scholarly journals Investigation of the Effects of Use of GNP and GNP Reinforced Nano-Fibers with Epoxy Adhesive on Tension Tests

2021 ◽  
Vol 11 (2) ◽  
pp. 175-181
Author(s):  
Edip ÇETKİN
Keyword(s):  
Epoxy Adhesive ◽  
Tension Tests

Intertester-Reliabilität des Upper Limb Neural Tension Tests (ULNT) 1

2019 ◽  
Vol 23 (02) ◽  
pp. 75-80
Author(s):  
Beate Schüßler ◽  
Andrea Pfingsten ◽  
Thomas Schöttker-Königer
Keyword(s):  
Upper Limb ◽  
Tension Test ◽  
Tension Tests

ZusammenfassungZur Überprüfung der Nervenleitfähigkeit werden Kraft, Reflexe und Sensibilität getestet. Bei der Untersuchung der Mechanosensitivität eines Nervs kommen neurodynamische Tests zum Einsatz. Der Upper Limb Neural Tension Test (ULNT) 1 bestimmt die Mechanosensitivität des N. medianus.Ziel der Studie war die Untersuchung der Intertester-Reliabilität des ULNT 1 von nicht spezialisierten Physiotherapeuten bei Probanden mit unilateralen Nacken- und/oder Armsymptomen.Die Therapeuten beurteilten binär und metrisch die Kriterien patientenspezifische Symptome, strukturelle Differenzierung und Bewegungsausmaß sowie das Gesamtergebnis bei 33 Patienten mit unilateralen Nacken- und/oder Armsymptomen. Bei den binären Daten bestimmte der Fleiss-Kappa und bei den metrischen Daten der Intraklassen-Korrelationskoeffizient die Reliabilität. Die zusätzlich erstellten Regressionsmodelle sollten den Einfluss der einzelnen Beurteilungskriterien auf die Gesamtentscheidung herausfiltern.Mit Ausnahme der Reproduzierbarkeit patientenspezifischer Symptome scheint die Beurteilung des ULNT 1 durch nicht spezialisierte Therapeuten nur schlecht vergleichbar zu sein. Da die metrische Bewertungsweise die individuellen Schwellenwerte besser darstellt, ist diese der binären vorzuziehen.

Effect of reduced graphene oxide on mechanical behavior of an epoxy adhesive in glassy and rubbery states

2021 ◽  
pp. 002199832110316
Author(s):  
Ata Khabaz-Aghdam ◽  
Bashir Behjat ◽  
EAS Marques ◽  
RJC Carbas ◽  
Lucas FM da Silva ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ambient Temperature ◽  
Mechanical Behavior ◽  
Reduced Graphene Oxide ◽  
Epoxy Adhesive ◽  
Ultimate Strain ◽  
Reduced Graphene

The mechanical behavior of an adhesive, in neat state and reinforced with up to 0.5 wt% of reduced graphene oxide (RGO) was investigated here. Tests were done at temperatures between the ambient temperature and the glass transition temperature ( Tg[Formula: see text] of the adhesive. Using a metal mold, cured plates of the neat and RGO reinforced epoxy adhesive were prepared. The adhesive powder and the bulk dumbbell-shaped specimens, obtained from cured adhesive plates, were subjected to differential scanning calorimetry (DSC) and tensile tests, respectively, to obtain the Tg as well as mechanical properties of the adhesives. The results indicated that adding RGO up to 0.5 wt% increased the glass transition temperature, the modulus of elasticity, and the strength of the adhesive. It was found that the presence of RGO reduced the adhesive’s strain at the break at the ambient temperature. However, at high temperatures, near the Tg, the ultimate strain of RGO-reinforced adhesives decreased slightly when compared to the ultimate strain of the neat specimens. This explains the reduction in toughness at ambient temperature obtained by adding RGO and the increase at high temperatures. Finally, the failure morphology of the neat and RGO-reinforced adhesive specimens was investigated using microscopic imaging of the specimens’ failure cross-sections, which supported and justified the experimental observations.

scholarly journals Comparison of Modified Mohr–Coulomb Model and Bai–Wierzbicki Model for Constructing 3D Ductile Fracture Envelope of AA6063

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianye Gao ◽  
Tao He ◽  
Yuanming Huo ◽  
Miao Song ◽  
Tingting Yao ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Fracture Criterion ◽  
Fracture Strain ◽  
Stress Triaxiality ◽  
Ductile Fracture Criterion ◽  
Forming Process ◽  
Tension Tests ◽  
Wide Range ◽  
Round Bar ◽  
Fracture Envelope

