Resin Flow Research Articles

Multiphysics simulation of an anisothermal reactive spontaneous capillary rise between electric rotor wires

Introduction: The rotor is the mobile component of an electric motor. A wound rotor is composed primarily of a steel core with insulated copper wires wound around it, after which the winding is immersed into a liquid acrylate-based thermosetting resin bath whose role is to ensure the performance and durability of the motor. This impregnation with resin between the wires occurs under controlled temperature settings to facilitate resin flow and polymerization. This process does not involve any pressurization to further facilitate resin flow between the wires; this suggests that, in addition to viscous effects, capillary and gravity forces play a significant role in the impregnation process.Methods: Our ultimate objective is to evaluate the quality of this impregnation. Doing so requires the characterization and simulation of a multi-material and multiphysics process in which heat transfer, polymerization kinetics, and resin flow are strongly coupled. This paper presents a fully coupled macroscopic multiphysics simulation of a unidirectional thermo-regulated capillary rise set-up.Discussion: The modeling choices made produced a good level of agreement with experimental data and enable explanation of a sudden change of regime observed at 120°C, which can be attributed to the polymerization and thermal gradients and their impact on fluid dynamics.

Necrophagy by insects in Oculudentavis and other lizard body fossils preserved in Cretaceous amber

When a vertebrate carcass begins its decay in terrestrial environments, a succession of different necrophagous arthropod species, mainly insects, are attracted. Trophic aspects of the Mesozoic environments are of great comparative interest, to understand similarities and differences with extant counterparts. Here, we comprehensively study several exceptional Cretaceous amber pieces, in order to determine the early necrophagy by insects (flies in our case) on lizard specimens, ca. 99 Ma old. To obtain well-supported palaeoecological data from our amber assemblages, special attention has been paid in the analysis of the taphonomy, succession (stratigraphy), and content of the different amber layers, originally resin flows. In this respect, we revisited the concept of syninclusion, establishing two categories to make the palaeoecological inferences more accurate: eusyninclusions and parasyninclusions. We observe that resin acted as a “necrophagous trap”. The lack of dipteran larvae and the presence of phorid flies indicates decay was in an early stage when the process was recorded. Similar patterns to those in our Cretaceous cases have been observed in Miocene ambers and actualistic experiments using sticky traps, which also act as “necrophagous traps”; for example, we observed that flies were indicative of the early necrophagous stage, but also ants. In contrast, the absence of ants in our Late Cretaceous cases confirms the rareness of ants during the Cretaceous and suggests that early ants lacked this trophic strategy, possibly related to their sociability and recruitment foraging strategies, which developed later in the dimensions we know them today. This situation potentially made necrophagy by insects less efficient in the Mesozoic.

Effect of void formation according to resin content on composite joint area

The field of application of Glass Fiber Reinforced Polymer expands as well as the size of the component where composite material is applied. Due to the size limitation of the prepreg used, it is difficult to apply 1ply to large parts. Many studies have been reported on the bolt joint that assembles parts and parts for the joint area, butt and overlap design for joining dissimilar materials, and mechanical properties. Although the mechanical properties of the joint areas are important, studies on the microstructure are also needed. In this study, the microstructure was observed by controlling the type of subsidiary materials in the bagging process by applying prepregs of the same composition. It was found that the air and resin flow inside the prepreg acted differently depending on the type of subsidiary material. The flow of resin during curing was inferred from the influence of subsidiary materials and explained by connecting it with the microstructure. The behavior of the resin determined thickness, resin, and void contents of the composite. This flow affects voids in the joint area, causing differences in microstructure and mechanical properties. There was no significant difference in the tensile strength of the laminate specimens manufactured according to the process, but the minimum strength was found in the specimens containing many void contents. The joint specimen showed a decrease in strength as the void content increased. It was discussed that this reduced the adhesive force of the specimen due to the effect of the void generated in the joint area.

An Overview of the Measurement of Permeability of Composite Reinforcements.

Liquid composite molding (LCM) is a class of fast and cheap processes suitable for the fabrication of large parts with good geometrical and mechanical properties. One of the main steps in an LCM process is represented by the filling stage, during which a reinforcing fiber preform is impregnated with a low-viscosity resin. Darcy's permeability is the key property for the filling stage, not usually available and depending on several factors. Permeability is also essential in computational modeling to reduce costly trial-and-error procedures during composite manufacturing. This review aims to present the most used and recent methods for permeability measurement. Several solutions, introduced to monitor resin flow within the preform and to calculate the in-plane and out-of-plane permeability, will be presented. Finally, the new trends toward reliable methods based mainly on non-invasive and possibly integrated sensors will be described.

