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The development of composite has spread in every industrial line. Composite is a solution to the demand for material with superior characteristics. One of the most needed characteristics is burning resistance. Extensive composite application encourages continuous innovation, including in terms of the use of natural fibers as a reinforcement. Research related to natural fibers is needed as an alternative to giving birth to environmentally friendly and economical composite. One of the natural fibers that can be utilized is bamboo fiber. Plants with very high growth rates are expected to be a sustainable alternative. The purpose of this study is to manufacture and test the burn resistance and mechanical property of the glass plate/bamboo fiber reinforced composite. There are 3 types of plates that will be manufactured, namely epoxy plates, glass fiber reinforced composite, and glass/bamboo fiber reinforced composite. glass fiber reinforced composite is manufactured with 4 glass fiber layers. Hybrid composites are manufactured with layers in the form of 2 glass fiber layers, bamboo layers, and 2 glass fiber layers in sequence. The GFRP and hybrid composites manufacturing method is by vacuum assisted resin transfer molding. The treatment of the 3 types of plates is burning with a duration of 15, 30, 45, and 60 seconds. The burnt results will be cut and tested according to ASTM D790. The results of the burn and bending tests show that the glass plate/bamboo fiber reinforced composite shows the highest burn resistance and the smallest decrease in bending power due to burnt treatment compared to the other 2 types of plates. [ABSTRACT FROM AUTHOR]

This study aims to know the effect of resin and hardener ratio of epoxy matrix on the manufacture of carbon fiber composite materials using the VARTM printing method on the mechanical properties of carbon fiber composites and to know the best formulation between resin and hardener used in the VARTM printing methods. This research is an experimental study, with the subject being a carbon fiber composite test sample made using the composition of resin and hardener epoxy matrix ratios that were varied and printed using the VARTM method. The resin and hardener ratios of an epoxy matrix are 60%:40%, 70%:30%, and 80%:20%. Processing and analysis of test data using descriptive statistical methods. The results of this study indicate carbon fiber composites printed by the VARTM method, the 70%:30% ratio, in higher tensile and flexural strengths of 10.8% and 35. 7% respectively, compared to the ratio of 60%:40%, while the 80%:20% resin and hardener ratio, a decrease in tensile and flexural strength respectively by 21% and 45.3% when compared to the 60%:40 % ratio. In addition, the 60%:40% ratio is the lowest density compared to 70%:30% and 80%:20% ratios. Next, the best formulation of resin and hardener ratio to increase the strength of carbon fiber composites printing using the VARTM method is 70%:30%. In contrast, for the density value, the best formulation is 60%:40%. [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]

This paper proposes a simple and accurate technique to quantify both fiber and void volume fractions of natural fiber composites. This technique involves the separate pyrolysis of natural fibers, polymer resin, and natural fiber/polymer composite in a pure nitrogen atmosphere. The remained fractional residuals of these materials are used for the determination of fiber and matrix weight fractions. Consequently, the void and fiber volume fractions of the natural fiber composite are calculated by having weight fractions, as well as the density of natural fiber, epoxy resin, and composite sample. To validate this new method, a number of silk/epoxy composites at various levels of void content were manufactured. Specific results are given for the random mat silk/epoxy laminates made by wet lay-up vacuum bagging (WLVB) process, as well as plain weave silk/epoxy laminates fabricated by the vacuum assisted resin transfer molding (VARTM) process. Using the proposed method, the void volume fractions of the random mat and plain weave silk composites are calculated to be 9.5% and 1.7%, respectively. The fiber volume fraction of random mat and plain weave laminates are also determined to be 18.7% and 46.3%, respectively. The representative scanning electron microscopy (SEM) images of those laminates are also presented to visually compare the void and fiber contents of the parts. The results demonstrate that the proposed method enables an accurate determination of the fiber and void contents in silk/epoxy laminates and can be extended to composites containing other types of natural fibers. [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]

Fiber-metal laminates (FML) are known for their excellent fatigue properties and for lightweighting. As a result, they are widely used in the aviation industry for the fuselage. The geometric complexity of these parts is limited to small one-dimensional and two-dimensional curvatures. To use FMLs for various industries, such as the automotive industry, new manufacturing techniques are needed to increase the formability of FMLs for more complex geometries. A new approach is the combination of deep drawing with thermoplastic resin transfer molding (T-RTM). This process makes it possible to produce three-dimensional FMLs in just one process step from the raw materials (metal sheet and dry fiber fabric) without preliminary stages, such as forming of textile or metal sheet. The process was developed based on a generic cup-shaped geometry. To use it for more complex geometries, numerical tools are needed for the prediction of forming behavior for part and tool design. The aim of this paper is to show a first approach to model this combined process for the tested generic geometry. With this approach, the interaction between the different deformation behaviors of the metal and the textile as well as their influence on the forming result of the hybrid fiber-metal laminate will be investigated. [ABSTRACT FROM AUTHOR]

