A new method for the determination of the coefficient of thermal expansion of solid materials

Abstract

A new experimental method (IIC, Infrared Image Correlation) for quick assessment of the coefficients of thermal expansion of solid materials is presented. The proposed method is based on performing a digital image correlation between thermal images acquired at different temperatures by means of an infrared camera. It allows the coefficient of thermal expansion of both isotropic and anisotropic bulk materials to be determined by measuring simultaneously the fractional increase in length and the actual thermal field over a small region of interest in which a dual-emissivity stochastic speckle pattern has been created. First results reported in this paper prove the effectiveness of the proposed method that can be applied either to carry out reference measurements in laboratory or to evaluate thermal stresses and strains on structural components in-field.

Non-contact measurement of linear thermal expansion coefficients of solid materials by infrared image correlation

“…By comparing the mean CTE values computed along the x and y directions, it can be concluded that brass exhibits, as expected, nearly isotropic thermal behaviour, since the small difference observed between the two values falls well within the measurement uncertainty (see section 4). Similar results were obtained by the authors testing Al alloy samples between 30 • C and 60 • C [16].…”

A Dilatometer for the Carbon Fiber Composite Tubes

“…The mechanical properties of the carbon fiber reinforced polymer structures (CFRP) significantly depend on the orientation of the fibers, the number of layers, layup technology and other factors.The unique feature of CFRP is the anisotropy of thermal expansion determined by the laying pattern of reinforcing fibers, namely the CTE is minimal along the fiber and maximum in the direction perpendicular to the fiber [25]. The increase in the number of reinforcing layers and the optimization of their reinforcement scheme make it possible to minimize thermal deformations of the construction.…”

Coeficiente de dilatación: diseño y construcción de un dilatómetro

“…Esto se debe, en gran medida a su importancia en todas estas áreas del conocimiento, pero también en que es una experiencia relativamente fácil de llevar a cabo. Así podemos encontrar una amplia gama de trabajos dedicados a la demostración de la ley de dilatación térmica lineal desde los métodos más elementales y algunos demostrativos como ser el de la pelota y el aro o utilizando dos reglas plásticas idénticas pero sumergiendo una en nitrógeno líquido [1-3] hasta los más elaborados y precisos de superposición de imágenes infrarrojas, interferometría o simplemente usando un láser para amplificar la dilatación producida [4][5][6][7][8]. Dos review [9 y 10], resumen adecuadamente el estado del arte en los métodos y tecnología disponibles actualmente.…”