Flow, curing and mechanical properties of thermoset resins – wood-fiber blends for potential additive-manufacturing applications

ABSTRACT This study examined the use of softwood mill residues (50–90%) with two thermosetting resins (i) urea-formaldehyde (UF) and (ii) phenol-resorcinol-formaldehyde (PRF) resin, for potential use in additive manufacturing (AM) of wood composite materials. The curing behavior of these blends was evaluated using differential scanning calorimetry and dynamic rheology. Curing kinetics was determined using the Kissinger and Cranes method. The presence of wood fibers reduced the curing peak temperatures for both resin blends at the same heating rates but curing peak temperatures increased with heating rates. The activation energy (Ea ) increased with the addition of wood for the wood-PRF blends but reduced for the wood-UF blends in comparison to the neat resins. Ea values were 51 and 271 kJ/mol for PRF and wood-PRF samples and 100 and 367 kJ/mol for UF and wood-UF samples. Frequency sweep flow curves of the green wood-resin blends showed shear thinning behaviors with viscosity values between 103–108 Pa.s at 30°C. Mechanical properties of the wood-resin composites generally showed a reduction in flexural modulus with an increase in wood content. Wet wood (50%)-PRF blend was successfully extruded and showed promise for use in AM; however, the wood-UF blend was not successful.

Simple stitch-assisted carbon fiber-aluminum laminates via out-of-autoclave process

Fiber–metal laminates (FMLs) are hybrid materials that provide the advantages of both metal and fiber-reinforced polymer composite (FRP) such as improved damage tolerance and impact strength, particularly in aerospace and automotive applications. However, the production of FMLs remains expensive because the manufacturing process is performed in an autoclave. In addition, delamination failure due to low interfacial adhesive strength between the metal and fiber layer is a problem that must be solved to improve the mechanical properties of FMLs. In this study, simple stitch-assisted carbon fiber-aluminum laminates were developed using vacuum-assisted resin transfer molding (VARTM). The FMLs produced through vacuum-assisted resin transfer molding were stitched with aramid fibers through holes on Al sheets for the resin flow associated with the VARTM. The mechanical properties of the FMLs were investigated by impact and compression after impact tests as well as double cantilever beam and flexural tests. The stitching effectively improved the interfacial strength and toughness owing to the anchoring between the aluminum and carbon fiber layers, thus preventing delamination crack propagation. As a result, the stitched FML with significantly improved interfacial adhesive and toughness was developed by the VARTM process, which will accelerate the application of FML to various lightweight structures.

Process-induced damage and its effect on strength of composite - aluminum alloy joint by FDS technique

Flow drilling screw (FDS) is a novel joining technique that enables high-speed joining of dissimilar metals with one-shot process of hole machining, female thread forming and fastening from one side. The damage after FDS process and its effect on joint strength and fracture behaviour near the screw by load-bearing tests for FDS joints between aluminum alloy and carbon fibre reinforced thermoplastics (CFRTP) are evaluated. Cross-sectional observation after joining process reveals that delamination in CFRTP is clearly suppressed and matrix resin is filled in the screw thread compared to the case with CFRP using thermosetting resin. In the joint strength test with shear loading and the cross-shaped tensile tests where the screw is pulled out in its axial direction, only the fibre micro-buckling is observed until fracture. These experimental results recommend that CFRTP laminates should be applied as composite side since this technique utilizes frictional heat by the screw that can contribute to plastic flow or deformation of the thermoplastic resin with high fracture toughness. It is also clarified that damage growth is further suppressed by using CFRTP/Al hybrid laminates where aluminum alloy sheets are inserted between CFRTP plies, which leads to improve the joint strength.

