Viscoelastic Damping and Wave Cutoff of Titanium Alloy and Lattices

Abstract

3D printed titanium alloy Ti5553 solid and octet truss lattice specimens were studied via resonant ultrasound spectroscopy, free decay of vibration and quasi-static methods to determine viscoelastic damping. Damping in solid alloy and a lattice was between 10−4 and 10−3. Much of the damping at high sonic frequency is attributed to stress induced heat flow between heterogeneities due to 3D printing. Pulsed wave ultrasound experiments disclosed reverberation in the cell structure of the lattice. Continuous wave ultrasound experiments showed that the transmissibility in the lattice rolls off beginning at about 50 kHz and becomes negligible above 110 kHz. By contrast, the polymer PMMA, though it is viscoelastic, readily transmits waves up to 1 MHz. The cut off frequency in the lattice is associated with the structure size, not intrinsic damping in the alloy. The octet truss lattice, in addition to providing good mechanical performance, is also an ultrasonic metamaterial. This article is protected by copyright. All rights reserved.