RP055 - Analysis and Control of the Resin Transfer Molding Process Using In-Mold Sensors; Ford Motor Company, D.J.Melotik, M.Czaplicki, T.J.Whalen and D.R.Day
ABSTRACT
Interest in the potential use of resin matrix composites for structural automotive components has grown dramatically in the last five years. This has been evidenced by the formation of an Automotive Composites Consortium composed of General Motors, the Chrysler Corporation and Ford Motor Company to investigate these materials. Efforts are underway within these member companies to study material properties, processing procedures, and energy management phenomena in order to allow the design of viable structural vehicle components (eg: crossmembers, bumper beams, and front-end rails) utilizing Resin Transfer Molding (RTM).
While progress is being made in all these areas of investigation, it is extremely important that processing feasibility be adequately understood and demonstrated. It is particularly necessary to understand and control the curing process in the mold in order to project acceptable cycle times. In this investigation a temperature, pressure, and cure (dielectric) sensor was mounted in the surface of an RTM mold. The cure behavior, mainly time to viscosity minumum and vitrification (determined from the dielectric data), was monitored as a function of various process parameters. These included mold temperature, resin presssure, resin chemistry, part thickness, and reinforcing fiber fraction. Results of cure sensitivity to the various controlled parameters and experiments with controlled press opening are presented. Dielectric sensor output was shown to be an excellent indicator for controlling press opening based on the vitrification event.
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RP124 - Resin Flow Front Reconstruction with Applications to Resin Transfer Molding (RTM), U.S.Army Research Laboratory, Shawn M. Walsh; CDEF Associates, C.E.Freese
ABSTRACT
The development of a new class of sensors has permitted composite materials researchers and engineers alike to obtain further insight on both the process and material used in composite fabrication. This sensor data can be used in several critical capacities, including fundamental observation of process/material phenomena and interaction, validation of increasingly sophisticated process simulations, and as a source of feedback in an on-line process control system. However, if one is to fully realize the potential of sensor data, provisions must be made to manipulate it as repidly and as meaningfully as possible. This paper presents the results of a recently developed numerical smoothing algorithm that, upon application to a field of retrieved sensor data, is capable of substantially enhancing visualization of resin flow during the resin transfer molding (RTM) process. This methodology will directly impact both observation of "wet" composite processes as well as provide a stream of sufficiently rich data to calculate and implement intelligent control decisions.
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RP058 - In-Process RIM Analysis with Microdielectric Sensors; Micromet Instruments, Inc., David D. Shepard, Huan L. Lee and David R. Day
ABSTRACT
Conventional thermoset reactions are studied dynamically by classical laboratory techniques such as FTIR. However, these methods are not very useful for high speed systems such as RIM where gelation can occur within three seconds and cure is complete by thirty seconds. Recently developed Microdielectric sensors and associated electronics can be operated with high sampling rates so that a measurement is recorded every 10 milliseconds. This paper will first review recent developments in microdielectric data reduction and high speed measurement capabilities. Several examples of in-mold RIM dielectric data will be presented. Critical points in the RIM reaction, such as time for resin to reach the far recesses of the mold, end of cure, and de-mold will be described utilizing the dielectric response. Finally, several methods for process control utilizing the microdielectric response are proposed.
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RP062 - Some Criteria for SRIM Processing of Large Parts; Shell Development, W.Richard Schmeal, George G. Viola, and Jerry Scrivo
ABSTRACT
Processing large parts by Structural Reaction Injection Molding (SRIM) features the conflicting requirements that the mold be filled prior to gelation and that quick and relatively complete reaction be achieved to allow successful post processing. Resins shoiuld be amenable to snap cure. In the case of polyisocyanurates, this means slow reaction to form urethanes followed by fast isocyanate trimerization. The mold, preform, and resin should be designed so that heat is transferred in ways which hinder early reaction of the advancing resin flow front yet enhance later reactivity. Some guidelines are presented.
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RP129 - Resin Flow Front and Cure Detection in RTM and other Resin Infusion Processes, Holometrix Micromet, David D. Shepard
ABSTRACT
Monitoring of the resin flow during the part filling of resin infusion processes is critical because the flow is responsible for the final mechanical properties of the part. A resin flow front analysis system been introduced based on technology developed by the U. S. Army Research Laboratory. The system is used for the in-process monitoring of resin flow and cure in Resin Transfer Molding (RTM), SCRIMPÂ, vacuum assisted RTM, and other resin infusion processes. The system consists of a sensor grid, an electronics package designed to rapidly interrogate the grid, and a Windows-based software program to control, record, and display the sensor data. The system measures the electrical properties at intersecting nodes of conductive wires or fibers that are manually laid out in the mold to form a grid pattern. When resin reaches each node, the electrical properties of that node will change and are recorded by the system to provides a map of the part filling process. The subsequent resin gel and onset of cure can also be detected. The data obtained with the system is not as sensitive to the end of cure as traditional AC resistance measurements.
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RP131 - Large Scale Implementation of Flow and Cure Sensing in a Thermoset Resin Infused Composite Structure, Roderic Don, Karl Bernetich, and John W. Gillespie, Jr., University of Delaware's Center for Composite Materials; Bruce K. Fink, U.S. Army Research Lab; Michael Louderback, Northrop Grumman Corporation
ABSTRACT
A highly successful demonstration of resin flow and cure sensing using the U.S. Army Research Lab's patented SMARTweave imbedded sensor technology was done on an Advanced Technology Transit Bus (ATTB) subcomponent at Northop Grummans's El Segundo plant. The part was fabricated using single-sided tooling, and consisted of a multi-layered woven preform, sandwiched around a foam core, which was infused with resin in a modified VARTM-type process. The flow of resin into portions of the part not visible to the eye was readily detected. This experiment was the largest application to date of the SMARTweave technology, and was performed by researchers from the University of Delaware's Center for Composite Materials.
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