Testing of substrate monoliths

Abstract

A method of testing a substrate monolith (1), the substrate monolith (1) comprising: i) a plurality of channels extending longitudinally along a Z-axis of the substrate monolith (1); and ii) an array of walls extending along the Z-axis and forming partitions between adjacent channels; wherein the array of walls comprises first walls (10) orientated parallel to a first-axis of the substrate monolith (1) and second walls (11) orientated parallel to a second-axis of the substrate monolith (1), the first-axis and the second-axis both being orthogonal to the Z-axis; the method comprising the steps of: a) applying an impulse (J) to the substrate monolith (1) with an impact tool (22) to induce mechanical vibrations in the substrate monolith (1); b) sensing the mechanical vibrations of the substrate monolith (1); c) determining a fundamental frequency of the sensed mechanical vibrations; and d) comparing the fundamental frequency of the sensed mechanical vibrations to a fundamental frequency obtained from testing of a second substrate monolith; wherein in step a) an impulse vector (30) of the impulse (J) has a non-zero first-axis component (31) and a non-zero second-axis component (32).

Dependencies are inferred from the claim text.