João Reis

Universidade Federal Fluminense | UFF · Mechanical Engineering Department (TEM)

Adhesive joints GFRP/Steel bonded with epoxy adhesive were exposed to the external environment for one year, a tropical environment with temperature variations, humidity, radiation, and salt spray, due to its proximity to the sea. The shear strength of the joint was measured over the exposure time, as well as their chemical and physical changes. Tg...

Glass Fiber Reinforced Polymer (GFRP) is commonly used in outdoor applications that expose it to environmental conditions capable of degrading its properties, notably ultraviolet (UV) radiation. In this study, we subjected GFRP to UV radiation for a duration of up to 180 days in an accelerated aging chamber. The composites underwent mechanical test...

The use of bonded composite patches is a promising repair/reinforcement method to extend service live of damaged structures. These patches are non-corroding, lightweight, easy to fabricate and have high specific modulus and strength. In this work, the tensile behavior of a patch-reinforced composite specimen with a central hole is analyzed experime...

Polypropylene (PP) is a semi-crystalline thermoplastic polymer that is often used to make automotive parts, packaging for consumer products and medical components, among others. The present paper focuses on the analysis of the thermomechanical behaviour of PP specimens in monotonic tensile tests at different strain rates and variable temperatures....

Metal structures can be repaired with composites using adhesives. However, because it involves polymeric materials, the environmental conditions of the structure can modify the behavior of the material, making its use unfeasible. Ultraviolet radiation (UV) is a degradation agent that has strong action on the polymeric materials, which are present i...

The present paper is concerned with the investigation of the inelastic behaviour observed in load-unload cyclic tests performed at 50°C in single lap joints composed of a polyurethane based composite reinforced with fibreglass bonded to an ASTM A1020 steel substrate using an epoxy adhesive. The experiments presented in this research show that the i...

Polymeric nanocomposites composed of an organic matrix and inorganic nanoparticles makes a useful union of the polymer functionalities, such as low weight and moldability, with the good mechanical, thermal and electrical properties of the nanofillers. The possibilities to improve mechanical or thermal properties, developing a new material, by nanop...

The application of adhesively bonded joints in petroleum industry over other traditional joining methods has increased significantly in recent years mainly because of the potential for light weight structures, fast repairing systems and low temperature applications. The principal benefits are design flexibility and joining of dissimilar materials....

This paper is concerned with the repair of through-wall corrosion damage in metallic pipes using bonded metallic patches. The focus is on the analysis of the influence of the thickness of the patch on the effectiveness of the repair. The goal is to assure that the pipe won’t leak once the repair is completed. Usually, in practical applications, a c...

This work investigates the repair of corrosion damage in metallic pipes using glass fiber reinforced plastic (GFRP) patches. The main idea is to analysis of the effect of the thickness of the GFRP patch and the patch surface roughness on the effectiveness of the repair. Commonly, to perform such repair, a composite sleeve wrap is used according to...

In recent decades, it has become essential to find and develop materials from non-petroleum sources that are more compatible with nature. The present work describes the mechanical properties of a composite with epoxy matrix reinforced with natural Curaua fibers. To improve the matrix-fiber interaction, the Curaua fibers were immersed in solutions w...

The present paper investigates the effect of temperature of unplasticized polyvinyl chloride (UPVC) under tension. UPVC specimens were tensile tested across a range of temperatures (from −20°C to 60°C). The UPVC, like other polymers, was strongly affected by temperature. Those below room temperature were more fragile but had greater tensile strengt...

Through-wall corrosion damage in pipelines can be repaired using a bonded metallic patch. Several parameters influence the repair performance, such as the surface preparation. Offshore oil platforms are restricted areas, and sparkling derived from surface preparation can have drastic consequences. Additionally, an industrial climber is required to...

The popularity of composite repair systems for underwater and underground pipelines has soared in recent times. The long-term performance of these repair systems must be verified under field conditions to gain confidence for any future applications. This article presents a result of long-term high-pressure hydrostatic tests of a composite repair sy...

Composite repair systems for metallic pipelines presenting a through-wall defect must be qualified in accordance with either ISO 24817 or ASME PCC-2 standards. This qualification method requires a number of hydrostatic tests to obtain the failure pressure. In the oil and gas industry, the failure pressure estimation is often performed using a linea...

