The AE examination method detects structurally significant flaws in FRP structures via test loading. The damage mechanisms that are detected in FRP include resin cracking, fiber debonding, fiber pullout, fiber breakage, delamination, and secondary bond failure.

Flaws in unstressed areas will not generate detectable AE.

Flaws located with AE may be examined by other methods.

1.1 This test method provides guidelines for acoustic emission (AE) examinations of fiberglass reinforced plastic (FRP) fan blades of the type used in industrial cooling towers and heat exchangers.

1.2 This test method uses simulated service loading to determine structural integrity.

1.3 This test method will detect sources of acoustic emission in areas of sensor coverage that are stressed during the course of the examination.

1.4 This test method applies to examinations of new and in-service fan blades.

1.5 This test method is limited to fan blades of FRP construction, with length (hub centerline to tip) of less than 10 ft, and with fiberglass content greater than 15 % by weight.

1.6 AE measurements are used to detect emission sources. Other nondestructive examination (NDE) methods may be used to evaluate the significance of AE sources. Procedures for other NDE methods are beyond the scope of this test method.

1.7 Values stated in inch-pound units are to be regarded as the standard. SI units given in parentheses are provided for information only.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.