Разработка укрупнённого адсорбера для переработки продуктивных растворов

Productive solutions obtained after leaching of ores have a complex composition, including a variety of non-ferrous and heavy metal cations. The method of extracting nickel from productive solutions after leaching of sulfide and lateritic ores is the most important process in hydrometallurgical processing. Sorption by ion-exchange resins is an alternative to existing technologies for nickel recovery from productive solutions. The ability to selectively extract nickel and regenerate makes polymeric ion-exchange resins one of the most popular sorbents in the modern world. The polymer resin sorption process avoids wastage of reagents, costly filtration, and poor nickel selectivity compared to other metal ions associated with solvent extraction processes. In order to conduct experimental studies of sorption using Amberlite IRC 748 polymer resin, it is necessary to calculate and design an adsorber. The objectives of the study include the determination of the geometric parameters of the adsorber, the parameters of the sorption/desorption process and the development of a process flow diagram. As a result of the research, an enlarged adsorber has been designed to extract nickel from the productive solution after bacterial-chemical oxidation of cobalt-copper-nickel sulfide ore, and a process flow diagram for the process of obtaining nickel salts from the productive solution has been developed. The volume of the adsorber, its height, diameter, diameter of the inlet fitting, the height of the sorbent layer, the required resin flow rate, and the duration of the process before regeneration are determined. To ensure the continuity of the process, taking into account the duration of bacterial-chemical oxidation, periodic regeneration of the sorbent, the number of adsorbers in a common installation is taken to be two. When the adsorption stage occurs in one of the apparatuses, the stage of regeneration and drying of the polymer resin proceeds in the other. The estimated sorption capacity of Amberlite IRC 748 resin was taken as 21.6 g of nickel per 0.1 kg of adsorbent. Resin desorption has been supposed to be carried out with a 10 % sulfuric acid solution, at a flow rate of 5 l/h.

Application of capacitive sensors and controlled injection pressure to minimize void formation in resin transfer molding

AbstractVoid formation as a result of irregular resin flow at the flow front is discussed and a practical method for reducing void formation during resin transfer molding (RTM) is introduced. In this study, a sensor system is developed for in situ measurement of resin velocity inside a closed cavity. Assisted by the acquired data, a resin injection system is augmented to automatically adjust the injection pressure and achieve a uniform flow front velocity. It is proven, that the developed system is suited to monitor the resin flow front and is able to sufficiently control flow velocity of a linear flow front. Test specimen produced by this method show significantly reduced void contents in comparison to a common resin transfer molding process.

Visualization and investigation of healing mechanism in carbon fiber reinforced Elium® composites

In this study, carbon fiber/Elium® composites are manufactured using the resin infusion manufacturing technique. Artificial cracks representing impact-induced delamination are incorporated during layup. The laminates are subsequently healed using several healing parameters. The bonding mechanisms are investigated through microscopic analyses and X-ray Computed Tomography (XCT). The mechanical performance of the healed composites is investigated through four-point bending tests. It is found that as the healing temperature is increased, the cracks are gradually healed by interdiffusion and macroscopic resin flow across each crack interface. The 3D models generated from XCT images show an increase in solid volume fraction from 48% to 70% at the optimum healing parameters. The flexural strength and flexural modulus of the undamaged composites subjected to optimized healing condition are significantly increased relative to the room temperature cured pristine samples. The residual flexural strength of the damaged samples healed at the optimum parameters is 96% of the reference condition. The SEM images confirm that delamination from the previously-healed crack interfaces is the most dominant failure mode in the healed samples, in contrast to fiber fracture and brittle failure in the undamaged reference composite samples. The results show that the damaged composite laminates can be effectively healed and repaired to as good as undamaged laminates using the interdiffusion mechanism.

Preform Porosity and Final Thickness Variability Prediction after Controlled Post-Infusion External Pressure Application with the FEA Model

One of the reasons for the insufficiently wide use of the low-cost and low-labor vacuum infusion process in the production of polymer composite structures is the uneven distribution of pore pressure, porosity, and preform thickness at the final stage of filling the preform with liquid resin. This article presents the results of a theoretical study of the factors that govern the effectiveness of the known method of external controlled pressure on the preform in order to eliminate or significantly reduce the listed disadvantages. The study includes an analysis of scenarios for the implementation of this method, which differ in the state of the resin gate when external pressure is applied to the preform (open or closed), as well as the pressure in the vacuum vent (maintained unchanged or gradually increased to atmospheric pressure). The research tool was a finite element (FE) model that simulates resin flow according to Darcy’s law and controlled boundary conditions for a thin-walled rectangular preform. The results of the study confirmed the effectiveness of the process in achieving a more uniform distribution of porosity and preform thickness and are good qualitative agreement with the results of borrowed experiments, revealing the conditions for the occurrence of critical situations associated with the possible penetration of air into the preforms through the vacuum port and the reverse flow into the preform of the resin previously forced out through the resin gate.

