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Highlights Microstructural analysis of resin flow in liquid composite molding is impeded by the absence of a characterization method that possesses both the required spatial and time resolution to capture the ongoing phenomena. An optimized UV‐flow freezing methodology is presented to rapidly capture dynamic flow behavior, followed by high‐resolution micro‐computed tomography (μCT) imaging to extract the flow front morphology. Optimisation of the resin strongly enhances the photopolymerisation kinetics, reducing the gelation time by up to 56%, while an adequate postcuring procedure at moderate temperature is proposed by introducing radical induced cationic polymerization. Additives are identified to facilitate facile variation of the capillary number while distortions of the flow front morphology are minimized by finetuning the experimental procedure. μCT imaging allows for a micron‐scale through‐thickness assessment of unsaturated flow at range of flow regimes corresponding to both capillary‐ and viscous‐dominated flow regimes while the corresponding saturation curves were derived by segmentation of the resulting images. An optimized method for evaluating microstructural flow in fibrous preforms. Optimisation of the resin composition allows for fast UV‐photopolymerisation. Additives identified for facile variation of the capillary number. Visualization of “frozen” microstructural flow by micro‐CT analysis. Applicable to broad range of flow conditions that normally cannot be captured. [ABSTRACT FROM AUTHOR]

Compression resin transfer moulding (CRTM) has been widely used to manufacture automotive parts with reduced production cycle times. With the development of fast curing thermosetting resins, the CRTM process is a viable option for the high production rates in the transportation industry. However, the dynamic resin curing behaviour poses a potential risk of manufacturing defects in the part. In order to reduce the risk during the development of the tool and the process parameters, this paper proposes a modelling framework for the CRTM process when using fast curing resin systems. The work specifically focused on the coupling between heat transfer, resin cure, resin flow and preform compaction using a commercial code, PAM-RTM. The tool captures accurately the preform filling, temperature and resin pressure evolution during the injection and compression phase. The application of the framework was demonstrated for a complex 3D demonstrator. The predicted preform filling had an accuracy of 73% for the flow front evolution compared to the experimental results. This work demonstrates the validity of the framework proposed when dealing with resin systems that are challenging to process. [ABSTRACT FROM AUTHOR]

In view of the limitation that the existing theoretical methods cannot reflect the influence of fiber wettability on permeability, the analytical expression of capillary pressure and the calculation formula of lateral dynamic permeability of fiber tow impregnation process were derived. The numerical simulation of the process of resin impregnated fiber tows was carried out by using a phase field method. The simulation results indicated that the numerical solution of the capillary pressure obtained by the phase field method was consistent with the analytical solution obtained from this paper. This proved the reliability of the developed method. The effects of fiber volume fraction and contact angle on the dynamic permeability were studied. The results indicated that this method could better characterize the effect of fiber wettability on the permeability and realize the dynamic prediction of the permeability at different impregnation radii. Compared to the existing permeability calculation methods, the developed method is more applicable and the calculation results are more accurate. [ABSTRACT FROM AUTHOR]

Short fiber-reinforced plastic (SFRP), which involves compounding discontinuous fibers with resin, exhibits excellent specific strength, specific stiffness, and moldability, along with low cost, making it particularly active in the automotive sector for the conservation of the Earth's environment and the efficient use of energy resources. SFRP is mainly manufactured by injection molding, but defects such as resin filling deficiency, void formation, and fiber agglomeration or orientation bias are possible, highlighting the importance of setting appropriate molding conditions to achieve proper fiber dispersion and orientation. Considering the vast number of molding parameters, including resin flow rate, mold temperature, and pressure, numerical analysis prior to experimental validation is deemed effective. Therefore, this study focuses on resin flow within the mold and aims to evaluate the influence of molding parameters on the skin layer, the outermost layer formed by the flow front during injection molding, through MPS-based analysis of local area migration in the flow front. As a result, it was elucidated that the rate of resin solidification progress is the dominant parameter affecting fiber orientation in the skin layer. [ABSTRACT FROM AUTHOR]

