摘要
框架式模具是碳纤维复合材料在热压罐中固化的重要工具,复合材料直接接触的模具型面的温度分布情况影响着产品固化质量。提高罐内温度分布均匀性,有助于减少碳纤维复合材料在固化过程中形成的残余应力和形变。针对框架式模具的型面温度场分布不均匀的问题,通过建立热压罐固化过程物理数学模型,分析成型过程中热压罐内温度分布,并与已知的实验数据相验证,模拟误差小于3%。研究流体流速、温度、工艺制度以及增加导流板对模具型面温度场的影响规律。结果表明,增大流体流速和在升温过程中设置适当的保温时间可以改善型面温度均匀性。在模具结构内添加导流板,可以调控罐内流体的流动,改善其内部温度均匀性,添加平面型导流板的模具最大温差降低了20.56 K,降幅达45%,且平均温度标准差降低了2.72 K。研究结果为复合材料在热压罐中成型工艺制度的制定提供了可靠理论数据。
[Background and purposes]Advanced carbon fiber reinforced composites(CFRP)have been widely applied in the aerospace field,due to their outstanding properties,such as high specific strength,high specific stiffness,excellent weight reduction effect and superior fatigue resistance.In the manufacturing of aircraft structures,major load-bearing components such as wings and fuselage are commonly fabricated using the autoclave molding process.As a crucial tool for the curing of CFRP components within the autoclave,the surface temperature distribution of frame molds directly affects the curing quality of the final products.Enhancing the uniformity of the temperature field within the autoclave helps reduce residual stress and deformation generated during the curing process,thereby improving the mechanical performance and dimensional stability of the composites.Existing studies have primarily focused on optimizing internal heat transfer characteristics and local structural designs of molds.However,research on the regulation of the overall flow field within the autoclave remains limited,and the interaction mechanism between mold structures and internal airflow has not been systematically and thoroughly studied.In this work,a frame mold was designed and constructed to simulate the temperature and flow fields during the autoclave molding of composite components.Flow guide plates were incorporated inside the mold to regulate the direction of fluid flow,aiming to improve the temperature distribution within the autoclave.Additionally,the effects of fluid velocity and temperature regimes on the heat transfer characteristics were examined.[Methods]To address the issue of non-uniform temperature distribution on the mold surface,a physical and mathematical model of the autoclave curing process was established.Computational fluid dynamics(CFD)numerical simulations were conducted to analyze the temperature distribution within the autoclave during the molding process.The simulation results were validated against existing experimental data,with the simulation error controlled within 3%.A systematic study was carried out to explore the influence of fluid velocities,temperature regimes,and the addition of flow guide plates within the mold structure on the temperature field characteristics.By setting various fluid velocities and temperature processes and designing different types of flow guide plates(such as flat-type and concave-type),the effects of each factor on the temperature distribution were systematically analyzed using the controlled variable method.[Results]The simulation results show that increasing the working fluid velocity significantly improves the heat transfer efficiency between air and the mold surface.When the fluid velocity increased from 2.5 m·s^(-1)to 7.0 m·s^(-1),the maximum temperature difference decreased from 45.21 K to 31.46 K,achieving a reduction of 30%.Meanwhile,the average temperature standard deviation dropped from 5.67 K to 3.08 K,indicating a marked improvement in temperature uniformity.Setting appropriate holding times during the heating process also contributed to reducing the average temperature standard deviation.When the number of holding stages increased from one to three,the maximum temperature difference decreased from 45.21 K to 31.82 K,representing a reduction of 29.64%,while the average temperature standard deviation decreased from 5.67 K to 5.27 K.Furthermore,adding flow guide plates within the mold structure effectively regulated the internal fluid flow and improved the temperature uniformity.Compared to the original mold without guide plates,the addition of a flat-type guide plate reduced the maximum temperature difference by 20.56 K(approximately 45%)and the average temperature standard deviation by 2.72 K.When compared with the concave-type guide plate,the flat-type guide plate still demonstrated superior performance,reducing the maximum temperature difference by 15.92 K(approximately 39%)and the average temperature standard deviation by 0.92 K.[Conclusions]Th influence of fluid velocity,temperature regimes,and the addition of flow guide plates on the temperature field uniformity of frame molds during the autoclave curing process was systematically studied,while feasible optimization strategies were proposed.The results indicate that moderately increasing the fluid velocity and setting appropriate holding times during the heating phase can significantly improve the uniformity of the mold surface temperature.Furthermore,regulating the internal fluid flow by adding flow guide plates,particularly flat-type plates,can greatly enhance the temperature uniformity compared to concave-type plates,thereby improving the curing quality of composite products.This research provides a theoretical basis for the optimization of autoclave molding processes for CFRP components and offers valuable guidance for the high-quality manufacturing of complex structured composite products.
作者
孙健
边佳敏
高连生
SUN Jian;BIAN Jiamin;GAO Liansheng(School of Materials Science and Engineering,Jingdezhen ceramic institute,Jingdezhen 333403,Jiangxi,China;Jingdezhen Branch,Jiangxi Research Institute,Beihang University,Jingdezhen 333403,Jiangxi,China)
出处
《陶瓷学报》
北大核心
2025年第4期821-829,共9页
Journal of Ceramics
关键词
复合材料
热压罐
模具
温度场
composite materials
autoclave
mold
temperature field
