0
TECHNICAL PAPERS

A Representation of Anisotropic Creep Damage in Fiber Reinforced Composites

[+] Author and Article Information
D. N. Robinson

Civil Engineering Department, The University of Akron, Akron, OH 44325-3905drobins7@tampabay.rr.com

W. K. Binienda1

Civil Engineering Department, The University of Akron, Akron, OH 44325-3905wbinienda@uakron.edu

1

Author to whom correspondence should be addressed.

J. Appl. Mech 72(4), 484-492 (Oct 28, 2004) (9 pages) doi:10.1115/1.1875512 History: Received February 09, 2004; Revised October 28, 2004

A creep damage model is presented that allows for anisotropic distributions of damage in composite materials. An earlier model by the writers allowed for anisotropic damage growth rate but, based on a scalar state variable, failed to account for anisotropic distributions of damage. A vectorial state variable is introduced that allows a representation of anisotropic damage distribution. As in earlier work, a fundamental assumption is that the principally damaging stress components are tensile traction and longitudinal shear at the fiber/matrix interface. Application of the creep damage model is made to calculations involving homogenously stressed composite elements under transverse tensile and longitudinal shear stress and to cross plied thin-walled tubes under tension/torsion. Although the emphasis is phenomenological, with focus on a mathematical structure for representing anisotropic distributions of damage, a meaningful creep damage model must rest on fundamental material science and microstructural examination. Verification experiments involving tension/torsion testing of thin-walled composite tubes together with detailed microstructural examination are discussed and outlined.

Copyright © 2005 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

(a) Microphotograph of the fiber/matrix interface of W∕Nb composite [2]; shows creep damage and nominal stress direction. (b) Schematic diagram of creep damage progression observed in [2].

Grahic Jump Location
Figure 2

(a) Transversely isotropic composite element; fiber direction out of page. Unit vector n¯ denotes normal to interfacial tangent planes at fiber/matrix interface. (b) Definition of (1,2,3) coordinates. Unit circle c (dashed) defined by n¯. Kachanov continuity distribution Ψ(n¯,0) mapped onto unit circle c. Undamaged Ψ=1.

Grahic Jump Location
Figure 3

(a) Composite element showing directional damage—normal to stress direction. (b) Continuity distribution (solid curve) in damaged state Ψ(n¯,t) mapped onto unit circle.

Grahic Jump Location
Figure 4

Damage of composite element under transverse tension. (a) Undamaged state (solid curve) Ψ(n¯,0)=1 at t=0. (b) Partial damage (solid curve) t>0. (c) Continuity distribution (solid curve) Ψ(n¯,t) at failure t=tF. (d) ψo vs t∕tF. (e) ε∕ε̇TNtF vs t∕tF showing acceleration of creep rate (solid curve).

Grahic Jump Location
Figure 5

Isotropic damage evolution. (a) Undamaged state (solid curve) Ψ=1 at t=0. (b) Partial damage (solid curve) t>0. (c) Isotropic failure (solid curve) Ψ=0 at t=tF.

Grahic Jump Location
Figure 6

Damage under stepwise stress history. (a) Partially damaged state (solid curve) at t=0.9tF just before change in stress direction. (b) Fully damaged state (solid curve) at t≈1.87tF after final stage of stress σ33=σo.

Grahic Jump Location
Figure 7

Damage of composite element under longitudinal shear. Continuity distribution Ψ(n¯,t) at failure t≈60tF (solid curve).

Grahic Jump Location
Figure 8

Damage under stepwise longitudinal shear/transverse tension. (a) Partial damage under longitudinal shear for t=50tF (solid curve). Distribution just before stress change to σ33=σo. (b) Continuity distribution Ψ(n¯,t) at failure (solid curve) after σ33=σo is applied for t≈tF.

Grahic Jump Location
Figure 9

Damage under stepwise longitudinal shear / transverse tension. Continuity distribution Ψ(n¯,t) at failure (solid curve) after application of longitudinal shear for t=50tF, then σ22=σo applied for t≈0.15tF.

Grahic Jump Location
Figure 10

Thin tube under tension/torsion reinforced with two fiber families a¯ and b¯ at ±ϕ. (a) Definition of coordinate axes (1,2,3). (b) Definition of fiber coordinate axes (1′,2′,3′). Fiber direction 1′. (c) Unit circle c viewing back along 1′ direction.

Grahic Jump Location
Figure 11

Continuity distributions for both fiber families at t=tF (solid curves). Positive twist with τ=σo.

Grahic Jump Location
Figure 12

Ψ¯o versus t∕tF. Dotted curve relates to continuity distributions of Fig. 1; solid curve relates to continuity distributions of Fig. 1.

Grahic Jump Location
Figure 13

Damage of tube under reversed twist history. Continuity distributions for both fiber families (solid curves) at t=0.9tF, under negative twist (τ=−σo) just prior to twist reversal.

Grahic Jump Location
Figure 14

Damage of tube under reversed twist history. Continuity distributions for both fiber families (solid curves) at failure, after final positive twist (τ=σo). Failure time is t≈1.9tF.

Grahic Jump Location
Figure 15

Damage of tube under reversed twist history. Creep strain history γ∕γ̇otF versus t∕tF (solid curve) showing creep rate acceleration approaching t≈1.9tF.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In