Fatigue crack identification using near-tip singular temperature field measured by lock-in thermography

Takahide Sakagami; Shiro Kubo; Yasuhiro Teshima

doi:10.1117/12.381548

30 March 2000 Fatigue crack identification using near-tip singular temperature field measured by lock-in thermography

Takahide Sakagami, Shiro Kubo, Yasuhiro Teshima

Proceedings Volume 4020, Thermosense XXII; (2000) https://doi.org/10.1117/12.381548
Event: AeroSense 2000, 2000, Orlando, FL, United States

Abstract

Applicability of the newly developed two different lock-in thermographic NDT techniques is discussed. One of the proposed techniques is based on the lock-in measurement of the singular temperature field, which appears near crack tips under the application of periodically modulated electric current. Experimental study is made on the resolution and the applicability in the detection of through-thickness cracks embedded in steel and aluminum alloy plate samples. Modulated electric current is applied to the cracked sample by an induction coil. Temperature amplitude and phase delay thermal images synchronized to the reference current modulation signal are taken by the lock-in thermography. Significant temperature rise related to singular temperature field is observed at the crack tips in the lock-in thermal images. It is found that the cracks are sensitively detected by the lock-in thermography technique combined with near-tip singular temperature field measurement. The other technique is based on the lock-in measurement of the surface temperature under the application of periodical xenon light heating. Experimental study is made on the applicability to the detection of flat objective body. In-phase and out-of-phase temperature amplitude images are taken by the lock-in thermography, synchronized to the reference signal of the electric shutter operation. It is found that the location and size of the defects can be identified by the localized contrast change in the out-of- phase images. Further, the depths of the defects can be identified from the heat penetration depth, which is changed by the frequency of thermal wave stimulation.

Citation Download Citation

Takahide Sakagami, Shiro Kubo, and Yasuhiro Teshima "Fatigue crack identification using near-tip singular temperature field measured by lock-in thermography", Proc. SPIE 4020, Thermosense XXII, (30 March 2000); https://doi.org/10.1117/12.381548

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available