The massive use of composite materials in industrial applications involves developing more accurate and rigorous mechanical behavior models. One of the most common process is RTM (Resin Transfer Molding). This process begins to become more and more mastered either in small or large deformation through several works describing elastic, hyperelastic or even viscoelastic models. However, the geometries become more and more complex which can generate cyclic loading (loading + unloading). Furthermore, the existing models do not make possible to characterize and simulate the unloading phase. Indeed, dissipative phenomena of energy through (hyper)elastic models are not considered. Some works in the literature propose an approach to describe the hysteresis behavior under small strain. But, in most cases, the shaping step of the RTM process leads to unavoidable large strain. The study presented here therefore focuses on dry fabrics subjected to cycling loading under large strain. These types of loads require a dissipative approach often described by a hysteretic behavior. The model developed in this paper concerns the in-plane shear mode and use an innovative coupling between the additive decomposition of Green Nahgdi and the multiplicative decomposition of Krner Lee. This allow the use of the intermediate configuration which represents the condition of the woven material once no more loading is applied to it. Hence, the constitutive modelling presented here is formulated in total Lagrangian. This model is finally validated experimentally through a picture frame test. At the end, some finite element simulations of the shaping phase of the RTM process are made. [ABSTRACT FROM AUTHOR]

The goal of this research project was to evaluate and compare the effect of fabric architecture on the processing and properties of composites made by Vacuum Assisted Resin Transfer Molding (VARTM). The fabric architectures investigated included plain weave, satin weave, and warpknit unidirectional. The fiber types included E-glass and standard modulus carbon fiber. Flat panels were fabricated with a lab scale VARTM process using an epoxy resin system. Fabric plies were cut to 45 cm x 30 cm (18 in. x 12 in.), and the number of plies used depended on the fiber areal weight of each fabric to produce panels of similar final thickness. The speed of resin infusion was recorded by visually monitoring the flow front which was visible through the bag. Fiber volume fraction was evaluated using thickness measurements, and porosity was investigated via optical microscopy. Mechanical testing was performed via tensile and 3-point flexure. The results showed the fabric type had minimal effect on the infusion speed with the exception of the plain weave and satin weave fiberglass. From the mechanical testing results, there are many comparisons made of the modulus, strength, and strain-to-failure results, for example carbon vs. glass, unidirectional vs. woven, tensile vs. flexure. The rule of mixtures was able to predict some but not all of these properties. The results, which are discussed in detail herein, illustrate the main advantage of selecting carbon vs. glass in stiffness driven applications. [ABSTRACT FROM AUTHOR]

Spring frame forming operations offer a number of unique advantages including tailor-able charge tensioning for ply drop locating, low cost stamp forming tooling concepts, rapid charge loading approaches, and rate enabling automated approaches to forming. Press forming thermoset composite components enables high rate manufacturing of small to medium sized parts. A set of demonstrators were manufactured with complex ply drops and pad ups in a matched mold process using CYCOM® 5320-1 prepreg, CYCOM® 970 prepreg, and a Solvay developmental resin, XEP-2750. The parts were manufactured in a simulated production environment on production equipment with trained production personnel. The part families incorporate features representative of primary and secondary aerospace structural composites with a number of processing characteristics including up to approximately 76 cm by 76 cm (30 in by 30 in) in-plane dimensions, a targeted 30 minute tool time, and the ability to accurately locate features like ply drops and pad-ups. These developments will lead to process specifications and controls for required, hot debulk cycles, preheat cycles, press consolidation and post cure as steps towards process implementation. [ABSTRACT FROM AUTHOR]

One of the three processing tracks within the RApid high-Performance Molding (RAPM) for Small Parts program performed under the DARPA Tailorable Feedstock and Forming (TFF) initiative focused on resin-infused composites. Lessons learned from previous preforming and part-fabrication trials were used to produce a complex-shaped part containing two deep-draw sections. A preforming approach to enable fabrication of the part without fiber distortion was developed. Furthermore, a low-cost tooling approach was applied to creating the preforms. Unlike earlier work in the program, low-pressure resin transfer molding (LPRTM), instead of high-pressure RTM (HPRTM) was used to ease the requirements on tooling pressures to enable lower-costs in tooling materials and tooling fabrication. The details of the tool designs, preform, and part fabrication will be discussed. [ABSTRACT FROM AUTHOR]

The high strain-rate compressive characteristics of a cross-ply carbon/epoxy laminated composite in the three principal material directions or fibre (1-), in-plane transverse (2-) and throughthickness (3-) directions are investigated on the conventional split Hopkinson pressure bar (SHPB) over a range of temperatures between 20 and 80 °C. A nearly 10 mm thick cross-ply carbon/epoxy composite laminate fabricated using vacuum assisted resin transfer molding (VaRTM) was tested. Cylindrical specimens with a slenderness ratio (= length/diameter) of 0.5 are used in high strain-rate tests, and those with the slenderness ratios of 1.0 and 1.5 are used in low and intermediate strain-rate tests. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine at elevated temperatures. A pair of steel rings is attached to both ends of the cylindrical specimens to prevent premature end crushing in the 1- and 2- direction tests on the Instron testing machine. It is shown that the ultimate compressive strength (or failure stress) exhibits positive strainrate effects and negative temperature ones over a strain-rate range of 10-3 to 10³/s and a temperature range of 20 to 80 °C in the three principal material directions. [ABSTRACT FROM AUTHOR]

