Evaluation of Temperature Gradients During Cure of a Thick Carbon Fiber/Epoxy Composite

The purpose of this study is to evaluate the development of thermal gradients throughout thick (1") carbon fiber composites and determine the effect of internal temperature distribution during cure on the observed mechanical properties in those composites. Composites up to 1.5" thick (56 plies) were fabricated with T700S/TC380 braided prepreg from Tencate following a modified vacuum bag layup procedure to include embedded thermocouples within the plies of the composite. Composite panels were cured in a programmable oven with thermocouple reading embedded throughout the panel thickness. Maximum temperature gradients measured between regions of the composite did not exceed 10 degrees C for any given composite thickness. The most significant temperature variation was measured between the mid-thickness plies and the tool-side surface plies. Although through thickness temperature variation during cure was small, a measureable variation in coupon glass transition temperature was recorded between the tool side plies and the remainder of the part, prior to post cure. Thermal and mechanical behavior of coupons taken from segments through the thickness of the part were comparable following a post-cure cycle

A Guide to Disability Statistics from the Survey of Income and Program Participation

This paper discusses the utility of the SIPP in disability analyses, including a summary of descriptive statistics on people with disabilities from multiple SIPP panels, including the most recent SIPP panel (2001). The findings provide insights into the various health, employment, income, and program participation outcomes that may be associated with different definitions of disability and illustrates the potential for using SIPP data in further disability analyses. Our descriptive findings highlight the differences in the demographic composition and outcomes across disability definitions, underscoring the importance of carefully selecting an appropriate disability conceptualization in generating disability statistics