Resin and fiber flow around the injection nozzle of a flat mold in injection molding was analyzed using the particle method that can easily track resin and fiber flow, and the effects of injection position of resin and fiber and injection time on resin and fiber flow behavior were evaluated. Resin flow was unstable near the flow front but was stable after the flow front was passed. Regarding fiber flow, many fibers were oriented perpendicular to the flow direction in the mold width direction. On the other hand, fibers were randomly oriented in the mold thickness direction. The difference in orientation between the thickness direction and the width direction is considered to be caused by the resin injected from the injection nozzle spreading in the width direction while decreasing its velocity. These results are likely to be greatly affected by parameters such as mold shape and injection speed, and further evaluation of these parameters is needed. [ABSTRACT FROM AUTHOR]

Compression resin transfer moulding (CRTM) has been widely used to manufacture automotive parts with reduced production cycle times. With the development of fast curing thermosetting resins, the CRTM process is a viable option for the high production rates in the transportation industry. However, the dynamic resin curing behaviour poses a potential risk of manufacturing defects in the part. In order to reduce the risk during the development of the tool and the process parameters, this paper proposes a modelling framework for the CRTM process when using fast curing resin systems. The work specifically focused on the coupling between heat transfer, resin cure, resin flow and preform compaction using a commercial code, PAM-RTM. The tool captures accurately the preform filling, temperature and resin pressure evolution during the injection and compression phase. The application of the framework was demonstrated for a complex 3D demonstrator. The predicted preform filling had an accuracy of 73% for the flow front evolution compared to the experimental results. This work demonstrates the validity of the framework proposed when dealing with resin systems that are challenging to process.

The Resin Transfer Moulding process receives great attention from both academia and industry, owing to its superior manufacturing rate and product quality. Particularly, the progression of its mould filling stage is crucial to ensure a complete reinforcement saturation. Contemporary process simulation methods focus primarily on physics-based approaches to model the complex resin permeation phenomenon, which are computationally expensive to solve. Thus, the application of machine learning and data-driven modelling approaches is of great interest to minimise the cost of process simulation. In this study, a comprehensive dataset consisting of mould filling patterns of the Resin Transfer Moulding process at different injection locations for a composite dashboard panel case study is presented. The problem description and significance of the dataset are outlined. The distribution of this comprehensive dataset aims to lower the barriers to entry for researching machine learning approaches in composite moulding applications, while concurrently providing a standardised baseline for evaluating newly developed algorithms and models in future research works. [ABSTRACT FROM AUTHOR]

Process simulation is frequently adopted to facilitate the optimization of the resin transfer molding process. However, it is computationally costly to simulate the multi-physical, multi-scale process, making it infeasible for applications involving huge datasets. In this study, the application of K-nearest neighbors and artificial neural network metamodels is proposed to build predictive surrogate models capable of relating the mold-filling process input-output correlations to assist mold designing. The input features considered are the resin injection location and resin viscosity. The corresponding output features investigated are the number of vents required and the resultant maximum injection pressure. Upon training, both investigated metamodels demonstrated desirable prediction accuracies, with a low prediction error range of 5.0% to 15.7% for KNN metamodels and 6.7% to 17.5% for ANN metamodels. The good prediction results convincingly indicate that metamodeling is a promising option for composite molding applications, with encouraging prospects for data-intensive applications such as process digital twinning. [ABSTRACT FROM AUTHOR]

The effective design of channels in dry tape preforms is crucial for achieving desired preform permeability for successful resin injection for composites manufacturing using Automated Fiber Placement (AFP) process. Achieving target gaps and their locations in the AFP layup is extremely challenging. This work investigates the correlation between the spatial variability of the preforms and the in-plane permeability using an X-ray Computed Tomography (XCT) based characterization framework. The tomographic images of two different dry carbon tape preforms with different tape widths were used to generate realistic and XCT based stochastic models to be used for numerical permeability predictions. The variability in the tape placement by the robotic head and its effect on preform permeability was also examined through stochastic geometric modeling of the laid preform. A benchmark transient permeability measurement set-up was utilized to obtain experimental in-plane preform permeability through 2D radial mold filling. The in-plane numerical permeability values showed significant scatter, with a coefficient of variance of 75%–130%, which deviated from the experimental measurements by approximately one order of magnitude. These findings strongly re-affirm that the experimental permeability measurement technique based on transient mold filling of dry fiber AFP preforms is complex however, the XCT based stochastic modeling technique is an effective way to estimate the permeability of dry fiber AFP preforms virtually. [ABSTRACT FROM AUTHOR]

