The Effect of Mechanical Prestrain on the Creep Response of Arall ® 4 Laminates

Abstract

The paper addresses the effect of mechanical prestrain on the creep response of Arall 4 laminates at 121°C. Arall 4 is a recently developed hybrid composite belonging to the Arall family of laminates composed of symmetrically laminated alternating layers of aramid/epoxy and aluminum. This particular variant has been developed for applications involving elevated temperatures up to 150°C. It is experimentally demonstrated that the substantial extent of creep at stress levels below the proportional limit observed in Arall 4 laminates at 121°C can be significantly reduced by mechanical prestraining. Mechanical prestraining alters the residual stresses in the aramid/epoxy and aluminum layers of Arall 4 which, in turn, leads to the reduction in creep strain. An analytical model is developed which simulates the prestraining process and the creep response of the hybrid composite. The demonstrated predictive capability of the model provides the analyst/designer/manufacturer with a rational tool for optimizing the creep response of Arall 4 for the given application.

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References

1. Vogelesang, L. B. and J. W. Gunnink. 1986. “ARALL: A Material Challenge for the Next Generation of Aircraft,” Materials and Design, 7(6).

2. Bucci, R. J. , L. N. Mueller , R. W. Schultz and J. L. Prohaska . “Arall Laminates—Results from a Cooperative Test Program,” Proc. Advanced Materials Technology 87: 32nd International SAMPE Symposium and Exhibition, Anaheim, CA. April 1987.

3. Vogelesang, L. B. , D. Chen , G. H. Roebroeks and A. Vlot . “ARALL Laminates: Past, Present and Future,” Proc. ARALL Laminates Users' Conference, Seven Springs, PA, October 26. 1987.

4. Lee, S. and T. R. Kipp.

“Arall Laminates Environmental Durability Test Results,”

Proc. ARALL Laminates Users' Conference. Seven Springs, PA, October 26, 1987.

5. Vogelesang, L. B. , J. W. Gunnink , D. Chen , G. H. Roebroeks and A. Vlot.

“New Developments in ARALL Laminates,”

Proc. ARALL Laminates Technical Review Meeting, Alcoa Laboratories, Alcoa Center, PA, June 29, 1988.

6. Bucci, R. J. , L. N. Mueller , L. B. Vogelesang and J. W. Gunnink.

“ARALL Laminates Properties and Design Update,”

Proc. 33rd International SAMPE Symposium and Exhibition. Anaheim, CA, March 7-10, 1988.

7. Pindera, M-J. , T. O. Williams and Y. Macheret. 1989. “Time-Dependent Response of Aramid-Epoxy-Aluminum Sheet, ARALL, Laminates,” Polymer Composites, 10(5):328-336.

8. Pindera, M-J. , T. O. Williams and Y. Macheret.

“Creep Optimization of ARALL-4 Laminates,”

Proc. Seventh International Conference on Composite Materials, ICCM-7, Guangzhou, China, November 22-24, 1989.

9. Williams, T. O. and M-J. Pindera. 1989. “Optimization of the Creep Response of ARALL-4 Laminates through Prestraining,” AM-89-06 Report, School of Engineering and Applied Science, Applied Mechanics Program, University of Virginia, Charlottesville. VA.

10.

10. Heckel, W. R. , R. J. Zaehring and H. P. Cheskis. 1972. “Optimization of the Range of Elastic Behavior of Unidirectional Composites by Prestraining,” Metallurgical Transactions, 3:2507–2513.

11.

11. Jones, R. M. 1975. Mechanics of Composite Materials. New York: McGraw-Hill Book Company.

12.

12. Carey, J. J. and C T. Herakovich. 1989. “Notch Sensitivity of Arall Laminates and Aluminum Alloys,” AM-89-08 Report, School of Engineering and Applied Science, Applied Mechanics Program, University of Virginia, Charlottesville, VA.

13.

13. Hidde, J. S. and C. T. Herakovich. 1990. “Notch Sensitivity of Arall Laminates,” AM-90-01 Report, School of Engineering and Applied Science, Applied Mechanics Program, University of Virginia, Charlottesville, VA.

14.

14. Bodner, S. R. and Y. Partom. 1975. “Constitutive Equations for Elastic-Vis***coplastic Strain Hardening Material,” Journal of Applied Mechanics, 42:385.