Addendum to 'Characterising the Strain and Temperature Fields in a Surrogate Bone Material Subject to Power Ultrasonic Excitation'

• Published in: Strain 2016-06, Vol.52 (3), p.186-190
• Main Author: Pierron, F.
• Format: Article
• Language: English
• Subjects: Bones; digital image correlation; Excitation; high strain rate; high-speed imaging; Polyurethane foam; Readers; Stiffness; Strain; Strain rate; Temperature; ultrasonic testing; virtual fields method
• ISSN: 0039-2103; 1475-1305
• DOI: 10.1111/str.12180

Recently, a very interesting article was published in Strain where a rigid polyurethane foam specimen was submitted to longitudinal vibrational excitation in the ultrasonic range. The authors showed that it was possible to measure time‐resolved strain response maps by combining digital image correlation and ultra‐high‐speed imaging. The objective of this discussion is to propose further analysis of the data published in that article, showing that it is possible to extract meaningful values for Young's modulus by using the acceleration field in the specimen as a load cell. The aim here is not to provide a complete solution to this problem but to alert the readers on the possibilities offered by this kind of test. This method is an interesting alternative where the energy is input repeatedly instead of in one go as in impact‐based tests. Full‐field vibration measurements have already been used in the past to identify stiffnesses but only in bending and at much lower strain rates. This article shows that the method can be extended to cover a much wider strain rate range. Finally, only global stiffness values were identified then, whereas here, maps of stiffnesses can be derived.