三维四向C/C预制体压实规律与高精度控制策略研究

Research on compaction law and high precision control strategy of 3D four-directional C/C preform

为实现预制体层间密实度均匀可调控,保证预制体产品质量一致性,基于胡克定律建立压实理论模型对不同截面尺寸预制体压实规律进行研究,揭示了压实载荷与压实次数的关系:在压实次数小于疲劳次数阶段,预制体受到的压实载荷随压实次数呈线性变化;在压实次数大于等于疲劳次数阶段,预制体受到的压实载荷不再随压实次数增加而发生变化;同时在编织不同截面尺寸预制体时,xoy截面积呈倍数增加,预制体受到的压实载荷近似呈倍数增长。基于三维四向C/C复合材料预制体成型工艺,建立预制体编织层数、压实厚度与纤维体积含量映射关系,并通过该映射关系进行不同截面尺寸预制体编织实验,得到压实载荷与厚度的变化曲线,其实验值与拟合值的最大偏差率小于3%,验证了理论模型的可行性。根据压实规律理论模型设计出压实装置双闭环控制系统,在该系统中预先设定映射关系所对应的厚度与压力值,在压实过程中借助传感器将采集到的厚度与压力值反馈至控制器,控制器根据偏差值控制压实装置输出值。最后通过观察其所编预制体截面,发现该预制体孔隙小而均匀,验证了该控制系统可输出最优压力值,能够保证预制体层间密实度均匀及产品质量的一致性。

In order to realize the uniform and controllable interlayer density of the preform and ensure the quality consistency of the preform products,based on Hooke's law,the compaction model was established to research the compaction law of different section size preforms for revealing the relationship between the compaction load and the compaction times:When the compaction times are less than fatigue times,the compaction load on the preform varies linearly with compaction times.When the compaction times are greater than or equal to fatigue times,the compaction load on the preform cannot change with the increase of compaction times.While weaving preforms with different cross-section sizes,as the xoy cross-section area increases by multiples,the compaction load on the preform increases approximately in multiples.Based on the 3D four-direction preform compaction process,the mapping relationship between the number of preform weaving layers,compaction thickness and fiber volume content was established.Through the mapping relationship,weaving experiments of the preform with different cross-sectional dimensions were carried out,and variation curves of compaction load and thickness were obtained.The maximum deviation rate between the experimental value and the fitted value is less than 3%,and the experimental results are consistent with the theoretical model,which verifies the correctness of the theoretical model.According to the theoretical model of compaction law,the double closed-loop control system of compaction device was designed.In the control system,the thickness and pressure values corresponding to mapping relationship were preset,and during the compaction process,the collected thickness and pressure values were fed back to the controller by means of the sensor.The controller controls the output value of the compaction device according to the deviation value.Finally,by observing the cross-section of the preform,it is found that the preform has small and uniform pores,which verifies that the control system can output the optimal pressure value,ensure the uniform interlayer density of the preform and the consistency of the product quality.