Mechanical Testing of
Composites
© 2003, P. Joyce
Tests Accepted by Mil-Hdbk-17
Test Category
Source of Test Method
ASTM
SACMA
D2539, C613
D5300
RM 23, RM 24
Volatiles content
D3530
--
Resin flow
D3531
RM 22
Resin gel time
D3532
RM 19
Fiber areal weight
D3776
RM 23, RM 24
Moisture content
D4019
--
Tack
--
--
HPLC
--
RM 20
E1252, E168
--
D4065, D4473
RM 19
E1356
RM 25
Prepreg tests
Resin content
IR
DMA (RDS)
DSC
© 2003, P. Joyce
Tests Accepted by Mil-Hdbk-17
Test Category
Source of Test Method
ASTM
SACMA
D5229
RM 11
Fiber volume
D3171, D2734
RM 10
Resin content
D3171, D2734
RM 10
Void content
D2584
--
D792, D1505
--
--
RM 10
D4065
RM 18
--
RM 18
E831
--
D696, E228
--
Equilibrium moisture content
D5229
RM 11
Moisture diffusivity
D5229
--
Thermal diffusivity
E1461
© 2003, P. Joyce
E1269
--
Lamina physical tests
Moisture conditioning
Density
Cured ply thickness
Glass transition temperature (dry)
Glass transition temperature
(wet)
CTE, out-of-plane
CTE, in-plane
Specific heat
--
Tests Accepted by Mil-Hdbk-17
Test Category
Source of Test Method
ASTM
SACMA
0°/Warp tension
D3039
RM 4, RM 9
90°/Fill tension
D3039, D5450
RM 4, RM 9
0°/Warp compression
D3410, D5467
RM 1, RM 6
90°/Fill compression
D3410, D5449
RM 1, RM 6
D3518, D5448, D5379
RM 7
Interlaminar shear
D5379
--
Short beam shear
D2344
RM 8
--
--
draft
RM 5
Lamina/Laminate
Mechanical Tests
In-plane shear
Flexure
Open-Hole Compression
© 2003, P. Joyce
Tests Accepted by Mil-Hdbk-17
Test Category
Source of Test Method
ASTM
SACMA
Open-Hole Tension
D5766
RM 5
Single shear bearing
draft
--
Double-shear bearing
draft
--
Compression after impact
draft
M2
Mode I fracture toughness
D5528
--
Mode II fracture toughness
draft
--
D3479
--
--
--
Lamina/Laminate
Mechanical Tests (cont.)
Tension/tension fatigue
Tension/compression fatigue
© 2003, P. Joyce
Laminate Testing
¾ ASTM D638 Tensile Properties of Plastics – dogbone specimen
© 2003, P. Joyce
Laminate Testing
¾ ASTM D3039 Tensile
Properties of PMC
Materials
¾ Used for most
aerospace composites
© 2003, P. Joyce
Laminate Testing
¾ ASTM D695 Compressive Properties of Rigid Plastics (1942)
¾ Uses an untabbed, dogboned, flat specimen
© 2003, P. Joyce
Laminate Testing
¾ Modified D695 Compression Test Method
¾Uses a straight sided specimen
¾Tabbed for strength (gage length to short to instrument using strain gages)
¾Untabbed for modulus
¾No ASTM standard governing this method
¾Defined in Boeing Specification Support Standard (BSS 7260, 1982) and
SACMA Recommended Test Method (SRM 1-88, 1988)
© 2003, P. Joyce
Laminate Testing
¾ Modified ASTM D695 - Mil-Hdbk-17 interprets this technique to be
for 0° direction properties of unidirectional coupons, and 0° and 90°
properties of fabric coupons only (and then only when unit cell size of
weave or braid is small.)
© 2003, P. Joyce
Laminate Testing
¾ ASTM D3410 Compressive Properties of PMC
Materials by Shear Loading
¾ Standard for high modulus carbon fiber composites (1980s)
¾ 0.5” gage length for strain gage sometimes buckles.
¾ Tab failure also problematic.
Celanese fixture © 2003, P. Joyce
Laminate Testing
¾ ASTM D3410 Compressive Properties of PMC
Materials by Shear Loading
¾ Standard for high modulus carbon fiber composites (1980s)
¾ 0.5” gage length for strain gage sometimes buckles.
¾ Tab failure also problematic.
IITRI fixture
© 2003, P. Joyce
Laminate Testing
¾ ASTM D6641 Compressive Properties using CLC
Fixture (2001)
¾ Evolved out of WTF ELSS fixture
¾ Uses straight sided, untabbed specimen
¾ Not recommended for unidirectional composites
© 2003, P. Joyce
Laminate Testing
¾ ASTM D2344 Short-Beam Strength of PMC Materials
¾ Low cost QC test
¾ Material screening
© 2003, P. Joyce
Laminate Testing
¾ ASTM D5379 Shear Properties of Composite Materials
by the V Notched Beam Method (Iosipescu)
© 2003, P. Joyce
Laminate Testing
(Iosipescu method)
© 2003, P. Joyce
Laminate Testing
¾ ASTM D3518 In-plane Shear (IPS)
¾ Uses ±45° laminate to extract shear properties.
