The mechanical behavior of textile composites (qualitative analysis)

Yasser GowayedDepartment of Textile Engineering

Auburn University

Textile Composites

• Steady Improvements in weaving technology has increased the availability of textile preforms

• Advantages include ease of handling, ability to conform to complex shape and improved residual strength after impact

• Successful application requires accurate prediction of thermo-mechanical properties and the rate of damage accumulation to allow design engineers to predict when components should be removed from service (relationship between micro damage and mechanical properties)

Textile vs. Laminated Composites

Laminated Composites Textile Composites

• High fiber vol. fraction

• High in-plane properties

• Low out-of-plane properties

• Low resistance to crack initiation and propagation

Low fiber vol. fraction

Low in-plane properties

High out-of-plane properties

Low resistance to crack initiation and high resistanceto crack propagation

Mechanical behavior: The Effect of Yarn Crimp

Intro to composites, Hull & Clyne

Plain weave

T. Norman et al. FiberTex ‘92

Mechanical behavior: The Effect of Yarn Crimp

Angle Interlock weave

Mechanical behavior: The Effect of Yarn Crimp

XYZ orthogonal weave

Mechanical behavior: The Effect of Yarn Crimp

3D braids

www.atlanticresearchcorp.com

Mechanical behavior: The Effect of Yarn Crimp

Knits

Univ. of Leuven, Belgium

Stitched Composites

Mechanical behavior: The Effect of Yarn Crimp

Laminated Composites

Textile Composite

Mechanical behavior: The Effect of Yarn Crimp

Layup 0/90 +/- 45

Woven Laminate Woven Laminate

Thickness (mm) 2.55 2.17 2.63 2.18Strength (MPa) 545 644 214 216Failure strain 1.02 1.02 4.1 6.7Modulus (GPa) 50.2 60.1 16.3 17.1Poisson’s ratio 0.06 0.04 0.72 0.75

Tensile properties of carbon/epoxy composites:

Bishop et al., Composites 84

Mechanical behavior: The Effect of Yarn Crimp

Layup Tensile Compressive

Woven Laminate Woven Laminate

0/90 (Curtis, ICCM 85) 597 714 542 613+/- 45 (Bishop, AGARC 83) 1102 1218 899 803+/- 45 (Curtis, ICCM 85) 903 892 815 705

Tensile and Compressive strength (MPa) of carbon/epoxy composites:

Mechanical behavior: The Effect of Yarn Crimp

Kollegal et al.

Tensile behavior of AS4/epoxy plain weave with on and off-axis loads

Mechanical behavior: The Effect of Yarn Crimp

Chian-Fong Yen et al.

Tensile behavior of CVI SiC/SiC plain weave

Mechanical behavior: The Effect of Yarn Crimp

Kollegal et al.

Shear behavior of AS4/epoxy plain weave with on and off-axis loads

Mechanical behavior: The Effect of Yarn Crimp

Mechanical behavior: The Effect of Yarn Crimp

www.materials-sciences.com

Local Fiber Failure Mechanisms Resulting from Compression of Kevlar/Epoxy Composites

Property 3-D braid Unidirectional Tape

Fiber Vol. Fraction 0.17 0.35Total Energy Absorbed (ft.lbs) 196 93.5Crack initiation energy (ft.lbs) 48.9 10.5Crack propagation energy (ft.lbs) 145.5 83Maximum impact load (lbs) 5600 2600

Impact Behavior

Impact properties of Alumina/Al-Li composites

Ko, et al. ASTM STP 964

Impact Behavior

Bishop, Textile Structural Composites

X-ray radiograph of fatigue damage at notches

Micrographic images of fatigue damage at notches

Fatigue Behavior

Bishop, Textile Structural Composites

Fatigue Behavior

Bishop, Textile Structural Composites

Crack Initiation: The Effect of Yarn Crimp

Laminated Composites

Textile Composite(3D XYZ woven)

Laminated Composites

Textile Composite(3D XYZ woven)

Crack Growth: The Effect of Yarn Crimp

Crack Growth: Micrographic images

Failure of plain weaves

Univ. of Leuven, Belgium

Crack Growth: Micrographic images

Failure of Angle Interlock weaves

T. Norman et al. FiberTex ‘92

T. Norman et al. FiberTex ‘92

Crack Growth: Micrographic images

Pretest condition of Angle Interlock weaves with stuffers

Crack Growth: Micrographic images

Failure of Angle Interlock weaves with stuffers

T. Norman et al. FiberTex ‘92

Textile Composites Imperfections - voids

Textile Composites Imperfections - voids