The present paper presents an analysis of the thermal aging process of a polyamide 66 at two different temperatures: −6 °C and 60 °C, and throughout a time span of 9000 h. The paper proposes a unified expression to estimate the mechanical behavior of the polyamide in tensile tests at the different aging stages. The goal is to present an algebraic e...

Diesel is an important fuel, partly because of the longevity and cleanliness of diesel engines. Often, polymers are in direct contact with diesel and understanding compatibility is critical. Polyoxymethylene (POM) is a thermoplastic used to manufacture automotive fuel pump gears and rotors due to its low coefficient of friction and thermal and dime...

The wide use of polymer matrix composites requires a greater understanding of their characteristics, especially the electrical conductivity at different conditions. These materials have attractive combination of properties, and they can replace with lower cost and greater efficiency metallic components. In this work, the electrical conductivity at...

Investigation of lignocellulosic fibers in polymeric composites is important for development of green technologies, to reduce the weight and cost of materials and reduce pollutant emissions. In this work, the influence of piassava fiber length was evaluated to verify the mechanical response when incorporated in fiber-reinforced epoxy composites con...

Composite structures currently used in the oil industry must meet strict requirements for design and safety reasons. They need to maintain strength under varied displacement rates throughout its lifetime. It is therefore critical to fully understand the fracture behavior of such composites. This work presents experimental results regarding the infl...

This paper is concerned with the failure analysis of elasto-plastic thin-walled pipes under combined internal pressure and axial loading (monotonic or alternating). Depending on the loading history (pressure and axial loading histories) the pipe may exhibit a different mechanical behavior due to the progressive accumulation of plastic deformation....

The mechanical behaviour of polymeric materials presents some peculiarities, especially regarding the evolution of their hardening under stresses above the proportional limit. For many types of polymers (Epoxy, Polyamides, Polyvinylidene, etc.) the elastic properties are not rate-dependent, and the behaviour is elasto-viscoplastic. Also, in the cas...

Natural fiber research is getting attention worldwide due to its sustainability and ecofriendly nature. It combines low density and interesting properties. Curaua fiber is an abundant natural fiber, which has low cost and several applications. The mechanical properties have a strong dependence on the interface adhesion between the fiber and the pol...

The design and qualification of composite repairs for pipelines usually requires hydrostatic tests for the determination of the failure pressure. In this work, the use of a shaft blister test to assess the failure pressure of composite repairs is proposed. Blister tests were conducted to investigate the interfacial debonding of a composite plate bo...

The modification of polymer properties through the addition of nanoparticles has lead to the development of the so-called nanocomposites. The purpose of this study was to observe the glass transition temperature by Differential Scanning Calorimetry (DSC) in epoxy/alumina nanocomposites. Analysis was carried-out for different volume fractions, rangi...

In this work, the mechanical response of a composite material based on glass fibers embedded in an epoxy resin was experimentally studied as a function of strain rate and temperature. It was shown that for the temperature range from 23 to 100 °C the elastic properties of the composite are significant affected and the strain rate influences only the...

The present paper proposes a unified expression to estimate the mechanical behaviour of polyamides in tensile tests at different temperatures. The goal is to present an algebraic equation able to describe the stress-strain curves that would be obtained using the ASTM D638-14 standard for a wide range of temperatures (roughly from -30 °C to 90 °C, e...

Adhesively bonded joints are being widely used in the fabrication process of aircraft and automobile structures. Surface roughness is an important parameter of product quality that strongly affects the performance of mechanical parts, as wel as production costs. This parameter highly influences the mechanical properties overall of such structures....

The research of natural fiber composites is growing due to the fact that the green materials combine low weight with good mechanical properties. Curaua fiber arises as a competitive natural fiber due to its abundance, low cost and a variety of applications. In this work, different weight fractions of Curaua fiber were used in order to obtain this n...

The present paper aims to perform an experimental and theoretical study regarding the inelastic deformation progressive accumulation observed in a polyvinylidene fluoride (PVDF) specimen machined from flexible pipe internal pressure sheaths under cyclic load-unload tensile tests and in monotonic tensile tests. Experiments show that the elastic mech...

Addressing the environmental problems caused by waste generated by Tetra Pak packaging, in this work, polyester based composites with 80% of polyester resin and 20% of silica sand were elaborated; where the silica sand was partially replaced by recycled cellulose from waste Tetra Pak containers at concentrations of 1, 2, 4 and 6% by weight. Both re...

