scholarly journals The Effect of Pre-Bond Contamination by Thermal Degradation and De-Icing Fluid on the Tensile Strength of Scarf Composite Bonded Joints

2021 ◽  
Vol 5 (7) ◽  
pp. 168
Author(s):  
Konstantinos Tserpes ◽  
Elli Moutsompegka
Keyword(s):  
Tensile Strength ◽  
Thermal Degradation ◽  
Repair Process ◽  
Bonded Joints ◽  
Cohesive Failure ◽  
Lap Shear ◽  
Tension Tests ◽  
Reference Samples ◽  
Different Levels ◽  
Combined Contamination

The synergistic effect of pre-bond contamination by thermal degradation and de-icing fluid on the tensile behavior of scarf composite bonded joints has been investigated experimentally. The contamination types considered are related to the repair process of composite aircraft structures. Three contamination scenarios have been considered: namely, thermal degradation (TD) and a combination of thermal degradation with two different levels of de-icing fluid (TD+DI1 and TD+DI2). DI2 is more severe than DI1. Contamination has been applied to one of the adherents while the other one has been intentionally left intact. Tension tests have been conducted on single-lap shear specimens. The experimental results were compared with the reference samples (REF) showing an increase in tensile strength for the TD specimens and a decrease in tensile strength for the TD+DI1 and TD+DI2 specimens. After the tension tests, the failure surfaces were evaluated to get a better insight of the failure mechanisms of the bondline and to assess the effect of contamination. The TD specimens presented an increased cohesive failure which is consistent with the increase of the failure load, while the combined contamination caused the failure of the composite adherents which again is consistent with the decrease of tensile strength of the scarf specimens.

Experimental and theoretical analysis of in-plane cohesive testing of paperboard

2016 ◽  
Vol 26 (6) ◽  
pp. 895-918 ◽  
Author(s):  
Johan Tryding ◽  
Gustav Marin ◽  
Mikael Nygårds ◽  
Petri Mäkelä ◽  
Giulio Ferrari
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Theoretical Analysis ◽  
Fracture Energy ◽  
Morse Potential ◽  
Cohesive Failure ◽  
Cohesive Stress ◽  
Maximum Slope ◽  
Tension Tests ◽  
Short Span

In-plane cohesive failure of paperboard was characterized by short-span uniaxial tension tests. Six paperboards' qualities were experimentally investigated, from which cohesive stress–widening curves were extracted. A fracture energy was defined, expressed in the tensile strength and maximum slope of the cohesive stress–widening relation. Analytical cohesive relations were derived based on the tensile strength and maximum slope, utilizing the Morse potential for diatomic molecules. It was experimentally found that the maximum slope and fracture energy depend on the tensile strength. The ratio of the maximum slope to the elastic modulus (stable length) was shown to be independent of the tensile strength.

Effect of adherend deflection on lap-shear tensile strength of laser-treated adhesive-bonded joints

2020 ◽  
Vol 97 ◽  
pp. 102481
Author(s):  
Hailang Wan ◽  
Junying Min ◽  
Jun Zhang ◽  
Jianping Lin ◽  
Chengcheng Sun
Keyword(s):  
Tensile Strength ◽  
Bonded Joints ◽  
Lap Shear ◽  
Adhesive Bonded Joints

Test Methods for Mechanical Properties of Structural Adhesives

2010 ◽  
Vol 97-101 ◽  
pp. 814-817 ◽  
Author(s):  
Jun Deng
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Elastic Modulus ◽  
Butt Joint ◽  
Test Methods ◽  
Joint Specimen ◽  
Lap Shear ◽  
Better Than

One of the greatest drawbacks to predicting the behaviour of bonded joints has been the lack of reliable data on the mechanical properties of adhesives. In this study, methods for determining mechanical properties of structural adhesive were discussed. The Young’s modulus, Poisson’s ratio and tensile strength of the adhesive were tested by dogbone specimens (bulk form) and butt joint specimens (in situ form). The shear modulus and shear strength were test by V-notched specimens (bulk form) and thick adherend lap-shear (TALS) joint specimens (in situ form). The test results show that the elastic modulus provided by the manufacturer is too low, the dogbone specimen is better than the butt joint specimen to test the tensile strength and elastic modulus and the TALS joint specimen is better than the V-notched specimen to test the shear strength.

