Method and apparatus for determining material structural integrity

Patent · Tue May 28 04:00:00 EDT 1996

OSTI ID:238066

Pechersky, M

A non-destructive method and apparatus for determining the structural integrity of materials by combining laser vibrometry with damping analysis techniques to determine the damping loss factor of a material are disclosed. The method comprises the steps of vibrating the area being tested over a known frequency range and measuring vibrational force and velocity as a function of time over the known frequency range. Vibrational velocity is preferably measured by a laser vibrometer. Measurement of the vibrational force depends on the vibration method. If an electromagnetic coil is used to vibrate a magnet secured to the area being tested, then the vibrational force is determined by the amount of coil current used in vibrating the magnet. If a reciprocating transducer is used to vibrate a magnet secured to the area being tested, then the vibrational force is determined by a force gauge in the reciprocating transducer. Using known vibrational analysis methods, a plot of the drive point mobility of the material over the preselected frequency range is generated from the vibrational force and velocity measurements. The damping loss factor is derived from a plot of the drive point mobility over the preselected frequency range using the resonance dwell method and compared with a reference damping loss factor for structural integrity evaluation. 3 figs.

• Assignee: Dept. of Energy, Washington, DC (United States)
• Patent Number(s): US 5,520,052/A/
• Application Number: PAN: 8-194,432
• OSTI ID: 238066
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
EQUIPMENT
MATERIALS
MEASURING METHODS
MECHANICAL VIBRATIONS
NONDESTRUCTIVE TESTING
RELIABILITY
TIME DEPENDENCE