DESIGN AND CONSTRUCTION OF MIXER WITH VARIABLE SPEED FOR MANUFACTURING NANOPARTICLE COMPOSITE MATERIALS

Variable speed mixer machine is a tool to help stir and mix resin with nanoparticles, design and build of the mixer plan the design of the variable speed mixer which aims to make the resin viscosity more evenly distributed in the manufacture of composites and determine the performance of the equipment produced by the variable speed mixer. This is because in manual mixing the mixed materials such as resin nanoparticles have not been mixed evenly or homogeneously. This mixer design tool can be used as a basis for developing work in the field of composite mixing, problems in composite manufacturing include; resin flow control and how to prevent the occurrence of white spots (white dots in the composite). y designing and using this variable speed mixer machine, the results of designing a mixer image with variable speed control using solid works software is the first step in working on a mixer design with variable speed control, after having data in the form of design drawings, a product design in the form of a mixer with variable speed is obtained. . speed control. It is known that the specifications of the mixer with variable speed for composites and nanoparticles are known, it is known that the working principle of a mixer with variable speed control for composites and nanoparticles can make the viscosity mixed more evenly. because the stirring speed regulated by the speed control has a constant speed. The results of testing the mixer machine with speed control, namely the motor can work according to the design plan, where the motor can produce rotation with the required variations and can be adjusted as needed.

Effect of the subsidiary materials of the manufacturing process on the microstructure of the composite laminate

AbstractComposite specimens with resin contents of 33.5%, 35.4%, and 35.9%, respectively, were manufactured by controlling the type of subsidiary material used in the bagging process for a composite material having the same composition. The effect of controlling the resin content on the microstructure and mechanical properties of composite specimens was investigated. The flow of resin and air during the cure process was inferred and explained by connecting it with the microstructure. Specifically, the behavior of the resin determined the thickness, density, and void of the composite laminate, which acted as a factor causing the difference in mechanical properties of the composite materials. As the resin content increased, there was no significant difference in tensile strength, but Young's modulus decreased. In the case of the compression test, there was a difference in mechanical properties due to the combined effect of the reinforcement and the resin. The maximum compressive strength value was shown in the process with low void content, and Young's modulus tended to decrease as the resin content increased. In the bagging process, the subsidiary material controlled the flow of resin and air, and caused a difference in microstructure, affecting the change of mechanical properties.

On the Resin Transfer Molding (RTM) Infiltration of Fiber-Reinforced Composites Made by Tailored Fiber Placement.

Tailored fiber placement (TFP) is a preform manufacturing process in which rovings made of fibrous material are stitched onto a base material, increasing the freedom for the placement of fibers. Due to the particular kinematics of the process, the infiltration of TFP preforms with resin transfer molding (RTM) is sensitive to multiple processes and material parameters, such as injection pressure, resin viscosity, and fiber architecture. An experimental study is conducted to investigate the influence of TFP manufacturing parameters on the infiltration process. A transparent RTM tool that enables visual tracking of the resin flow front was developed and constructed. Microsection evaluations were produced to observe the thickness of each part of the composite and evaluate the fiber volume content of that part. Qualitative results have shown that the infiltration process in TFP structures is strongly influenced by a top and bottom flow layer. The stitching points and the yarn also create channels for the resin to flow. Furthermore, the stitching creates some eye-like regions, which are resin-rich zones and are normally not taken into account during the infusion of TFP parts.

VARTM process of composites using double-bag air cushion method

This article introduced the double-bag air cushion method (DBACM) as an economical and efficient manufacturing process of polymer composites associated with the vacuum-assisted resin transfer molding (VARTM) process. The method utilizes an improved double-bag along with several air cushions to create distribution channels for enhancing the resin flow during infusion. Experimental evaluation on resin infusion behavior and mechanical properties, including ultimate strength, void content, surface finish, and thickness uniformity, is performed for composites reinforced with both jute fibers and glass fibers. Results showed that the DBACM reduces the infusion time by more than 26.0% as compared with traditional VARTM. The difference in ultimate strength of the part between the DBACM and the VARTM is about 2.9%–3.9%. The void content of the E-glass composites is 1.3%–1.5% due to the few fissure-like microvoids, whereas the void content of the jute composites is high, about 2.4%–4.0%, because of the sparse spherical macrovoids. Additionally, there are no major differences in surface finish and thickness uniformity between the parts fabricated by DBACM and by conventional VARTM.