For control and monitoring purposes, knowledge of the current state of the flow-front in a vacuum assisted resin transfer moulding (VARTM) process is essential. The permeability of the medium and viscosity of the epoxy can change during the infusion process. Especially for online monitoring of the infusion process there is a need for a fast and fairly accurate, possibly virtual sensor system which can handle such parameter variations. Stochastic-differential equations (SDEs) based estimation of the flow-front dynamics can offer a good trade-off between physics and data-driven estimators. In this paper, we analyze the effect of parameter variations on an SDE based spatio-temporal estimator of the flow-front dynamics in a VARTM process. [ABSTRACT FROM AUTHOR]

This work addresses the manufacturing of tubular composite structures by means of bladder-assisted resin transfer molding using elastomeric bladders. In order to achieve successful processing of such parts, knowledge of the compaction and impregnation behavior of the textile preform is vital. Hence, efficient analytical models that describe the influencing parameters of the preform compaction and filling stage were developed and verified through practical experiments. A process window describing optimal and critical operating conditions during the injection stage was created by evaluating the impact of the relevant process pressures on filling time. Finally, a cascaded injection procedure was investigated that particularly facilitates the manufacturing of long composite tubes. [ABSTRACT FROM AUTHOR]

In this work, a Cyber Physical System called Hybrid Twin is proposed for composite parts manufactured from RTM. This allows to introduce in the virtual twin of the parts the defect and the final properties induced by the real manufacturing process and to use on line data collection for predictive maintenance. [ABSTRACT FROM AUTHOR]

Wet compression moulding (WCM) provides large-scale production potential for continuously fiber reinforced components as a promising alternative to resin transfer moulding (RTM). Lower cycle times are possible due to parallelization of the process steps draping, infiltration and curing during moulding (viscous draping). Experimental and theoretical investigations indicate a strong mutual dependency between the physical mechanisms, which occur during draping and mould filling (fluid-structure-interaction). Thus, key process parameters, like fiber orientation, fiber volume fraction, cavity pressure and the amount and viscosity of the resin are physically coupled. To enable time and cost efficient product and process development throughout all design stages, accurate process simulation tools are desirable. Separated draping and mould filling simulation models, as appropriate for the sequential RTM-process, cannot be applied for the WCM process due to the above outlined physical couplings. Within this study, a two-dimensional Darcy-Propagation-Element (DPE-2D) based on a finite element formulation with additional control volumes (FE/CV) is presented, verified and applied to forming simulation of a generic geometry, as a first step towards a fluid-structure-interaction model taking into account simultaneous resin infiltration and draping. The model is implemented in the commercial FE-Solver Abaqus by means of several user subroutines considering simultaneous draping and 2D-infiltration mechanisms. Darcy’s equation is solved with respect to a local fiber orientation. Furthermore, the material model can access the local fluid domain properties to update the mechanical forming material parameter, which enables further investigations on the coupled physical mechanisms. [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]

Due to its high strength and low weight properties, structural components made from carbon fiber reinforced composites (CFRCs) are increasingly being utilized in the automotive, aerospace, and wind power industries. A common matrix material for these composites is epoxy resin, which it is very brittle in nature and limits applications of these CFRCs. Introducing rubber fillers is known to increase the toughness of epoxy resin, but is at the expanse of strength and modulus. However, nanosilica particles have been known to increase mechanical properties when added to epoxy resin. Therefore, this research focuses on the effects of introducing both core-shell rubber elastomer nanoparticles and nanosilica particles into the matrix to form a hybrid carbon fiber reinforced epoxy nanocomposite. The nanoparticles were dispersed into the epoxy resin through high shear mixing and the composites were manufacturing using the Vacuum Assisted Resin Transfer Molding (VARTM) process. Analyzing the dispersion and structure of the resulting nanocomposites was done using a scanning electron microscope (SEM). Furthermore, the static mechanical and fatigue properties were characterized. In characterizing the fatigue, a S-N curve and stiffness degradation model was developed. The hybrid showed increases in tension, flexural, and inter-laminar shear strength compared to the control composite. The hybrid also showed significant enhancements in fatigue life and stiffness degradation when compared to the control composite, as well as composites containing only the core-shell or silica nanoparticles. This research could further support future work related to the expansion of carbon fiber reinforced nanocomposites structural application in the automotive, aerospace, and wind power industries. [ABSTRACT FROM AUTHOR]

One of the main challenges in expanding composites use in various applications is the part manufacturing cost. While out of autoclave processes have been evolving to address this issue, it always comes at the expense of lower quality. This has left engineers with the task of balancing the race between production cost, speed and parts' quality. While processes such as sheet molding (SMC), bulk molding (BMC) and wet compression molding (WCM) offer fast production rate, parts manufactured with these processes lack the good performance and quality needed for many applications. To address this drawback, process such as High Pressure Resin Transfer Molding (HP-RTM) may be used to improve the quality at the cost of higher initial capital needed and slower production. A new process is designed and developed by Huntsman Advanced Materials that combines the HP-RTM and WCM benefits into single technique. Dynamic Fluid Compression Molding (DFCM) is a new process that can be used to mass produce high quality parts. This process addresses the low quality, high waste of resin and fiber and lack of robustness of WCM. It also offers faster production rate, lower working pressure and no fiber movement compared to HP-RTM. [ABSTRACT FROM AUTHOR]