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

In this study, hot stamping tests on continuous glass fiber (GF)-reinforced thermoplastic (PP) composites were conducted under different process parameters using a self-designed hemispherical hot stamping die with a heating system. The effects of parameters such as preheating temperature, stamping depth, and stamping speed on the formability of the fabricated parts were analyzed using optical microscopy and scanning electron microscopy (SEM). The test results show that the suitable stamping depth should be less than 15 mm, the stamping speed should be less than 150 mm/min, and the preheating temperature should be about 200 °C. From the edge of the formed parts to their pole area, a thin-thick-thin characteristic in thickness was observed. Under the same preheating temperature, the influence of stamping depth on the thickness variation of the formed parts was more significant than the stamping speed. The primary defects of the formed parts were cracking, wrinkling, delamination, and fiber exposure. Resin poverty often occurred in the defect area of the formed parts and increased with stamping depth and stamping speed. [ABSTRACT FROM AUTHOR]

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

This article presents the numerical analysis and experimental investigation for the manufacturing of a foam core sandwich spoiler by vacuum-assisted resin injection (VARI) process. To find an injection scheme that guarantees both a good impregnation of the preform and a filling time compatible with the process window, the finite element model (FEM) was applied to analyze the effect of different injection schemes on the resin flow front patterns. Based on the obtained results, two optimal injection schemes are selected to form the spoiler structure. The experimental results show that the best molding quality can be achieved from the thick-end injection with a thin-end exit scheme. The comparison between simulation and experimental results shows that the overall deviation of the numerical analysis on resin flow time is 15.9%. [ABSTRACT FROM AUTHOR]

In this paper, interlayer toughening composites were prepared by the z-directional injection RTM process (z-RTM), which has the advantage of increasing the interlaminar toughness and shortening the filling time and completely impregnating the fibers. The nonwoven fabrics and dot matrix structure material were used as ex situ interlayer toughening agents. The effect of the interlayer toughening agent structure on the resin flow behavior during the z-RTM process was investigated. The macro-flowing and micro-infiltration behaviors of the resin inside the preforms were deduced. The permeability of the fabric preforms with different toughening agents was investigated. The results show that the introduction of the nonwoven structure toughening agent makes the macro flow slow, and the flow front more uniform. The toughening agent with a dot matrix structure promotes the resin macro flow in the preforms, and shortens the injection time. The z-directional permeability of the preform with a dot matrix structural toughening agent is one order of magnitude lower than that of the non-toughened preform, while being higher than the preform toughened by the nonwoven fabric preforms, which is helpful for the further applicability of the z-RTM process. Furthermore, the mode II interlaminar fracture toughness of composites was evaluated. [ABSTRACT FROM AUTHOR]

A geometric modeling platform based on the virtual fiber-voxel element is proposed to characterize textile reinforcement in a cost-effective way, which could reflect the systemic local changes of the tow path and tow cross-section. The finite volume method is used to solve the governing equation of the boundary value problem, and the permeability of the fabric is calculated by using the flow field data obtained from the model. The flow field analysis and pressure drop in flow direction of different thickness unit cells suggest that the size of inter-tow channels play a vital role in determining the overall in-plane permeability values. The flow channels of the inter tow in warp direction were found to be greater than in the weft direction, which causes the overall permeability to be anisotropic. [ABSTRACT FROM AUTHOR]

This paper explores the application of a novel adaptive consolidation sensor framework for the characterisation of composite precursors. The designed framework develops material-driven test programmes in real-time and defines robust material models for the studied composite precursor. The proposed approach allows to remove any subjective judgement about the material behaviour and to reduce human involvement at the experimentation stage. The proposed framework along with the developed data transfer/acquisition hardware setup was put to the test within several characterisation exercises. Two different material systems were tested. The output of the proposed testing method—model and properties for the tested materials—is compared with the results of the conventional deterministic characterisation tests.

