SD
S.R. De Barros
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5 records found
1
Adhesive bonding of fiber-reinforced polymer (FRP) patches is increasingly used to strengthen steel structures. While carbon FRP (CFRP) and epoxy adhesives are the primary materials in industrial applications, this study explores hybrid Carbon/Flax FRP as an alternative for reinforcing steel plates under flexural loading. Four composite layups were tested: F5 (flax), C5 (carbon), CFC, and FC (carbon/flax hybrids). These patches were bonded to steel plates using three adhesives: a flexible and ductile silane-modified polymer (SMP-FD), a medium flexibility-ductility acrylate (ACR-MFD), and a rigid and brittle epoxy (EP-RB), representing a wide range of adhesive properties. Three-point bending tests were conducted to evaluate mechanical performance compared to unreinforced steel plates. Results demonstrated that composite patch bonding significantly enhances load-bearing capacity. The EP-RB adhesive provided the highest reinforcement, followed by ACR-MFD and SMP-FD. Hybrid FC and CFC configurations achieved reinforcement comparable to or greater than pure carbon (C5), highlighting the potential of hybrid designs for structural applications.
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Adhesive bonding of fiber-reinforced polymer (FRP) patches is increasingly used to strengthen steel structures. While carbon FRP (CFRP) and epoxy adhesives are the primary materials in industrial applications, this study explores hybrid Carbon/Flax FRP as an alternative for reinforcing steel plates under flexural loading. Four composite layups were tested: F5 (flax), C5 (carbon), CFC, and FC (carbon/flax hybrids). These patches were bonded to steel plates using three adhesives: a flexible and ductile silane-modified polymer (SMP-FD), a medium flexibility-ductility acrylate (ACR-MFD), and a rigid and brittle epoxy (EP-RB), representing a wide range of adhesive properties. Three-point bending tests were conducted to evaluate mechanical performance compared to unreinforced steel plates. Results demonstrated that composite patch bonding significantly enhances load-bearing capacity. The EP-RB adhesive provided the highest reinforcement, followed by ACR-MFD and SMP-FD. Hybrid FC and CFC configurations achieved reinforcement comparable to or greater than pure carbon (C5), highlighting the potential of hybrid designs for structural applications.
For strengthening or rehabilitation of existing structures, patches of fiber-reinforced polymers (FRP) materials are being adhesively bonded to the existing metallic structures. So far, Carbon FRP (CFRP) are the main composite materials industrially implemented for metal structural reinforcement, due to their reliability and high mechanical performances. However, multiple researchers have highlighted the negative environmental impact of synthetic composite materials, and interest is shifting towards the use and development of bio-based composite materials. This paper presents an FE numerical investigation of the use of Hybrid Carbon/Flax FRP as an alternative solution for structural reinforcement of steel plates under flexural loading. Four different configurations of patches are studied to be bonded to steel rectangular plates, and three point bending tests are numerically modelled to simulate the flexural behaviour of the assemblies. Compared to the unreinforced steel plate baseline, reinforcements C5, F5, CFFFC, and FFFCC exhibited improvements of 149%, 120%, 137%, and 145% in bending stiffness, respectively.
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For strengthening or rehabilitation of existing structures, patches of fiber-reinforced polymers (FRP) materials are being adhesively bonded to the existing metallic structures. So far, Carbon FRP (CFRP) are the main composite materials industrially implemented for metal structural reinforcement, due to their reliability and high mechanical performances. However, multiple researchers have highlighted the negative environmental impact of synthetic composite materials, and interest is shifting towards the use and development of bio-based composite materials. This paper presents an FE numerical investigation of the use of Hybrid Carbon/Flax FRP as an alternative solution for structural reinforcement of steel plates under flexural loading. Four different configurations of patches are studied to be bonded to steel rectangular plates, and three point bending tests are numerically modelled to simulate the flexural behaviour of the assemblies. Compared to the unreinforced steel plate baseline, reinforcements C5, F5, CFFFC, and FFFCC exhibited improvements of 149%, 120%, 137%, and 145% in bending stiffness, respectively.
Journal article
(2023)
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Mohamed Amine Tazi, Rosemere de Araujo Alves Lima, Enio Henrique Pires da Silva, Mouad Jebli, Sofia Teixeira De Freitas, Pascal Casari, Silvio de Barros
Using fiber-reinforced composite patches for repairing damaged structures made of metal or/and concrete is an interesting and widely available solution on the market using synthetic materials. These repairing patches are bonded on the structures’ surfaces to increase their strength against internal stresses, as well as protect them from external physico-chemical attacks, thereby limiting crack propagation. Natural fibers offer a potential alternative to replacing glass or carbon fibers commonly used for bonded repair patches. Similarly, bio-based polymers represent an important sustainable alternative for partially or entirely replacing the petroleum-based polymers. In this study, an epoxy matrix reinforced with flax fiber is proposed as the material for the patches, and bonded to a steel plate using four different types of adhesive materials, including a castor-oil derived polyurethane resin. Floating roller peel tests were performed to assess the adhesion and viability of these new patches. The resulting peeling loads and fracture surface analysis are presented. Polyurethane demonstrates promising performance for epoxy-to-steel joints, but major improvements of the bio-based polyurethane application process and curing conditions may be necessary for its successful industrial implementation.