Compared to autoclave based processes, RTM offers several key advantages. This includes: high internal and external complexity, less waste, lower volatile emissions, higher production rates, and excellent surface finish. However, the injection of high pressure - high temperature resin presents a tooling challenge in cases where trapped geometries exist. A large opportunity exists for new tooling technology that can withstand RTM conditions and be easily extracted from the composite after the cure cycle. A new tooling system ("RTM Core") is presented and compared against other washout systems and their ability to withstand resin transfer conditions in industrial processes. RTM Core tooling materials are designed to withstand high temperature-high pressure process conditions without the need for complicated surface sealants and are designed to be removable with tap water. Our research will cover the preliminary characterization of tooling system properties, mechanical behavior, and initial results from a composite manufactured using resin transfer molding. [ABSTRACT FROM AUTHOR]

Resin transfer molding is a process that has been subject to considerable practical and theoretical development for aerospace applications since the early 1980s. It is an effective method for producing complicated composite parts, however processing and tooling for large parts remain a challenge. The resin transfer molding process is dominated by complex process dynamics including the filling phase where low void level is essential, the cure cycle where fast and secure solidification is required and finally, the optimal design of the tool and the overall production cycle. This paper discusses the development of a series of two component toughened epoxy RTM resin systems. The materials offer a wide process window for optimal infusion and exhibit on-tool cure time from < 20 mins at 130°C, followed by oven post cure at < 228°C for maximum Tg. The neat resins demonstrate an excellent balance of toughness and Tg, with Resin A exhibiting a dry (wet) Tg of 226°C (211°C) and G1c of 929 J/m2 and Resin B exhibiting a dry (wet) Tg of 267°C (260°C) and G1c of 334 J/m2. Composite panels have been produced and evaluated with interlaminar shear strength, open hole compression and open hole tension reported as > 50 MPa, > 240 MPa and > 380 MPa respectively. This new range of RTM resins offer opportunities for faster production of large, complex composite parts, with excellent mechanical properties and elevated service temperature. [ABSTRACT FROM AUTHOR]

Benzoxazine resin has been studied extensively as a potential matrix for aircraft interior composites, due to its inherent flame retardance and relatively low cost, however its acceptance into the industry is currently hindered by poor processability at desirable temperatures. This research sought to develop a formulation capable of meeting both aircraft interior flammability requirements and viscosity requirements for resin transfer molding, while maintaining acceptable mechanical properties. Flammability properties were studied in accordance with FAR 25.853, while rheological and mechanical properties were studied using rotational rheometery and dynamic mechanical analysis, respectively. Furthermore, a model was developed for the prediction of resin viscosity as a function of temperature and formulation composition. Model accuracy was evaluated over a wide range of temperatures, and revealed good correlation at temperatures where resin was above its minimum viscosity. [ABSTRACT FROM AUTHOR]

Carbon fiber composite structures have been increasing in usage for aerospace applications due to their low density and high strength and stiffness properties. For certain applications such as commercial aircraft engines, high service temperature materials are increasingly being desired. Traditional epoxy resin systems which are suitable for the resin transfer molding process are deficient in either service temperature or impact resistance, limiting the expansion of their usage. A series of new resin transfer molding resins have been developed by 3M for carbon fiber composite structure which increase the service temperature of conventional epoxy resins while retaining the impact resistance. These systems are described in this paper with supporting neat resin and composite laminate data. [ABSTRACT FROM AUTHOR]

The high pressure resin transfer molding (HP-RTM) process has the potential for high-volume production of continuous fiber-reinforced components in the automotive industry. The development of robust equipment, new process variants and highly reactive matrix systems lead to significant reductions of the cycle time in recent years. The paper addresses the manufacturing of carbon fiber reinforced plastic (CFRP) laminates using different matrix systems. To evaluate the matrix influence on the material properties, matrix dominated test methods were selected for evaluation of the mechanical properties. The test plates were made with the HP-RTM process at constant process parameters using carbon fiber fabrics. Only the matrix-specific supplier instructions for processing of the matrix systems (mixing ratio, temperature of components in HP-RTM equipment and mold) were varied in the study. Three Polyurethane (PU) systems and one Epoxy (EP) system were used for the characterization of the matrix dominated properties. To identify the interlaminar shear properties, two test methods were selected and compared to each other: The Short-Beam Shear (SBS) Test and the Edge Shear Test (ESH). To obtain the damage tolerance under impact loading, the energy absorptions for each material combination during instrumented drop tower tests were investigated. The results show the impact of the different Epoxy and Polyurethane matrix systems on the laminate performance. [ABSTRACT FROM AUTHOR]

The goal of this work is to develop study and characterize the structural evolution of thermoplastic matrix during the thermoplastic Resin Transfer Molding process. To attain this objective, the reaction kinetic and its properties for forming process of PA-matrix were investigated as an alternative for the production of thermoset systems. Through this work, various formulations of PA with anionic polymerization from caprolactam were studied. Reaction kinetic were determined depending on processing parameters and chemistry. Besides, we present some promising routes to insitu monitor the process of thermoplastic composites with tailored mechanical and physical properties. The dielectric analysis technique and FTIR spectroscopy was coupled to rheology and used to monitor the reaction versus time, temperature and the type of catalyst. Indeed we characterize both the structure and chemorheological properties of PA formulations. Based on the obtained results, the TRTM cycle processing window for good impregnation of the fiber reinforcement were purposed as well the injection time, the reaction temperature and composition. [ABSTRACT FROM AUTHOR]

