Underwater Robotic Welding of Lap Joints with Sandwiched Reactive Multilayers: Thermal, Mechanical and Material Analysis
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.310
Underwater Robotic Welding of Lap Joints with Sandwiched Reactive Multilayers: Thermal, Mechanical and Material Analysis Aseel Hussein1, Ayesha Alkhoori1, Abdelaziz Al Zaabi1, Cesare Stefanini1, Federico Renda1, Syed Jaffar1, Ibrahim Emre Gunduz2, Kyriaki Polychronopoulou1, Claus Georg Rebholz3 and Charalabos Constantinos Doumanidis1 1
Department of Mechanical Engineering, Khalifa University, P.O. 127788, Abu Dhabi, U.A.E.
2
Department of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, U.S.A.
3
Department of Mechanical-Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
ABSTRACT
Underwater welding using reactive materials pre-deposited at the junction surfaces as a selfcontained, in-situ ignitable heat source mitigates external power and gas supply requirements. Consequently, lending itself to robotic implementation eliminating the cost along with health and safety hazards of human welder-divers. This project reports on lap joining of aluminum sheets with sandwiched commercial reactive Ni-Al multilayers that are perforated to allow for melt fusion under compression upon ignition, in saline and deionized water as well as air for comparison. Finite-element thermal simulations are employed to study the resulting welding temperature field and melt conditions. Infrared pyrometry and thermocouple measurements during welding were used to validate the computational simulations. The lap joints are subjected to standard shear testing, and comparable compliance, strength and toughness values of the welds are assessed for underwater and dry joints. Scanning electron (SEM) of the weld sections reveal rapidly melting and solidifying microstructures of the parent metal, with minimal melt flow and perfusion of nickel aluminide aggregates from the reacted multilayers, and no signs of cavitation.
INTRODUCTION Construction and maintenance of underwater infrastructure such as lying of underwater pipelines and cables, building artificial archipelagos and seaside residential complexes essentially needs the services of professional divers. These tasks face numerous occupational hazards due to the harsh ambient environment. Exposing humans to such conditions might affect the diver’s physical and functional abilities. The pressure of the surrounding environment exerted on the diver at deep depths, causes the nominal volume of the diver’s lungs to decrease resulting in carbon dioxide retention which might eventually cause death [1]. In addition, there is a risk of being toxified by the diving gas
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used for breathing in deep underwater. Furthermore, divers are allowed to spend a limited time underwater since there is a risk of getting electrocuted if a certain duration of time is exceede
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