Impregnation and in-plane resin flow of film-stacking material under compression process were investigated. The understanding of this phenomenon is the key to optimize the impregnation process under pressure rollers in a double-belt press for organo-sheet production. The stack of carbon fiber woven fabrics and viscous fluid were compressed in a flat open-edge mold under various controlled conditions using a testing machine. The impregnation, in-plane flow, and pressure profile were characterized from the experimental observations. Furthermore, a theoretical model was developed to describe the impregnation and in-plane flow behavior. The model prediction showed decent agreement with the experimental data. The developed model will be useful to optimize the process parameters of double belt press process. [ABSTRACT FROM AUTHOR]

This paper addresses the development of a digital twin, based on an inversion procedure, integrating process monitoring with simulation of composites manufacturing to provide a real time probabilistic estimation of process outcomes. A computationally efficient surrogate model was developed based on Kriging. The surrogate model reduces the computational time allowing inversion in real time. The tool was implemented in the filling stage of an resin transfer molding processing of a carbon fiber reinforced part resulting in the probabilistic prediction of unknown parameters. Flow monitoring data were acquired using dielectric sensors. The inverse scheme based on Markov Chain Monte Carlo uses input parameters, such as permeability and viscosity, as unknown stochastic variables. The scheme enhances the model by reducing model parameter uncertainty yielding an accurate on line estimation of process outcomes and critical events such as racetracking. The inverse scheme provides a prediction of filling duration with an error of about 5% using information obtained within the first 30% of the process. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper proposes a novel approach to model the in-plane resin flow in deformable thin-walled fiber preforms for liquid composite molding processes. By ignoring the through-thickness flow in large scale thin-walled components, the 3-D resin flow is simplified to an in-plane flow inside the preform by a specialized divergence theorem. Shell kinematics are used to describe the fiber preform deformation, and the compressible flow is modeled in the context of the free surface flow in porous media. For simplicity and efficiency, the normal stretch, which is driven by the internal fluid and applied external pressure, represents the fiber preform expansion and compression. As compared with full 3-D models, the proposed shell model significantly reduces the problem size, while it still represents the primary physical phenomena during the process. The effects of neglecting the through-thickness flow are illustrated in a numerical example that compares the flow for a set of preforms with different thickness. The model is demonstrated from the numerical example of the mold filling in a doubly curved thin-walled fiber preform. Due to the applied vacuum and the consequent resin flow motion, the relevant deformation of the preform is observed. [ABSTRACT FROM AUTHOR]

Featured Application: The influence of empty channel design on resin flow in a porous plate is studied. Constructal design is used for geometric investigation of I and T-shaped channels. The multiphase resin/air flow in the porous plate is solved numerically. T-shaped configurations with long branches lead to the best impregnation performance. Permanent air voids arise in the domain for very thin T-shaped channels. This numerical study aims to investigate the influence of I and T-shaped empty channels' geometry on the filling time of resin in a rectangular porous enclosed mold, mimicking the main operating principle of a liquid resin infusion (LRI) process. Geometrical optimization was conducted with the constructal design (CD) and exhaustive search (ES) methods. The problem was subjected to two constraints (areas of porous mold and empty channels). In addition, the I and T-shaped channels were subjected to one and three degrees of freedom (DOF), respectively. Conservation equations of mass and momentum for modeling of resin/air mixture flow were numerically solved with the finite volume method (FVM). Interaction between the phases was considered with the volume of fluid method (VOF), and the effect of porous medium resistance in the resin flow was calculated with Darcy's law. For the studied conditions, the best T-shaped configuration resulted in a filling time nearly three times lower than that for optimal I-shaped geometry, showing that the complexity of the channels benefited the performance. Moreover, the best T-shaped configurations were achieved for long single and bifurcated branches, except for configurations with skinny channels, which saw the generation of permanent voids. [ABSTRACT FROM AUTHOR]

