Improvement in metals joining with the application of modified adhesive that is low in weight, resistant to crack propagation while absorbing impact, can withstand a wide range of temperature and has a higher hardness than welded joints.
In A Bit More Details
This is to investigate the joint efficiency between the adhesive bonding method and welding methods. This is to prove the joining method of adhesive bonding is applicable in using for heavy industry while the designer can benefit its light weight property.
Specimen Preparation: Arc Welding Method
In the experiment, we using different types of aluminium joining methods available in the market such as Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) which are for strong assembly structures. (Note: the welded joints were applied with different levels of welding current input).
Specimen Preparation: Adhesive Bonding Method
Adhesive bonding "Specimen A", the joint is bonded using the mixture. The mixture is a combination of Cyanoacrylate and Sodium bicarbonate. And another adhesive bonding "Specimen B" is with the application of Epoxy fix for steel that is readily available in the market.
Experiment Set-Up:
These sample specimens with different joining methods have experimented with electromechanical tensile testing machine, Vickers hardness tester, “Charpy” impact tester setup and Scanning Electron Microscopic instrument for microstructure observation.
Experiment Findings: Arc Welding Method
From the investigation observation, GMAW joints are higher in strength than GTAW joints. GMAW joint can have a higher strength than GTAW joint since GMAW have a rapid automated heating and cooling effect (This is heat treating, which will change a metallic filler property to harder and increase its tensile strength). We found that using aluminium filler will cause a significant increase in weight to the overall assembly of components. Besides that, these welding technologies produce heat to the base metal which will degrade their properties such as lower tensile shear strength. Hence, it is common for crack formation to initiate at the welded joint.
Experiment Findings: Adhesive Bonding Method
We found that an over-lapping joint Specimen A using adhesive is harder than both welded parallel joint specimens. (Note: overlapping and parallel joint specimens are in the same thickness). For the parallel joint experiments, the adhesive parallel bonded aluminium results in lower fracture energy (energy required to open unit area of crack surface) compared to the welded parallel joint aluminium. This show that the adhesive parallel bonded specimen is tough enough to give a small resistance from the external impact more or at least the same as the welded joint specimens. This show, adhesives are flexible to impact but very quick to reform back to its shape in characteristic, as the Specimen A don't have a break point as shown in the monitor result.
Therefore, this experiment shows in the future, modification can be made to improve the downside of using adhesive such as it high elasticity characteristic, and make it applicable as new joining technology to benefit its lightweight property and high withstand in a wide range of temperatures.
Author: Muhammad Hani Danial Bin Khairul Imran, University of Nottingham 2018
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