Kondratiev Andrii, Píštěk Václav, Vambol Oleksii, Otrosh Yurii, Kučera Pavel, Kučera Ondřej
Department of Building Technology and Construction Materials, O.M. Beketov National University of Urban Economy in Kharkiv, Marshal Bazhanov Str. 17, 61002 Kharkiv, Ukraine.
Institute of Automotive Engineering, Brno University of Technology, Technická 2896/2, 616 69 Brno, Czech Republic.
Polymers (Basel). 2022 Jun 13;14(12):2392. doi: 10.3390/polym14122392.
Currently, prefabricated panel structures are typical products made of polymeric composite materials. The integrity of the composite panels, their structure and accuracy of making a contour are largely associated with the manifestation of residual technological stresses. The above phenomena and associated stress-strain behaviour inevitably occur in the process of moulding of the composite products. However, their value, nature, time of occurrence and dynamics of growth can be fully controlled and regulated. The paper deals with the study of the effect of moulding pressure on the quality of a composite product. A dependence is presented that allows us to determine the time for the degassing of the polymeric composite material package at the given temperature and pressure to obtain a monolithic and nonporous structure. It is shown that the peak of the maximum volatile-matter yield for the considered binder types lies in the temperature range where the degree of curing does not exceed 10%; that is, the viscosity values do not prevent the removal of volatile fractions. The effect of moulding pressure on the values of the volume content of the reinforcing material has been studied, and the dependence of the required thickness of the absorbent layer on the parameters of the package of polymer composite material and pressure has been obtained. The dependence of the required thickness of absorbent layer on the parameters of the package of polymeric composite material and pressure has been obtained. The mathematical model developed by us provides an opportunity to predict the stress-strain behaviour of a composite structure at any time during the moulding process. The model is closely related to chemo-viscous and thermal models. It allowed us to synthetize a method for choosing the rational parameters of the moulding process (temperature, pressure, and time), materials of additional layers and equipment. The experiments proved the presence of several defects, such as de-lamination of edges, waviness, swelling and poor adhesion of upper layers in the specimen of the composite panel cooled stepwise in the absence of the vacuum pressure. The surface quality of the specimen of the panel cooled stepwise under vacuum pressure was significantly better, and no visible defects were observed. The obtained theoretical values of deflections, considering the change in physic-mechanical characteristics that depend on the temperature and rheonomic properties of the material, showed an error that did not exceed 7%, compared to the experimental data. Our results can be applied at the enterprises engaged in designing and manufacturing panel structures of polymeric composite materials.
目前，预制板结构是由聚合物复合材料制成的典型产品。复合板的完整性、其结构以及轮廓制作的精度在很大程度上与残余工艺应力的表现有关。上述现象及相关的应力应变行为在复合产品成型过程中不可避免地会出现。然而，它们的值、性质、出现时间和增长动态可以得到充分控制和调节。本文探讨了成型压力对复合产品质量的影响。给出了一种依赖关系，使我们能够确定在给定温度和压力下聚合物复合材料包的脱气时间，以获得整体且无孔的结构。结果表明，对于所考虑的粘合剂类型，最大挥发物产率的峰值处于固化程度不超过10%的温度范围内；也就是说，粘度值不妨碍挥发性组分的去除。研究了成型压力对增强材料体积含量值的影响，并得到了吸收层所需厚度与聚合物复合材料包参数和压力的依赖关系。得到了吸收层所需厚度与聚合物复合材料包参数和压力的依赖关系。我们开发的数学模型提供了一个机会，可以预测成型过程中任何时刻复合结构的应力应变行为。该模型与化学粘性和热模型密切相关。它使我们能够综合出一种选择成型工艺（温度、压力和时间）、附加层材料和设备的合理参数的方法。实验证明，在没有真空压力的情况下逐步冷却的复合板试样中存在几种缺陷，如边缘分层、波纹、肿胀和上层粘结不良。在真空压力下逐步冷却的板试样的表面质量明显更好，未观察到明显缺陷。考虑到取决于材料温度和流变特性的物理力学特性变化而得到的挠度理论值与实验数据相比，误差不超过7%。我们的结果可应用于从事聚合物复合材料板结构设计和制造的企业。
