Quality modeling and analysis of polymer composite products

The present article gives a new direction for quality modeling and analysis of polymer matrix composite products. Quality of composite products depends upon conformance of requirements of the customer. These requirements are translated into design specifications of all the contributing factors and subsystems up to component level of composite system. Quality of interaction amongst different subsystems, sub‐subsystems, and other factors affects quality of products are also to be considered. Therefore, the present article considers quality of subsystems as well as quality of all interactions together and modeled using graph theory, matrix algebra as quality graph, quality matrix, and quality permanent function of the composite product. These models are useful to design quality of every subsystem and factors in such a manner that can lead to achieve six‐sigma limits (almost zero error) i.e. 3.34 defects per million products produced. A number of analytical tests derived from these models help to carry out optimum selection of qualities of subsystems and interactions for designing competitive composite products. SWOT (strength–weakness–opportunities–threats) analysis integrated with these models becomes very powerful tool to convert an unsuccessful product into successful competitive product. Evaluation, ranking, and comparison procedures can be developed with the help of these proposed models. Coefficients of similarity and dissimilarity are developed for comparison among feasible products. Step‐by‐Step procedure based on systems approach is useful to designer, manufacturer at conceptual stage of design, and during manufacturing stages of composite products. This is basically a virtual prototyping methodology of complete system, leading to high quality competitive composite products. POLYM. COMPOS. 27:329–340, 2006. © 2006 Society of Plastics Engineers     

Cure kinetics and rheology characterization of soy‐based epoxy resin system

A novel soy‐based epoxy resin system was synthesized by the process of transesterification and epoxidation of regular soy bean oil, which has the potential to be widely usable in various composite manufacturing processes. Cure kinetics and rheology are two chemical properties commonly required in process modeling. In this work, the cure kinetics and rheology of the soy‐based resin system were measured by means of differential scanning calorimetry (DSC) and viscometer. DSC was used to measure the heat flow of dynamic and isothermal curing processes. The cure kinetics models of the different formulations were thus developed. A Brookfield viscometer was used to measure the change in viscosity under isothermal conditions. A novel neural network‐based model was developed to improve modeling accuracy. The models developed for cure kinetics and rheology for soy‐based epoxy resin system can be readily applied to composite processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3168–3180, 2006     

Effective properties of particle reinforced polymeric mould material towards reducing cooling time in soft tooling process

Cooling time in soft tooling process using conventional mold materials is normally high. Although increase of effective thermal conductivity of mold material by inclusion of high thermally conductive fillers reduces the cooling time, it affects other properties (namely, stiffness of mold box and flow ability of melt mold material), which play important roles in soft tooling process. Therefore, to apply composite polymer in soft tooling process as mold material simultaneous studies of these properties are important. In this work, extensive experimental studies are made on the effective thermal conductivity, modulus of elasticity and viscosity of composite polymeric mold materials namely Polyurethane and RTV (Room Temperature Vulcanizing)‐2 silicone rubber, with aluminum and graphite particle reinforcements. To find suitable models of the effective properties of composite mold materials, which are required to decide the optimum amount of filler content before actual application, attempts are made to fit the experimental results using various models reported in the literature. Finally, different aspects in reducing cooling time in soft tooling process and further activities are reported. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

过程工业新产品开发的研究及展望

对离散制造业中新产品开发的组织，管理模式及其系统方法和技术研究方面已取得的成果进行了综述，并建议结合过程工业的特点，借鉴离散工业的新产品开发研究成果，深入开展过程工业新产品开发的系统方法与技术的研究。     

Experimental and numerical analysis of flow behavior in the FASTRAC liquid composite manufacturing process

The success of resin infusion during liquid composite processing depends on several factors; including the complete impregnation of the dry performs, the processing conditions, and the tooling used during processing. New process developments based on the Fast Remotely Actuated Channels (FASTRAC) process aid the infusion with the creation of preferential resin flow paths using a non-contact tooling. Experiments to understand and study the infusion behavior with the presence of the FASTRAC non-contacting tooling have been performed, and compared with vacuum-assisted processes without such tooling. Experimental studies indicate that the infusion time with FASTRAC channel configurations is significantly less despite the additional volume regions to be infused during processing. The use of a non-contacting interchangeable tool, the improved infusion behavior, and the significant reduction in the infusion time provide significant advantages for processing advanced composite systems, including the potential to use high viscosity resin systems, and process automation. The process simulation models of the experimental configurations based on the thin shell model configurations have been compared with experimental observations. Studies indicate that the process simulation models and approaches employed clearly emulate the infusion behavior seen when the channels are present, validating the modeling strategies employed. Similar simulation approaches will thus be effective to study and understand various FASTRAC tooling configurations while processing complex composite structures. Polym. Compos. 25:384–396, 2004. © 2004 Society of Plastics Engineers.     

