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Injection-molded fiber-reinforced resins exhibit anisotropic mechanical properties due to the orientation of the fibers caused by resin flow. Therefore, the prediction of fiber orientation is important for predicting the function of injection-molded fiber-reinforced resin products. In previous reports, fiber orientation behavior has been observed in simple resin flow specimens such as flat plates. In this paper, fiber orientation was observed in the flat and rib parts of a ribbed two-point gate flat plate. As a result, the fiber in the center of the wall thickness was oriented in the flow direction in the rib section after flow-front meet, confirming a five-layer orientation different from that previously reported. To verify the fiber orientation mechanism, the velocity distribution and velocity history of the resin were measured. It was found that the fibers near the wall surface were oriented by shear forces, while the fibers in the center of the rib wall thickness were oriented by a combination of elongation flow and shear forces. [ABSTRACT FROM AUTHOR]

Resin flow analysis in the injection cycle of an RTM process was investigated. Fiberglass and carbon fiber mats were used as reinforcements with EPON 826 epoxy resin. Numerical models were developed in ANSYS finite element software to simulate resin flow behavior into a mold of conical shape. Resin flow into the woven fiber mats is modeled as flow through porous media. The injection time for fiberglass/epoxy composite is found to be 4407 seconds. Required injection time for the carbon/epoxy composite is 27022 seconds. Higher injection time for carbon/epoxy part is due to lower permeability value of the carbon fibers compared to glass fiber mat. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Manufacturing defects such as microvoids are common in thermoset composite components and are known to negatively affect their strength. The resin pressure developed in and the resin flow out from the laminates during cure have been reported to be the primary factors influencing the final void content of a composite component. In this work, the effect of laminate edge conditions during the cure process on the formation of microvoids was experimentally investigated. This was achieved by fabricating eight-ply laminates from TenCate® BT250/7781 prepreg in a hot-press at a constant cure pressure of 170 kPa while limiting the laminate perimeter available for resin flow by 0%, 25%, 50%, 75%, and 100%. The individual plies of these five laminates were conditioned at 99% relative humidity before curing to maximize the moisture present in the lay-up before fabrication. The presence of moisture in the lay-ups was expected to promote void formation and allow the effect of restricting flow at the edges of a laminate to be better identified. The restriction of resin outflow was found to cause the average characteristic void diameter to decrease by 17% and void content to rise by 33%. This phenomenon was identified to be a result of the outflow restriction increasing the number of voids trapped within the laminate and indicates that for laminates cured at low pressures resin outflow is the dominant mechanism for void reduction. [ABSTRACT FROM AUTHOR]

Wet-RTM (Resin Transfer Molding) molding applies the resin onto the surface of the reinforcements and then the resin flows into the fabric with mold compression. This process is gaining attention thanks to car marker’s use in recent years. Since both the fabric layup and charge location affect resin flow, it’s not easy to know the resin flow behavior in complex mold cavity. In this study, we predict the resin flow in Wet-RTM process by using the novel three-dimensional simulation tool which can consider the Darcy’s law and moving boundary problem in compression process. The simulation results demonstrate the effect of the anisotropic permeability and initial resin location variation by flow front evolution and pressure distribution during the compression stage. It could help user to determine the fabric layup and charge location before manufacturing processes to save try and error costs. [ABSTRACT FROM AUTHOR]

Liquid Composite Molding (LCM) is one of the most widespread Out-Of-Autoclave (OOA) class of processes used to manufacture components in composite material. In this process a dry preform of fibers is impregnated by a flow of liquid resin, which is forced to move through the reinforcement by a pressure gradient. One of the most challenging aspects in LCM processes is to achieve a complete impregnation of the reinforcing fibers. Unsatisfactory impregnation can occur at different scales, in terms of dry spots (macro scale), entrapped air between the tows (meso scale), or inside the tow between the fibers (micro scale). In order to achieve an acceptable component, the preform must be saturated at each scale. Due to this reason, the necessity to enhance the flow in LCM processes arises. The aim of this work is to investigate the capability of microwave preheating to improve the resin flow in a Vacuum Assisted Resin Transfer Molding (VARTM) process. In particular, the resin is forced to pass through the resonant cavity of a microwave heater before the impregnation, in order to increase its temperature and reduce its viscosity. Feedback signals are collected by thermocouples, positioned into the pipes, and dielectric sensor, embedded in the die. [ABSTRACT FROM AUTHOR]