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Using fiber-reinforced composite patches for repairing damaged structures made of metal or/and concrete is an interesting and widely available solution on the market using synthetic materials. These repairing patches are bonded on the structures’ surfaces to increase their strength against internal stresses, as well as protect them from external physico-chemical attacks, thereby limiting crack propagation. Natural fibers offer a potential alternative to replacing glass or carbon fibers commonly used for bonded repair patches. Similarly, bio-based polymers represent an important sustainable alternative for partially or entirely replacing the petroleum-based polymers. In this study, an epoxy matrix reinforced with flax fiber is proposed as the material for the patches, and bonded to a steel plate using four different types of adhesive materials, including a castor-oil derived polyurethane resin. Floating roller peel tests were performed to assess the adhesion and viability of these new patches. The resulting peeling loads and fracture surface analysis are presented. Polyurethane demonstrates promising performance for epoxy-to-steel joints, but major improvements of the bio-based polyurethane application process and curing conditions may be necessary for its successful industrial implementation.
Book chapter
(2023)
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Bamber Blackman, Fengzhen Sun, Sofia Teixeira de Freitas, Silvio de Barros, Marcio Moreira Arouche, Alojz Ivankovic
This chapter discusses the mixed-mode loading of adhesive joints. The importance of mixed-mode loading is first introduced and then test methods commonly used to measure the mixed-mode fracture resistance of adhesive joints are presented and briefly discussed. The approaches to determine the fracture resistance are briefly reviewed and then the partitioning of mixed-mode fracture energies is discussed. The limitations of the local singular field and global approaches to mixed-mode partitioning are discussed and the use and application of a semianalytical cohesive zone analysis partitioning scheme is evaluated. The limitations of the global partitioning approach are further discussed in the context of developing a scheme to design and analyze adhesive joints with dissimilar adherends (a bi-material interface). A longitudinal strain criterion is proposed in addition to the matching of flexural rigidities and the approach is validated numerically. Finally, the practical issues of crack stability, failure path selection, and the use of mixed-mode failure envelopes is considered.
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This chapter discusses the mixed-mode loading of adhesive joints. The importance of mixed-mode loading is first introduced and then test methods commonly used to measure the mixed-mode fracture resistance of adhesive joints are presented and briefly discussed. The approaches to determine the fracture resistance are briefly reviewed and then the partitioning of mixed-mode fracture energies is discussed. The limitations of the local singular field and global approaches to mixed-mode partitioning are discussed and the use and application of a semianalytical cohesive zone analysis partitioning scheme is evaluated. The limitations of the global partitioning approach are further discussed in the context of developing a scheme to design and analyze adhesive joints with dissimilar adherends (a bi-material interface). A longitudinal strain criterion is proposed in addition to the matching of flexural rigidities and the approach is validated numerically. Finally, the practical issues of crack stability, failure path selection, and the use of mixed-mode failure envelopes is considered.
This work investigates the effect of long-term environmental exposure on the performance of composite-to-metal bonded joints. Specimens are manufactured using a carbon-fiber reinforced polymer (CFRP) co-bonded to a steel member with epoxy adhesive and aged in a salt spray chamber. The mixed-mode fracture behavior of the non-aged and aged specimens is assessed using the mixed-mode bending (MMB) test apparatus. The fracture energy is calculated using the finite elements method and an analytical approach, the strain-based method (SBM). The SBM showed to be a simple and accurate method to obtain the total fracture energy and the fracture mode ratio of the bi-material specimen. Ageing increased the fracture toughness at crack initiation by 27% for specimens loaded at 20% mode II and 7% for specimens loaded at 15% mode II. This can be related to the shear behavior and plasticization of the adhesive material. During crack propagation, the fracture toughness remained similar for specimens loaded at 20% mode II and decreased by 15% in specimens loaded at 15% mode II. Fractography analysis together with chemical characterization showed that the penetration of moisture at the edges of the fracture surface produced adhesive failure in these regions affected by moisture. Moreover, the failure mode at the unaffected regions of the fracture surface shifted from cohesive to a combination of thin-layer cohesive and adhesive failure after ageing. The results contributed to describe the effect of ageing on the fracture behavior of bonded materials.
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This work investigates the effect of long-term environmental exposure on the performance of composite-to-metal bonded joints. Specimens are manufactured using a carbon-fiber reinforced polymer (CFRP) co-bonded to a steel member with epoxy adhesive and aged in a salt spray chamber. The mixed-mode fracture behavior of the non-aged and aged specimens is assessed using the mixed-mode bending (MMB) test apparatus. The fracture energy is calculated using the finite elements method and an analytical approach, the strain-based method (SBM). The SBM showed to be a simple and accurate method to obtain the total fracture energy and the fracture mode ratio of the bi-material specimen. Ageing increased the fracture toughness at crack initiation by 27% for specimens loaded at 20% mode II and 7% for specimens loaded at 15% mode II. This can be related to the shear behavior and plasticization of the adhesive material. During crack propagation, the fracture toughness remained similar for specimens loaded at 20% mode II and decreased by 15% in specimens loaded at 15% mode II. Fractography analysis together with chemical characterization showed that the penetration of moisture at the edges of the fracture surface produced adhesive failure in these regions affected by moisture. Moreover, the failure mode at the unaffected regions of the fracture surface shifted from cohesive to a combination of thin-layer cohesive and adhesive failure after ageing. The results contributed to describe the effect of ageing on the fracture behavior of bonded materials.