无人机复合材料构件整体辅助定位工装的制作技术

本文主要介绍了小型无人机复合材料结构件的特点及成型蜂窝夹层结构板件中梁缘条、肋缘条和框层压板结构用整体辅助定位工装,并详述了整体辅助定位工装的制作工艺过程。     

Autoclave manufacturing of thick composites

Autoclave manufacturing of thermoset composites is determined mainly by heat transfer phenomena. As a matter of fact, the consolidation of composite laminates takes place by the progress of the polymerization, which is activated thermally. The design and control of the autoclave process relies on the capability to manage the relationship between the temperature-pressure cycle of the heat carrier fluid and the temperature distribution through the manufacturing part. In particular, in industrial cases, the main limitations reside in the correct evaluation of the local convective heat transfer conditions through the autoclave and in the evaluation of the local thermal inertia arising from the bagging-tooling system. In this study, the autoclave manufacturing of thick laminates has been addressed by modeling the heat transport phenomena occurring through the composite, the bagging and the tooling system. A new methodology for the evaluation of the energy transfer regimes has been proposed accounting for the heat fluxes from the bag and the tool side, the temperature through-the-thickness gradients and the heat generated by the resin polymerization reaction. The proposed approach enables the prediction of the temperature history of the autoclave assembly without knowledge of the effective thermal inertia of the two external layers, which could be difficult to evaluate owing to possible deformations of the bag during the manufacturing cycle and nonuniform shape of the metallic tool along the part. Experimental data from industrial autoclave runs have been collected and analyzed to validate the method.     

Stochastic analysis of isothermal cure of resin systems

Curing of catalyzed resin systems is an important and critical processing step in the fabrication of reinforced thermosetting composite materials. Strong uncertainties inherent in the associated process and material parameters, however, pose a stiff challenge to robust commercial manufacturing of quality composites in practice. Although deterministic models have been developed over the years to simulate the cure process, analysis of the effects of the parameter uncertainties on the process performance and the product quality variabilities has been the subject of little attention, and forms the focus of this study. This paper presents a methodology for a systematic analysis of the effects of the process and material parameter uncertainties on the isothermal curing of thermosetting resin systems. A stochastic model is developed, and parameteric studies are presented to systematically examine the effects of the uncertainties in the processing temperature and the kinetic parameters on the process output variabilities. Optimum parameter spaces that minimize the variance of the output parameters are identified, as a first step towards robust manufacturing of composites.     

A new kinetic and viscosity model for liquid composite molding simulations in an industrial environment

Liquid composite molding is broadly used for manufacturing composite parts. Apart from the preforming of the dry fibrous material, mold filling and curing of the resin are the main steps in the manufacturing process. For process simulation numerical methods, like finite element methods are applied. Flow models describing the flow behavior through a porous medium are well established. The ability to predict and monitor the curing process in liquid composite molding is crucial for manufacturing process optimization in case of application of rapid curing resin systems. Based on differential scanning calorimetry and rheological experiments, cure kinetics and viscosity of a resin system were characterized. A new kinetic and complex viscosity model is proposed to predict epoxy resin properties in numerical modeling of liquid composite molding. The semi-empirical models are simple to use and therefore suitable for process optimization in an industrial environment. Both models were validated by a fitting to the experimental data by the Levenberg-Marquardt method. A process to determine the initial values for the fitting procedure is also proposed. The predictions of the validated models were in good agreement with the measured data, and are therefore applicable for numerical process optimization. Polym. Compos. 25:255–269, 2004. © 2004 Society of Plastics Engineers.     

Double‐vacuum‐bag technology for volatile management in composite fabrication

A nonautoclave vacuum bag process using atmospheric pressure alone that eliminates the need for external pressure supplied normally by an autoclave or a press is an attractive method for composite fabrication. This type of process does not require large capital expenditures for tooling and processing equipment. The traditional single‐vacuum‐bag (SVB) process is best suited for molding epoxy matrix‐based composites because of their superior flow and the absence of reaction byproducts or other volatiles. This is not the case for other classes of materials such as polyimides and phenolics. Polyimides and phenolics are cured by condensation reactions which generate water as a reaction byproduct. In addition, these materials are commonly synthesized as oligomers using solvents to facilitate processability. Volatiles (solvents and reaction byproducts) management therefore becomes a critical issue. SVB molding, without additional pressure, normally fails to yield void‐free quality composites for these classes of resin systems. A double‐vacuum‐bag (DVB) process for volatile management in composite fabrication using common molding equipment was designed and built at the NASA Langley Research Center. This experimental DVB process affords superior volatiles management compared with the traditional SVB process. Void‐free composites are consistently fabricated as measured by C‐scan and optical photomicroscopy for high‐performance polyimide and phenolic resins. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Rapid thermal cycling with low thermal inertia tools

