Influence of Die Profiles and Cracks on Joint Buttons on the Joint Quality and Mechanical Strengths of High Strength Aluminium Alloy Joint

2012 ◽  
Vol 548 ◽  
pp. 398-405 ◽  
Author(s):  
De Zhi Li ◽  
Li Han ◽  
Zong Jin Lu ◽  
Martin Thornton ◽  
Mike Shergold
Keyword(s):  
Aluminium Alloy ◽  
High Strength ◽  
Bottom Layer ◽  
Peel Strength ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Increase Productivity ◽  
Small Cracks ◽  
Joint Quality ◽  
Mechanical Strengths

Currently, self-piercing riveting (SPR) is a major technology used by manufacturers to join aluminium body structures to reduce vehicle weight. Normally, for SPR of one specific stack more than one die, rivet, and velocity combination can be applied. Which parameter combination is chosen is depending on the surrounding joints. In order to increase productivity and reduce the number of robots used, it is preferred to use the same rivet/die combination for as many joints as possible. This means for the same stack, different die may be used. To see the influence of die profiles on joint quality, a DF die, which would generate severe cracks and a DC die, which would generate no cracks or only small cracks, were used to join two stacks with a high strength aluminium alloy, AA6008T61, as the bottom layer. The joint quality was analyzed, and the static and fatigue strengths of these stacks were studied. Results showed that cracks on joint buttons might reduce static and fatigue lap shear strength but had no obvious influence on static and fatigue T peel strength for the joints studied.

Influence of Rivet Tip Geometry on the Joint Quality and Mechanical Strengths of Self-Piercing Riveted Aluminium Joints

2013 ◽  
Vol 765 ◽  
pp. 746-750 ◽  
Author(s):  
De Zhi Li ◽  
Li Han ◽  
Mike Shergold ◽  
Martin Thornton ◽  
Geraint Williams
Keyword(s):  
Automotive Industry ◽  
Fuel Efficiency ◽  
Peel Strength ◽  
Strength Reduction ◽  
Lap Shear Strength ◽  
Lightweight Structures ◽  
Lap Shear ◽  
Riveting Process ◽  
Joint Quality ◽  
Mechanical Strengths

Due to the drive from legislations, fuel efficiency, and CO2 emission, the application of aluminium lightweight structures in automotive industry have been increased significantly. Self piercing riveting (SPR) has been one of the major joining technologies for aluminium structures due to its advantages to some traditional joining technologies. There are some standard parameters that will influence the joint quality and mechanical strengths of an SPR joint. However, even for the same parameters used, sometimes the joint quality and mechanical strengths of SPR joints could still be significantly different, which may cause joint failure or strength reduction. One reason found is the variation of rivet specifications between different batches. In this paper, the influence of rivet tip geometry on the joint quality and mechanical strengths was studied. The results showed that rivets with sharper tips flared more during riveting process, and joints with sharper rivets had higher lap shear strength; however, the influence of rivet geometry on T peel strength could be different for different rivets, and rivet tip geometry did not have an obvious influence on joint fatigue strengths.

scholarly journals Influence of Corrosion of Self-Piercing Riveted High Strength Aluminium Alloy Joints with Button Cracks on the Mechanical Strength

2018 ◽  
Vol 5 ◽  
Author(s):  
Dezhi Li ◽  
Li Han ◽  
Andreas Chrysanthou ◽  
Mike Shergold
Keyword(s):  
Fatigue Strength ◽  
Mechanical Strength ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
High Strength ◽  
Peel Strength ◽  
Lap Shear ◽  
Obvious Change ◽  
Shear Fatigue ◽  
Small Cracks

For high strength aluminium alloys, such as AA6008T61 and AA6111 PFHT, when they are joined as the bottom material by self-piercing riveting (SPR), they tend to crack at the joint buttons. These cracks, especially those penetrated to the rivets, may cause galvanic corrosion problem with the steel rivet. In this paper, the mechanical strength of four stack/die combinations with different joint button cracking severity was studied before and after salt-spray corrosion test. The results showed that corrosion on the severely cracked joints was worse than that on the joints with small cracks and the corrosion on the stack with the same top and bottom material was less than that on the stack with different top and bottom materials. For all joints the static lap shear strength after corrosion was improved, but the static T peel strength after corrosion was slightly reduced or did not have obvious change. The results also showed that after corrosion the lap shear fatigue strength of the specimens with severe cracks did not have obvious change, but the lap shear fatigue strength of the specimens with small cracks slightly reduced.

