This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Ifju, P. G. Articles by Liu, S.-C. Search for Related Content Social Bookmarking                         What's this?

A Novel Method to Measure Residual Stresses in Laminated Composites

Dept. of Aero. Eng. Mech. & Eng. Sci., University of Florida, 231 Aerospace Bldg., P.O. Box 116250, Gainesville, FL 32611-6250

Brian C. Kilday

Dept. of Aero. Eng. Mech. & Eng. Sci., University of Florida, 231 Aerospace Bldg., P.O. Box 116250, Gainesville, FL 32611-6250

Xiaokai Niu

Dept. of Aero. Eng. Mech. & Eng. Sci., University of Florida, 231 Aerospace Bldg., P.O. Box 116250, Gainesville, FL 32611-6250

Shao-Chun Liu

Dept. of Aero. Eng. Mech. & Eng. Sci., University of Florida, 231 Aerospace Bldg., P.O. Box 116250, Gainesville, FL 32611-6250

A non-destructive method, called the Cure Referencing Method (CRM), was developed to measure the residual stresses in laminated composites. The method incorporates the use of moiré interferometry (a laser based optical method) and replication of diffraction gratings on the surface of laminates in the autoclave during cure. This allows the strains due to resin shrinkage and thermal expansion to be referenced back to the stress free state. For thermoset matrix composites, the stress free state exists just prior to matrix solidification. To determine the residual stress in multidirectional laminates, the strain difference from cure temperature to room temperature was first measured. Then, by doing the same for a unidirectional panel, that was cured simultaneously with the multidirectional laminate, the free thermal expansion of the unidirectional lamina could be defined for the multidirectional case. Using laminate theory, the residual stresses in each ply of the multidirectional laminate were calculated accordingly. The method was evaluated by measuring the residual stresses in balanced symmetric cross-ply, unbalanced symmetric cross-ply and symmetric angle-ply AS4/3501-6 graphite/epoxy laminates. To determine the repeatability of the method, five separate autoclave runs were performed, each with the three multidirectional panels, and the unidirectional panel.

Journal of Composite Materials, Vol. 33, No. 16, 1511-1524 (1999)
DOI: 10.1177/002199839903301603


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				M. B. Prime and M. R. Hill Measurement of Fiber-scale Residual Stress Variation in a Metal-matrix Composite Journal of Composite Materials, December 1, 2004; 38(23): 2079 - 2095. [Abstract] [PDF]

				H. Aykul Residual Stress Analysis of Clamped Supported Thermoplastic Matrix Composite Laminated Plates Under Transverse Loading Journal of Reinforced Plastics and Composites, November 1, 2003; 22(17): 1589 - 1606. [Abstract] [PDF]

				H. Aykul, C. Atasi, and H. Akbulut Elastic-Plastic Stress Analysis and Plastic Zone Propagation in Fibre-Reinforced Thermoplastic Laminates Using Finite Element Method Journal of Reinforced Plastics and Composites, September 1, 2001; 20(14-15): 1301 - 1325. [Abstract] [PDF]