Material properties of three syntactic foams

Material properties have been determined for three product samples of syntactic foam manufactured by CMT Materials, Inc., namely HYTAC-W, HYTAC-WF, and HYTAC-XTL. Cuboids of approximate dimensions 60×60×30 mm were fabricated by machining. The material density was determined from measurements of the sample mass and dimensions. The longitudinal- and transverse-wave sound speeds were determined as the quotients of sample thickness and respective time-of-flight measurement of an ultrasonic pulse transmitted through the sample. The possible anisotropy of each sample was investigated by the sound speed measurements. This was found to be weak, less than 0.1% for the W and WF types, but as much as 2% for the XTL type. Mean values for the respective properties of the W control-sample were 716 kg/m
³
, 2110 m/s, and 1121 m/s; for the WF control-sample: 867 kg/m
³
, 2708 m/s, and 1389 m/s; for the XTL control-sample: 712 kg/m
³
, 2672 m/s, and 1361 m/s. The effect of soaking on the properties was also investigated. Measurement methods are described, measurement statistics are given, and results are also expressed in terms of the elastic moduli. Measurements of acoustic backscattering spectra from spheres fabricated from the same product samples were performed, but will be described in a future paper.