Bark beetles are major causes of conifer mortality worldwide. We quantified genetic contributions to key chemical and physical traits in lodgepole pine that contribute to defense against mountain pine beetle, a native tree-killing herbivore. Assays were conducted with mature trees in replicated provenance trials. Among chemical defenses, monoterpene composition (relative proportions of various compounds) had higher genetic variability than monoterpene concentration (absolute quantities). Additionally, constitutive concentrations had higher genetic variabilities than induced concentrations elicited by simulated attack. Resin flow elicited by mechanical wounding likewise showed very low genetic variability. In previous studies with this and related systems, induced monoterpene concentration and resin flow are the two best predictors respectively of which trees will survive outbreaks under natural conditions. This means that expression of the most efficacious defense traits is strongly influenced by environmental factors. These low heritabilities despite their survival values likely arise from specific life history and ecological aspects of this system, such as the lengthy period between when lodgepole pines begin cone production and become large enough for brood development, the extended viability of serotinous cones post-mortem , the high heterogeneity of both resources and stressors that trees experience across landscapes, and a strong proximate-neighbor effect on tree mortality arising from beetle aggregation pheromones. However, low heritability values do not preclude long-term evolvability and coadaptation of defenses, for which there is extensive mechanistic and associational evidence in this system. Among other traits we evaluated, sesquiterpenes had higher genetic variability than monoterpenes. Sesquiterpenes are not known to influence conifer-bark beetle interactions but have anti-herbivore properties in some other plant-insect systems. The lengths of lesions formed in response to simulated attack showed no heritable component and likewise do not predict tree survival in nature. Bark texture was highly heritable and is known to influence beetle post-landing orientation and colonization patterns, but whether it influences survival patterns at the whole-tree level is unknown. Relationships between tree defenses and growth were generally positive, suggesting that environmental heterogeneity in resource quality among trees supersedes potential underlying substrate allocation processes within trees. Similarly, relationships between various defense traits were generally positive rather than showing trade-offs, suggesting conifer resistance to native bark beetles entails coordinated defense syndromes. Implications to tree breeding, forest management, and coevolution between long-lived plants and rapidly reproducing herbivores are discussed. The extent to which these trends may apply to other bark beetle systems is evaluated, along with specific priorities for future research. • We quantified the heritability of traits affecting tree defense to bark beetles. • Monoterpene composition has higher genetic variability than monoterpene quantity. • Constitutive terpene quantity has higher genetic variability than induced quantity. • Resin flow, like induced terpene quantity, is under high environmental influence. • In nature high induced terpene quantity and resin flow most increase tree survival. [ABSTRACT FROM AUTHOR]

Resin transfer molding and vacuum-assisted resin transfer molding are two of the most commonly used liquid composite molding processes. For resin transfer molding, mold filling simulations can predict the resin flow patterns and location of voids and dry spots which has proven useful in designing the mold and injection locations for composite parts. To simulate vacuum-assisted resin transfer molding, even though coupled models are successful in predicting flow patterns and thickness distribution, the input requires fabric compaction characterization in addition to permeability characterization. Moreover, due to the coupled nature of flow and fabric compaction, the simulation is computationally expensive precluding the possibility to optimize the flow design for reliable production. In this work, we present an alternative approach to characterize and use an "effective" permeability in the resin transfer molding solver to simulate resin flow in vacuum-assisted resin transfer molding. This decoupled method is very efficient and provides reasonable results. The deviations in mold filling times between experiments and simulations for the resin transfer molding process with E-glass CSM and carbon 5HS were 4.7% and 1.0%, respectively, while for the vacuum-assisted resin transfer molding case using "effective permeability value" with E-glass CSM and carbon 5HS fabrics were 11.1% and 12.3%, respectively, which validates the approach presented. [ABSTRACT FROM AUTHOR]

Abstract Composite stiffened structures that are widely used in engineering inevitably produce various defects in manufacturing and service. In order to detect them, a microwave nondestructive testing platform is built in this paper, which simply combines near-field and far-field microwave scanning imaging. 0.4 mm metal hole, 0.5 mm and 1 mm inclusions and 0.1 mm thick debonding are detected by high resolution microwave near-field imaging. Internal poor resin infusions defects in 39 mm thick hat stiffener are detected by high penetration microwave far-field imaging. Far-field microwave images the shape and internal structure of stiffener by adjusting stand-off distance. Detection of the fiber wrinkling defects demonstrates the effectiveness of combining near-field and far-field imaging methods, saving 95% of the scan imaging time. Feature-based image stitching technique is adopted to obtain the full-size image of the large stiffened composite structure. [ABSTRACT FROM AUTHOR]

This numerical study aims to investigate the influence of I and T-shaped empty channels’ geometry on the filling time of resin in a rectangular porous enclosed mold, mimicking the main operating principle of a liquid resin infusion (LRI) process. Geometrical optimization was conducted with the constructal design (CD) and exhaustive search (ES) methods. The problem was subjected to two constraints (areas of porous mold and empty channels). In addition, the I and T-shaped channels were subjected to one and three degrees of freedom (DOF), respectively. Conservation equations of mass and momentum for modeling of resin/air mixture flow were numerically solved with the finite volume method (FVM). Interaction between the phases was considered with the volume of fluid method (VOF), and the effect of porous medium resistance in the resin flow was calculated with Darcy’s law. For the studied conditions, the best T-shaped configuration resulted in a filling time nearly three times lower than that for optimal I-shaped geometry, showing that the complexity of the channels benefited the performance. Moreover, the best T-shaped configurations were achieved for long single and bifurcated branches, except for configurations with skinny channels, which saw the generation of permanent voids.