In this work, hybrid process coupling "Reactive Extrusion" and "Resin Transfer Molding" machine (T-ERTM) equipped with an instrumented mold was designed and developed. Polyamides model matrix according to two kinds of polymerizations were studied as well anionic and chain extension reactions. For the former, different ratios of catalyst and activator were investigated. For the latter, various formulations of prepolymer with chain extender (CA) were studied at different stoichiometry ratios and temperatures. Since that both reaction kinetics are very fast to be monitored at short times by usual technics, the chemo-rheological evolutions were firstly studied ex-situ by coupling rheology with FTIR and dielectric spectroscopy (DRS). Secondly, the T-ERTM process with an "instrumented mold" was developed with specific dielectric sensors in order to in-situ track viscosity and reaction evolution. The in-situ results corroborate the ex-situ ones aforementioned. Overall, a processing window was obtained for each reactive system to ensure a good preform impregnation for the manufacturing of complex and continuous glass fiber-reinforced parts. Herein, the Time-Temperature-Transformation- equivalent diagrams were established to obtain Thermoplastic composites with tailored mechanical and physical properties. [ABSTRACT FROM AUTHOR]

Canister systems are used for the purpose to hold, launch, and transport missiles. Metallic materials are generally preferred in canisters due to their well-known production techniques. Composites in canisters has been started to use for lowering production costs and weights while increasing the performance of missile systems. There are several manufacturing methods such as RTM (Resin Transfer Molding), fiber placement, 3D braiding, thermoplastic injection, and filament winding for canister production. However, none of these methods is a continuous process and cost-efficient. On the other hand, the pultrusion method is a cost-effective and automated process for manufacturing continuous, constant cross-section composite profiles. In this paper, the manufacturing route of a complex shaped pultruded canister profile, materials selection stages, material and part characterization procedures used in our project are presented. The design stage of a canister is given by examining the requirements of canister system. Material alternatives are evaluated by taking pultrusion process and canister requirements into consideration. Physical, thermal, and mechanical tests are conducted during materials selection, process optimization, qualification, and mass production stages of the project. Firing tests from canister profile are followed through as the system qualification. Design, test, and manufacturing stages of pultruded canister profile are also provided. [ABSTRACT FROM AUTHOR]

Manufacturing near-net shape preforms of fibre-reinforced composites has received growing interest from industry. Traditionally, a preform was made from 2D fabrics, but recently, it has been shown that 3D structures can be used with success. Various methods of forming 3D fibre architectures exist and are widely used, such as knitting, braiding and nonwovens; with weaving being the predominant technology for carbon fibre composites. In 3D weaving, weft, warp and binder fibres run across, along and through the fabrics. Producing a unitised single-piece fabric and subsequently reducing the takt time required for rapid composite manufacturing are two of the main advantages of using 3D woven preforms. In this work, a recently developed 3D weaving design software was used to design a set of different weave structures made of five layers: multilayer, orthogonal and angle-interlock. A standard Dobby loom was used to weave the 3D fabrics. In addition, 2D plain weave fabric was produced to provide a benchmark comparison. Flat composite panels were manufactured using resin transfer moulding (RTM). The panels were then characterised physically through density measurements and fibre-volume-fraction analysis and mechanically by flexural testing. X-ray Computed Tomography (CT) and optical microscopy were also carried out to validate the manufacturing quality of the dry fabrics and composites produced. Finally, a large automotive composite demonstrator was manufactured out of single-piece 3D woven preform. [ABSTRACT FROM AUTHOR]

Resin flow during Vacuum Assisted Resin Transfer Molding (VARTM) process when distribution media (DM) is used on top of reinforcement is largely affected by the presence of pinholes though the thickness of the fabric. Pinholes are gaps at locations where fiber tows in two different directions intersect when woven or stitched to construct the fiber preform. The variation in through thickness preform permeability is caused by the variation in the pinhole size which can dramatically change the resin flow pattern through the thickness and result in void formation. The phenomenon of pinhole variation was modeled to simulate the VARTM process with DM on top of four layers of fiber preform. Three values of increasing permeability of DM were selected to study its effect on the resin flow and void percentages. For each DM case, 100 numerical simulations were executed. It was found that void formation is influenced by the variation in pinhole sizes and the percentage of voids increased with higher DM permeability (KDM). Flow front at the bottom became more uneven and irregular with higher KDM, which led to higher percentage of voids during the filling process. This work clearly demonstrates that small flaws such as pinhole diameter variation during textile manufacturing can influence the yield in composite manufacturing and calls for better tolerances in textile production. It also points out that lower DM permeability can make the process more robust and reduce or eliminate void formation. [ABSTRACT FROM AUTHOR]

