This paper describes some observations taken from a series of tests in which a polyurethane rubber has been used as a soil substitute. The specification of the polyurethane is described as well as the techniques which were developed to mould it into a variety of shapes with consistent properties. The tip deflection of bender elements under excitation was characterised using a laser velocimeter both in air and also when protruding into a specimen. These results show that results taken from “self monitoring benders” are erroneous. Very thin synthetic samples allow us to establish the relationship between transmitter bender and receiver bender which are touching. Using the transfer function from this system it is possible to establish how to isolate the non-soil parts of subsequent transmissions. Significant crosstalk was experienced. This is characterised and the effect of artificially removing crosstalk on frequency domain measurements is discussed.
This paper describes some obse …
AUTORI: Greening P., Rio J., Arroyo M. RIG ANNO: 2006 NUMERO: 2 Numero di pagina: 48