AbstractDuctile fracture of metal often occurs in the plastic forming process of parts. The establishment of ductile fracture criterion can effectively guide the selection of process parameters and avoid ductile fracture of parts during machining. The 3D ductile fracture envelope of AA6063-T6 was developed to predict and prevent its fracture. Smooth round bar tension tests were performed to characterize the flow stress, and a series of experiments were conducted to characterize the ductile fracture firstly, such as notched round bar tension tests, compression tests and torsion tests. These tests cover a wide range of stress triaxiality (ST) and Lode parameter (LP) to calibrate the ductile fracture criterion. Plasticity modeling was performed, and the predicted results were compared with corresponding experimental data to verify the plasticity model after these experiments. Then the relationship between ductile fracture strain and ST with LP was constructed using the modified Mohr–Coulomb (MMC) model and Bai-Wierzbicki (BW) model to develop the 3D ductile fracture envelope. Finally, two ductile damage models were proposed based on the 3D fracture envelope of AA6063. Through the comparison of the two models, it was found that BW model had better fitting effect, and the sum of squares of residual error of BW model was 0.9901. The two models had relatively large errors in predicting the fracture strain of SRB tensile test and torsion test, but both of the predicting error of both two models were within the acceptable range of 15%. In the process of finite element simulation, the evolution process of ductile fracture can be well simulated by the two models. However, BW model can predict the location of fracture more accurately than MMC model.

Fatigue behavior of adhesively bonded glass fiber reinforced plastic composites with different overlap lengths

2015 ◽  
Vol 229 (7) ◽  
pp. 1292-1299
Author(s):  
E Kara ◽  
A Kurşun ◽  
MR Haboğlu ◽  
HM Enginsoy ◽  
H Aykul
Keyword(s):  
Glass Fiber ◽  
Fatigue Behavior ◽  
Laminated Composite ◽  
Element Model ◽  
Treatment Method ◽  
Epoxy Adhesive ◽  
Lap Joints ◽  
Adhesively Bonded ◽  
Glass Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced

The joining techniques of lightweight and strong materials in the transport industry (e.g. automotive, aerospace, shipbuilding industries) are very important for the safety of the entire structure. In these industries, when compared with other joining methods, the use of adhesively bonded joints presents unique properties such as greater strength, design flexibility, and reduction in fuel consumption, all thanks to low weight. The aim of this study was the analysis of the tensile fatigue behavior of adhesively bonded glass fiber/epoxy laminated composite single-lap joints with three different specimen types including 30, 40 and 50 mm overlap lengths. In this study, composite adherents were manufactured via vacuum-assisted resin transfer molding and were bonded using Loctite 9461 A&B toughened epoxy adhesive. The effect of a surface treatment method on the bonding strength was considered and it led to an increment of about 40%. A numerical analysis based on a finite element model was performed to predict fatigue life curve, and the predicted results showed good agreement with the experimental investigation.

scholarly journals A study on the numerical modelling of UHPFRC-strengthened members

2018 ◽  
Vol 199 ◽  
pp. 09001
Author(s):  
Renaud Franssen ◽  
Serhan Guner ◽  
Luc Courard ◽  
Boyan Mihaylov
Keyword(s):  
Numerical Modelling ◽  
High Performance ◽  
Concrete Structures ◽  
Concrete Members ◽  
High Durability ◽  
Tension Tests ◽  
The World ◽  
Aging Infrastructure ◽  
New Generation ◽  
Modelling Approach

The maintenance of large aging infrastructure across the world creates serious technical, environmental, and economic challenges. Ultra-high performance fibre-reinforced concretes (UHPFRC) are a new generation of materials with outstanding mechanical properties as well as very high durability due to their extremely low permeability. These properties open new horizons for the sustainable rehabilitation of aging concrete structures. Since UHPFRC is a young and evolving material, codes are still either lacking or incomplete, with recent design provisions proposed in France, Switzerland, Japan, and Australia. However, engineers and public agencies around the world need resources to study, model, and rehabilitate structures using UHPFRC. As an effort to contribute to the efficient use of this promising material, this paper presents a new numerical modelling approach for UHPFRC-strengthened concrete members. The approach is based on the Diverse Embedment Model within the global framework of the Disturbed Stress Field Model, a smeared rotating-crack formulation for 2D modelling of reinforced concrete structures. This study presents an adapted version of the DEM in order to capture the behaviour of UHPFRC by using a small number of input parameters. The model is validated with tension tests from the literature and is then used to model UHPFRC-strengthened elements. The paper will discuss the formulation of the model and will provide validation studies with various tests of beams, columns and walls from the literature. These studies will demonstrate the effectiveness of the proposed modelling approach.

Evaluation of a structural epoxy adhesive for timber-glass bonds under shear loading and different environmental conditions

2019 ◽  
Vol 95 ◽  
pp. 102425 ◽  
Author(s):  
Žiga Unuk ◽  
Andrej Ivanič ◽  
Vesna Žegarac Leskovar ◽  
Miroslav Premrov ◽  
Samo Lubej
Keyword(s):  
Environmental Conditions ◽  
Epoxy Adhesive ◽  
Shear Loading
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