热氧老化对三维四向编织碳/环氧复合材料压缩性能的影响

文章分别采用失重法、XPS分析法以及压缩性能测试,研究了三维四向编织碳/环氧复合材料以及环氧树脂浇注体在140℃下加速热老化168h、360h、720h、1200h以后的热氧老化规律和老化机理。结果表明:随着老化时间的延长,基体被氧化,发生了化学老化,单位面积失重和压缩强度保留率均随老化的进行而下降。     

Regression model for predicting the air resistance of fabric made from doubled yarns and with different weave structures

The purpose of the investigation is to model the effect of doubled yarns produced from conventional and compact yarns in three different combinations and weave structures on the air resistance of fabrics. A series of woven fabrics differing only in weave structures and having the common count and fabric sett was produced from three types of doubled yarns, namely compact/compact, conventional/conventional and compact/conventional. The hybrid combination was produced principally to reduce the cost of manufacturing doubled yarns. Essential data for the fabrics such as CFF (crossing over firmness factor), FYF (floating yarn factor), FFF (fabric firmness factor), mass per unit area, thickness and porosity were determined. Air resistance was determined by performing the standard test KES-F8 API. Analysis of the results in respect of fabrics produced from the compact/compact, conventional/conventional and conventional/compact yarns shows a strong correlation between the air resistance, porosity, CFF, FYF, FFF, mass per unit area and thickness (R = conventional/conventional 0.97, compact/compact 0.861, conventional/compact 0.974) and the generated statistical models have given the satisfactory prediction of air resistance. Among the parameters, thickness exerts a strong influence on the air resistance. It is concluded that in order to predict air resistance, a number of parameters are needed and any conclusion which has been drawn using only CFF and FYF should be treated with caution. Also the possibility of cost saving as a result of using hybrid doubled yarn has been pointed out.