Elevated temperature tests Al 2024-T351strain
rate of 1 s-1
9
Room temperature tests - Ti-6-4
10
Elevated temperature testsTi-6-4strain rate 1
s-1
11
Ballistic Impact Tests

• Flat panel tests
• Subcomponent tests

12
Flat Panel Tests

• Design projectile so that ballistic impact
  velocity is between 600-900 ft/sec
• 15 square panels rigidly clamped on four sides
  with a 10 square aperture
• Cylindrical projectile with a large radius nose,
  normal impact

13
Impact Gun
14
Preliminary Test Fixture
15
Test Fixture
16
Projectiles
17
Subcomponent specimen
Half Ring Specimen
Projectile
18
Large gas gun
19
Instrumentation

• Point strain on backside (strain gages)
• Impact velocity
• Exit velocity
• Projectile orientation
• Full field displacement/strain (stereo photo
  instrumentation)

20
Point strain measurement
Rosette
Unidirectional gage
21
High speed video
22
Projectile Orientation
Z
X
e2
e3
e1
Y
23
Full-field displacement and strain
24
Material Model Creation

• LS-DYNA material model(s) will be created for
  each tested material
• As much as possible, current material models will
  be utilized
• New constitutive models will only be created if
  needed

25
Material Model Selection

• Initially, models which directly use the stress
  strain curves will be selected
• Specifically, Mat 24, Piecewise Linear
  Plasticity, Mat 81, Plasticity with Damage, and
  Mat 123 Modified Piecewise Linear Plasticity will
  be examined
• Full stress strain behavior including strain rate
  effects will be included

26
Practice and Verification

• As much as possible, the material model
  parameters and curves will be generated from
  mechanical property tests, both static and
  dynamic
• All of the ballistic tests will be simulated
  using the new material models and appropriate
  meshes
• The ballistic tests will be used to verify the
  accuracy and robustness of the material models

27
Internet Database

• All information related to the tests and models,
  including raw data, high speed video, test
  parameters, DYNA input decks will be contained in
  the database
• Cooperating users will have on-line access to all
  data and models
• Users will have the opportunity to submit their
  own models and data, subject to certain quality
  criteria
• Objective is to continue developing the database
  with additional materials, including composite
  materials.