New phthalonitrile resin formulation based on the low-melting phosphorus-containing monomer bis(3-(3,4-dicyanophenoxy)phenyl) phenyl phosphate recently reported by our research group, common phthalonitrile 1,3-bis (3,4-dicyanophenoxy)benzene and aromatic diamine as curing agent was developed. The resin processing properties (melt viscosity 150 mPa⋅s at 150°C) allowed to produce carbon fiber composites by vacuum infusion molding process and resin transfer molding at 150 °C. The curing cycle consisting of 3 hours at 180 °C and post-curing at 375 °C was required to achieve the best thermal properties. After post-curing the obtained composites demonstrated up to 90 % mechanical properties retention at 400 °C (τr.t.12 = 60-80 MPa). Flame retardant properties were investigated and the composites demonstrated extremely high LOI > 80 %. Thus easily processable phthalonitriles with quick curing and excellent heat resistant and flame retardant properties were developed. [ABSTRACT FROM AUTHOR]

This work came about from a senior design project to develop a composite toed boot as an alternative to steel toed boots. Three materials were utilized, a carbon preimpregnated (prepreg) fabric, a Kevlar/carbon hybrid fabric and steel. Two techniques were utilized for processing the composite materials, a pseudo-autoclave and vacuum assisted resin transfer molding (VARTM). The pseudo-autoclave was developed as a more affordable means for processing the carbon prepreg. VARTM was used to process the Kevlar/carbon hybrid fabric. Mechanical and physical properties were measured, these included Impact Energy testing, three point flexural testing and density measurements. These measurements provided a means for obtaining the fiber volume fraction on the composite materials to better analyze the results. The testing showed that the carbon prepreg processed by the pseudo-autoclave gave below optimal results while the Kevlar/carbon fiber composite processed by VARTM provided the best product. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the bearing/bypass interaction of a carbon fiber reinforced three-dimensional woven ply to ply composite. The composite was reinforced with a three-dimensional woven ply to ply preform and injected with PR520 epoxy resin using a resin transfer molding (RTM) process. The preform was woven with 24K IM7 carbon fiber tows in the warp and weft directions. Results of filled-hole tension and compression, single-fastener bearing, and double-fastener bearing are presented and discussed. All bearing experiments are single-shear and include supported single-fastener tensile and compressive loading, and supported double-fastener tensile and compressive loading. A 6.35 mm nominal diameter Hi-Lok steel alloy pin with an aluminum alloy collar was used for filled-hole tension and compression, as well as for all bearing experiments. The experimental study presented in this paper demonstrates that a practical bearing/bypass interaction diagram can be constructed for a three-dimensional woven composite using the same procedures and standardized test methods recommended in the literature for two-dimensional laminated composites. Representative stress-strain curves for filled-hole tension and compression are presented, as well as for single-fastener bearing and double-fastener bearing under tensile and compressive loading. Findings and practical recommendations on the bearing/bypass performance of the three-dimensional woven composite are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, we present an experimental method to analyze the heat transfer during the consolidation of thermoplastic composite injected at low pressure by Resin Transfer Moulding process (RTM). The composite is based on thermoplastic resin (new generation of low viscosity PA 66) with glass fiber (50 vol%). A specific injection unit composed of an extrusion system and connected to an extruder piston is used to inject the PA 66 in a closed mold heated at 280 °C. The preform is prepared a quasi-unidirectional glass fabrics, optimized to improve the impregnation during the injection phase. The mold is instrumented with two pressure sensors at the inlet and the outlet of the mold to ensure that the filling phase is complete. During the consolidation, the crystallization was observed on the data recorded by a heat flux sensor and also by the thermocouples placed in the preform. The experimental heat flux was compared to numerical results for validation purpose. Finally, no shearing effect, potentially induced by the flow between fibers, on the crystallization kinetics was observed. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90􀂃􀈥 0􀂃). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods. [ABSTRACT FROM AUTHOR]

Resin transfer molding (RTM) allows for autoclave-free production of aerospace and automotive components with desirable properties and excellent surface finish. Traditional RTM resins are formulated to release a minimal quantity of volatiles during cure in order to reduce porosity. However, newer resins such as benzoxazines, which offer superior mechanical and thermal performance, may have higher levels of cure-induced volatile release. The proposed study analyzes volatile release and the effects of residual solvent within a commercially available benzoxazine/epoxy system. First, the resin is characterized using thermogravimetric analysis (TGA) to determine the kinetics of volatile effervescence during cure. Resin samples are then cured in a mini-RTM under various pressures to correlate TGA data with part microstructure. After curing, the samples are analyzed in a nuclear magnetic resonance (NMR) spectrometer for residual solvent contaminants. Lastly, a dynamic mechanical analyzer (DMA) is used to quantify the effect of residual solvent on the thermomechanical properties of the final part, including stiffness and Tg. The NMR and DMA data provide an understanding of the effects of residual volatile contaminants in the final product and the dependence on processing parameters. Furthermore, the study provides a basis for formulation optimization that reduces volatile release and improves part quality. [ABSTRACT FROM AUTHOR]