This paper presents an integrated true three-dimensional simulation of resin flow and wire sweep in microchip encapsulation. A FVM-based decoupled solution algorithm with the hybrid elements capability is adopted to calculate the resin flow during mold filling. Furthermore, a highly flexible mesh generation technique especially tailored for the IC packages is also proposed to mesh the model with high quality element both in the flow and gapwize directions. Thanks to the efficiency of the proposed methodology in terms of CPU time and memory requirement, the industrial packages with complex geometry and high pin count can be analyzed with minimum model simplification. Finally, a user-friendly integrated environment is also developed to link the flow analysis with structure analysis to provide the total solution for wire sweep assessment. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Consolidation is a crucial step in manufacturing of composite parts with prepregs because its role is to eliminate inter- and intra-ply gaps and porosity. Some thermoset prepreg systems are toughened with thermoplastic particles. Depending on their size, thermoplastic particles can be either located in between plies or distributed within the inter-fibre regions. When subjected to transverse compaction, resin will bleed out of low-viscosity unidirectional prepregs along the fibre direction, whereas one would expect transverse squeeze flow to dominate for higher viscosity prepregs. Recent experimental work showed that the consolidation of uncured toughened prepregs involves complex flow and deformation mechanisms where both bleeding and squeeze flow patterns are observed [1]. Micrographs of compacted and cured samples confirm these features as shown in Fig.1. A phenomenological model was proposed [2] where bleeding flow and squeeze flow are combined. A criterion for the transition from shear flow to resin bleeding was also proposed. However, the micrographs also reveal a resin rich layer between plies which may be contributing to the complex flow mechanisms during the consolidation process. In an effort to provide additional insight into these complex mechanisms, this work focuses on the 3D numerical modelling of the compaction of uncured toughened prepregs in the cross-ply configuration described in [1]. A transversely isotropic fluid model is used to describe the flow behaviour of the plies coupled with interplay resin flow of an isotropic fluid. The multi-scale flow model used is based on [3, 4]. A numerical parametric study is carried out where the resin viscosity, permeability and inter-ply thickness are varied to identify the role of important variables. The squeezing flow and the bleeding flow are compared for a range of process parameters to investigate the coupling and competition between the two flow mechanisms. Figure 4 shows the predicted displacement of the sample edge with the multi-scale compaction model after one time step [3]. The ply distortion and resin flow observed in Fig.1 is qualitatively retrieved by the computational model. [ABSTRACT FROM AUTHOR]

Epoxy/Kevlar composites have been manufactured by conventional Vacuum Infusion process and the Pulse Infusion technique. Pulse Infusion allows to control the pressure of the vacuum bag on the dry fiber reinforcement by using a proper designed pressure distributor that induces a pulsed transverse action and promotes the through thickness resin flow. The realized composite panel have been mechanically characterized by performing tensile and short beam shear tests according with the ASTM D3039 and ASTM D2344/D 2344M standard respectively in order to investigate the effect of Pulse Infusion on the tensile strength and ILSS. [ABSTRACT FROM AUTHOR]

Measurement of the fiber orientation in a carbon fiber composite material is crucial in understanding the load carrying capability of the structure. As manufacturing conditions including resin flow and molding pressures can alter fiber orientation, verification of the as-designed fiber layup is necessary to ensure optimal performance of the structure. In this work, the development of an eddy current probe and data processing technique for analysis of fiber orientation in carbon fiber composites is presented. A proposed directional eddy current probe is modeled and its response to an anisotropic multi-layer conductor simulated. The modeling results are then used to finalize specifications of the eddy current probe. Experimental testing of the fabricated probe is presented for several samples including a truncated pyramid part with complex fiber orientation draped to the geometry for resin transfer molding. The inductively coupled single sided measurement enables fiber orientation characterization through the thickness of the part. The fast and cost-effective technique can be applied as a spot check or as a surface map of the fiber orientations across the structure. This paper will detail the results of the probe design, computer simulations, and experimental results. [ABSTRACT FROM AUTHOR]

A parallel computational environment for modeling the resin transfer molding manufacturing process has been developed at the U.S. Army Research Laboratory. This environment utilizes an implicit numerical method for modeling resin flow, a thermal model for analyzing convection and conduction, and a resin kinetics model to compute the heat generated and degree of resin cure during the curing process. The computing environment also includes a multiscale thermal residual stress model for computing the distortions and residual stresses in the composite component caused by the manufacturing process. All of these models have been tied together within a parallel object-oriented programming framework. This paper will discuss the computing environment in detail and its utility to real world applications. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Properties of fiber-reinforced composite are dominated by the microstructure of the fabricated part rather than the properties of constituent materials. As the microstructure of composite is related to the flow-processing route of the fiber-reinforced suspensions and the geometry of the mold, the microstructure of composite can be tailored in order to achieving high-performance composites by exercising control over the flow processing. Thus, numerical methods are used to model the resin flow, the fiber orientation, and mold design, and they become important challenges during molding process. In our previous research, a theoretical fiber-fiber interaction model with a global fiber interaction coefficient was developed. In this study, the three-dimensional (3D) fiber orientation distribution is predicted by combining our developed fiber interaction model and improved Anisotropic Rotary Diffusion - Retarding Principle Rate (iARD-RPR) model. The fiber orientation calculation started from the gate, and from a random orientation to alignment orientation is investigated at that location as the inlet boundary condition. Moreover, simplified deformation behavior of fountain flow was employed for fiber orientation in the flow front region. In experimental, short-glass fiber-reinforced polyamide 6 specimens produced using plate-shaped cavity having three different thicknesses ranging from 2 mm to 4 mm and with the fiber contents ranging from 30 wt% to 65 wt% are carried out using injection molding. 3D fiber orientation observation and measuring are exactly and automatically examined by Micro-computed tomography system. Comparisons with experimental results, it is showed that this advanced prediction methodology can be effectively used for the 3D fiber orientation prediction in high filler content composite parts. [ABSTRACT FROM AUTHOR]

