Hot Press Joining Optimization of Polyethylene to Aluminium Alloy AA6061-T6 Lap Joint Using Design of Experiments

Abstract

Abstract. The hot press method is used to join a poly-ethylene plate of thickness 4 mm with an aluminium alloy AA6061-T6 plate of thickness 1.5 mm. A preanodizing process is crucial for the success of such joint. The anodizing was performed under a current density of 200 A/m 2 , temperature 24°C, sulphuric acid 5 wt. % and for a 60 minutes. Three period parameters were considered in the hot pressing process; temperature: 115 and 135°C, pressure: 2, 6, and 10 bar and pressing time: 1, 2, 3, 4 and 5 minutes. The joint specimens are tested by shear tensile test, microstructure, energy dispersive spectrometry, differential scanning calorimetric and thermo grvanometric analysis. The results of shear tensile were analyzed using design of experiments. Minimum and maximum shear tensile force were found at temperature T = 115°C where; F min = 680N and F max = 2800N. From Pareto chart, the applied pressure had the most significant effect on the shear tensile force of the joint specimens compared to temperature and joining time. The main effect plot showed that optimum value of shear tensile force was obtained at joining conditions of T = 135°C, P = 6 bar and t = 3 minutes. The tested specimens exhibited an interfacial shear failure, extension and necking in the region of polymer with a ductile fracture. The mechanical interlocking of polymer element in the anodizing surface is approximately 15 µm. The melting point and glass transmission temperature of PE are decreased after the hot press.

New Method to Distinguish Adhesion and Cohesion Stresses in Metal/Polymer Composites

“…The pure HDPE tensile strength presents a higher value than any other result found in previous studies for Al/HDPE composites [18][19][20] . Those results suggest that even in a predominantly cohesive failure, as occurred in sample 3, the maximum stress applied to separate PE from aluminum is still smaller than the resistance to rupture the organic area of the polymer alone.…”

“…The multiple image analyses and failure areas met the tensile strength results of Table 2, once the different samples with different mechanical results and percentage of failures converge to identical contributions to cohesive and adhesive failures. Besides, for the result obtained using the new method, some PE and aluminum composite references and tests showed a great variability of results in the adhesion tests performed according to previous methods 18,19 . The numbers obtained depend on several factors, but it is important to correlate the failure areas ( Figure 6) with maximum loads to define where the weak point in the structural composite is.…”

“…Table 1 maximum stress values were used in the genetic algorithm evolution programming criteria. Considering the study by Hussein et al in composites made of PE and aluminum sheets using hot pressing, the maximum shear force was up to 2,800.00 N, where a ductile fracture was observed, predominant in the polymer 18 . The maximum tensile strength value seen on Table 1, which is 2,242.56 N, also presented the maximum stress with the larger cohesive failure area.…”

“…It also determined and delimited the interface areas -aluminum adhesion and cohesion (bulk) of HDPE. That is due to the aluminum rupture stress being much higher than that of HDPE and also to adhesion in the interface 18 . were organized according to the type of failure.…”

In-Plane Shear Strength of Single-Lap Co-Cured Joints of Self-Reinforced Polyethylene Composites

“…Adhesive bonding may be performed by secondary bonding, involving the usage of adhesives between the parts [ 49 , 50 ], or by co-curing, where the matrix of the composite is cured in contact with the desired adherend and, hence, cure and bonding happen simultaneously. For thermosets, the co-cure has to be performed during the cure of the second adherend, be it another composite [ 45 , 51 , 52 , 53 , 54 , 55 ] or a metal [ 56 , 57 , 58 , 59 ]. Kim et al [ 51 ] evidenced the superior failure strength of co-cured joints without adhesive for carbon/epoxy laminates compared to those with adhesive or secondary bonding.…”