“…The reason for the increase in joint strength of joints modified with date palm fibres was reported to be the change in the path and arresting the crack propagation.Figure 9.Long parallel date palm fibre arrangement along the bondline. 74 …”
Section: Methods To Increase the Mechanical Performance Of Natural Fi...mentioning
confidence: 99%
“…cork) on adhesive or adhesive joints properties. [113][114][115][116] For instance, 88 Delzendehrooy et al 74 studied the effect of date palm fibres (short and long), extracted from different parts of the plant (i.e. mesh, rachis, petiole and bunch), on the static strength of aluminum bonded joints.…”
This paper presents an overview of the recent developments in the main methods used to increase the mechanical performance of composite adhesive joints with focus on joints with natural fibre reinforced composite (NFRC) adherends. First, the main factors that affect the performance of composite adhesive joints were briefly discussed. Further, the main methods used to increase the mechanical performance of natural fibre-reinforced composite adhesive joints are presented. Since, the literature regarding these methods applied to NFRC adherends is relatively scarce, in addition, promising techniques applied to synthetic fibre-reinforced composite joints, which behave in a similar manner and whose results can be extrapolated with a great deal of confidence to NFRCs are also briefly discussed. Finally, some conclusions and an outlook on critical challenges and future perspectives are summarized. The application of sustainable green composites may further increase in many structural and non-structural applications if their joining behaviour is well-known and established.
“…The reason for the increase in joint strength of joints modified with date palm fibres was reported to be the change in the path and arresting the crack propagation.Figure 9.Long parallel date palm fibre arrangement along the bondline. 74 …”
Section: Methods To Increase the Mechanical Performance Of Natural Fi...mentioning
confidence: 99%
“…cork) on adhesive or adhesive joints properties. [113][114][115][116] For instance, 88 Delzendehrooy et al 74 studied the effect of date palm fibres (short and long), extracted from different parts of the plant (i.e. mesh, rachis, petiole and bunch), on the static strength of aluminum bonded joints.…”
This paper presents an overview of the recent developments in the main methods used to increase the mechanical performance of composite adhesive joints with focus on joints with natural fibre reinforced composite (NFRC) adherends. First, the main factors that affect the performance of composite adhesive joints were briefly discussed. Further, the main methods used to increase the mechanical performance of natural fibre-reinforced composite adhesive joints are presented. Since, the literature regarding these methods applied to NFRC adherends is relatively scarce, in addition, promising techniques applied to synthetic fibre-reinforced composite joints, which behave in a similar manner and whose results can be extrapolated with a great deal of confidence to NFRCs are also briefly discussed. Finally, some conclusions and an outlook on critical challenges and future perspectives are summarized. The application of sustainable green composites may further increase in many structural and non-structural applications if their joining behaviour is well-known and established.
“…To improve the bonding strength and reliability, numerous studies have been carried out, including different pretreatment methods of the bonding surface of the substrate; toughening of adhesive by adding inorganic particles, carbon nanotubes, , and short fibers; − the use of functionally graded and mixed adhesive; , and so on. Many different surface treatment methods have been used to improve bonding strength by enhancing the roughing of surface roughness or changing the surface free energy of the substrate, such as sandblasting technology, chemical etching, plasma etching, − laser activation, , and so on.…”
The present paper
provides a solution to enhance the reliability
of bonding. The effect of the nonwoven carbon tissue (NWCT) composite
adhesive layer on the bonding strength and reliability of aluminum
alloy of single lap joints (SLJ) was investigated by embedding NWCT
into the epoxy adhesive layer. The bonding strength, Weibull distribution,
metallography of cross section, and fracture surface morphology of
NWCT specimens were investigated. The results showed that the average
bonding strength and Weibull characteristic strength (WCS) of NWCT-reinforced
specimen were 16.78 and 17.17 MPa, which increased by 70.2 and 66.7%,
respectively, compared with the neat specimen, and the Weibull modulus
increased from 11.46 to 22.83, which indicated that NWCT specimens
had higher bonding reliability. The mechanism of microcrack formation
was obtained by analyzing the cross section of specimen loaded 95%
WCS without macroscopic damage. The metallographic section showed
that the microcrack of the neat specimen originated from the adhesive–aluminum
interface, while the microcracks of the NWCT specimen originated from
the interface between short carbon fibers (SCF) and adhesive. Typical
failure modes were gained from visual observation and SEM. The failure
mode of the neat specimen included more Al–adhesive interface
failure, while the NWCT specimen included more internal failure of
adhesive–SCFs with the fracture, pullout, peeling, and slippage
of SCFs improving the toughness and bonding strength of the adhesive
layer. The bridging effect of SCFs in the adhesive layer reinforced
by NWCT can even the load and release the stress to improve the bonding
reliability.
“…The studies are also conducted on the improvement of mechanical adhesive and rheological properties as well as improvement of durability and resistance to damage at fatigue loads of adhesives and adhesive joints by using various reinforcements and additives in the form of micro-and nanoparticles [4][5][6][7]. With environmental aspects in mind, attempts are made to improve the properties of adhesives by using additives of natural origin in the form of micro-and nanofibers deposited in the adhesive joint [8][9][10]. Delzendehrooy et al [10] proved that the strength of lap joints reinforced with Rachis fibres Polymers 2021, 13, 2873 2 of 21 in the amount of 2% by weight, which were previously treated with a NaOH solution, increased by 140%.…”
Section: Introductionmentioning
confidence: 99%
“…With environmental aspects in mind, attempts are made to improve the properties of adhesives by using additives of natural origin in the form of micro-and nanofibers deposited in the adhesive joint [8][9][10]. Delzendehrooy et al [10] proved that the strength of lap joints reinforced with Rachis fibres Polymers 2021, 13, 2873 2 of 21 in the amount of 2% by weight, which were previously treated with a NaOH solution, increased by 140%. There are also attempts to develop new adhesives formulas based on natural materials such as linseed oil [11].…”
Double lap adhesive connections made of Sika® PS and Monolith EP2579-1 were studied experimentally in shear tests. The destructive shear tests were conducted under a quasi-static load at 20 °C and 80 °C. The aim was to study the impact of elevated temperature on the load capacity of the joint and make a comparative analysis of the results for two types of adhesives: polyurethane Sika® PS (flexible) and epoxy Monolit EP 2579-1 (rigid). The impact of adhesive layer thickness (t = 1, 2 and 4 mm) on the structural response of the joint was tested in two temperature ranges. A distinct impact of the temperature on the joint deformability was noticed. A visual assessment of the joint failure was performed and the initiation and form of failure was described. At 20 °C, the ultimate loading for epoxy adhesive joint depending on the joint thickness (t) was greater than for the polyurethane joint by, respectively, 282% for t = 1 mm, 88% for t = 2 mm and 279% for t = 4 mm. It was proved that the temperature increases to 80 °C in case of both adhesives reduces the mean destructive force in comparison with the measurements made at 20 °C. For the Sika® PS (PUR two-component polyurethane) adhesive, the greatest load capacity decrease was measured for the joint of thickness t = 2 mm (55%), and in case of the epoxy adhesive for the joint of thickness t = 4 mm (89%). It was found that after reaching the destructive force the flexible joints retain a partial load capacity contrary to the rigid joints.
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