Liquid composite molding is manufacturing techniques that involve the injection or infusion of catalyzed liquid resin into a mold to impregnate a dry fiber preform. The challenges of LCM processes are related to the obtaining of a complete wetting of the reinforcement as well as a reduction of the void to obtain a final product with high mechanical properties. The heating of the resin prior the injection into the mold cavity has proven to be useful to improve the LCM processes. The increasing of temperature results in a reduction of resin viscosity and allows the resin to flow more easily through the reinforcement; the cure stage is also improved resulting in a reduction of global process time required. Besides the conventional solutions to heat up the resin based on the thermal conduction, in-line microwave heating is a suitable method to heat dielectric materials providing an even temperature distribution through the resin, thereby avoiding a thermal gradient between the surface and the core of liquid resin, which could result in a premature and uncontrolled cure. In the present work, an in-line microwave system, manually controlled, have been coupled with a VARTM apparatus to heat the resin before the infusion. In addition, parallel-plate dielectric sensors and pressure sensors, embedded into the mold, were employed to track the flow front through the fiber reinforcement in two distinct cases: unheated resin and pre-heated resin. The aim of work was to assess the effectiveness of microwave pre-heating to improve the macro and micro-impregnation of dry preform. The obtained results showed capability of in-line microwave heating to shorten the impregnation of dry fabric and provide a homogeneous wetting of fibers. [ABSTRACT FROM AUTHOR]

The industrialization of the resin transfer molding process is a major objective in reducing production cost for FRPs thus making it more competitive for use in large scale applications. Normally, shorter cycle times run into the risk of quality inconsistencies. The creation of voids is influenced by various process parameters, such as mold temperature, resin flow rate and fiber volume content. With knowledge of the effects of these parameters on the process, a specific approach to reducing void content is made while reducing processing time. In order to achieve this objective, in particular, capillary forces and its influence on impregnation of the fiber bundle were examined. A DOE approach was chosen to lead to the determination of interactions. The results target at a pre-determination of required process parameter to obtain consistent part quality with reduced cycle time. [ABSTRACT FROM AUTHOR]

An array of 14 x 40 turn-insulated steel conduits, encompassed by the vertical and horizontal ground insulation designed for use in the ITER CS Modules, was fabricated using a specified vacuum-pressure, epoxy-resin, impregnation process. Detailed observations were conducted to assess resin impregnation and conduit realignment under the gravitational pressure of the weight of the stacked conduit. Electrical measurements were conducted to assess the voltage breakdown of turn and ground insulation. Observations were conducted of samples extracted from the resin-impregnated array to assess resin penetration and porosity and insulation quality. Dimensions were measured to obtain reliable estimates of changes in insulation build prior to, and following, resin impregnation and cure. Details of the resin transfer process are provided. [ABSTRACT FROM AUTHOR]

In this paper has a numerical framework for multiphysical simulation of resin-impregnation, heat-transfer and cure in a resin-injection pultrusion process been developed. Using the framework, the material flow through the pultrusion die was studied for the manufacture of a 100 mm thick glass fibre reinforced polyurethane (thermoset) composite profile. The results demonstrated that while curing is initiated near the heated die-walls, a yet stronger reaction is simultaneously obtained at the centre of the profile. The results were qualitatively compared to measurements from an industrial pultrusion line, which confirmed the trends of the material flow. [ABSTRACT FROM AUTHOR]

