NONDESTRUCTIVE EVALUATION OF STRUCTURAL DEFECTS

QUALITY CONTROL OF COMPOSITES IS VITAL FOR THEIRSAFE USE IN VARIOUS FIELDS. THE RECENT INTRODUCTION OF A LOW COST PRESSURE SENSOR USING A FIERCE SENSITIVE RESISTOR (FSR), MAKES IT POSSIBLE TO DEVELOP A COST EFFECTIVE, REAL TIME MONITORING DEVICE FOR COMPOSITES DURING THE MANUFACTURING PHASE. THE PROPOSED CONCEPT IS BASED ONMONITORING THE PRESSURE AT SELECTED LOCATIONS WHERE IT IS INFLUENCED BY UNDESIRED ELEMENTS LIKE OVERBLEEDING, VOLATILE TRAPPING, ETC. MISSION RESEARCH CORPORATION (MRC) IS PROPOSING TO DEVELOP A REAL TIME SENSING SYSTEM FOR THE COMPOSITE MATERIAL PROPERTIES DURING CURE USING FSR. MRC WILL BE SUPPORTED BY DOUGLAS AIRCRAFT COMPANY (DAC), A COMPONENT OF THE MCDONNELL DOUGLAS CORP. (MDC) DURING ITS EXPERIMENTAL PHASE. A LOW COST (ABOUT $20 A SENSOR) PRESSURE SENSOR USING FSR WILL BE USED AS A MEANS OF IMPROVING THE QUALITY OF COMPOSITE MATERIAL AND ASSURING DEFECT FREE PRODUCT. PRESSURE SENSORS WILL BE EMBEDDED INTO CURINGLAMINATES IN AN AUTOCLAVE AND THE EFFECT OF COMBINED CHANGES IN PRESSURE AND TEMPERATURE WILL BE EXAMINED. THEORETICAL AS WELL AS EXPERIMENTAL ANALYSIS WILL BE MADE TO ESTABLISH THE FEASIBILITY OF THE CONCEPT. THE EFFECT OF TEMPERATURE ON THE IN-SITU SENSOR READING WILL BE ESTABLISHED. THE EFFECT OF PROCESSING DEFECTS THAT AFFECT THE MATERIAL PROPERTIES WILL BE EXAMINED. THIS WILL INCLUDE POROSITY, RESIN RICHNESS, WRONG TYPE OF RESIN SYSTEM, VARIATIONS IN CURE CYCLE, AND LOSS OF VACUUM. EFFORTS WILL ALSO BE MADE TO IDENTIFY THE DIFFERENT STAGES OF THE CURE PROCESS: OUTGASSING, RESIN FLOW, GELATION, POST CURING, ETC.ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THIS PROPOSAL DEALS WITH THE FEASIBILITY OF USING A LOW COST PRESSURE SENSOR BASEDON FORCE SENSITIVE RESISTORS FOR REAL TIME CONTROL OF COMPOSITE MANUFACTURING. IF SUCCESSFUL, THE PHASE I RESULTS WILL BE IMPLEMENTED TO DEVELOP AN EXPERT CURE MONITORING SYSTEM THAT WILL BE