2D-5 Combining X-Rays and Ultrasound to Determine Micro-Elasticity

We continue our quest to determine localized micro- elasticity by combining a standing ultrasonic wave pattern and SAXS X-ray diffraction (CuK
_alpha
1.54 Aring) to map the local elastic modulus. This was done in 20times20times1.5 mm
³
dry Scots pine (Pinus Sylvestris L) soft wood and high-density polyethene (HDPE), acting as homogenized wood phantom samples. An Atmel Atmega 8515 (8 bit, 16 MHz) microprocessor launches and upholds a resonant lambda/2 wave pattern in the radial wood direction using a 100 Hz feedback loop. By varying the transmitted ultrasonic power, it is possible to alter the local stress within the volume probed by the 1 mm
²
X-ray beam. The local strain in unit crystals is determined from changes in the width and position of the X-ray diffraction peaks. The results indicate that the method is applicable for localized quantitative elasticity mapping.