Solid freeform fabrication processes offer the manufacturing flexibility for tools with low thermal inertia and internal conformal channels for rapid thermal cycling in injection molding. This article analyzed each step of a rapid thermal cycling process and provided quantitative guidance for tooling design. The proposed design methodology was tested on a three‐dimensional (3D) printed benchmark tool with truss support. Rapid cooling test on the benchmark tool resulted in the mold time constant shorter than 2.3 s and the cavity temperature uniformity better than 3°C. Preliminary tests demonstrated the technical feasibility of using a solid freeform fabrication process to fabricate low thermal inertia tools for improved heat management in injection molding. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Mind the gap: Ensuring laboratory‐scale testing of an electrospinning product meets commercial‐scale needs

Plant & Food BioProcessing has developed a process to electrospin denatured whole‐chain marine collagen. The collagen is routinely tested on laboratory‐scale electrospinning equipment, but when it is electrospun on industrial equipment, the conditions and the product testing criteria differ from those used in the laboratory. A laboratory electrospinning machine was modified to simulate industrial conditions (≥30 kV). Then, several parameters (voltage, working distance) were adjusted from laboratory‐ to commercial‐scale. These changes did not affect average fiber diameter or deposition rate. The optimum electrospinning conditions were a mixture of laboratory‐ and commercial‐scale conditions (30–50 kV; 10 cm working distance). Reducing the working distance by 5 cm improved the production rate by up to 75%. These changes resulted in better repeatability of electrospun fibers over multiple production runs, with fewer adjustments of solutions and parameters. We recommend this approach to design materials and processes relevant to industrial manufacturing of electrospun fibers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44836.     

Optimizing Drying Conditions for Vacuum-Assisted Microwave Drying of Green Peas (Pisum sativum L.)

Green peas were dried in a vacuum-assisted microwave drying system. The effects of microwave power levels (100–300 W) and system vacuum (50–400 mm Hg) on drying parameters (viz. drying efficiency and drying time) and some quality attributes (viz. linear shrinkage, apparent density, green color, rehydration, and sensory attributes) of dehydrated peas were analyzed by means of response surface methodology. A face-centered central composite design was used to develop models for the responses. Analysis of variance showed that a second-order polynomial model predicted well the experimental data. The system microwave power level strongly affected quality attributes of dehydrated peas and drying parameters. A higher vacuum during drying resulted in a better quality product. Microwave power of 237.31 W and a 360.22 mm Hg vaccum were found to be optimum drying conditions for vacuum-assisted microwave drying of green peas.     

Auto OEMs Tap AM/3DP for Low-Volume Parts

Although additive manufacturing and 3D printing (AM/3DP) were originally used by automakers to prototype parts faster, the auto industry has greatly expanded its use of the technology to improve tooling and molding of plastic parts (see part 1 of this series in Plastics Engineering, Sept. 2020, p. 14), as well as to quickly produce aftermarket parts for older vehicles whose original tooling has become lost and for original equipment manufacturer (OEM) parts on specialty vehicles whose build volumes are too low to justify conventional tooling.     

TEM Series looks to wood-plastic composites

NFM Welding Engineers manufactures the TEM Series of co-rotating, intermeshing compounding twin-screw extrusion systems. The company says that this offers a high torque-per-free volume and high screw speed. The TEM Series can process a wide variety of plastics compounds including wood-plastic composite materials, such as PVC, polyethylene and polypropylene, in combination with most woods including pine, maple and oak. NFM adds that the system requires no pre-drying or pre-mixing, saving capital equipment costs, plant space and maintenance. End product can either be directly extruded or pelletized for direct feed to a single screw system. The TEM Series is available in models from 26–240 mm.This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news     

Synthesis and optimization of membrane cascade for gas separation via mixed‐integer nonlinear programming

Currently, membrane gas separation systems enjoy widespread acceptance in industry as multistage systems are needed to achieve high recovery and high product purity simultaneously, many such configurations are possible. These designs rely on the process engineer's experience and therefore suboptimal configurations are often the result. This article proposes a systematic methodology for obtaining the optimal multistage membrane flow sheet and corresponding operating conditions. The new approach is applied to cross‐flow membrane modules that separate CO₂ from CH₄, for which the optimization of the proposed superstructure has been achieved via a mixed‐integer nonlinear programming model, with the gas processing cost as objective function. The novelty of this work resides in the large number of possible interconnections between each membrane module, the energy recovery from the high pressure outlet stream and allowing for nonisothermal conditions. The results presented in this work comprise the optimal flow sheet and operating conditions of two case studies. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1989–2006, 2017     