The control techniques applied in Liquid Composite Molding processes have been extensively worked out by many different research groups abroad. In this work, the original use of artificial vision technology in order to redirect the flow path during mold filling appears as a major objective of online control strategy. In this study, a process performance index developed in a previous work is used to define the mold gate opening sequence. The Vacuum Assisted Resin Transfer Molding (VARTM) and Vacuum Assisted Resin Infusion (VARI) have been selected as the main processes of study. The expert system will make use of numerical simulation in order to obtain a previous physical understanding of the flow behaviour in different manufacturing conditions. Some examples of the installation are presented and discussed. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Liquid Composite Molding (LCM) processes are increasingly used to produce composite parts. Most of those processes involve compression of the fiber reinforcement and resin flow. In order to accurately model LCM processes, a good knowledge of fiber reinforcement behavior in compression is required. Several models have already been published, but none of them include permanent deformations. Also because of the large deformation involved in the processes, a finite strain formulation is proposed. Results are given for a glass twill-weave fabric. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Solid Rocket Booster (SRB) structures were protected from heating due to aeroshear, radiation and plume impingement by a Thermal Protection System (TPS) known as Marshall Sprayable Ablative (MSA-2). MSA-2 contains Volatile Organic Compounds (VOCs) which due to strict environmental legislation was eliminated. MSA-2 was also classified as hazardous waste, which makes the disposal very costly. Marshall Convergent Coating (MCC-1) replaced MSA-2, and eliminated the use of solvents by delivering the dry filler materials and the fluid resin system to a patented spray gun which utilizes Convergent Spray Technologies spray process. The selection of TPS material was based on risk assessment, performance comparisons, processing, application and cost. Design of Experiments technique was used to optimize the spraying parameters. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Carpet is one of the most ancient and highly preferred fibrous three-dimensional floors covering mankind's living style. It becomes solid waste after seven to nine years, and its decomposition becomes a challenging task. The present experimental work incorporated the nanomaterial in carpet waste polymer composites for lightweight applications. The carbon-based nanomaterial (CBN) in the form of Multi-Wall Carbon Nano Tube (MWCNT) and Graphene oxide (Go) was used to enhance the carpet waste/epoxy composites. Physio-mechanical investigations characterization evaluated the feasibility of the developed composites. The results showed that adding 1D nanofiller improves the discarded waste polymer nanocomposites' mechanical properties and physical properties over the 2D nanofiller. The statistical data analysis revealed that the supplement of 0.5 wt.% of MWCNT enhanced tensile, flexural, and compression load of 38.42%, 61.85% and 50% over the neat epoxy-based discarded polymer composites. Furthermore, physical properties were analyzed and found to enhancement in fire retardancy and water uptake, respectively, over pristine specimens. The outcomes of the present work demonstrate that the developed nanocomposites can be used in wall tiles, sound barriers, low-strength tooling components, roadside barrier materials, etc. [ABSTRACT FROM AUTHOR]

To see the flow pattern that occurs in the Pelton turbine blade mold, it is seen by comparing the pressure drop and the comparison of the pressure drop with the speed using Solidworks software. The moving fluid makes the propeller rotate and produces energy to move the rotor. The research was conducted to see the process of resin pouring in the Pelton turbine blade mold using Solidworks software. From the simulation results, the velocity value is 0.0003 m/s, the pressure drop is 35495.65 Pa at 0.000475 m/s velocity pressure drop =52012.65 Pa and 0.00065 m/s =77152.41 Pa at velocity 0.00825 m/s obtained pressure drip =115700.58 Pa. the velocity value with the pressure drop value is directly proportional, that is, if the velocity value is greater, the pressure value is also greater and the comparison value between pressure drop with the incoming velocity value from the Z-axis (vertical) is also directly proportional. The appropriate speed for numerical analysis using Solidworks software is 0.0003 m/s. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer composites have been used for various applications. There is increasing interest in the study of the seawater immersion effect of these materials. In this research, the alteration of tensile and shear behavior properties due to seawater absorption of the immersed Kevlar/Vinyl ester composite was evaluated. The composite materials were manufactured using vacuum assisted infusion method. ASTM D3039 and ASTM D5379 were used as the standards for tensile and shear tests. Tensile and shear performances were evaluated before and after immersion in seawater for 11 days. The experimental results show that tensile strength decreased by 7.5% from an average value of 421.18 MPa to 389.27 MPa. Whereas, the shear strength decreased by 1.6% from an average value of 14.6 MPa to 14.46 MPa. [ABSTRACT FROM AUTHOR]

During thermoforming process, the consolidation deformation mode of thermoplastic prepregs is one of the key deformation modes especially in the consolidation step, where the two resin flow phenomena: resin percolation and transverse squeeze flow, play an important role. This occurs a viscosity behavior for consolidation mode. Based on a visco-hyper-elastic model for the characterization of thermoplastic prepregs proposed by Guzman, which involves different independent modes of deformation: elongation mode, bending mode with thermo-dependent, and viscoelastic in-plan shearing mode with thermo-dependent, a viscoelastic model completed with consolidation behavior will be presented in this paper. A completed three-dimensional mechanical behavior with compaction effect for thermoplastic pre-impregnated composites is constituted, and the associated parameters are identified by compaction test. Moreover, a seven-node prismatic solid-shell finite element approach is used for the forming simulation. To subdue transverse shear locking, an intermediate material frame related to the element sides is introduced in order to fix nodal transverse shear strain components. Indeed, the enhanced assumed strain method and a reduced integration scheme are combined offering a linear varying strain field along the thickness direction to circumvent thickness locking, and an hourglass stabilization procedure is employed in order to correct the element’s rank deficiency for pinching. An additional node is added at the center providing a quadratic interpolation of the displacement in the thickness direction. The predominance of this element is the ability of three dimensional analysis, especially for the transverse stress existence through the thickness of material, which is essential for the consolidation modelling. Finally, an intimate contact model is employed to predict the evolution of the consolidation which permits the microstructure prediction of void presented through the prepreg. Several tests including a thermoforming test are launched to evaluate the consolidation model and the accuracy of the proposed element. [ABSTRACT FROM AUTHOR]

