A comparative evaluation of quasi-isotropic laminates composed of either braided triaxial fabric or woven fabric

Mike Braley, A&P Technology Brandon Strohminger, A&P Technology Barry Meyers, TenCate Advanced Composites

Objective

• Compare braided reinforcement to woven reinforcement – 3k (“light”) and 12k (“heavy”) architecture.

• Mechanical testing – In-plane mechanical property characterization.

• Impact testing – 1 lb gelatin bird strike.

Quasi-isotropic triaxially braided fabric

• QISO™ triaxial braided fabric – Fiber angles of 0°/±60°. – Quasi-isotropic and balanced in a single ply.

• Simple layup

– All plies oriented at 0°.

Dry Fabric Characteristics

Fabrics were then prepregged to 38%wt RC with TenCate’s TC-275-1 epoxy resin.

Laminate Characteristics and Layup

Note: Matched laminate FAW for braided and woven laminates.

Laminate Cure

• Laminate cure – Autoclave cure by TenCate Advanced Composites – 135°C (275°F) cure cycle.

• Quality Check – UT C-scans – Weight and thickness measurements. Results below.

Coupon Test Matrix

• All mechanical testing was completed by a third party testing house, Cincinnati Test Laboratories.

• *Denotes an industry accepted modification to the ASTM 3039 test method.

Light Fabric Mechanical Results

Heavy Fabric Mechanical Results

Impact Testing

• (5) QISO and (5) woven laminates impact tested by the University of Dayton Research Institute. – Laminates were 25”x25” – Heavy or 12k architecture

• Impact projectiles were cylindrical gelatin birds

– 2.75” diameter and 5” long – 1 lb weight

Impact Results

13% Δ

QISO- front of panel (7929 J)

QISO- back of panel (7929 J)

Woven- back of panel (7205 J)

Why? • Less undulation, straighter yarns provide

better translation of fiber properties. • Uniformity - same architecture layer to

layer reduces interlaminar shear stresses. • Interlocked multiaxial architecture

– enables superior load distribution around stress concentrations (OHT, OHC).

Axial Yarns

QISO-H Weave Heavy

Bias Yarns

QISO-H Weave Heavy

Future Work • Additional coupon tests of QISO vs Woven

– Evaluate 2x2 woven twill construction – Progressive damage test and analysis with DIC and high speed video – Laminate with mid-plane layer mis-aligned at 100

– 300 off-axis tensile and compression – Instrumented Dyna-Tup to define BVID threshold

• Additional impact tests – Woven vs QISO at increased Vf – QISO vs Aluminum with composite projectiles

Thank you,

Questions?

Acid Digestion Results

Light Fabric Results

Heavy Fabric Results