Pii: S0963-8695(99)00044-4
نویسندگان
چکیده
Pulsed infrared laser irradiation was used to positively identify small fatigue cracks on the surface of fatigue damaged Ti–6Al–4V specimens. The resulting transient thermoelastic deformation perceptibly changes the opening of partially closed surface cracks without affecting other scatterers, such as surface grooves, corrosion pits, coarse grains, etc. that might hide the fatigue crack from ultrasonic detection. We found that this method, which was previously shown to be very effective in 2024 aluminum alloy, must be modified in order to successfully adapt it to Ti–6Al–4V titanium alloy, where significant thermo-optical modulation was found even from straight corners or open notches. This spurious modulation is caused by direct thermal modulation of the sound velocity in the intact material rather than thermal stresses via crack closure. Different methods have been developed to distinguish direct thermal modulation from crack-closure modulation due to thermoelastic stresses. It was found that the modified thermo-optical modulation method can increase the detectability of hidden fatigue cracks in Ti–6Al–4V specimens by approximately one order of magnitude. q 2000 Elsevier Science Ltd. All rights reserved.
منابع مشابه
Pii: S0963-8687(00)00044-5
This paper is concerned with the cognitive infrastructure underpinning the socially situated process of knowledge management in dynamic contexts. It describes the cognitive congruence framework (Fourth International Conference on Competence Based Management (1998); Knowledge Management and Organizational Competence, Oxford University Press (2001)) and shows how it can be used as a sensemaking d...
متن کاملThe relative success of alternative approaches to strategic information systems planning: an empirical analysis
متن کامل
Pii: S0963-8687(99)00020-7
Information technology (IT) organizations are facing important challenges. They must respond to new technologies and business applications and at the same time provide quality services that satisfy the present needs of their client organizations. The Chief information officer (CIO) of a Danish financial institution experienced increasing problems with internal recruitment of managers with suffi...
متن کاملInternational NGOs: networking, information flows and learning
.................................................................................................................................... 1 A. INGO DEVELOPMENT AND CONTEXT................................................................................ 2 B. ADVOCACY, ACCOUNTABILITY AND LEARNING: NETWORKING AND INFORMATION STRATEGIES........................................................................
متن کاملIT spending in the midst of the Asian economic downturn: a Singapore perspective
The Asian economic downturn has severely affected the revenue and profitability of companies operating in Asia. This has in turn caused a significant number of companies to reduce their spending on IT, particularly in the countries that have been most affected by the downturn. While IT spending is an immediate and visible effect of the downturn, less visible changes in managerial attitudes towa...
متن کامل