0
RESEARCH PAPERS

Optimal Cool-Down in Linear and Nonlinear Thermoviscoelasticity and the Effects of Initial Stress

[+] Author and Article Information
L. Chen1

Department of Mechanical, Aerospace & Biomedical Engineering, The University of Tennessee, Knoxville, TN 37996-2030

J. Cao

Department of Mechanical, Aerospace & Biomedical Engineering, The University of Tennessee, Knoxville, TN 37996-2030

Y. J. Weitsman2

Department of Mechanical, Aerospace & Biomedical Engineering, The University of Tennessee, Knoxville, TN 37996-2030

While isotropy and constraints’ rigidity are not essential to the current formulation (see (5)), the assumption of a thin plate is imperative since it allows the approximation that temperature depends on time only and not on spatial coordinates.

Negative values of curing stresses are physically impossible because in the present case cure shrinkage occurs against rigid boundary constraints.

1

Corresponding author.

2

Current address: GE Aviation, Baltimore, MD.

J. Eng. Mater. Technol 128(4), 484-488 (Jul 14, 2006) (5 pages) doi:10.1115/1.2345438 History: Received October 11, 2005; Revised July 14, 2006

This article concerns the minimization of residual thermal stresses in geometrically constrained adhesive layers and thin polymeric composite lay-ups with emphasis on the role of initial stresses. Such residual stresses evolve during cure and subsequently during post-cure cool-down. The cure stresses play the role of initial stress superimposed on the thermoviscoelastic response that governs to cool-down phase. Optimization is achieved by following a time-temperature path that achieves the best counter play between temperature as a stress inducing and a stress reducing agent. When viscoelastic nonlinearity is considered such contradictory effect is played by stress itself, in which case an initial stress may have a beneficial effect.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Topics: Temperature , Stress
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

The linear optimal temperature and nominal stress paths of the standard solid with and without an initial stress (A=2.5, B=20, A1=0.3, A2=0.6, λ=1, TI=100°C, TF=30°C, (1−ν)σ0∕α=10)

Grahic Jump Location
Figure 2

The linear optimal temperature and nominal paths of the power law with (marked by x) and without (marked by •) an initial stress (A=7.5, B=4, A1=0.15, A2=0.25, t0=1, n=0.25, TI=100°C, TF=20°C, (1−ν)σ0∕α=10)

Grahic Jump Location
Figure 3

The optimal linear temperature and nominal stress paths for power law relaxation with and without an initial stress (same parameters as in Fig. 2) plotted near t=0

Grahic Jump Location
Figure 4

The nonlinear optimal temperature and stress paths for the standard solid (A=10, B=1, A1=0.05, A2=0.4, λ=1, TI=100°C, TF=−20°C, β=0.1). Comparative values for the linear case (β=0) are shown by the triangular symbols.

Grahic Jump Location
Figure 6

Comparison of the initial stress levels and final stresses for the nonlinear cases (A=10, B=1, A1=0.05, A2=0.4, λ=1, TI=100°C, TF=−30°C, β=0.1, (1−ν)σ0(1)∕α=2.5, (1−ν)σ0(2)∕α=5.0, (1−ν)σ0(3)∕α=7.5, (1−ν)σ0(4)∕α=10). Initial nominal stress: (1−ν)σ̂0∕α; final nominal stress: (1−ν)σ(tf+)∕α.

Grahic Jump Location
Figure 5

The nonlinear optimal temperature and stress paths of the standard solid (A=10, B=1, A1=0.05, A2=0.4, λ=1, TI=100°C, TF=−20°C, β=0.1, (1−ν)σ0∕α=10)

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