High thermal conductivity PPS is expected to be applied to cooling cases of in-vehicle parts because of its light weight and high heat dissipation. However, the flowing behavior of this resin is so peculiar that it can causes breakage at the flow front during the filling process, resulting in short shots and cracks on the surface layer at the end of the flow. In order to suppress these defects, it is necessary to elucidate the filling behavior and obtain the requirements for optimization. We thus here intend to visualize the filling behavior of high thermal conductivity PPS. To achieve this goal, we develop an in-process visualization system to reveal both thermal and kinetic behavior of the resin while the resin is filling in the cavity. In the system, a sapphire prism glass is utilized in the mold for visualization since it shows high strength, high heat conduction, and high infrared transmittance. Both a high-speed visible camera for kinetic behavior and an infrared camera for thermal behavior are used. With the developed system, we successfully obtain the filling behavior of thermal conductivity PPS for the first time. Visualization experiments show that the temperature of conventional PPS gradually decreases from the tip of the flow to the rear. On the other hand, the temperature of the high thermal conductivity PPS drops sharply from the tip of the flow to the rear, and the breakage at the flow front near the cavity wall is generated. Our interpretation is that the flow front near the cavity wall can be easily broken when it is stretched since the ductility of the high thermal conductivity PPS largely decreases because of the rapid temperature drop. [ABSTRACT FROM AUTHOR]

The permeability measurements of synthetic fibre reinforcements have been getting a lot of interest in literature to date, however, there is limited research on permeability studies of natural fibre reinforcements. The permeability behaviour of reinforcement depending on the fabric's complex architecture, this leads to the difficulties in developing analytical models due to this variation and complexity. In practice, there are several difficulties in developing methodology especially, selecting the most appropriate methods either via experimental, theoretical and/or modelling works best suited. Therefore, the selection for the most suitable methods would require careful and systematic decision in choosing the most appropriate methods to be suited to the scope of work. This paper intends to give an important start in this challenging task for a decision, through a systematic de cision matrix analysis considering several methods in order to weigh their strength and limitations. A simple decision matrix method was performed for each of cases, by identifying the main factors which were the cost, time, applicability, reliability, limitations, and suitability of each method. The factors were assigned their relative importance accordingly. A methodology framework has been proposed for permeability prediction via modelling, simulation and experimental works. A well designed experimental and simulation works is important influencing the results and conclusions to be drawn depend to a large extent on how the data is collected. [ABSTRACT FROM AUTHOR]

Understanding the void formation is important to reduce the void content percentages and their morphology such as the shape and size, as it can affect the mechanical performance of composites. In this paper, several case studies with regards to the void and moisture content studies of fiber reinforced composites for both, synthetic and natural based fibers, respectively, are presented and reviewed. The main aim is to determine the most appropriate and suitable methods via experimental, theoretical and/or modelling works with regards to the pre-impregnated (pre-preg) and woven natural fabric reinforced composites. A simple decision matrix method was performed for each of cases, by identifying the main factors which were the cost, time, complexity, reliability, limitations, and suitability of each method. The factors were assigned their relative importance accordingly. The determination void and moisture content are essential in the author's work, with regards to the formation of voids during impregnation in solvent coating process as well as during lay-up and composite fabrication process. This paper intends to give an important start in this challenging task for a decision, through a systematic decision matrix analysis and several methods has been considered as the conclusion to be drawn based on their strength and limitations. [ABSTRACT FROM AUTHOR]

For the U.S. fabricated ITER Central Solenoid (CS), six, almost identical, modules will be fabricated, then stacked together. The electrical insulation systems of the CS modules consist of turn, layer, and ground insulation. These electrical systems also serve to bond the coil conductors together. For this purpose, an epoxy resin is transferred into the coil assembly using a carefully designed vacuum-pressure impregnation process. The most important testing procedures, data, and design criteria for the key low-temperature, mechanical, and electrical properties are reviewed. Design of these systems is discussed. [ABSTRACT FROM AUTHOR]

Selected mechanical properties of glass/epoxy laminate candidates for use in the electrical turn and ground insulation of the ITER Central solenoid (CS) modules were measured. Short-beam shear and flexural tests have been conducted on various E-glass cloth weaves/epoxy laminates at 295 and 77 K. Types of glass weave include 1581, 7500, 7781, and 38050, which represent both satin and plain weaves. The epoxy, planned for use for vacuum-pressure impregnation of the CS module, consists of an anhydride-cured bisphenol F resin system. Inter-laminar shear strength, flexural elastic modulus, and flexural strength have been measured. The data indicate that these properties are dependent on the volume percent of glass. Short-beam shear strength was measured as a function of the span-to-thickness ratio for all laminates at 77 K. Comprehensive fractography was conducted to obtain the failure mode of each short-beam shear test sample. [ABSTRACT FROM AUTHOR]

