Failure mode maps of lap joints under the tensile shear testing condition

Abstract The tensile shear strength of veneer lap joints was characterised. The joints were produced with an Automated Bonding Evaluation System (ABES) using urea-formaldehyde (UF) as well as melamine-urea-formaldehyde (MUF) adhesive formulated for particleboard production. At a fixed heating temperature of 110°C, a systematic increase in bond strength was observed for both adhesives with increasing cure time. The absolute bond strength was significantly higher for MUF compared to UF. Nanoindentation experiments with the same specimens used for ABES revealed a very hard, stiff and brittle character of the UF resin, whereas the MUF proved significantly less hard and stiff, and less brit-tle. Wood cell walls in contact with adhesive, i.e., where adhesive penetration into the cell wall was assumed, showed significantly altered mechanical properties. Such cell walls were harder, stiffer and more brittle than unaffected reference cell walls. These effects were slightly more pronounced for UF than for MUF. Comparing UF and MUF, the micro-mechanical properties of cured adhesive and interphase cell walls confirm earlier observations that tougher adhesives can lead to higher macroscopic bond strength. In strong contrast to that, no obvious correlation was found between micromechanical properties and the strong cure time dependence of macroscopic bond strength.

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Three-Layer Clad Strip Casting Using a Vertical Type Tandem Twin Roll Caster

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.773.171 ◽

2018 ◽

Vol 773 ◽

pp. 171-178

Author(s):

Toshio Haga ◽

Kentaro Okamura ◽

Hisaki Warari ◽

Shinichi Nishida

Keyword(s):

Aluminum Alloy ◽

Strip Casting ◽

Tensile Shear ◽

Shear Testing ◽

Roll Speed ◽

Solidification Temperature ◽

Twin Roll Caster ◽

Twin Roll

This paper shows improvements made to a vertical type tandem twin roll caster and the appropriate casting conditions necessary to cast three-layer clad strips, the base strip of which has a lower solidification temperature than the overlay strip. In experiments, 4045 aluminum alloy was used for the base strip and 3003 aluminum alloy was used for the overlay strips. The roll speed was 30 m/min. By connecting the overlay strips to the base strip one at a time and cooling the base strip to between 450 and 530°C after applying the first overlay strip, a sound three-layer clad strip – defined as one in which the interfaces between strips are clear and do not separate during bending-to-failure tests – could be cast. The tensile shear testing between the base and second overlay strip was improved as the base-strip temperature was increased to 450-530°C range.

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Effect of Autoclave Cure Time and Surface Preparation on Film Adhesive Bond in Lightweight Material Joints

Volume 2: Computer Technology and Bolted Joints ◽

10.1115/pvp2018-84009 ◽

2018 ◽

Author(s):

Isotta Morfini ◽

Luca Goglio ◽

Giovanni Belingardi ◽

Sayed A. Nassar

Keyword(s):

Failure Mode ◽

Load Transfer ◽

Mechanical Performance ◽

Surface Preparation ◽

Adhesive Bond ◽

Lap Joints ◽

Mode Analysis ◽

Bonding Parameters ◽

Film Adhesive ◽

Cure Time

This study investigates the effect of cure time and surface roughness on mechanical performance of single lap joints (SLJ). Test joints are made of aluminum/aluminum or aluminum/magnesium adherends that are autoclave-bonded using a commercially available film adhesive. Joint mechanical performance is assessed in terms of the static load transfer capacity (LTC), fatigue life and failure mode. Except for the cure time, all the rates of the other autoclave-bonding parameters are kept constant; namely, the level of cure temperature and pressure, as well as the rates of autoclave heating, cooling, pressurization and depressurization. Test data, failure mode analysis, discussion, observations and conclusions are provided.

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Experimental investigation on adhesive bonding of similar and dissimilar weld joint used for automotive applications

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211063116 ◽

2021 ◽

pp. 095440892110631

Author(s):

Rohit Verma ◽

Lochan Sharma ◽

Mayank Chauhan ◽

Rahul Chhibber ◽

Kanwer Singh Arora

Keyword(s):

Tensile Strength ◽

Failure Mode ◽

Adhesive Bonding ◽

Lap Joints ◽

Mode Analysis ◽

Dissimilar Joints ◽

Bonding Parameters ◽

Adhesion Failure ◽

Failure Mode Analysis ◽

Length Changes

The automobile industry has started using adhesive bonding to join load bearing components which aerospace industry has been using for decades. Adhesive lap joints are used frequently in the manufacture of automobile. In present study, structural adhesives were used to join the aluminium alloy (AA5083 H111) with the HSS dual phase (DP780) steel. Adhesive bonding appears to be one of the appropriate methods of joining dissimilar materials. The aim of this work is to analyze the tensile strength of similar and dissimilar joints. The influence of various parameters was also investigated such as the overlap length and the bondline thickness of specimens. In DP steel, there is 22% increase in strength for similar lap joint when overlap length changes from 10 mm to 15 mm, while there is 45% increase in strength when it varies from 15 mm to 20 mm. Similarly in case of Al alloy, there is 26% increased strength for similar lap joints when length varies from 10 mm to 15 mm, while it increased to 42% when length changes from 15 mm to 25 mm and there is about 35% increase in strength for length varies from 20 mm to 25 mm. In case of dissimilar joints, firstly there is about 16% increase in strength then there is 5% decrease while after that there is 45% increase in strength. Adhesion failure, cohesion failure and mixed failure were obtained experimentally during failure mode analysis. As the strength of joint increases, failure mode shows a transition from adhesion failure to cohesion failure. From the literature survey it is evident that limited work has been carried out on analysis of shear-tensile strength of adhesively bonded steel and aluminium joint with variation in bonding parameters. Not much work on failure mode analysis of bonded joints during tensile testing has been reported. In present work a noval attempt has been made to analyze the shear-tensile strength and failure mode of adhesively bonded steel and aluminium joint with variation in bonding parameters.

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Influence of Welding Speed on Characteristics of Non-Axisymmetric Laser-Tungsten Inert Gas Hybrid Welded Mg/Al Lap Joints with Zn Filler

Materials ◽

10.3390/ma13173789 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3789

Author(s):

Xinze Lv ◽

Hongyang Wang ◽

Liming Liu

Keyword(s):

Solid Solution ◽

Intermetallic Compounds ◽

Welding Speed ◽

Solidification Rate ◽

Eutectic Structure ◽

Lap Joints ◽

Inert Gas ◽

Heat Sources ◽

Base Metals ◽

Tensile Shear

A non-axisymmetric laser-tungsten inert gas (TIG) heat source was designed to join Mg–Al dissimilar metals with pure Zn filler at a series of welding speeds (500–900 mm/min). Laser and TIG heat sources respectively acted on Al and Mg base metals to precisely control their dissolution into the welding pool. The solidification rate of liquid metal was controlled by adjusting the welding speed, then the reaction process of Mg, Al and Zn could be accurately regulated. The results indicated that various microstructures including Al solid solution, Zn solid solution, Mg–Zn intermetallic compounds (IMCs) and eutectic structure formed in the joint produced at different speeds. Lower welding speed (500 mm/min) caused the microstructure coarsening and higher welding speed (900 mm/min) would lead to the enrichment of MgZn2 intermetallic compounds. At the optimal welding speed of 800 mm/min in particular, fine MgZn2 IMCs grains uniformly distributed in the Al and Zn solid solution. The tensile-shear load reached a maximum of 1052.5 N/cm and the joint fractured at the fusion zone near the Al base metal.

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