The purpose of this work is to investigate the behavior of the epoxy diglycidyl ether of bisphenol A (BADGE) reinforced with carbon nanotubes when tested in tensile and flexural modes at different cross-head rates and temperatures. Tensile and flexural tests were performed under three temperatures (25 °C, 50 °C and 75 °C), varying the cross-head ra...

The use of composites to repair localized corrosion damage in metallic pipelines has significantly increased in the past years. Repair techniques using polymer-based composites are interesting, since they do not require draining the line and stop operation. However, pipelines conveying liquids may work at elevated temperatures, what can be a limita...

Despite of some polymeric compounds vulnerability to different types of radiation, high polymer, as epoxy adhesives, had prospered in the nuclear industry because their mechanical properties to high doses of ionizing radiation is maintained. Because of this, epoxy adhesives are widely used in nuclear applications: nuclear power plants, aerospace co...

This research work aims to experimentally evaluate the fracture mechanics of polymer mortars reinforced with barley residue from the brewing industry. Barley reinforced polymer mortar samples were manufactured from 1% to 10% of barley residue, in weight, as aggregate substitute. Then, the resin content was varied from 12% to 20% in 5% of barley res...

In offshore installations, the use of piping is crucial for transporting different kinds of fluids. In this kind of environment, corrosion is one of the major damage mechanisms of the metallic pipelines, due to aggressive fluid and atmosphere. Duplex and Super duplex stainless steel pipes are increasingly being used in offshore platforms due to the...

Polymers are viscoelastic materials and the use of polymeric materials has grown on the world stage due to its good mechanical properties. In the oil area, the polymeric materials are often used in the manufacture of some of the layers that make up the flexible tubes. Dynamic Mechanical Analysis is an excellent method to obtain information about vi...

Despite of some polymeric compounds vulnerability to different types of radiation, high polymer, as epoxy adhesives, had prospered in the nuclear industry because their mechanical properties to high doses of ionizing radiation is maintained. Because of this, epoxy adhesives are widely used in nuclear applications: nuclear power plants, aerospace co...

The present paper is concerned with the experimental and theoretical investigation of the progressive accumulation of inelastic deformation observed in cyclic tension tests performed on a particular polyamide. The elastic properties are not strongly affected by the strain rate, but the strain hardening induced by the plastic deformation is rate-dep...

The present paper is concerned with the experimental investigation of the progressive accumulation of deformation observed in cyclic tension tests performed in a polyamide (nylon 12). The elastic properties are not strongly affected by the strain rate, but the strain hardening induced by the plastic deformation is rate-dependent. Thus, the material...

The temperature effect on bending and shear strength of single lap joints, composed by metal-composite substrates with fixed geometry was evaluated in this paper. The tests provide analysis associated with a system frequently used in the oil and gas industry, characterized by the use of polymeric composite materials with adhesives for repairing and...

There is a growing demand for polymeric composite materials, mainly, in industrial applications. For instance, bipolar plates for polymer electrolyte fuel cell in automobile applications. This kind of composite can replace with lower cost and greater efficiency metallic components. The basic requirement is that the composite must possess adequate e...

The object of this study was to evaluate the flexural strength of glass fiber reinforced polyurethane composites under variable displacement rates. Flexural tests have been conducted at a range of displacement rates included 0.2, 2, 20, 100, 200, 1000 mm/min. Specimens with identical geometry have been used in all the tests. This particular composi...

The thermomechanical behavior of Polyvinylidene fluoride (PVDF) was studied. The experiments were performed under a range of temperatures (50 ° C up to 130 ° C). The temperature greatly influences the mechanical response of PVDF. In particular, the yield stress is increased with decrease in strain rate for the lower temperatures and the ultimate te...

In the construction of a flexible pipe, an inner polymeric pressure sheath is the only layer which seals the conveyed fluid within the pipe structure. Therefore, understanding the mechanical behaviour of this polymer material is crucial to safe and reliable operation. Polyamide is a commonly used pressure sheath material, other options being polyvi...

Mixed-mode fracture, in the form of critical stress intensity factors of polymer mortar reinforced with particles from waste Tetra Pak® aseptic carton packages was investigated. Data from previous work was used for conclusions on this work. Slight increase and subsequent decrease in critical stress intensity factors was observed with the addition o...