One of the most critical input parameters with respect to the LCM modeling software is the permeability of the reinforcement. Without a reliable characterization of the fiber preform neither mathematical models nor computer simulations would be able to provide useful information. To fully characterize fiber reinforcements it is necessary to measure its principal permeabilities. As permeability is an intrinsic property of a fibrous material, it ought to be evaluated experimentally following a reliable and standardized procedure. This paper deals with the manufacturing of an affordable set-up to characterize permeability of common LCM reinforcement following the standard of the FPCM international conference series. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of the effect of the graphene nanoparticles on the mechanical properties of glass fiber reinforced epoxy composite. The composites were fabricated using vacuum infusing molding. Dispersion of graphene nanoplatelets was done using bath sonicator and mechanical stirring. The physical and mechanical properties were examined according to ASTM standards. Results showed that there was a significant improvement in tensile and flexural properties by the addition of 0.25% of graphene nanoplatelets in the glass/epoxy composite. Tensile strength and modulus were enhanced by 27.62 % and 41.26 %, respectively. Flexural strength and modulus have been improved by around 27.62 % and 41.26 %, respectively. Graphene platelets can be hybridized with glass/epoxy composite to improve the mechanical performance. [ABSTRACT FROM AUTHOR]

In this research, the aim of the study is to investigate the mechanical properties of eco-hybrid natural polymer of kenaf and glass fibre. The specimens were fabricated using vacuum infusion technique and joining into single lap bolted joint. The mechanical fasteners of Huck lock bolt were used as joining method with the bondline length of 64 mm. The investigation was conducted under two different conditions of dry and wet of 50°C for water immersion of 20 days. The effect of moisture was defined in bolted joints materials. The tensile test with a speed rate of 1 mm/min was conducted for both condition using 100 kN load cell until total failure of specimen. The experimental results were plotted into load displacement and stress strain curve for each environment. [ABSTRACT FROM AUTHOR]

This is a preliminary study aiming at presenting the possibilities of characterization of reactive materials in a few short experiments performed in HFC-200, a calorimetric cell placed inside a DMA (Dynamic Mechanical Analyzer). Like in RTM (Resin Transfer Process), the reactive liquid resin is injected inside the preheated cell. Each isothermal injection provide heat flux linked to reaction rate, dynamic mechanical properties and shrinkage according to time. The fact that all results are obtained on the same experiments repeated at different temperatures ensure minimal errors linked to samples size and characterization methods along with very efficient operations. Results obtained on an Elium® reactive thermoplastic resin will be presented and discussed. [ABSTRACT FROM AUTHOR]

This work aims at providing a parametric solution of LCM processes, and in particular RTM, when the location of the injection gate is assumed being a model parameter. It is well known that parameters can be easily considered as model extra-coordinates within the Proper Generalized decomposition framework. Then, the use of separated representations allows efficiently circumventing the curse of dimensionality, and then calculating very efficiently the so-called computational vademecums that contain all the solutions of the problem at hand for any choice of the material, process or geometrical parameters. However, even if the construction of such parametric solutions within the PGD rationale is nowadays in most of cases mature, using both intrusive or non-intrusive approaches, the last approach induces spurious solutions when interpolating solutions exhibiting localization. The present paper shows a parametric geometric approach for RTM processes where the injection gate is a parameter. For that purpose an interpolative mapping will be successfully proposed and employed. [ABSTRACT FROM AUTHOR]

A dedicated custom-built experimental setup and testing methodology were designed and manufactured for the investigation of the inter-ply friction behavior of Carbon/Epoxy fabric prepregs at varying interfacial temperatures, rates, and compaction pressures. The experimental parameters were selected in the ranges corresponding with those in the pregelation phase of the consolidation processes in autoclave processing of laminates and sandwich panels. A thorough understanding of the inter-ply frictional shear forces during the consolidation was obtained, suggesting a strong dependence on the process conditions and the dominance of mixed lubrication regime. Continuous experiments were conducted to determine the state of friction over the course of full-cure cycle. The observed differences were shown to be primarily dependent on both the resin viscosity and the distribution of the resin on the prepreg surface. Identification of dominating trends also suggested the high sensitivity of the results to the surface roughness of the prepreg. [ABSTRACT FROM AUTHOR]

There are many unsolved molding phenomena in the hot-runner mold system, which are caused by complicated flow channels installed with actuated valve-pins inside the high temperature manifold. In the injection molding of large or long-sized products, melts are made to flow continuously by sequentially switching gate-opening one by one from upstream to the area contacting the flow front. Valve gates are appropriately controlled to open/close by the so called “cascade control system”, to prevent weld-lines, decrease flow pressure loss, etc. However compared to the single gate system, more complicated flow behaviors are expected to occur when the valve gate near the flow front is opened at the times of open gates. We attempted to visualize the melt behaviors inside hot-runner mold with a cascade control of two sets of valve gates (upstream VG1 and downstream VG2) . Through this visualization experiment, the following results were confirmed. (1) In the case of the direct gate system, where multi-gates are located inside the mold cavity, the flow front velocity was observed to rapidly rise up to 5 or 6 times in a moment after a small amount of back flow, due to low pressure loss at the flow front area just after switching the gate open from VG1 to VG2. (2) In the case of sub-runner systems, where multigates are located in the tub area outside the cavity, the later VG1 is switched to VG2, the higher the velocity peak of the melts flowing into the cavity from VG2. All these drastic velocity changes may influence upon surface transcription conditions, leading to surface defects on molded samples. [ABSTRACT FROM AUTHOR]

