scholarly journals Influence of Embedding Fiber Optical Sensors in CFRP Film Adhesive Joints on Bond Strength

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1665 ◽  
Author(s):  
Neele Grundmann ◽  
Hauke Brüning ◽  
Konstantinos Tserpes ◽  
Tim Strohbach ◽  
Bernd Mayer
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Optical Glass ◽  
Glass Fibers ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Film Adhesive ◽  
Static Tensile

The increasing utilization of carbon fiber reinforced plastic (CFRP) in the aeronautical industry calls for a structural health monitoring (SHM) system for adhesively bonded CFRP joints. Optical glass fiber with inscribed fiber Bragg gratings (FBGs) is a promising technology for a SHM system. This paper investigates the intrusive effect of embedding optical glass fibers carrying FBGs on adhesive bond strength and adhesive layer thickness and quality. Embedding the optical glass fibers directly in the adhesive bond has the advantage of directly monitoring the targeted structure but poses the risk of significantly reducing the bond strength. Optical glass fibers with different cladding diameters (50, 80, 125 µm) and coating types (polyimide, with a thickness of 3−8 µm, and acrylate, with a thickness of ~35 µm) are embedded in structural and repair film adhesives here. Without embedded optical glass fibers, the film adhesives have an adhesive layer thickness of ~90 µm (structural) and ~100 µm (repair) after curing. The intrusive effect of the fiber embedding on the adhesive bond strength is investigated here with quasi static and fatigue single lap joint (SLJ) tensile shear tests. Also, the influence of hydrothermal aging procedures on the quasi static tensile shear strength is investigated. It is found that optical glass fibers with a total diameter (glass fiber cladding + coating) of ~145 µm significantly reduce the quasi static tensile shear strength and increase the adhesive layer thickness and number of air inclusions (or pores) in the structural film adhesive joints. In the repair adhesive joints, no significant reduction of quasi static tensile shear strength is caused by the embedding of any of the tested fiber types and diameters. However, an increase in the adhesive layer thickness is detected. In both adhesive films, no effect on the quasi-static tensile shear strength is detected when embedding optical glass fibers with total diameters <100 µm. The applied aging regime only affects the repair film adhesive joints, and the structural film adhesive joints show no significant reduction. A polyimide-coated 80 µm optical glass fiber is selected for fatigue SLJ tensile shear tests in combination with the more sensitive structural film adhesive. No significant differences between the S-N curves and tensile shear fatigue strength of the reference samples without embedded optical fibers and the samples carrying the polyimide-coated 80 µm optical glass fibers are detected. Thus, it is concluded that the influences of embedding optical glass fibers with total diameters <100 µm on the fatigue limit of the tested film adhesive joints is negligible.

scholarly journals Chitosan-Based Adhesive: Optimization of Tensile Shear Strength in Dry and Wet Conditions

2021 ◽  
Vol 2 (1) ◽  
pp. 110-120
Author(s):  
Maisa Abdelmoula ◽  
Hajer Ben Hlima ◽  
Frédéric Michalet ◽  
Gérard Bourduche ◽  
Jean-Yves Chavant ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Shear Strength ◽  
Bond Strength ◽  
Water Resistance ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Spread Rate ◽  
Assembly Time ◽  
Deacetylation Degree ◽  
Dry And Wet Conditions

Commercial adhesives present a high bond strength and water resistance, but they are considered non-healthier products. Chitosan can be considered as an interesting biosourced and biodegradable alternative, despite its low water resistance. Here, its wood bonding implementation and its tensile shear strength in dry and wet conditions were investigated depending on its structural characteristics. Firstly, the spread rate, open assembly time, drying pressure, drying temperature, and drying time have been determined for two chitosans of European pine double lap specimens. An adhesive solution spread rate of 1000 g·m−2, an open assembly time of 10 min, and a pressure temperature of 55 °C for 105 min led to a bond strength of 2.82 MPa. Secondly, a comparison between a high molecular weight/low deacetylation degree chitosan and a lower molecular weight/higher deacetylation degree chitosan was conducted. Tests were conducted with beech simple lap specimens in accordance with the implementation conditions and the conditioning treatments in wet and dry environments required for thermoplastic wood adhesive standards used in non-structural applications (EN 204 and EN 205). The results clearly revealed the dependence of adhesive properties and water resistance on the structural features of chitosans (molecular weight and deacetylation degree), explaining the heterogeneity of results published notably in this field.