フローフロント合流部の樹脂流動挙動による繊維配向メカニズムの検証

フローフロント合流部の樹脂流動挙動による繊維配向メカニズムの検証

Finite element solution of electro-magnetic-thermo-chemical problem in microwave assisted pultrusion processes

New finite element models and algorithms are developed for a solution of coupled electro-magnetic-thermo-chemical problem arising in microwave assisted pultrusion processes. In the first algorithm stage, the microwave set-up is predefined according to the requirements on energy-effectiveness and homogeneity of generated absorption field, in the second – an iterative procedure preserving the dependence of dielectric material properties on microwave frequency, temperature and degree of cure is applied to avoid resin overheating and flow from the die exit, and to guarantee a required profile quality. These holistic simulation tools are built by using the general-purpose finite element software ANSYS that makes available various modelling and analysis features of the finite element package and results in considerable savings in design time and costs. To demonstrate features and benefits of electromagnetic heating, the pultrusion process for a production of the rod profile with diameter of 16 mm and made of polyester resin POLRES 305 BV and glass fibers 4800 tex is developed. Based on the results of parametric study executed for the microwave assisted pultrusion set-ups with different ceramic dies, finite element modelling and coupled analysis aspects are discussed. • Coupled electro-magnetic-thermo-chemical problem has been formulated. • New finite element models and algorithms has been developed. • Finite element modelling and coupled analysis aspects have been discussed. • Microwave assisted pultrusion process has been developed.

Monitoring of three-dimensional resin flow front using hybrid piezoelectric-fiber sensor network in a liquid composite molding process

In this paper, a hybrid piezoelectric-fiber sensor network is developed to monitor the three-dimensional resin flow front of thick composite parts in the vacuum assisted resin infusion (VARI) process. Three different approaches based on non-invasive and integrated piezoelectric lead-zirconate-titanate (PZT) sensor network are developed to detect the three-dimensional resin flow front globally. To check the location of the invisible three-dimensional flow front inside the preform, multiple fiber optic sensors are embedded as flow sensors in different layers. The measurements from the piezoelectric and fiber optic sensor networks are then combined as a complement of each other to estimate the three-dimensional resin flow front. The applicability of the proposed hybrid sensor network is investigated on a thick carbon fiber reinforced plastic specimen with three different thicknesses at different locations. Experimental results confirm that the hybrid piezoelectric-fiber sensor network is capable of successfully estimating the three-dimensional flow front in situ and in real-time, achieving smart health monitoring.

Investigation of the way to enhance the synergistic effect between polyimide and graphene on the tribological performance of polytetrafluoroethylene composites

AbstractIn this article, two different preparation methods were employed to explore the way to maximize the synergistic effect between polyimide (PI) and graphene (Gr) on the friction and wear of polytetrafluoroethylene (PTFE) composites. Results indicate that the incorporation of Gr into PI firstly is more beneficial for the improvement of tribological performance rather than the blending of Gr and PTFE firstly. The incorporation of Gr into PI firstly enhances the wear resistance of PI/Gr phases. Gr fillers is not taken away easily by the plastic flow of PTFE resin and Gr will accumulate on the wear surface of PI/Gr. The synergistic effect of PI and Gr will play a better role in the friction and wear of PTFE/PI/Gr. However, the wear performance of PI phases cannot be enhanced effectively by the blending of Gr and PTFE firstly. And Gr will be taken away by the severe wear of PTFE phases in PTFE/Gr/PI. Only tiny Gr accumulates on the wear surface of PI phases, the synergistic effect of PI and Gr will not play a better role in friction and wear.

Controlling resin flow in Liquid Composite Moulding processes through localized irradiation with ultraviolet light

AbstractA vacuum infusion process was implemented to produce composite specimens from a random glass filament mat and an acrylic modified polyester resin curable upon irradiation with ultraviolet (UV) light. Through localized irradiation with UV light during the reinforcement impregnation, the viscosity of the flowing resin was increased selectively. This allowed converging–diverging flow patterns with defined inclusions to be realized and racetracking along reinforcement edges to be suppressed. The approach is based on radical photopolymerisation. Here, the degree of cure and the viscosity of the resin increase under direct irradiation, such that the resin gels and the flow stalls in a matter of seconds, but remain unchanged in areas covered with an opaque mask. While this study is concerned with the feasibility of the process, potential practical applications are in flow control for Liquid Composite Moulding, that is, compensation for local variations in the fiber volume fraction and permeability of reinforcements.