Flowability of resin and fibers during forming process of short fiber-reinforced plastics was evaluated by Moving Particle Semi-implicit (MPS) particle-simulation. For injection molding of short fiber-reinforced plastics, there are several design parameters. It is inefficient in terms of time and cost to optimize the parameters based on experimental procedures. In this study, a numerical prediction using M P S particle-simulation was applied. In particular, a new analysis method of local flow accompanied by change of time and analysis area was developed to solve discrepancies of the distribution of velocity between global injection area and local flow area. As the numerical results, resin flow and fiber orientation in injection molding had same tendency with global injection molding analysis and the proposed M P S analysis. Therefore, it is concluded that the proposed method contributed to evaluate resin flow and fibers in injection molding process of short fiber-reinforced plastics. [ABSTRACT FROM AUTHOR]

Part I of this two-part paper presented the framework to integrate the simulation of resin flow and stress development during the manufacturing process of composites. In the current paper, the integrated approach developed in Part I for isotropic materials is extended to the case of transversely isotropic materials. Various numerical examples are considered in which the results obtained from the integrated approach are compared to those generated from the previously established models for processing induced stress development. These comparisons serve to elucidate the importance of accounting for the spatial and temporal variations in the resin volume fraction during processing and its effect on stress development. Such effects cannot be investigated in a non-integrated simulation environment where volume fraction variations due to resin flow have to be mapped sequentially from the flow simulation onto the next phase of the process simulation which treats the resin as an elastic or viscoelastic solid. [ABSTRACT FROM AUTHOR]

Process modelling of thermoset matrix composites is typically divided into two distinct and sequential steps: (i) flow-compaction analysis before gelation of the resin when it behaves in a fluid-like manner, and (ii) thermomechanical analysis after gelation when appreciable modulus and thereby stress development occurs. This two-part paper presents a novel approach to integrate the simulation of resin flow and stress development seamlessly during the processing of composites. Part I lays the theoretical foundation for the simpler case of isotropic materials while Part II extends the methodology to the case of transversely isotropic materials. The formulation is implemented in a 2D plane strain finite element code written in MATLAB. Relevant numerical examples are presented to demonstrate both aspects of flow-compaction and stress development throughout the curing process of thermoset matrix composite materials. The effects of resin flow on the development and the final values of residual stresses are investigated. [ABSTRACT FROM AUTHOR]

This study analyses the influence of the random filament arrangement in fibre bundles on the resin flow behaviour. Transverse steady-state resin flow that occurs behind a liquid resin flow front was simulated numerically through statistically equivalent micro-structures at high-fibre volume fractions, Vf > 0.6, as observed in fibre bundles. The need of applying a minimum gap distance between neighbouring filaments was overcome by automated local mesh refinement. The derived permeability values showed significant scatter. Convergence of these values was determined at a ratio of flow length to filament radius greater than 20 for all three analysed fibre volume fractions. Mean permeabilities were between 6 and 10 times lower than those predicted for a hexagonal fibre array. A statistical model is proposed, which is able to predict the scatter of observed permeabilities based on simple micro-structural descriptors. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Composite part design process proceeds with the designers' gradually eliminating the uncertainty in design parameters. However, the analysis tools that have been developed to aid this process require the designer to decide precise parameter values at the very beginning of the design stage which reduces their effectiveness. To improve their utility, this paper introduces a management strategy to integrate multi-disciplinary analysis modules with CAD software and account for design uncertainties during the design stage. Interdependent cross-disciplinary design parameters are separated in accordance with their uncertainty levels, and different fidelity analysis models are assigned to each set of parameters accordingly. As the design process proceeds, more precise design parameters are input for analysis modules that have higher level of fidelity. This management method resembles the practical design flow and is therefore intuitive to the designer in the decision-making process. An example using this approach to develop multidisciplinary composite wind blade with such design and analysis software is shown to illustrate its effectiveness and efficiency in complex composite part design. [ABSTRACT FROM AUTHOR]