Comprehensive study on the influence of different pretreatment methods and structural adhesives on the shear strength of hybrid CFRP/aluminum joints

2021 ◽  
pp. 1-29
Author(s):  
Jochen Schanz ◽  
Dieter Meinhard ◽  
Isabell Dostal ◽  
Harald Riegel ◽  
Anjali K. M. De Silva ◽  
...  
Keyword(s):  
Shear Strength ◽  
Structural Adhesives ◽  
Comprehensive Study

Elastomer Modification of Structural Adhesives

1985 ◽  
Vol 58 (3) ◽  
pp. 622-636 ◽  
Author(s):  
Alphonsus V. Pocius
Keyword(s):  
Fracture Toughness ◽  
Shear Strength ◽  
Physical Properties ◽  
Yield Stress ◽  
Peel Strength ◽  
Phase System ◽  
Two Phase ◽  
Structural Adhesives ◽  
Thermosetting Polymers ◽  
The Matrix

Abstract An attempt has been made to review the highlights of the chemistry and physical properties of the rubber modification of structural thermosetting polymers that are used as adhesives. The elastomers are added in order to improve the characteristics of these structural thermosets such that they would be more useful as structural adhesives. The addition of an elastomer acts to increase the resistance of the structural thermoset to crack propogation. The resistance to crack propogation is obtained either by plasticization to increase the ductility of the thermoset or by generation of a two-phase system where the structural polymer forms a matrix in which the phase-separated elastomeric particles are imbedded. In the case of flexibilization by plasticization, the increase in peel strength (fracture toughness) is accompanied by a decrease in shear strength (modulus) at high temperatures. In the case of the two phase system, the matrix properties are unaffected for the most part, and increases in peel strength are not accompanied by significant decreases in high-temperature shear strength. In the case of flexibilization, the increase in fracture toughness is accomplished by increasing the ductility of the resin while in the case of the two-phase system, the rubber particles act as stress concentrators to cause conditions of exceeding the yield stress of the matrix near the particles. Exceeding the yield stress increases the amount of plastic deformation of the matrix. We have briefly reviewed the chemistry and physical properties of phenolic, epoxy, acrylic, and polyimide structural adhesives and their modification with vinyl, nitrile, acrylic, siloxane, and other types of elastomers.

scholarly journals Comparative Study on the Impact Wedge-Peel Performance of Epoxy-Based Structural Adhesives Modified with Different Toughening Agents

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1549
Author(s):  
Gyeong-Seok Chae ◽  
Hee-Woong Park ◽  
Jung-Hyun Lee ◽  
Seunghan Shin
Keyword(s):  
Shear Strength ◽  
Automotive Industry ◽  
Impact Resistance ◽  
High Energy ◽  
Epoxy Adhesive ◽  
Absorbed Energy ◽  
Structural Adhesives ◽  
Epoxy Adhesives ◽  
The Impact ◽  
Modified Epoxy

Epoxy adhesives are widely used in various industries because of their high heat and chemical resistance, high cohesion, and minimal shrinkage. Recently, epoxy adhesives have been applied in the automotive industry as structural adhesives for lightweight vehicles. However, the brittleness of the epoxy is an obstacle for this application, since the automotive industry requires epoxy-based structural adhesives to have a high level of high-speed impact resistance. Hence, we used phenol-terminated polyurethane (PTPU) as a toughening agent for epoxy adhesives and compared the results with those that were obtained with carboxyl-terminated butadiene acrylonitrile copolymer (CTBN). The high-energy impact resistance of the epoxy adhesives was measured by the impact wedge-peel (IWP) test, and the shear strength was measured by the single lap joint test. As a result, the 20 wt % PTPU-modified epoxy adhesive showed remarkably higher total absorbed energy (25.8 J) during the IWP test and shear strength (32.3 MPa) as compared with the control epoxy adhesive (4.1 J and 20.6 MPa, respectively). In particular, the total absorbed energy of the PTPU-modified epoxy adhesive was much larger than that of the CTBN-modified epoxy adhesive (5.8 J). When more than 10 wt % PTPU was added, the modified epoxy adhesives showed stable crack growth and effectively transferred external stress to the substrate. These results were explained by changes in the glass transition temperature, crosslinking density, and morphology due to the toughening agents.

