Methods for process-related resin selection and optimisation in high-pressure resin transfer moulding (original) (raw)
Siam Review - SIAM REV, 1997
Resin Transfer Molding (RTM) has drawn interest in recent years as an attractive technique for the manufacture of advanced ber reinforced composite materials. A major issue in this new manufacturing process is the reduction of voids during the resin ll process so that products with high quality are manufactured. Process modeling is particularly useful in understanding, designing, and optimizing the process conditions. The purpose of this paper is to illustrate the important application of mathematical and numerical modeling to this industrial problem. First, an overview of the RTM process, its manufacturing problems, and related background issues is given. A survey of various RTM models developed in recent years by researchers in this eld are then presented. Finally, as an application, a novel two phase ow model, developed recently by the authors, is proposed to study the formation and migration of the macro voids, a major manufacturing problem. The unique feature of this model is the identi cation of local pressure as a major mobilization factor of these macro voids. It is demonstrated that the model is in good agreement with experimental results.
Material Characterization for Reliable Resin Transfer Molding Process Simulation
Applied Sciences, 2020
Resin transfer molding (RTM) technologies are widely used in automotive, marine, and aerospace applications. The need to evaluate the impact of design and production critical choices, also in terms of final costs, leads to the wider use of numerical simulation in the preliminary phase of component development. The main issue for accurate RTM analysis is the reliable characterization of the involved materials. The aim of this paper is to present a validated methodology for material characterization to be implemented and introduce data elaboration in the ESI PAM-RTM software. Experimental campaigns for reinforcement permeabilities and resin viscosity measurement are presented and discussed. Finally, the obtained data are implemented in the software and then compared to experimental results in order to validate the described methodology.
Experimental and numerical investigations of pressure-controlled resin transfer molding (PC-RTM)
Advanced Manufacturing: Polymer & Composites Science
To increase the use of fiber reinforced lightweight structural components in the automotive industry, their manufacturing processes have to obtain demanding economic requirements. One possibility is to use Compression Resin Transfer Molding (CRTM), which is fast and can be highly automated. One disadvantage can be the very high cavity pressure during injection. To avoid this disadvantage, a pressure-controlled RTM (PC-RTM) process was developed. PC-RTM uses a variable mold gap height and an embedded pressure sensor to control the cavity pressure actively during mold filling. In this work, we investigate this process by experiments and simulations with varying initial mold gap and controlled cavity pressure. We show that PC-RTM is a viable manufacturing process with short cycle times and high robustness. Furthermore, the simulations are validated by comparison to the experiments and show the same process characteristics.
IOP Conference Series: Materials Science and Engineering, 2018
An experimental study of the process pressure characteristics prevailing in an RTM mould during the preform impregnation stage is presented. The pressure data is analysed with respect to a superposition of preform compaction and hydraulic fluid pressure. A methodology is proposed to isolate the hydraulic fluid pressure from the preform compaction pressure involving knowledge about the compressibility behaviour of the reinforcing material. For this purpose, the preform compressibility and relaxation behavior was studied by means of transverse compaction tests on both, unsaturated as well as the saturated sample stacks. The resulting isolated hydraulic fluid pressure is finally compared with numerical predictions derived from flow simulations, revealing good overall agreement. The findings of this work will contribute to realize the concept of model-based processing of fibre-reinforced polymer composites by means of the RTM process.
Modeling Of Resin Transfer Molding
Resin Transfer Molding (RTM), as a method for the manufacture of advanced fiber reinforced composite materials, is attractive because it offers the possibility of lower manufacturing costs and more complex shapes than traditional methods. A major issue in this new manufacturing process is the elimination of void spaces in the resin fill operation, so that products with high quality are manufactured. Process modeling is particularly useful in understanding, designing, and optimizing the process conditions to achieve this goal. In this paper we report on our program with the Advanced Technology & Development Center at Northrop Grumman and demonstrate how modeling could improve the manufacturing process and enhance product quality. We review the manufacturing process and related issues and present a manufacturing process model, developed recently by the authors. This model is applied to study the formation and migration of air bubbles in the preform, a major RTM manufacturing problem, ...
