Ultrasonic Field Inspection of a Historic Cast Iron Portal Strut

摘要

This paper describes the ultrasonic field testing of a Cast Iron Portal Strut for the Harpers Ferry National Historical Park. The objective of this testing was to determine the structural integrity of this historic piece for safe exhibition in the museum. The testing was conducted using longitudinal wave at 5 MHz frequency in the through-transmission mode. Time-of-flight measurements and frequency domain analysis (parameters in the Power Spectral Density curve) of the received ultrasonic signals were used to detect the presence of defects such as blow holes that may initiate failure due to the self weight of the cast iron specimen. The testing led to conclusive identification of defective areas. Based on the locations of the defects it was recommended that the cast iron specimen be supported at four locations.