A Comparison of Measured and Calculated Thermal Stresses in a Hybrid Metal Matrix Composite Spar Cap Element

Jenkins, Jerald M. and Taylor, Allan H. and Sakata, I. Frank (1985) A Comparison of Measured and Calculated Thermal Stresses in a Hybrid Metal Matrix Composite Spar Cap Element. Technical Report NASA TM-86729, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

A hybrid spar of titanium with an integrally brazed composite, consisting of an aluminum matrix reinforced with boron-carbon-coated fibers, was heated in an oven and the resulting thermal stresses were measured. Uniform heating of the spar in an oven resulted in thermal stresses arising from the effects of dissimilar materials and the anisotropy of the metal matrix composite. Thermal stresses were calculated from a finite element structural model using anisotropic material properties deduced from constituent properties and rules of mixtures. Comparisons of calculated thermal stresses with measured thermal stresses on the spar are presented. It was shown that failure to account for anisotropy in the metal matrix composite elements would result in large errors in correlating measured and calculated thermal stresses. It was concluded that very strong material characterization efforts are required to predict accurate thermal stresses in anisotropic composite structures.

EPrint Type:	NASA Technical Memorandum
Keywords:	Material properties, Metal matrix composite, Thermal stress
Subjects:	(31 - 39) Engineering: (39) Structural Mechanics
ID Code:	575
Deposited On:	30 January 2006
Additional Information:	20 pages.