Laminate structure of fiber preform is an important factor in determining the processing conditions of liquid composite molding as well as mechanical properties of fiber reinforced composite product. In resin transfer molding process, fiber preform deforms undesirably by the flow pressure of resin, which causes defectives in size, properties and appearance of the final composite products. Therefore, process condition should be strictly controlled in order to prevent preform deformation in the molding process. Several types of fiber deformation such as slip, wrinkle, and contraction are observed by structural and process related factors. In this study, structural factors of fiber preform affecting the flow induced fiber deformation in resin transfer molding are investigated, which include fiber volume fraction and laminate structure of fiber preform. Effects of laminate structure are investigated by measuring two important factors which are hydrodynamic friction coefficient between fiber and mold surface and bulk stiffness of fiber preform in the mold. The former is related to slip and the latter is related wrinkle and contraction of fiber preform. Several kinds of fiber mat such as unidirectional and woven fabrics are tested and the resulting flow induced deformations are predicted and compared with the observed deformations in resin transfer molding. Woven structure of the most outer layer was an important factor in friction related deformation and the overall structure of the fiber preform affected the local deformations such as wrinkle and compaction. It is expected that the unexpected fiber deformation can be prevented by optimum design of laminate structure considering fiber deformation as well as mechanical properties of composite. [ABSTRACT FROM AUTHOR]

As part of the European Space Agency (ESA) Future Launchers Preparatory Programme (FLPP), SONACA (BELGIUM) and BRM (USA) companies joined their competences to develop a new concept of structural European launcher cryogenic upper inter-stage composite ring. This challenging program targeted the replacement of an ARIANE traditional aluminum ring by a lighter and affordable multi-functional composite structure. The ARIANE 5 aluminum specification was used as the basis of the design concepts, with adaptation to a future launcher 4.3 m diameter. After a preliminary design phase, involving selection of different manufacturing routes, material and processes by elementary tests made at coupon level, the 3D orthogonal weaving process was selected as the best candidate to realize a full scale ring demonstrator. The structure was designed, stressed and verified by test by SONACA, and the 3D weaving was optimized in close collaboration with BRM. Five 90° segment carbon fiber dry preforms were produced by BRM using the most advanced weaving automated technology. All these segments were injected by SONACA using their expertise in RTM process. The parts were controlled both geometrically and wrt internal defects by NDT. A 30° segment was successfully submitted to five static load cases up to failure, showing a TRL of 5. Four 90° segments were assembled by CFRP splices to exhibit a full ring demonstrator. [ABSTRACT FROM AUTHOR]

The Resin Transfer Molding (RTM) process consists of injecting a resin that will cure or solidify in the cavity of a mold where a fibrous preform has been placed. Injection is a critical phase of the process that requires simulation in order to predict potential defects and improve the injection strategy. In recent years, interest in short cycle time RTM part production has grown, especially in the automotive industry. Reduced injection and curing times are sought via usage of low viscosity, fast curing resins mixed on-line. In these conditions, it is essential to closely track the properties and repartition of the resin in the part. However, this is not possible with classical singlescale techniques that are too macroscopic to catch the details influencing the injection. Therefore, a new, flexible, dual-scale simulation approach to treat reactive injection cases is described in the presented work. This technique proposes both an adaptation of the permeability in the unsaturated area and a flexible microscopic filling strategy that enables the use of heterogeneous element sizes. Degree of cure, temperature, and viscosity are updated and transported at each time step in the mold channels and in the tows of the fabric. [ABSTRACT FROM AUTHOR]

Automated manufacturing of dry preforms for composite structures has shown to improve control and repeatability of fiber orientation as well as to increase process speed. This paper proposes an integrated braiding solution for curved centerline mandrels with axisymmetric sections. It combines the flexibility of a seven degrees of freedom industrial manipulator with a 144 carriers radial braiding machine. The mandrel is braided by keeping its centerline coincident with braider's central axis, ensuring constant radial tension of yarns along the process. Pre-processing starts by defining mandrel's centerline using Frenet-Serret frames. Du et al. braiding model is used to relate the braid's architecture with the mandrel's take-up speed. The convergence zone length is synchronized with the mandrel's positions in order to diminish the transitory regime. Based on the centerline definition and take-up speeds, a multi-objective algorithm optimizes the path of the manipulator. The braiding solution's repeatability, accuracy and precision were validated on an industrial system. Two mandrels with increasing complexity were braided. Fiber angles were measured by imaging. A statistical analysis done on the measured fiber angles confirms the predictions made using the integrated braiding solution. [ABSTRACT FROM AUTHOR]

The internal geometry of textile composites is subjected to a significant amount of variability. An improved assessment of the quality of any composite material is achieved by identification and simulation of the inherent uncertainty in the reinforcement geometry. By following this strategy, many random realistic representations of the textile reinforcement can be generated based on experimental data of only a few textile samples. This work presents such a roadmap with its successive steps to characterise the spatial scatter in the internal structure of any textile composite (short- and long-range) and simulate random models possessing the measured statistical information on average. Three main steps can be distinguished: (1) collection of experimental data and statistical analysis, (2) stochastic multi-scale modelling of the reinforcement, and (3) construction of virtual specimens in a geometrical pre-processor such as WiseTex. The methodology is demonstrated for a typical carbon-epoxy 2/2 twill woven composite produced by resin transfer moulding, but is applicable to any woven textile or other topology with minor modifications. [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]

The paper addresses new variants of the high pressure resin transfer molding (HP-RTM) process namely high pressure injection RTM (HP-IRTM) and high pressure compression RTM (HP-CRTM) for manufacturing of carbon fiber reinforced composites with high fiber volume content. Both these processes utilize high-pressure RTM equipment for precise dosing and mixing of highly reactive epoxy resin and amine hardener with relatively high throughput rates. The paper addresses results of a study which investigated cavity pressure measurement for both the HP-RTM process variants using a specially designed highpressure RTM mold. The investigations indicate that the cavity pressure built up is a characteristic of the selected process variant. Further the relationship between the applied press force and the cavity pressure in HP-CRTM process was studied. [ABSTRACT FROM AUTHOR]