Evaluating weld properties of conventional and swept friction stir spot welded 6061-T6 aluminium alloy

2019 ◽  
Vol 9 (8) ◽  
pp. 851-860 ◽  
Author(s):  
S. Suresh ◽  
K. Venkatesan ◽  
Elango Natarajan ◽  
S. Rajesh ◽  
Wei Hong Lim
Keyword(s):  
Shear Strength ◽  
Aluminium Alloy ◽  
Rotational Speed ◽  
Shear Fracture ◽  
Shear Loading ◽  
Tool Rotational Speed ◽  
Lap Shear Strength ◽  
Friction Stir ◽  
Lap Shear ◽  
Weld Properties

6061-T6 aluminium alloy is a tempered grade aluminium material that is extensively used, particularly in space and automotive applications. The conventional and swept friction stir spot welding (FSSW) joints are prepared by varying tool rotational speed at four different levels. The mechanical properties, microstructure and mode of failure in both types of FSSW are evaluated and reported. The high plastic deformation and fine grains influenced the increase in hardness of the weld joints based on the Hall-Petch equation. The highest lap shear strength of 5.31 kN is observed in swept FSSW sample prepared at 1400 rpm. Interestingly, 1600 rpm decreased the lap shear strength due to insufficient friction between base metal and tool in the higher tool rotational speed. The minimum microhardness is noticed in heat-affected zone (HAZ) of both cases. Conventional FSSW samples showed shear fracture, nugget pullout fracture and circumferential fracture under lap shear loading, whereas swept FSSW showed only the circumferential fracture.

scholarly journals Prediction of Lap Shear Strength and Impact Peel Strength of Epoxy Adhesive by Machine Learning Approach

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 872
Author(s):  
Haisu Kang ◽  
Ji Hee Lee ◽  
Youngson Choe ◽  
Seung Geol Lee
Keyword(s):  
Machine Learning ◽  
Shear Strength ◽  
Linear Correlation ◽  
Peel Strength ◽  
Epoxy Adhesive ◽  
Data Sets ◽  
Ann Model ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
The Impact

In this study, an artificial neural network (ANN), which is a machine learning (ML) method, is used to predict the adhesion strength of structural epoxy adhesives. The data sets were obtained by testing the lap shear strength at room temperature and the impact peel strength at −40 °C for specimens of various epoxy adhesive formulations. The linear correlation analysis showed that the content of the catalyst, flexibilizer, and the curing agent in the epoxy formulation exhibited the highest correlation with the lap shear strength. Using the analyzed data sets, we constructed an ANN model and optimized it with the selection set and training set divided from the data sets. The obtained root mean square error (RMSE) and R2 values confirmed that each model was a suitable predictive model. The change of the lap shear strength and impact peel strength was predicted according to the change in the content of components shown to have a high linear correlation with the lap shear strength and the impact peel strength. Consequently, the contents of the formulation components that resulted in the optimum adhesive strength of epoxy were obtained by our prediction model.

Heat-Sealing Properties of Compression-Molded Wheat Gluten Films

2007 ◽  
Vol 1 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Sung-Woo Cho ◽  
Henrik Ullsten ◽  
Mikael Gällstedt ◽  
Mikael S. Hedenqvist
Keyword(s):  
Shear Strength ◽  
Wheat Gluten ◽  
Peel Test ◽  
Mold Temperature ◽  
Peel Strength ◽  
Minor Effect ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Heat Sealing ◽  
A Minor

The impulse heat-sealing properties of wheat gluten films were investigated. Films containing 30 wt% glycerol were compression molded at 100–130 °C and then sealed in a lap-shear or peel-test geometry at 120–175 °C. The tensile properties of the pristine films and the lap-shear and peel strength of the sealed films were evaluated and the seals were examined by scanning electron microscopy. Glycerol was added to the film surfaces prior to sealing in an attempt to enhance the seal strength. It was observed that the wheat gluten films were readily sealable. At a 120 °C sealing temperature and without glycerol as adhesive, the lap-shear strength was greater than or similar to that of polyethylene film, although the peel strength was poorer. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed, especially in the absence of glycerol adhesive, from a cohesive (material failure) to an adhesive type. From previous results, it is known that the high-temperature (130 °C) compression-molded film was highly cross-linked and aggregated, and this prevents molecular interdiffusion and entanglement and thus leads to incomplete seal fusion and, in general, adhesive failure. The presence of glycerol adhesive had a beneficial affect on the peel strength but no, or only a minor, effect on the lap-shear strength.

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