Smart automated control

Overall an intelligent closed-loop system produces more consistent parts because the advancement to the next stage of cure is based on the resin achieving a certain molecular state rather than on time. The advancement of the viscosity and degree of cure is monitored. Final cure is defined by a universal degree of cure. This is a more consistent way to produce composite parts than simply subjecting them to the same time-temperature schedule when batch variations and differences in prefabrication handling are present. 

PROCESSING TOOL n frequency/time frequency dependent frequency/time molecular models impedance measurement molecular mobility models data base 

As an aside, we note that the FDEMS sensor input information can also be used to detect the onset of phase separation in toughened thermoset systems and to monitor cure in thin film coatings and adhesive bond lines. It is particularly important that the FDEMS sensor is also very sensitive to changes in the mechanical properties of the resin due to degradation. As such, it can be used for accelerated aging studies and as a dosimeter to monitoring the composite part during use to determine the knockdown in the required performance properties with time. 

In summary an FDEMS sensor system can be used to monitor the processing properties in situ during the fabrication process of a composite part. A smart sensor control system can be used to monitor resin properties for reproducability-quality assurance, to ensure fabric impregnation, and to control and optimize the composite fabrication process intelligently through in situ sensor feedback. 

David E. Kranbuehl appreciates partial support from the NSF Science and Technology Center at Virginia Polytechnic Institute and State University under Contract DMR91-2004, a NASA Langley grant NAGI-23 and support from the Douglas Aircraft Corporation. 

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In situ frequency dependent electromagnetic-impedence measurements provide a sensitive, convenient, automated technique to monitor the changes in macroscopic cure processing properties and the advancement of the reaction in situ in the fabrication tool. This chapter discusses the instrumentation, theory, and several applications of the techniques, including isothermal cure, complex time—temperature cure, resin film infusion, thick laminates, and smart, automated control of the cure process. 

Figure 4.21 shows the sensor output for the smart automated sensor expert system-controlled run. The resin reached the center sensor at 37 min. The viscosity is maintained at a low value by permitting slow increases in the temperature. At 60 min, fabric impregnation was complete. The resin was advanced during a 121 °C hold to a predetermined value of degree of cure of 0.35, based on the Loos model s predictions of the extent of the exothermic effect. This value of a is clearly dependent on panel thickness. Then at 130 min, the ramp to 177°C was begun. Achievement of an acceptable complete degree of cure was determined by the sensor at 190 min. Then the cure process was shut down. 

Figure 4.21 Sensor output for the smart automated sensor expert system-controlled run...

Figure 4.20 Schematic of the FDEMS sensor smart system for monitoring quality and for expert automated process control...

The commercial development of computer-based control systems for tractors and other agricultural implements has provided a platform that enables coded mapped information to be effectively transferred from a desktop computer to the tractor cab. Initially developed in conjunction with GPS field location for yieldmapping applications, this type of system is now being incorporated into tractors and specialised application vehicles (see Figure 4.6). These can be used to give access to the treatment map in the field, and hence control signals for the application system. Data transfer is commonly by smart cards with current systems, but it is likely that future developments will use radio/telephone connections to automate the data transfer process (Miller, 1999). 

The use of pattern recognition techniques in conjunction with sensor arrays constitutes a promising approach for multicomponent analysis and for improved selectivity [26]. Similarly, a smart sensor system that employs a temperature-controlled array of SAW sensors, automated sample preconcentration, and pattern recognition has been described [27], The proposed technology seems to offer a satisfactory solution for the problems associated with non-selective adsorption by coating materials. 

Grate J W, Rose-Pehrsson S L, Venezky D L, Klusty M and Wohltjen H 1993 Smart sensor system for trace organophosphorus and organosulfur vapor detection employing a temperature-controlled array of surface acoustic wave sensors, automated sample preconcentration and pattern recognition Anal. Chem. 65 1868... 

Plasma processing will continue to be of critical importance for fabricating ULSI devices [269], More complex patterns with finer dimensions down to a few hundred A, as well as films with properties tailored to more specific applications are expected in the future. These stringent requirements will necessitate integrated processing and process automation with sophisticated smart sensors for real-time process control. In particular, real-time surface sensors will be indispensable. 

Auxiliary process control allows external devices to be controlled during winding, allowing further automation. The winding pattern can turn simple devices on and off or activate smart devices that can interact with the winding process. Fiber tension can be controlled and varied automatically during winding. 

This brochure contains over 100 full-color pages of the latest state-of-the art products from the company s automation line including programmable logic controllers, smart relays, enclosures, process measurement and control devices, motion control sensors, human machine interface, pushbuttons, proximity sensors, relays and timers, and wire connections. Also included is a user-friendly index for easy product search, economical choices, popular models, and accessories. 

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