In this paper, a numerical study of compression and transfer molding of rubber materials will be presented. A three dimensional analysis is used for the numerical study. The program developed can predict the flow pattern, temperature, degree of cure, stresses within a part and press force change during filling and post-filling. Of particular interest is the change of stresses within a part and press force during post-filling due to thermal expansion of a material and the degree of cure. PVT, viscosity and curing kinetics data of one the rubber material are used for the calculation of pressure during filling and post-filling. [ABSTRACT FROM AUTHOR]

The evaluation of damages caused during processing, assembly or usage of fibre reinforced plastics is still a challenge. The use of inspection technology like ultrasonic scanning enables a detailed damage analysis but requires high investments and trained staff. Therefore, the visual inspection method is widely used. A drawback of this method is the difficult identification of barely visible damages, which can already be detrimental for the structural integrity. Therefore an approach is undertaken to integrate microencapsulated dyes into the laminates of fibre reinforced plastic parts to highlight damages on the surface. In case of a damage, the microcapsules rupture which leads to a release of the dye and a visible bruise on the part surface. To enable a wide application spectrum for this technology the microcapsules must be processable without rupturing with established manufacturing processes for fibre reinforced plastics. Therefore the incorporation of microcapsules in the filament winding, prepreg autoclave and resin transfer moulding (RTM) process is investigated. The results show that the use of a carrier medium is a feasible way to incorporate the microcapsules into the laminate for all investigated manufacturing processes. Impact testing of these laminates shows a bruise formation on the specimen surface which correlates with the impact energy level. This indicates a microcapsule survival during processing and shows the potential of this technology for damage detection and characterization. [ABSTRACT FROM AUTHOR]

Increase in demand for natural fiber composites are raising today because of more advantage when compared to traditional fiber composites. In the present work, natural fiber composite material is processed by vacuum assisted resin transfer molding technique and the fibers are maize stalk fibers with matrix of unsaturated polyester resin. With suitable catalyst and accelerator composite material is fabricated and thermal properties for the material is examined by thermal gravimetric analyzer, differential scanning calorimeter and the results are also compared with finite element method. [ABSTRACT FROM AUTHOR]

Miniaturization of clustered high power LEDs by direct molded optics is an upcoming development. This paper discusses the transfer molding process of high aspect ratio optical domes for high brightness multi-LED packages. The fabrication process is separated in three subjects; First mold-cavity manufacturing techniques are discussed. Secondly the mechanics of the hyper-elastic release foils are characterized and analyzed using finite element analysis. Thirdly, silicone flow behavior is characterized for the optimization of the silicone injection parameters and package design. Finally the results are combined to produce an operational demonstrator containing 45 domes, with a height of 7 mm, molded directly on a single board containing LEDs. [ABSTRACT FROM PUBLISHER]

In order to maximize product throughput, an increasing number of electronic packages, such as Small Outline Transistor (SOT) package, are manufactured in a package array mold. Due to the complicated structure design of the package and mold cavity, wire sweep is becoming an increasingly severe problem. In this study, the numerical model which had been validated by experimental work was used for wire sweep analysis. Firstly, the leadframe structure was studied. Given the thin thickness of leadframe and the relative position to the bond wire loop, the leadframe structure has very limited influence on the wire sweep value. Besides, for fixed width and length of the die, the wire sweep behavior was simulated to examine the influence of the die height (thickness). The results show that the thinner the die, the smaller the wire sweep. Furthermore, the effect of cavity height on wire sweep value was also estimated. Based on the previous simulation and analyses, the ratio of the die height to that of the cavity was introduced as an index to optimize the flow pattern of epoxy molding compound (EMC) in order to find a guideline for package and cavity design to avoid the wire sweep issue. In addition, the influence of injection velocity and viscosity of EMC on wire sweep during transfer molding process were inspected and discussed according to the simulation results as well. It can be further concluded that the velocity plays the key role in resulting in the severe wire sweep in package array mold during transfer molding process. [ABSTRACT FROM PUBLISHER]

This paper represents the fabrication study of a novel material which is a combination of chopped E-glass, expandable polystyrene (EPS) and epoxy resin. The material is a novel hybrid material which can be used for different purposes. In the study, silane-treated chopped E-glass fibers were mixed with EPS beads in different ratios and fabricated with resin transfer molding method in laboratory scale. The material has promising characteristics and can be used for different purposes especially in automotive applications. The material has 102,04±19,16 HV1 (1kgf - 9.806 N) micro-hardness value under 20 seconds dwelling time and the water absorption of the material 2,485% in 240 hours (by weight) as maximum and the average water absorption was 1,246% for all specimens. Another important result of the material is the quasi-homogenous structure which is not generally possible with particulate reinforced materials. This hybrid material combines the properties of both discontinuous glass fibers and EPS beads particulates. The material promises low cost by combining the glass fibers and EPS beads. [ABSTRACT FROM AUTHOR]