Development and exploitation of shape-generating molding tools made of polymer composite materials in the production of aircraft composite structures

Abstract

The problem of rational design of the structure, manufacturing of shape-generating molding tools made of polymer composite materials and its use in forming thin-walled composite structures by vacuum infusion is viewed. Taking into account the requirement of minimum deformations of warping of the molded composite structure caused by residual stresses as a result of polymerization of the binder, the necessity of creating such equipment in two stages is justified. This implies both: a master mold making on CNC and producing the most open composite mold used for molding finished structures. Using the example of a thin-walled aircraft structure of complex geometry, the possibility of obtaining a process scheme and controlling the modes of manufacturing a composite mold and a part molded on it applying a developed computer modeling tool, that uses experimentally determined characteristics of components (reinforcing glass, carbon fabrics, thermosetting resins) and CAD models of the molded structure as initial information, is shown. The necessary experimental equipment, experimental technique and data processing to obtain the dependences of compressibility and permeability on the degree of binder filling of composite molds, and also on the ratio of externally applied compression and internal pressure, are viewed evidence from an 8-layer fiberglass preform T-10-14. For the consistent description of the viscosity of thermo-reactive resins, which evolves within the process and depends on temperature, degree of polymerization and time, a semi-empirical model is proposed, the parameters of which can be found in an empirical way by methods of differential scanning calorimetry and rheometry. The use of the developed computer modeling tool to maximize the level and equalization of the specific volume of the reinforcing component in the body of the molded structure, reducing the duration of the vacuum infusion process is illustrated by the example of three strategies for controlling external compression and vacuum pressures.