铺丝工艺参数优化及典型工艺缺陷对性能影响研究

发布时间：2018-07-10 05:39

本文选题：自动铺丝 + 参数优化　；参考：《南京航空航天大学》2016年硕士论文

【摘要】：自动铺丝技术集成了CAD/CAM、数控、加热等技术,兼备了自动铺带技术与纤维缠绕技术的优点,是当今先进复合材料十分重要的成形技术之一。预浸丝束的铺放工艺性直接影响了铺放质量,是自动铺放过程顺利进行的保证,亦决定了产品性能的优劣。本文以大型复合材料构件自动铺放为背景、以国产碳纤维预浸料为研究对象,用南京航空航天大学自主研发的自动铺丝机,分别研究了相关工艺参数在平面顺直铺放过程、以及平面曲线铺放过程对铺放质量产生的影响,并进行了工艺参数优化。在此基础上,研究了典型工艺缺陷的存在对铺放试件相关力学性能的影响。(1)在考虑预浸丝与模具表面及其层间贴合情况下,提出了一种较为完善的铺放质量评价方法。利用该评价方法分别研究了铺放温度T、铺放压力F、铺放速率v对于铺放质量的影响,发现随着铺放温度、压力的增加铺放质量先提升后降低;随着铺放速率的增加铺放质量呈下降趋势。(2)分析了平面曲线铺放过程中预浸丝束易产生的缺陷类型及其产生机制;并且通过有效贴合长度比来表征丝束曲线铺放的效果,并利用丝束临界回转半径表征丝束平面侧弯变形能力——特定铺放条件下,有效贴合长度比越大,丝束临界回转半径越小,丝束平面侧弯能力越强,铺放效果越好。利用上述方法分别研究了各工艺参数对于铺放质量及丝束平面侧弯变形能力的影响:发现丝束临界回转半径随铺放温度的增加而减小;丝束临界回转半径随着铺放压力的增加先减小到某临界值后再增大;丝束临界回转半径随着铺放速率的增加而增大。(3)以单向层合板为研究对象,研究了铺丝工艺中增减纱带来的缺陷(横向间隙、搭接)对复合材料构件性能的影响。含两种典型缺陷(含缺陷层两两丝束之间横向间隙、搭接量均为1mm)的固化后复合材料力学性能:(1)当横向间隙增大至1mm时,试件横向拉伸强度下降12.62%、弯曲强度下降17.82%、而对纵向拉伸强度、试件厚度及弹性模量影响不大。(2)当横向搭接增大至1mm时,试件横向拉伸强度强度上升23.65%、弯曲强度上升3.35%、厚度增加9.06%、而对纵向拉伸强度、弹性模量影响不大。
[Abstract]:Automatic wire laying technology integrates CAD / CAM, numerical control, heating and so on. It has the advantages of automatic tape laying and filament winding. It is one of the most important forming technologies of advanced composite materials. The laying process of prepreg wire bundles has a direct impact on the laying quality, which is the guarantee of the smooth process of automatic laying, and also determines the quality of the product. In this paper, based on the automatic placement of large composite components and the domestic carbon fiber prepreg as the research object, the process of parallel laying of the related technological parameters in the plane is studied using the automatic filament-laying machine developed by Nanjing University of Aeronautics and Astronautics and Aeronautics and Astronautics, respectively. The influence of plane curve laying process on laying quality is also discussed, and the process parameters are optimized. On this basis, the influence of the typical process defects on the mechanical properties of the laying test piece is studied. (1) A more perfect evaluation method of laying quality is put forward considering the bonding of prepreg wire and die surface and its interlayer. The influence of laying temperature T, laying pressure F and laying rate v on laying quality was studied by using the evaluation method. It was found that with the increase of laying temperature, the laying quality increased first and then decreased. With the increase of laying rate, the laying quality tends to decrease. (2) the defect types and the mechanism of prepreg wire bundles are analyzed in the process of plane curve laying, and the effect of bundle curve placement is characterized by the effective bonding length ratio. The critical rotation radius of the wire bundle is used to characterize the deformation ability of the wire bundle plane lateral bending under certain laying conditions. The larger the effective bonding length ratio is, the smaller the critical rotation radius of the wire bundle is, the stronger the lateral bending ability of the wire bundle is, and the better the laying effect is. The effects of the process parameters on the laying quality and the lateral bending ability of the wire bundles are studied by using the above method. It is found that the critical radius of rotation decreases with the increase of laying temperature. The critical radius of rotation decreases to a certain critical value and then increases with the increase of laying pressure, and the critical radius of rotation increases with the increase of laying rate. (3) the unidirectional laminated plate is taken as the research object. The influence of the defects (transverse gap, lap joint) on the properties of composite components caused by the addition and decrease of yarn in the process of wire laying was studied. The mechanical properties of the composite with two typical defects (transverse gap between two bundles with defect layer and overlap ratio of 1mm) are as follows: (1) when the transverse gap increases to 1mm, The transverse tensile strength and flexural strength of the specimen decreased 12.62 and 17.82 respectively, while the thickness and elastic modulus of the specimen had little effect on the longitudinal tensile strength. (2) when the transverse lap increased to 1mm, The transverse tensile strength of the specimen increased 23.65, the bending strength increased 3.35, the thickness increased 9.06, but the longitudinal tensile strength and elastic modulus were not affected.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB33

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