scholarly journals Fracture toughness of structural adhesives for the automotive industry

2018 ◽  
Vol 8 ◽  
pp. 561-565 ◽  
Author(s):  
Marco Alfano ◽  
Chiara Morano ◽  
Fabrizio Moroni ◽  
Francesco Musiari ◽  
Giuseppe Danilo Spennacchio ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Automotive Industry ◽  
Structural Adhesives

Designing Soft Reactive Adhesives by Controlling Polymer Chemistry

MRS Bulletin ◽  
2003 ◽  
Vol 28 (6) ◽  
pp. 424-427 ◽  
Author(s):  
Agnès Aymonier ◽  
Eric Papon
Keyword(s):  
Automotive Industry ◽  
Ease Of Use ◽  
Large Strains ◽  
Structural Adhesives ◽  
Wide Range ◽  
Step Growth ◽  
Visible Irradiation ◽  
Step Growth Polymerization ◽  
Uv Visible ◽  
Activation Heat

AbstractSoft reactive adhesives (SRAs) are polymer-based materials (e.g., polyurethanes, polysiloxanes, polydienes) designed to be further vulcanized or slightly cross-linked through external activation (heat, moisture, oxygen, UV–visible irradiation, etc.), either at the time of their application or within a subsequent predefined period. They are used mainly as mastics, or sealing compounds, in a wide range of industrial and commercial fields such as construction, footwear, and the automotive industry. Generally deposited as thick films, SRAs behave as structural adhesives; their low elastic moduli accommodate large strains between the bonded parts without incurring permanent damage. Other outstanding attributes of SRAs are their resistance to solvents, their ability to withstand aggressive environments, and their ease of use. This article discusses examples of SRAs and, more specifically, shows how the cross-linking chemistry, mainly through step-growth polymerization, provides their primary advantages.

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.

Applied Research of the Flexible Epoxy Resin Curing Agent

2012 ◽  
Vol 535-537 ◽  
pp. 2499-2502
Author(s):  
X. Wang ◽  
S. R. Zheng ◽  
R. M. Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Applied Research ◽  
Curing Agent ◽  
Structural Adhesives ◽  
Resin Curing ◽  
The Impact

Epoxy resin structural adhesives modified by flexible curing agent. Dependening on the mechanical properties of epoxy resins on the flexible curing agent content was studied. The impact fracture toughness was discussed in terms of fracture surface fractography.

New Developments in Structural Adhesives for the Automotive Industry

1987 ◽  
Vol 22 (2) ◽  
pp. 153-165 ◽  
Author(s):  
U. T. Kreibich ◽  
A. F. Marcantonio
Keyword(s):  
Automotive Industry ◽  
New Developments ◽  
Structural Adhesives

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.

scholarly journals Comparative Study of the Impact Wedge-Peel Performance of Epoxy Structural Adhesives Modified with Functionalized Silica Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 469
Author(s):  
Gyeong-Seok Chae ◽  
Hee-Woong Park ◽  
Kiok Kwon ◽  
Seunghan Shin
Keyword(s):  
Fracture Toughness ◽  
Silica Nanoparticles ◽  
Functional Groups ◽  
Impact Resistance ◽  
Crosslinking Density ◽  
High Energy ◽  
Mode I ◽  
Mode I Fracture ◽  
Structural Adhesives ◽  
Mode I Fracture Toughness

Epoxy structural adhesives have strong adhesion, minimal shrinkage and high thermal and chemical resistance. However, despite these excellent properties, their high-energy impact resistance should be improved to satisfy the increasing demands of the automotive industry. For this reason, we used four types of silica nanoparticles with different surface groups, such as polydimethylsiloxane (PDMS), hydroxyl, epoxy and amine groups, as toughening agents and examined their effect on the glass transition temperature (Tg), crosslinking density and phase separation of epoxy structural adhesives. High-energy impact resistance, mode I fracture toughness and lap shear strength were also measured to explain the effect of surface functional groups. Silica nanoparticles with reactive functional groups increased the mode I fracture toughness of epoxy structural adhesives without sacrificing the crosslinking density. Although the mode I fracture toughness of epoxy structural adhesives could not clearly show the effect of surface functional groups, the dynamic resistance to cleavage obtained by impact wedge-peel tests showed quite different values. At a 0.3 vol% content, epoxy-functionalized silica nanoparticles induced the highest value (40.2 N/mm) compared to PDMS (34.1 N/m), hydroxyl (34.9 N/mm), and amine (36.1 N/m). All of these values were significantly higher than those of pristine epoxy structural adhesive (27.7 N/mm).

Light Weight Steel Technology Used in a Vehicle Design: Safety CAE Analysis

2001 ◽  
Author(s):  
Jamil M. Alwan ◽  
Chi-Chin Wu ◽  
Thomas H. Sheng ◽  
Chunhui (Kevin) Li ◽  
Yi Liu
Keyword(s):  
Fuel Consumption ◽  
Automotive Industry ◽  
Weight Reduction ◽  
High Strength Steel ◽  
High Strength ◽  
Structural Adhesives ◽  
Tailor Welded Blanks ◽  
Ultra High Strength Steel ◽  
Environmental Requirements ◽  
Structural Foams

Abstract The automotive industry is facing new environmental requirements that call for more stringent rules to protect the environment and reduce material and resources usage. As such, the automotive industry is in more need to reduce fuel consumption and control emissions in order to meet the new environmental requirements. One of the methods that helps in acheiving lower fuel consumption targets is weight reduction. Making cars lighter sounds plausable, but is it acheivable without affecting vehicle Safety as well as other customer demands for more comfort and better vehicle performance (Criteria that are a must in today’s stringent safety requirements and competitive environment.). The body-in-white (BIW) accounts for about 25% of the total vehicle weight, and thus it provides a great opportunity for weight reduction. However, the challenge is not only to reduce the vehicle’s BIW weight, but also to maintain competitive vehicle functionality in Safety, NVH and Durability. The studied technologies include: Generic Body Architecture, Tailor Welded Blanks, Ultra High Strength Steel, Structural Foams, and Structural Adhesives. Each of these technologies was benchmarked in terms of weight savings, vs Safety, NVH, and Durability functionalities. The models that were used for the technology prove outs are based on generic modified Body Architecture CAE models. It was shown that the total weight savings acheived from architecture alone was 24 lb (out of 707 lb initial BIW weight, thus making the weight savings close to 3.4%). In addition, the combination of Tailor welded blanks and Ultra high strength steel has resulted in an 80 lb reduction in the BIW weight, which is close to 11.3%. Structural foams showed an effective increase in roof crush strength, and showed potential enhancement for frontal crash pulses as well as potential shortening of front ends. On the other hand, structural adhesives showed enormous NVH benefits in stiffness with as little as 1% energy absorption enhancement for crash. Thus producing the perfect method to compensate the reduced body stiffness due to sheet metal gage reduction and replacement with Ultra High strength steel. By such both safety and NVH functionalities are complemented without weight increase.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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