Study On Preparation And Properties Of Spread Tow And Spread Tow Fbric Composites

Compared with the traditional carbon fiber fabric,the spread tow fabric has the advantages of small thickness,light weight,good pavement,good design ability and low buckling angle of the yarn in the fabric which can effectively increasing the utilization rate of the mechanical properties of the carbon fiber,reducing the stress concentration caused by buckling,and enhances the mechanical properties of the composites.In this paper,spread tow and spread tow fabric were produced by using self-made tow spreading device and spread tow weaving machine,and the properties of spread tow and spread tow fabric composites were discussed.The main research contents are as follows:A tow spreading device is designed in combination with the mechanical multi roller method.In view of the problems encountered in the experiment,the unwinding mechanism,the tow spreading mechanism,the pulling mechanism and the winding mechanism in the tow spreading device are designed and improved.On the basis of traditional semi-automatic weaving machine,the weaving machine structure and the traditional weaving process were improved,so that it can be used to produce spread tow fabric.The effects of spread tow rod / roll,wrap angle,heating temperature and spreading tow speed on the width of spread tow are analyzed.The results show that the width of spread tow becomes larger by increasing the number of spreading rods and the wrap angle,but the carbon fibers can be easily damaged;heating the carbon fiber during the spreading process can increase the width of spread tow without substantially damaging the carbon fiber;increasing the spread speed results in a decrease in the coefficient of friction between the carbon fiber and the spreading rod,and a decrease in the heating time of the carbon fiber,which results the width of the spread tow decrease first and then increase with the increase of the spreading speed.The epoxy resin infiltration speed and height of spread tows are significantly higher than the original yarn.By observing the cross section of carbon fiber spread tow after infiltration experiment,it is found that there is no obvious resin rich area and fiber dense area.The distribution of monofilament is uniform,and the uniformity of resin infiltration is improved.Spreading treatment can lead to the breakage of carbon fiber monofilament.With the increase of the spreading rate,the amount of broken carbon fiber gradually increases.Compared with the traditional carbon fiber fabric,the yarn buckling angle is smaller,higher degree of yarn straightening,and the stress concentration phenomenon has been greatly improved in the spread tow fabric.The tensile and compressive properties of the spread tow fabric composites have been greatly improved.Meanwhile,they have a good inhibition effect on the generation and propagation of cracks during the loading process.The gap of tensile and compressive properties between self-developed spread tow fabric and foreign commercial spread tow fabric is small?...