OCT-Einschweißtiefenüberwachung bei Unterdruck/OCT-based weld penetration monitoring at reduced ambient pressure – Influence of reduced ambient pressure on the OCT signal quality in laser deep penetration welding

2021 ◽  
Vol 111 (11-12) ◽  
pp. 863-868
Author(s):  
Thorsten Mattulat ◽  
Ronald Pordzik ◽  
Peer Woizeschke
Keyword(s):  
Penetration Depth ◽  
Ambient Pressure ◽  
Laser Beam Welding ◽  
In Situ Monitoring ◽  
Deep Penetration ◽  
Weld Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Non Destructive

Die optische Kohärenztomographie (OCT) erlaubt die zerstörungsfreie In-situ-Überwachung der Einschweißtiefe beim Laserstrahlschweißen. Für dieses Verfahren wird hier der Einfluss von verringerten Umgebungsdrücken auf die Messqualität untersucht. Es wird gezeigt, dass sich bei niedrigerem Umgebungsdruck deutlich größere Signalanteile aus dem Bereich des Bodens der Dampfkapillare zurückerhalten lassen. Auf diese Weise steigen die effektive Messfrequenz und die Erkennbarkeit von Änderungen der Einschweißtiefe.   Optical coherence tomography (OCT) enables non-destructive in-situ monitoring of the weld penetration depth during laser beam welding. For this technology, the influence of reduced ambient pressures on the measurement quality is investigated. It is shown that significantly larger signal components are obtained from the bottom of the vapor capillary at lower ambient pressure increasing the applicable measurement frequency and the detectability of changes in the weld penetration depth.

scholarly journals In situ monitoring of the influence of water on DNA radiation damage by near-ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marc Benjamin Hahn ◽  
Paul M. Dietrich ◽  
Jörg Radnik
Keyword(s):  
Dna Damage ◽  
Radiation Damage ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
In Situ Monitoring ◽  
Strong Increase ◽  
Oh Radicals ◽  
Strand Breaks ◽  
X Ray

AbstractIonizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

Simulation of Three-Dimensional Transient Behavior of Molten Pool in Laser Deep Penetration Welding

2016 ◽  
Vol 43 (11) ◽  
pp. 1102004
Author(s):  
夏胜全 Xia Shengquan ◽  
何建军 He Jianjun ◽  
王 巍 Wang Wei ◽  
吕学超 Lü Xuechao ◽  
张彤燕 Zhang Tongyan
Keyword(s):  
Molten Pool ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Deep Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding

Numerical Simulation of Temperature Field during Laser Deep Penetration Welding

2011 ◽  
Vol 675-677 ◽  
pp. 865-867
Author(s):  
Ren Ping Wang ◽  
Y.P. Lei
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Computational Analysis ◽  
Energy Equation ◽  
304 Stainless Steel ◽  
Deep Penetration ◽  
Governing Equations ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Laser Keyhole Welding

A computational analysis is achieved during laser deep penetration welding. Multiple reflection and absorption are implemented simultaneously with the ray tracing technique in the keyhole. With all the governing equations including continuity, momentum and energy equation, the VOF method is adopted to trace the free surface of the molten pool. Temperature field is achieved by numerical simulation. The laser keyhole welding experiments on 304 stainless steel sheet showed that the computational results agree well with experimental results.

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