Modeling and Simulation of Compression Resin Transfer Molding
2006
Accomplishments Analysis of the current modeling approach for CRTM, as well as for some of the physical phenomena involved in the process, such as preform deformation, revealed certain weaknesses in the numerical approach and, more importantly, significant gaps in fundamental understanding of underlying physics. New governing relations for the general Liquid Composite Molding (LCM) and, in particular, for CRTM have been proposed. These relations describe the process in general and should help not only in process modeling but also in identifying the needs in material characterization.
Polymer Engineering & Science, 2000
The cure kinetics of a high performance PR500 epoxy resin in the temperature range of 160-197°C for the resin transfer molding (RTM) process have been investigated. The thermal analysis of the curing kinetics of PR500 resin was carried out by differential scanning calorimetry (DSC), with the ultimate heat of reaction measured in the dynamic mode and the rate of cure reaction and the degree of cure being determined under isothermal conditions. A modified Kamal's kinetic model was adapted to describe the autocatalytic and diffusion-controlled curing behavior of the resin. A reasonable agreement between the experimental data and the kinetic model has been obtained over the whole processing temperature range, including the mold filling and the final curing stages of the FtTM process.
In the curre nt work, first of all, a ge ne ral the ore tical twophase mode l was propose d to simulate the flow in the resin transfer molding RTM. This mode l has bee n wide ly use d in ge ologic me dia and pe trole ums reservoirs and satisfie d re sults have bee n give n. The similarity betwee n these me dium and our composite domain e ithe r in he terogene ity or in fluid flo w has motivate d this choice . Base d on multiphase darcy's law, the mode l has bee n deve lope d to simulate the saturation distribution for two compressible immiscible phases which are resin and the air, it may control the formation of the void in composite mate rial. The n, a particular case of the mode l was simulate d nume rically which is we ll known as the bucke ly-le vrett mode l. Using the first time the control volume -finite e leme nt CV/FEM method, the results of this study agree qualitative ly with e xpe rime ntal and nume rical findings.
A model for resin viscosity during cure in the resin transfer moulding process
Composites Part A: Applied Science and Manufacturing, 2002
A cure model has been developed for the viscosity of two-part epoxy/amine resins, focussing on low extents of cure-the most important region for the mould-filling stage in resin transfer moulding. A key advantage of the model is that it is not explicitly dependent on the extent of cure; therefore, the model can be used to predict the viscosity during cure without the need for determining the resin cure kinetics. The model parameters are obtained from isothermal viscosity -time measurements at constant shear rate. Examples are shown and data are given for five different resins in the temperature range 20 -70 8C. The model is applied to simulate non-isothermal cure and compared against experimental data. q
Development of resin transfer molding process using scaling down strategy
Polymer Composites, 2013
The virtually developed resin transfer molding (RTM) manufacturing process for the large and complex composite part can be validated easily with the trial experiments on the scaled down mold. The scaling down strategy was developed using Darcy's law from the comparisons of mold fill time and mold fill pattern between full-scale product and scaled down prototype. From the analysis, it was found that the injection pressure used in the scaled down mold should be the fullscale injection pressure by the times of square of geometrical scale down factor, provided the identical injection strategy and raw material parameters were applied on both the scales. In this work, the RTM process was developed using process simulations for a large and complex high-speed train cab front and it was validated by conducting experiments using a geometrically scaled down mold. The injection pressure as per the scaling down strategy was imposed on the scale downed high-speed train cab front mold and a very close agreement was observed between the flow fronts of experimental and simulated results, which validates the scaling down strategy and the virtually developed RTM process for the full-scale product.