Shear strength of structural adhesives

1987 ◽  
Author(s):  
SCOTT MALAZNIK ◽  
MICHELE ARMET
Keyword(s):  
Shear Strength ◽  
Structural Adhesives

scholarly journals COMPREHENSIVE STUDY OF THE PROPERTIES OF FINE-GRAINED CONCRETE UNDER DYNAMIC TENSION AND SHEAR

2020 ◽  
Vol 82 (4) ◽  
pp. 442-457
Author(s):  
M.E. Gonov
Keyword(s):  
Shear Strength ◽  
Dynamic Properties ◽  
Test Sample ◽  
Dynamic Strain ◽  
Shear Stresses ◽  
Direct Tension ◽  
Fine Grained ◽  
Kolsky Method ◽  
Wide Range ◽  
Comprehensive Study

An experimental study of the dynamic properties of fine-grained concrete under tensile and shear stresses has been carried out. A comprehensive study of the dynamic properties of concrete allows obtaining experimental data and constants. These data and constants are needed to equip dynamic strain and fracture models. The system of experiments is based on modifications of the Kolsky method. This system of experiments allows one to determine a wide range of strength and time characteristics of concrete under shock loading. The experimental setup according to the Kolsky method includes a system of measuring rods between which a test sample is installed, a gas gun for accelerating a cylindrical striker, strain gauges, a speed meter, recording and computing equipment with a software package. Conducted dynamic tests of concrete in a wide range of deformation rates (102–104 s–1). In experiments on direct tension and to determine the ultimate tensile stress of fine-grained concrete during splitting, two speed modes are implemented. In tests of shear strength, a modification of the Hopkinson split bar method was used to determine the dynamic shear strength, in which a sample made of the material under study is located in a rigid holder cut at an angle to the sample axis. The pulse recorded in the reference dipstick is used to plot the shear stress in the sample over time. Shear tests were carried out for three speeds. The results of the performed experiments on tensile, splitting and shearing are presented in the form of diagrams of stress versus deformation and stress versus time. The obtained characteristics can be used to equip computational experiments in the study of the strength of concrete structures subjected to dynamic influences.

scholarly journals Structural Adhesives Tapes Based on a Solid Epoxy Resin and Multifunctional Acrylic Telomers

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3561
Author(s):  
Mateusz Weisbrodt ◽  
Agnieszka Kowalczyk ◽  
Krzysztof Kowalczyk
Keyword(s):  
Shear Strength ◽  
Elevated Temperature ◽  
Epoxy Resin ◽  
Dynamic Viscosity ◽  
The Self ◽  
Aviation Fuel ◽  
K Value ◽  
Curing Behavior ◽  
Structural Adhesives ◽  
Pressure Sensitive

Thermally curable pressure-sensitive structural adhesives tapes (SATs) were compounded using a solid epoxy resin and multifunctional acrylic telomer solutions (MATs) prepared by a thermally initiated telomerization process in an epoxy diluent containing two kinds of telogens (CBr4 or CBrCl3). Dynamic viscosity, K-value, and volatile mater content in MATs (i.e., MAT-T with CBr4, MAT-B with CBrCl3) were investigated in relation to telogen type and content. The influence of MATs on the self-adhesive features and curing behavior of UV-crosslinked tapes as well as on the shear strength of thermally cured aluminum–SAT–aluminum joints was investigated as well. Increasing the telogen dose (from 5 to 15 wt. parts) caused significant improvement in the adhesion (+315% and +184%), tack (+147% and +298%), and cohesion (+414% and +1716%) of SATs based on MAT-T and MAT-B, respectively. Additionally, MATs with high telogen content (especially the MAT-T-type) improved the resistance of cured joints to aviation fuel, humidity, and elevated temperature. The highest overlap shear strength values were registered for SATs based on MATs containing 7.5 wt. parts of CBr4 (16.7 MPa) or 10 wt. parts of CBrCl3 (15.3 MPa).

scholarly journals Chitin–amyloid synergism and their use as sustainable structural adhesives

2021 ◽  
Author(s):  
Luiz G. Greca ◽  
Kevin J. De France ◽  
Johanna Majoinen ◽  
Nico Kummer ◽  
Otso I. V. Luotonen ◽  
...  
Keyword(s):  
Shear Strength ◽  
Single Component ◽  
High Shear ◽  
Structural Adhesives ◽  
High Shear Strength

Chitin, lysozyme, and lysozyme amyloids are evaluated as single-component and composite structural adhesives. A high shear strength is observed for chitin and lysozyme, which can be further improved by at least 25% upon compositing.

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

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