The present work is concerned with the analysis of composite sleeve reinforcement systems for metallic pipelines with localized corrosion that impair the serviceability. In these systems, a piping or vessel segment is reinforced by wrapping it with concentric coils of composite material. The goal is to propose a simple methodology to estimate the f...

Most of the currently available technologies require the use of materials with unusual combinations of properties that cannot be met by the metallic alloys, ceramic or conventional polymeric materials. The polymer composites are designed to meet the requirements and challenges of the industry, where there is an increasingly growing demand for speci...

Waste reuse has become increasingly important in construction, especially when it deals with the reduction on the consumption of natural materials and use of waste from other industries. The purpose of this work was to evaluate the use of red mud waste, alumina metallurgical residue, as natural aggregate substitute in epoxy polymer mortars. Various...

Withdrawn by author’s request

The thermomechanial properties of polymeric nanocomposites are related to the quality of the adhesion between matrix and nanoparticle. Since the adhesion is related to the nature of the materials and the surface available for chemical, electrostatic and mechanical interactions among these materials, weak bonding forces between alumina (inorganic) a...

The interest of many research groups regarding manufacture of composite materials by using natural fibers is increasing world-wide. The main objectives involve the improvement of mechanical properties, mainly those related to resistance and elasticity. In the present study in a first stage, polymer concrete specimens were elaborated by using an uns...

There is a growing demand for polymeric composite materials, mainly, in Industrial applications. For instance, bipolar plates, for polymer eletrolyte fuel cell, in automobile applications. This kind of composite can replace with lower cost and greater efficiency metallic components. The basic requirement is that the composite must possess adequate...

Design of polymer concrete involves extensive studies on their materials in order to get improved properties; specifically on the physicochemical properties of both polymer resin and mineral aggregates, including size and shape of the last one. Alternative studies are focusing on using different materials or methods to obtain such improvements. In...

In the last years, ecological concerns have resulted in the interest to substitute petroleum-based materials by renewable resources-based ones. Natural oils constitute an excellent alternative for the development of natural composites. The aim of this work is to evaluate the use of natural polymer, manufactured from castor oil, as substitute to syn...

Aluminum is one of the most abundant elements, and its global production generates an immense amount of industrial waste, which is the red mud. Thus, it is necessary to develop technologies aimed to reusing red mud. In this context, this work aims to experimentally examine variations in the effective thermal conductivity of polymers, modified with...

Construction industry has a significant grow in the past few years. Following that rate, the amount of residue produced from that growth also increases. The need to find alternatives apart from disposing that residue in landfills have led researchers to find new materials from disposal residues. In this paper, kraft paper from cement bags used in b...

From the past decades, growing global awareness concerning natural resources and recycling has resulted in the interest on biocomposites. Natural fibers embedding on natural polymers constitute an excellent alternative for the development of biocomposites. The aim of this work is to evaluate the use of natural fibers, piassava (Attalea Funifera Mar...

The purpose of this work is to investigate experimentally the effects of mixed-mode I/II loading on the fracture behavior of polymer mortars. Three point bend beam specimens with offcenter notch were used in plane-strain fracture toughness tests. Two approaches have been simultaneously used to determine the crack opening displacements. The crack mo...

The modification of polymer properties through the addition of nanoparticles has lead to the development of the so-called nanocomposites. The purpose of this study was to investigate the effect of Al2O3 and CuO nanoparticles on the thermo-physical properties of epoxy- and polyester-based nanocomposites. Analysis was carried out for different volume...

The increasing awareness of the environment protection has contributed to concerns regarding alternative procedures for recycling of plastic wastes. Since chemical processes are high cost, energy and often environment harmful, thermo-mechanical techniques of recycling rises as a good alternative. This research deals with mechanical characterization...

The wide use of polymer matrix composites requires a greater understanding of their characteristics, especially the electrical conductivity at different conditions. These materials have attractive combination of properties, they can replace with lower cost and greater efficiency metallic components. In this work, the electrical conductivity at diff...

The wide use of polymeric composite requires a greater understanding of their characteristics. These materials have attractive combination of properties, it can replace with lower cost and greater efficiency, metallics components. The basic requirement is that the composite must possess adequate electrical and mechanical properties for the particul...

The wide use of polymeric materials requires a greater understanding of their characteristics. It is necessary to know the behavior of these materials when subjected in their use conditions. These materials have attractive combination of properties, it can replace with lower cost and greater efficiency, metallic components. One of the many examples...