Porosity reduction using optimized flow velocity in Resin Transfer Molding
Composites Part A-applied Science and Manufacturing, 2008
Liquid Composite Molding (LCM) regroups a number of well known manufacturing techniques of polymer composites based on resin injection through fibrous reinforcements. LCM processes such as RTM (Resin Transfer Molding) have been increasingly used to manufacture parts for a wide range of industrial applications and were shown to be cost effective in the low to medium range of volume production. To improve the performance of these processes, more scientific knowledge of the impregnation phenomena is required. In LCM processing, injection pressure dominates the impregnation of the fibers. In RTM, the formation of macro/micro-voids entrapped between or within the fiber tows is a function of the capillary pressure, the porosity of the fiber bed and the local fluid velocity. The presence of these voids within the laminate is a common source of micro-cracking that reduce short and long term mechanical properties.
This study addresses different 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 high-performance continuous-fiber-reinforced composites. These two HP-RTM process variants are well suited for automotive structural component manufacturing in short cycle time (cycle time < 5 min). The paper deals with understanding the effect of the most important process parameters on the cavity pressure profile for the selected process variants. The studies were conducted using industrial scale process equipment and process parameters. The results of this study provide a deeper understanding of correlation between selected process parameters such as process variant, mold gap size and maximum applied press force on the mold cavity pressure profile and resulting laminate properties.
A New Model for the Simulation and Improvement of Resin Transfer Molding Process
In the curre nt work, first of all, a general theoretical two-phase model was propose d to simulate the flow in the resin transfer molding RTM. This mode l has bee n wide ly use d in ge ologic me dia and pe trole ums reservoirs and satisfie d re sults have been given. The similarity betwee n these me dium and our composite domain e ithe r in he terogene ity or in fluid flo w has motivate d this choice. Base d on multiphase darcy's law, the model has been developed to simulate the saturation distribution for two compressible immiscible phases which are resin and the air, it may control the formation of the void in composite mate rial. The n, a particular case of the model was simulate d nume rically which is we ll known as the buckely-le vrett mode l. Using the first time the control volume-finite element CV/FEM method, the results of this study agree qualitative ly with e xpe rime ntal and nume rical findings.
Advanced Composites Letters, 1999
A low-pressure compression was applied after complete resin injection in the manufacture of resin transfer moulded (RTM) glass-fibre-reinforced laminates. Representative laminates were produced and their fibre volume fractions (V f s) compared with that of laminates manufactured under conventional vacuum-driven RTM. The intralaminar and overall V f s were examined from images generated through scanning electron microscopy (SEM), and each manufacturing process was compared for its ability to produce uniform high V f composites.
DESIGN AND FABRICATION OF A LABORATORIAL RESIN TRANSFER MOULDING
The objective of this work was design a laboratorial Resin Transfer Moulding Equipment to process composites. The following methodology was fulfilled: Design and manufacture of the equipment, testing its process capabilities, injection tests in the processing stations, manufacturing of composite plates and further characterization. The materials used in the experiments were glass fiber mat (450g / m2), base glass fiber fabric (600 g / m2), a medium viscosity 1.0 Arazyn Ara Ashland ® # 08 unsaturated polyester resin and 50 Butanox. Small and large area plates were produced with dimensions of: 175x125x5mm and 340x340x5mm respectively. Based on the results experiments, it is concluded that it was possible the design, development and manufacture of a resin injection equipment RTM for laboratory use with low cost and low energy losses, for the manufacture of composites with two reinforcement kind: mat and fabric, with different weights and thin.
Matrix Characterization and Development for the Vacuum Assisted Resin Transfer Molding Process
2001
The curing kinetics and viscosity of an epoxy resin system, SI-ZG-5A, have been characterized for application in the vacuum assisted resin transfer molding (VARTM) process. Impregnation of a typical carbon fiber perform provided the test bed for the characterization. Process simulations were carried out using the process model, COMPRO [8], to examine heat transfer and curing kinetics for a fully impregnated panel, neglecting resin flow. The predicted viscosity profile and final degree of cure were found to be in good agreement with experimental observations.