¾ Strictly a shear design allowable
¾ Not used for QC
© 2003, P. Joyce
Laminate Testing
¾ ASTM D790 Flexural Properties of Un-Reinforced and
Reinforced Plastics
© 2003, P. Joyce
Laminate Testing
¾ASTM D6484 Open Hole Compressive Strength of PMC
Laminates (1999)
¾After Boeing Specification Support Standard BSS 7260,
also described in SACMA Recommended Method SRM 3-88.
© 2003, P. Joyce
Laminate Testing
¾ASTM
D6742 Filled Hole Tensile/Compressive Strength
w
Ne Laminates (2002)
of PMC
© 2003, P. Joyce
Laminate Testing
¾Creep testing
¾Creep is defined as the change in a property
over time when subjected to a constant forcing
function.
¾Creep should be considered if the end use
¾involves high stress in the matrix dominated
direction
¾high temperature
¾or exposure to a harsh chemical environment
© 2003, P. Joyce
Laminate Testing
¾Creep is especially important in composites with
a thermoplastic matrix, particularly as TsÆTg
¾Creep is expected to be small in thermoset matrix
composites, due to cross-linking.
¾Creep testing is not used to provide primary
design data, rather designs should be checked for
creep deformation.
© 2003, P. Joyce
Testing Fabric-Reinforced
“Textile” Composites
¾Refer to ASTM D 6856 Standard Guide for . . .
¾Discusses special testing considerations for
textile composites.
© 2003, P. Joyce
Adhesives Testing
¾ ASTM D1002 Single Lap Shear is the most common &
industry standard test for:
¾ QC in-process inspection to verify mixing, cure, and surface preparation.
¾ Screening for materials selection.
“five finger” Al specimens
© 2003, P. Joyce
Specimens machined from
composite laminate
Adhesives Testing
¾ ASTM D3528 Double Lap Shear minimizes peel, results
in higher, more consistent shear strength.
Type
TypeABspecimen
specimen
© 2003, P. Joyce
Adhesives Testing
¾ ASTM D3165 Notched Lap Shear
¾ QC for large laminated assemblies (voids)
¾ Compatibility of different resin systems
© 2003, P. Joyce
Adhesives Testing
¾ ASTM D1780 Adhesive Creep
¾ Apply constant load and
measure deflection of scribe
marks.
© 2003, P. Joyce
Adhesives Testing
¾ ASTM D1876 Tee Peel
¾ Requires two flexible adherends (Al)
© 2003, P. Joyce
Adhesives Testing
¾ ASTM D3167 Floating
Roller (Bell) Peel
¾ One rigid, one flexible
adherend
© 2003, P. Joyce
Sandwich Testing
¾ ASTM C297 Flatwise Tensile Strength of Sandwich
Constructions (used as workmanship verification, unless very
reliable NDE being used.)
© 2003, P. Joyce
Sandwich Testing
¾ ASTM C393 “Long Beam” Flexure
¾ 4 point bending produces uniform bending moment in the center section.
¾ Specimen is sized to induce compression failure in upper skin, not core
shear.
¾ Also demonstrates that skin to core strength is adequate to achieve
designed facesheet compression stress.
Paste Photo Here
© 2003, P. Joyce
Sandwich Testing
¾ ASTM C393 Beam Flexure
¾ Performed in addition to FWT on co-cured sandwich if
rigorous structural requirement.
¾ Accounts for any knockdown from wrinkling/dimpling.
¾ Usually yields lower strength & modulus than solid facesheet
tension or compression test.
© 2003, P. Joyce
Sandwich Testing
¾ Mil-Std 401B Core Shear
¾ Used to verify core splice performance.
¾ Can also be used to compare different surface preparations.
¾ Standard configuration uses
¾ 0.062” Al facesheets
¾ 8.1 pcf Al core
© 2003, P. Joyce
Sandwich Testing
¾ ASTM D1781 Climbing Drum Peel
¾ Used for characterization of adhesives for Al facesheet construction
¾ Workmanship test
© 2003, P. Joyce
References
¾
¾
¾
¾
¾
¾
Course Notes, Test Methods for Composite Materials, Adams, D. (1991)
Mil-Hdbk-17 Composite Materials Handbook
Mil-Hdbk-23A Structural Sandwich Composites
Wyoming Test Fixtures, Product Catalog No. 106 (2000)
ASTM Annual Book of Standards (2001)
Engineering Mechanics of Composite Materials, Daniel, I.M. and Ishai, O. (1994)
© 2003, P. Joyce