Manufacturing and impact characterization of soy‐based polyurethane pultruded composites

Composites have several advantages such as high corrosion resistance, high strength to weight ratio, and lower maintenance costs over conventional materials. The major cost drivers for composites are raw materials and manufacturing process. Automated manufacturing processes like pultrusion and low cost raw materials can significantly lower the cost of composites. Polyurethane (PU) resin systems are commonly used in the pultrusion industry as they have higher performance characteristics and manufacturing feasibility when compared to conventional resin systems such as polyester and vinyl ester. Manufacturing cost can be further decreased by the use of bio‐based materials such as soy‐based resin systems. In the present work, solid pultruded panels have been manufactured using the base PU and two soy‐based PU resin systems. Pultruded panels were subjected to low velocity impact testing. Soy‐based PU resin systems showed comparable properties to that of the base PU resin system and is a viable alternative to the conventional petroleum‐based PU. POLYM. COMPOS., 35:1070–1077, 2014. © 2013 Society of Plastics Engineers     

可持续的多功能纳米涂层的设计:一种目标驱动的多尺度系统论方法(英文)

Polymer nanocomposites have a great potential to be a dominant coating material in a wide range of applications in the automotive,aerospace,ship-making,construction,and pharmaceutical industries.However,how to realize design sustainability of this type of nanostructured materials and how to ensure the true optimality of the product quality and process performance in coating manufacturing remain as a mountaintop area.The major challenges arise from the intrinsic multiscale nature of the material-process-product system and the need to manipulate the high levels of complexity and uncertainty in design and manufacturing processes.In this work,the challenging objectives of sustainable design and manufacturing are simultaneously accomplished by resorting to multiscale systems theory and engineering sustainability principles.The principal idea is to achieve exceptional system performance through concurrent characterization and optimization of materials,product and associated manufacturing processes covering a wide range of length and time scales.Multiscale modeling and simulation techniques ranging from microscopic molecular modeling to classical continuum modeling are seamlessly coupled.The integration of different methods and theories at individual scales allows the quantitative prediction of macroscopic system performance from the fundamental molecular behavior.Furthermore,mathematically rigorous and methodologically viable approaches are pursued to achieve sustainability-goal-oriented design of material-process-product systems.The introduced methodology can greatly facilitate experimentalists in novel material invention and new knowledge discovery.At the same time,it can provide scientific guidance and reveal various new opportunities and effective strategies for achieving sustainable manufacturing.The methodological attractiveness will be fully demonstrated by a detailed case study on the design of thermoset nanocomposite coatings.     

Optimization method to reduce three-dimensional thermal gradients in resin transfer molding

Presently, the mold and resin are heated to promote resin flow and shorten curing period in order to improve manufacturing efficiency of resin transfer molding (RTM). This nonisothermal manufacturing process easily generates three-dimensional thermal gradients in the direction of resin flow and thickness of composite part. However, the existing heating systems only consider the thermal gradients along thickness direction. The thermal gradients in direction of resin flow cannot be reduced which will lead to residual stress even deformation and cracking in composite part. This article aims at reducing the three-dimensional thermal gradients in the direction of resin flow and thickness of composite part. Based on the theory of energy and fluid flow, an optimization method of heating system design by using numerical simulation is proposed. The results show this method reduces the three-dimensional thermal gradients effectively in composite part manufactured by RTM process. This study can provide powerful tools for heating system design to manufacture composites products in polymer industry. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48948.     

Feed distribution in distillation: Assessing benefits and limits with column profile maps and rigorous process simulation

This contribution describes the column profile map (CPM) methodology for designing distributed feed distillation columns. For non‐sharp product distributions, a case study shows that energy savings of approximately 35% can be obtained if the feed stage(s) are designed optimally. Feed distribution allows capital cost savings, expands operating leaves, and can obtain greater separation feasibility. However, this column only has benefits in ternary and higer‐order systems and when product distributions are non‐sharp. To validate these counter‐intuitive claims, a real Benzene, p‐Xylene, Toluene system is modeled using CPMs, and the resulting design parameters are transported to Aspen Plus^®. Using a sum of squared errors objective function to quantify savings, a cost saving trend very similar to the one predicted by the CPM method is obtained. This article therefore describes a complete design methodology for distributed feed systems and provides convincing evidence of benefits of such a system. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1668–1683, 2013