Effect of cellulase-assisted refining on the thermal degradation of bleached high-density paper

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 703-712 ◽  
Author(s):  
Emilia Vänskä ◽  
Tapani Vuorinen
Keyword(s):  
Tensile Strength ◽  
Thermal Degradation ◽  
Specific Energy Consumption ◽  
Degree Of Polymerization ◽  
High Density ◽  
Pulp Fibers ◽  
Enzymatic Pretreatment ◽  
Burst Strength ◽  
Degradation Reactions ◽  
Cellulase Treatment

Abstract Pulp was treated with cellulase, and the chemical, physical, and optical properties of the refined pulps in paper sheets were measured in terms of the degree of polymerization of cellulose, tensile strength, elongation, burst strength, light scattering, and brightness. The sheets were thermally treated for 20 and 60 min at 225°C in the presence of 1% and 75% (v/v) water vapor. The cellulase treatment intensified the fibrillation of fibers and reduced the specific energy consumption during refining. It was demonstrated based on the water retention value that the refining modified the water-bonding ability of the pulp fibers, which was further enhanced in the case of cellulase-treated pulps. However, the enzymatic pretreatment impaired the physical properties, such as the tensile strength, elongation, and burst strength of the high-density paper. These changes further reduced the thermal strength stability of the paper. In addition, considerable brightness loss of the cellulase-treated high-density paper was observed compared to the reference paper, indicating more severe thermal degradation reactions as a consequence of enzyme-assisted refining.

Effects of AP and AP-ethyl on the properties of PA6

2017 ◽  
Vol 31 (12) ◽  
pp. 1609-1618
Author(s):  
Long Lijuan ◽  
He Wentao ◽  
Li Juan ◽  
Xiang Yushu ◽  
Qin Shuhao ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fracture Surface ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cone Calorimeter Test ◽  
Mean Size ◽  
The Mean

In this work, the effects of inorganic phosphinate flame retardant of aluminum hypophosphite (AP) and organic phosphinate flame retardant of ethyl substituted phosphinates (AP-ethyl) on the thermal degradation, flame performance, and mechanical properties of polyamide 6 (PA6) were investigated. Scanning electron micrograph showed AP with the shape of bulk and the mean size of 8 μm while AP-ethyl with irregular shape and the mean size of 30 μm. Thermal analysis indicated that the thermal degradation behavior of flame-retardant PA6 was different from pure PA6. Moreover, the cone calorimeter test results revealed that peak heat release rate (PHRR) of PA6/AP (85/15) and PA6/AP-ethyl (85/15) decreased by 51% and 64%, respectively, compared with pure PA6. Furthermore, pure PA6 showed ductile stress–strain curve with the tensile strength of 54.8 MPa. However, PA6/AP and PA6/AP-ethyl displayed brittle stress–strain curve and their tensile strength decreased to 52.3 and 47.1 MPa, respectively. In addition, pure PA6 showed a glossy and tough fracture surface morphology. The rough fracture surface morphologies for PA6/AP and PA6/AP-ethyl were observed, and the interface of PA6/AP was more obscure than that of PA6/AP-ethyl. Consequently, the small particle size of AP had a more uniform dispersion in PA6 matrix.

Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates

2018 ◽  
Vol 31 (1) ◽  
pp. 86-96 ◽  
Author(s):  
R Vini ◽  
S Thenmozhi ◽  
SC Murugavel
Keyword(s):  
Tensile Strength ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Spectroscopic Techniques ◽  
Scanning Calorimetry ◽  
Limiting Oxygen Index ◽  
Weight Percentage ◽  
Ul 94

In this study, azomethine polyphosphonates were synthesized by solution polycondensation of phenylphosphonic dichloride with various azomethine diols such as [4-(4-hydroxy phenyl) iminomethyl] phenol, [(4-(4-hydroxy-3-methoxy phenyl) iminomethyl)] phenol and [4-(4-hydroxy-3-ethoxy phenyl) iminomethyl] phenol using triethylamine catalyst at ambient temperature. The structure of the synthesized polymers was confirmed by Fourier transform infrared and 1H-, 13C- and 31P- nuclear magnetic resonance spectroscopic techniques. Thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. The TGA data showed that the synthesized polyphosphonates produce high char yield at 600°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. One of the synthesized polyphosphonate was blended with commercial diglycidyl ether of bisphenol-A (DGEBA) resin in various weight percentage and cured with commercial curing agent triethylene tetramine (TETA). The polyphosphonates-blended epoxy thermosets have tensile strength in the range of 5–41 MPa and the percentage of elongation at breaks was 4–18. It was found that the incorporation of polyphosphonates into epoxy thermoset decreased the tensile strength from 41 MPa to 5 MPa, whereas the elongation at break value increased with increase in the weight percentage of polyphosphonate. The influence of polyphosphonates on the flame retardancy of blended thermosets was examined by limiting oxygen index (LOI) and vertical burning (UL-94) tests and found that the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 24–26. Broido and Horowitz–Metzger methods have been used to study the thermal degradation kinetic parameters.