We investigated the electrical properties of a unique solid array capacitor with 6 capacitances consisting of 4 electrodes and 3 organic dielectrics in single body. The unique solid array capacitors with 4 electrodes and 3 dielectrics were composed of Cu/organics Di-electric/Cu/organics Di-electric/Cu/organics Di-electric/Cu with horizontal arrays structure. It was made by a new and unique fabrication process. A 4 cu sheet and a 3 organic sheet are stacked up in a vertical direction. The stacked materials are then pressed vertically using temperature, pressure, and time. The pressed samples were mechanically cut into the designed sizes in the transverse and longitudinal directions. When the cutted sample is laid flat, a 4 cu electrode and 3 organic di-electrics can be made a unique solid array capacitor horizontally. A size of the completed array capacitor is 3x4.86x0.5mm and 2.7x3.6x0.5mm. The length of the electrode and organic Di-electric is about 0.5 mm at plane. The thickness of the fabricated array capacitor in the vertical direction is 0.5 mm. It has 6 capacitances with a series-type structure. The capacitance values calculated by the formula and the measured capacitance values were compared with each other. C1, C2, and C3of Sample1 and Sample2 show that the difference between the calculated value and the measured value is as small as about 5% or less for a 0.349 pF of sample 1 and a 0.301 pF of sample 2. C4, C5, and C6 were compared within 13 ~ 15% of the calculated and measured values. The variation of the measured capacitance was confirmed to be within 15%. [ABSTRACT FROM AUTHOR]

Two types of basalt fibre reinforced epoxy laminates were realized by overlapping flat and twill woven basalt fabrics by resin infusion. Rectangular specimens, cut from the panels were impacted at penetration and at increasing energy values, to investigate the damage onset and propagation. A non-destructive technique, Ultrasound testing (UT), was adopted to investigate the internal damage. Despite the difficulties to obtain information by UT method due to the high amount of signal absorbed, the technique, properly calibrated, proved to be very useful in providing information about the presence, the shape and the extent of the delaminations. The results were compared at the aim to investigate the effect of the fiber architecture (textile). The experimental results indicate a similar impact behavior between basalt flat and twill composites but in the case of the twill a minor delaminated area was detected, even if a higher absorbed energy was recorded [ABSTRACT FROM AUTHOR]

The one-shot (full part) forming of tidal turbine blades by RTM (Resin Transfer Molding) process is a complex process due to the complexity of reinforcements and geometry of blades. In this work, beside the experimental tests which have been realized using IRT JV high capacity machines, the RTM simulations using Moldex3D RTM software have been carried out. First of all, simulations have been done on a 1/7th scale part in order to determine the best injection strategy. Different tested strategies vary by the disposition of injection points (Inlet)/vacuum points (Outlet). Then, the chosen strategy has been applied on the full scale part (∼ 7m length) of high thickness with more complex reinforcement draping. In both cases, the stage of meshing is important to take into account the draping plan with different fiber orientation and fiber types. Attention should be paid on the neck of the blade as the structure of reinforcement changes. A sensitivity study of different parameters (permeability, pressure, temperature) has been then done to understand their influence on the injection time. The permeability which lies to the choice of reinforcement type and fiber volume fraction plays an important role. As the thickness of the part is high, an experimental campaign for measuring the 3D permeability is required. Among the process controllable parameters, the pressure seems the fastest way to reduce the injection time. However, increasing the injection pressure (or the vacuum) could deform the reinforcement. Moreover, the maximal pressure depends on the machine capacity. The influence of temperature shows the thermo-dependence of resin viscosity, the injection time thus decreases as the temperature increases. Nevertheless, the gel time is more limited for injection stage if the resin is heated too much. [ABSTRACT FROM AUTHOR]

Trial and error approach is not a suitable method to optimize the pultrusion process because of the high times required for the start up and the wide range of possible combinations of matrix and reinforcement. On the other hand, numerical approaches can be a suitable solution to test different parameter configuration. One of the main tasks in pultrusion processes is to obtain a complete and homogeneous resin polymerization. The formation of cross-links between polymeric chains is thermally induced but it leads to a strong exothermic heat generation, hence the thermal and the chemical phenomena are mutually affected. It requires that the two problems have to be modelled in coupled way. The mathematical model used in this work considers the composite as a lumped material, whose thermal and mechanical properties are evaluated as function of resin and fibers properties. The numerical pattern is based on a quasi-static approach in a threedimensional Eulerian domain, which describes both thermal and chemical phenomena. The data obtained are used in a simplified C.H.I.L.E. (Cure Hardening Instantaneous Linear Elastic) model to compute the mechanical properties of the resin fraction in the pultruded. The two combined approaches allow to formulate a numerical model which takes into account the normal (no-penetration) and tangential (viscosity/friction) interactions between die and profile, the pulling force and the hydrostatic pressure of the liquid resin to evaluate the stress and strain fields induced by the process within the pultruded. The implementation of the numerical models has been carried out using the ABAQUS finite element suite, by means of several user subroutines (in Fortran language) which improve the basic software potentialities. [ABSTRACT FROM AUTHOR]

