Combined lock-in thermography and heat flow measurements for analysing heat dissipation during fatigue crack propagation
Journal Title: Frattura ed Integrità Strutturale - Year 2015, Vol 9, Issue 34
Abstract
During fatigue crack propagation experiments with constant force as well as constant stress intensity lock in thermography and heat flow measurements with a new developed peltier sensor have been performed. With lock in thermography space resolved measurements are possible and the evaluation allows to distinguish between elastic and dissipated energies. The specimens have to be coated with black paint to enhance the emissivity. The thickness of the coating influences the results and therefore quantitative measurements are problematic. The heat flow measurements are easy to perform and provide quantitative results but only integral in an area given by the used peltier element. To get comparable results the values measured with thermography were summarized in an area equivalent to that of the peltier element. The experiments with constant force show a good agreement between the thermography and the heat flow measurements. In case of the experiments with a constant stress intensity some differences become visible. Whereas the thermography measurements show a linear decrease of the signal with rising crack length, the heat flow measurements show a clearly nonlinear dependency. Obviously the measured energies in thermography and peltier based heat flow measurement are not comparable.
Authors and Affiliations
J. Bär, A. Vshivkov, O. Plekhov
Keywords
Related Articles
- EP ID EP138397
- DOI 10.3221/IGF-ESIS.34.51
- Views 58
- Downloads 0
Propagazione di fratture longitudinali in gasdotti caratterizzati da bassa duttilità
Il presente lavoro propone l’analisi di propagazione di una frattura fragile longitudinale di un gasdotto interrato basata sulla valutazione dell’energy release rate. Viene illustrata l’implementazione della sudd...
The study of a defect evolution in iron under fatigue loading in gigacyclic fatigue regime
The work is devoted to the study of the damage accumulation in iron under gigacyclic fatigue (VHCF) regime. The study of the mechanical properties of the samples with different state of life time existing was...
Analisi termica per la valutazione del comportamento a fatica di provini soggetti a successive serie di carichi
Partendo dalla osservazione che provini precedentemente danneggiati hanno un limite di fatica differente (vedi Miner) viene esaminato il comportamento di un acciaio soggetto a serie di carichi affaticanti al fine di veri...
Growth behavior of fatigue cracks in ultrafine grained Cu smooth specimens with a small hole
In order to study the growth mechanism of fatigue cracks in ultrafine grained copper, stresscontrolled fatigue tests of round-bar specimens with a small blind hole as a crack starter were conducted. The hole was...
Multi-scale approach for the analysis of the stress fields at a contact edge in fretting fatigue conditions with a crack analogue approach
This paper describes a novel method to model the stress gradient effect in fretting-fatigue. The analysis of the mechanical fields in the proximity of the contact edges allows to extract nonlocal intensity factors...