Effect of aluminium substrate thickness on the lap-shear strength of adhesively bonded and hybrid riveted-bonded joints

2020 ◽  
pp. 095440892091343
Author(s):  
VC Beber ◽  
N Wolter ◽  
B Schneider ◽  
K Koschek
Keyword(s):  
Shear Strength ◽  
Failure Process ◽  
Lap Joints ◽  
Substrate Thickness ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Definition Of ◽  
Structural Adhesive

For lightweight materials, e.g. aluminium, the definition of proper joining technology relies on material properties, as well as design and manufacturing aspects. Substrate thickness is especially relevant due to its impact on the weight of components. The present work compares the performance of adhesively bonded (AJ) to hybrid riveted-bonded joints (HJ) using aluminium substrates. To assess the lightweight potential of these joining methods, the effect of substrate thickness (2 and 3 mm) on the lap-shear strength (LSS) of single lap joints is investigated. An epoxy-based structural adhesive is employed for bonding, whilst HJs are produced by lockbolt rivet insertion into fully cured adhesive joints. The stiffness of joints increased with an increase of substrate thickness. HJs presented two-staged failure process with an increase in energy absorption and displacement at break. For HJs, the substrate thickness changed the failure mechanism of rivets: with thicker substrates failure occurred due to shear, whereas in thinner substrates due to rivet pulling-through. The LSS of 2 mm and 3 mm-thick AJs is similar. With 2 mm-thick substrates, the LSS of HJs was lower than AJs. In contrast, the highest LSS is obtained by the 3 mm-thick HJs. The highest lightweight potential, i.e. LSS divided by weight, is achieved by the 2 mm-thick AJs, followed by the 3 mm-thick HJs with a loss of ca. 10% of specific LSS.

scholarly journals Requirements and Variability Affecting the Durability of Bonded Joints

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1468 ◽  
Author(s):  
Rhys Jones ◽  
Daren Peng ◽  
John G. Michopoulos ◽  
Anthony J. Kinloch
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Upper Bound ◽  
The United States ◽  
Fatigue Threshold ◽  
Growth Equation ◽  
Bonded Joints ◽  
Cohesive Failure ◽  
Structural Adhesives

This paper firstly reveals that when assessing if a bonded joint meets the certification requirements inherent in MIL-STD-1530D and the US Joint Services Standard JSSG2006 it is necessary to ensure that: (a) There is no yielding at all in the adhesive layer at 115% of design limit load (DLL), and (b) that the joint must be able to withstand design ultimate load (DUL). Secondly, it is revealed that fatigue crack growth in both nano-reinforced epoxies, and structural adhesives can be captured using the Hartman–Schijve crack growth equation, and that the scatter in crack growth in adhesives can be modelled by allowing for variability in the fatigue threshold. Thirdly, a methodology was established for estimating a valid upper-bound curve, for cohesive failure in the adhesive, which encompasses all the experimental data and provides a conservative fatigue crack growth curve. Finally, it is shown that this upper-bound curve can be used to (a) compare and characterise structural adhesives, (b) determine/assess a “no growth” design (if required), (c) assess if a disbond in an in-service aircraft will grow and (d) to design and life in-service adhesively-bonded joints in accordance with the slow-growth approach contained in the United States Air Force (USAF) certification standard MIL-STD-1530D.

scholarly journals Bonding of plywood 

2016 ◽  
Vol 62 (No. 4) ◽  
pp. 198-204
Author(s):  
M. Brožek
Keyword(s):  
Tensile Strength ◽  
Testing Machine ◽  
Strength Testing ◽  
Bonded Joints ◽  
Rupture Force ◽  
Oblique Direction ◽  
Direction Angle ◽  
Economical Evaluation ◽  
Wood Bonding ◽  
Strength Tests

The contribution contains results of bonded joints strength tests. The tests were carried out according to the modified standard ČSN EN 1465 (66 8510):2009. The spruce three-ply wood of 4 mm thickness was used for bonding according to ČSN EN 636 (49 2419):2013. The test samples of 100 × 25 mm size were cut out from a semi-product of 2,440 × 1,220 mm size in the direction of its longer side (angle 0°), in the oblique direction (angle 45°) and in the direction of its shorter side (crosswise – angle 90°). The bonding was carried out using eight different domestic as well as foreign adhesives according to the technology prescribed by the producer. All used adhesives were designated for wood bonding. At the bonding the consumption of the adhesive was determined. After curing, the bonded assemblies were loaded using a universal tensile-strength testing machine up to the rupture. The rupture force and the rupture type were registered. Finally, the technical-economical evaluation of the experiments was carried out. 

Sign in / Sign up

Export Citation Format

Share Document