ASTM-E2075/E2075M:15(R2020) pdf free download – Standard Practice for Verifying the Consistency of AE-Sensor Response Using an Acrylic Rod.
5.1 Ensure that the acrylic rod, sensors and couplant have been allowed to stabilize to the ambient temperature of the examination environment.
5.2 Place the prepared acrylic rod horizontally on a suitable hard, flat surface, such as a benchtop. with the reference mark(s) facing vertically up (12 o’clock). The rod may be secured with tape or other means no closer than 30.5 cm (12 in.] from the reference mark.
5.3 Prepare and power-up the AE measurement system including preamplifier (if used) and connecting cables: allow warm up time as necessary. Verify the system’s performance. Verification may be accomplished on the rod using a reference sensor that is dedicated to this purpose and not exposed to the hazards of field use: or, it may be accomplished by electronic procedures such as those described in Practice E750 or Guide 1i2374.
5.4 Mount the sensor to he tested Ofl the flat end of the rod using the prescribed couplant and normal good application techniques (refer to Guide E50). Wipe off old couplant before mounting. Mount the sensor in the six o’clock position so that it is resting on the same surface supporting the acrylic rod. This will prevent slipping of the sensor during sensor verification. If the sensor is a side connector type, have the connector pointing in the 3 o’clock direction as shown in Fig. I.
5.5 Using the pencil lead source, break lead with the end of the lead in the center of the reference mark, within 0.5 mm [0.020 in.1 with a lead extension of 2.5 ± 0.5 mm [0. 1 ± 0.02 in.]. A Nielsen shoe may he used to obtain a consistent 30° angle between the lead and the surface. Hold the pencil pointing towards the sensor hut with its axis approximately 22° (a quarter of a right angle) off from the axis of the rod, so that the lead flies off to one side and does not hit the sensor. Fingers may be rested Ofl the rod on the side away from the sensor to steady the pencil, but there must be no finger contact or other materials in contact with the rod between pencil and sensor, except for the hard surface on which the acrylic rod is resting. As a general guide. use the 10.2 cm [4 in.] reference mark when breaking 0.3 mm 10.012 in.I pencil lead and the 30.5 cm 112.0 in.1 reference mark when using 0.5 mm 10.02 in.1 pencil lead. If using the 10.2 cm [4.0 in.] reference mark and the sensor amplitude response is 90 dB or greater, move to the 30.5 cm 112 in.j reference mark instead to avoid possible saturation effects, which might compromise the test results.
5.6 Make three consistent lead breaks for each sensor, recording amplitude fCSOflSCS on a sensor performance vciification form, similar to that shown in Appendix Xl. As a general rule, determine the average sensor amplitude response and proceed to the next sensor.
5.7 Acceptance criteria, which should be assigned prior to conducting this practice by the testing organization, should he documented, for example as shown in Appendix X I, and applied to the sensor data recorded. Sensors failing the criteria should not he used during the examination, and should be returned for a more comprehensive analysis. repaired or discarded.
6. Precision and Bias
6.1 Temperature variations are known to affect the acoustic absorption properties of the acrylic rod.