Pre-impregnated thermoplastic composites have recently attached increasing interest in the automotive industry for their excellent mechanical properties and their rapid cycle manufacturing process, modelling and numerical simulations of forming processes for composites parts with complex geometry is necessary to predict and optimize manufacturing practices, especially for the consolidation effects. A viscoelastic relaxation model is proposed to characterize the consolidation behavior of thermoplastic prepregs based on compaction tests with a range of temperatures. The intimate contact model is employed to predict the evolution of the consolidation which permits the microstructure prediction of void presented through the prepreg. Within a hyperelastic framework, several simulation tests are launched by combining a new developed solid shell finite element and the consolidation models. [ABSTRACT FROM AUTHOR]

This study aims to establish a numerical strategy allowing to take into account the capillary and wetting issues, considered on the macroscopic scale as a discontinuity of pressure at the fluid-gas interface, and surface tension force balance at the local scale. This modelling is based on the Brinkman/Darcy and Stokes equations solved by a finite element stabilized method. Specific numerical methods are implemented to deal with the discontinuity of pressure field across the flow front. One of the challenges lies in modelling across scales capillary force effects in infusion-based processes to scale-up rules for flows at the process scale, because the computation cost of numerical simulations at local scales is too not tractable industrially. [ABSTRACT FROM AUTHOR]

In recent years, a large number of structures that were built during the period of high economic growth in Japan is beginning to show signs of aging. For example, the structural performance of steel structures has degraded due to corrosion. One measure that has been proposed and studied to address this issue is the adhesive bonding method, which can be used to repair and reinforce these structures. However, this method produces brittle fracture in the adhesive layer and is difficult to maintain after bonding. To solve the problem faced by this method, a clarification of the mechanical properties inside the adhesive is necessary. Then this background, a fiber Bragg grating (FBG) sensor has been used in this study. This sensor can be embedded within the building material that needs repairing and reinforcing because an FBG sensor is extremely small. Eventually based on this, a three-point bending test of a carbon fiber reinforced plastic (CFRP) strengthened steel plate that was embedded with an FBG sensor was conducted. This paper demonstrates that an FBG sensor is effectively applicable for sensing when damage occurs. [ABSTRACT FROM AUTHOR]

The resin infusion process (RIP) has developed as a low cost method for manufacturing large fibre reinforced plastic parts. However, the process still presents some challenges to industry with regards to reliability and repeatability, resulting in expensive and inefficient trial and error development. In this paper, we show the implementation of 2D numerical models for the RIP using the open source simulator DuMux. The idea of this study is to present a model which accounts for the interfacial forces coming from the capillary pressure on the so-called representative elementary volume (REV) scale. The model is described in detail and three different test cases-a constant and a tensorial permeability as well as a preform/Balsa domain - are investigated. The results show that the developed model is very applicable for the RIP for manufacturing of composite parts. The idea behind this study is to test the developed model for later use in a real application, in which the preform medium has numerous layers with different material properties. [ABSTRACT FROM AUTHOR]

Various unsolved defects are known to occur in hot-runner molds, such as stagnation of resins in the manifold channel, asymmetrical cavity filling behavior, flow marks, gate marks, etc. We have been clarifying the causes of various molding defects specifically using visualization technologies inside mold cavity and manifold. This report introduces and discusses the following topics, particularly focusing on clarifying the behavior of resins; (1) Comparison of the imbalanced cavity filling phenomena in between side-fed and center-fed types of valve-gate hot-runner systems, (2) Visualization analysis of the melt flow behaviors and stagnation phenomena inside hot-runner manifolds, (3) Behavior of each stagnant melt around the valve-pin and inner hot-nozzle surfaces, (4) Void generation phenomena remaining on the surface of the valve-pin tip, (5) Melt temperature distribution on the cavity surface during the filling process, (6) Melt temperature profile inside the flowing melt injected from the valve gate, etc. [ABSTRACT FROM AUTHOR]

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160a, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated. [ABSTRACT FROM AUTHOR]

This work describes a successful attempt toward the development of CFRCs based on nanofilled epoxy resins. The epoxy matrix was prepared by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows to reduce the viscosity of the initial epoxy precursor and facilitate the nanofiller dispersion step. As nanofiller, multiwall carbon nanotubes (MWCNTs) were embedded in the epoxy matrix with the aim of improving the electrical properties of the resin used to manufacture CFRCs. Panels were manufactured by Resin Film Infusion (RFI) using a non-usual technique to infuse a nano-filled resin into a carbon fiber dry preform. [ABSTRACT FROM AUTHOR]