A Study on the Effects of Clearance and Interference Fits in a Pin-Loaded Cross-Ply FGRP Laminate

Abstract

The elastic behavior of a cross-ply fiber glass-reinforced epoxy laminate loaded in tension through a pin fitted with clearance and interference is examined. A nonlinear contact analysis using the Finite Element Method and an experimental study by Speckle Interferometry are performed, showing fairly good correlation. An interesting comparison is performed between FEM results and Hertzian contact theory. Major conclusions are: (I) clearance causes high compressive stress in the bearing area, and does not influence the peak tensile stress; (2) interference has beneficial effects on the joint, as (a) it lowers the peak circumferential stress, and (b) it decreases the change of stress due to the application of the load. This last conclusion suggests that interference can improve the fatigue life of the joint.

Keywords

composite materials mechanical fastening pin-loaded holes clearance fit interference fit nonlinear finite element analysis phase-stepped Digital Speckle Pattern Interferometry

Get full access to this article

View all access options for this article.

References

1. Rowlands, R. E. , Rahman, M. U. , Wilkinson, T. L. and Chaing, Y. I. 1982. "Single- and multiple-bolted joints in orthotropic materials." Composites, 13,3:273-279.

2. Pradhan, B. and Ray, K. 1984. "Stresses around partial contact pin-loaded holes in FRP composite plates." J. of Reinforced Plastics and Composites, 3,1:69-84.

3. Eriksson, L. I. 1986. "Contact stresses in bolted joints of composite laminates." Composite Structures, 6,1-3:57-75.

4. Hyer, M. W. , Klang, E. C. and Cooper, D. E. 1987. "The effects of pin elasticity, clearance and friction on the stresses in a pin-loaded orthotropic plate." J. of Composite Materials, 21,3:190-206.

5. Sendeckyj, G. P. and Richardson, M. D. 1974. "Fatigue behavior of a graphite-epoxy laminate loaded through an interference-fit pin." Proceedings of 2nd Air Force Conference on Fibrous Composites in Flight Vehicle Design, Tech. Rep. AFFDL-TR-74-103, Air Force Flight Dynamics Lab, WPAFB, Ohio.

6. Ramamurthy, T. S. 1989. "Recent studies on the behavior of interference fit pins in composite plates." Composite Structures, 13,2:81-99.

7. Herrera Franco, P. J. 1985. A Study of Mechanically Fastened Composite Using High Sensitivity Interferometric Moiré Technique. Ph.D. Dissertation, Michigan State University, East Lansing, MI 48824.

8. Grant, R. J. , Smart, J. and Stanley, P. 1994. "A parametric study of the elastic stress distribution in pin-loaded lugs." J. of Strain Analysis, 29,4:299-307.

9. Jones, R. and Wykes, C. 1983. Holographic and Speckle Interferometry, 1st Edition: Cambridge University Press.

10.

10. Creath, K. 1984. "Digital Speckle Pattern Interferometry (DSPI) using a 100 × 100 imaging array." SPIE, 501:292-298.

11.

11. Creath, K. 1985. "Phase-shifting speckle interferometry." Applied Optics, 24, 18:3053-3058.

12.

12. Vrooman, H. A. and Maas, A. M. 1991. "Image processing algorithms for the analysis of phase-shifted speckle interference patterns." Applied Optics, 30,13:1636-1641.

13.

13. Jia, Z. and Shah, S. P. 1994. "Two-dimensional electronic-speckle-pattern interferometry and concrete-fracture processes." Experimental Mechanics, 34,3:262-270.

14.

14. Lekhnitskii, S. G. , Tsai, S. W. and Cheron, T. 1968. Anisotropic Plates. New York, London and Paris: Gordon and Breach Science Publishers.

15.

15. Cloud, G. L. and Lanza di Scalea, F. 1996. "High-precision strain measurement by phase-stepped digital speckle pattern interferometry." Proc. of XXV AIAS National Conference and International Conference on Material Engineering, Gallipoli, Italy:3 11-318.

16.

16. Cloud, G. L. and Lanza di Scalea, F. 1996. "Determination of stress around a single pin-loaded hole in fiber-reinforced plastic using phase-stepped digital speckle pattern interferometry." Proc. of XXV AIAS National Conference and International Conference on Material Engineering, Gallipoli, Italy:319-326.

17.

17. Matthews, F. L. 1987. Joining fiber-reinforced plastics. London and New York: Elsevier Applied Science.

18.

18. De Jong, T. 1977. ,"Stresses around pin-loaded holes in elastically orthotropic or isotropic plates." J. of Composite Materials, July 1977, 11:313-331.

19.

19. Love, A. E. H. 1920. Theory of elasticity (3rd Edition). Cambridge University Press.

20.

20. Fuller, C. E. and W. A. Johnston . 1919. Applied Mechanics Vol. II—Strength of Materials. New York: John Wiley & Sons, Inc.