Tensile shear strength of UF- and MUF-bonded veneer related to data of adhesives and cell walls measured by nanoindentation

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Frank Stöckel ◽  
Johannes Konnerth ◽  
Wolfgang Kantner ◽  
Johann Moser ◽  
Wolfgang Gindl
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Bond Strength ◽  
Cell Walls ◽  
Urea Formaldehyde ◽  
Lap Joints ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Interphase Cell ◽  
Cure Time

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.

Study on effects of pre-treatment and surface roughness on tensile-shear strength of 2060 Al–Li alloy adhesive joints

2016 ◽  
Vol 93 (8) ◽  
pp. 613-625 ◽  
Author(s):  
Xiaohong Zhan ◽  
Jicheng Chen ◽  
Cheng Gu ◽  
Qingyu Peng ◽  
Jie Chen ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Adhesive Joints ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Pre Treatment

Effects of Surface Treatment and Loading Speed on Adhesive Strength of Aluminum to Polycarbonate Lap Joints

2004 ◽  
Vol 261-263 ◽  
pp. 405-410 ◽  
Author(s):  
Do Won Seo ◽  
Ho Chel Yoon ◽  
J.Y. Lee ◽  
Jae Kyoo Lim
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Surface Treatment ◽  
Adhesive Strength ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Mechanical Removal ◽  
Strength Of Adhesive Joints

The bonding strength of adhesive joints is influenced by the surface roughness of the joining parts. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, it is showed that surface treatment affects adhesive strength and durability of aluminum/polycarbonate single-lap joints, and loading speed affects tensile-shear strength of adhesive joints. To evaluate the effect of surface treatments on the adhesive strength, several surface treatment methods are used, that is, cleaning, grinding, SiC polishing and sand blasting. It is showed that an optimum value of the surface roughness exists with respect to the tensile-shear strength of adhesive joints. The adhesive strength shows linear relationship with the surface roughness and loading speed. And the mechanical removal of disturbing films of lubricants, impurities and oxides make adhesive strength increase significantly.

scholarly journals Porosity Characteristics and Effect on Tensile Shear Strength of High-Strength Galvanized Steel Sheets after the Gas Metal Arc Welding Process

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1077 ◽  
Author(s):  
Seungmin Shin ◽  
Sehun Rhee
Keyword(s):  
Shear Strength ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
High Strength ◽  
Galvanized Steel ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Tensile Test Specimen ◽  
Metal Arc Welding

In this study, lap joint experiments were conducted using galvanized high-strength steel, SGAFH 590 FB 2.3 mmt, which was applied to automotive chassis components in the gas metal arc welding (GMAW) process. Zinc residues were confirmed using a semi-quantitative energy dispersive X-ray spectroscopy (EDS) analysis of the porosity in the weld. In addition, a tensile shear test was performed to evaluate the weldability. Furthermore, the effect of porosity defects, such as blowholes and pits generated in the weld, on the tensile shear strength was experimentally verified by comparing the porosity at the weld section of the tensile test specimen with that measured through radiographic testing.

Enhancement of the tensile shear strength for joining low-ductility aluminium to high-strength steel by using electrically-assisted mechanical clinching (EAMC)

2021 ◽  
pp. 095440542199565
Author(s):  
Abozar Barimani-Varandi ◽  
Abdolhossein Jalali Aghchai
Keyword(s):  
Shear Strength ◽  
High Strength Steel ◽  
High Strength ◽  
Fe Model ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Electroplastic Effect ◽  
Fracture Displacement ◽  
Electrically Assisted ◽  
Mechanical Clinching

The present work studied the enhancement of the tensile shear strength for joining AA6061-T6 aluminium to galvanized DP590 steel via electrically-assisted mechanical clinching (EAMC) using an integrated 2D FE model. To defeat the difficulties of joining low-ductility aluminium alloy to high-strength steel, the electroplastic effect obtained from the electrically-assisted process was applied to enhance the clinch-ability. For this purpose, the results of experiments performed by the chamfering punches with and without electrically-assisted pre-heating were compared. Joint cross-section, failure load, failure mode, fracture displacement, material flow, and failure mechanism were assessed in order to study the failure behaviour. The results showed that the joints clinched at the EAMC condition failed with the dominant dimpled mechanism observed on the fracture surface of AA6061 side, achieved from the athermal effect of the electroplasticity. Besides, these joints were strengthened 32% with a much more fracture displacement around 20% compared with non-electrically-assisted pre-heating.

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