Permeability Test And Simulation Research Of 3D Woven Preform

Three-dimensional(3D)woven composites have broad application prospects in the fields of aerospace,weaponry,and automobiles due to their good integrity and excellent mechanical properties.The high-efficiency and low-cost liquid integral molding process,for example resin transfer molding(RTM)process,is the basic molding process of 3D textile composites,in which the permeability characteristics of 3D woven preforms have a crucial impact on its molding quality and stability.As an important parameter of RTM mold filling process,permeability describes the impediment of the preform to resin flow,which determines the accuracy of the simulation analysis of the resin transfer molding process,and then affects the choice of injection scheme and the design of the mold.The purpose of this article is to carry out relevant research on the permeability of 3D woven preforms.First,the in-plane and transverse permeability of the 3D woven preform were measured experimentally.Based on the ultrasound measurement,an accurate and fast transverse permeability test method of 3D woven preforms was developed to solve the problem that the transverse permeability is difficult to measure by conventional methods.Then,based on the developed numerical model,the preform permeability tests were simulated and the test results were verified.At the same time,a simplified model of an aero-engine stator blade was established,and simulation analysis and process optimization of the RTM process of the blade were carried out.Based on the tomography of a preform,a unit-cell model of the preform was established,and then the permeability of the 3D woven preform was further predicted by numerical simulation.In order to accurately measure the in-plane and transverse permeability of the 3D woven preform,the in-plane and transverse permeability test devices were developed in this paper.The radial method and the ultrasonic measurement method were employed to evaluate the in-plane and transverse permeability of the 3D woven preform(include type A and B).PAM-RTM software was used to simulate the in-plane and transverse permeability tests process of the two kinds of 3D woven preforms.The comparison with the experimental data verified the reliability of the experimental data.In addition,a simplified model of an aero-engine stator blade was established and four different injection schemes were designed and simulated.The surface injection through the blade root was selected as the best injection scheme after comparison.And this scheme was further selected to study the effects of filling pressures on the resin filling process.The CT tomography was performed on a preform in the in-plane permeability test to observe the direction and cross-sectional shape of the yarn,and the internal unit cell structure of the preform was analyzed.After obtaining the yarn parameters from the CT image,the internal unit cell geometric model of the preform was established using Tex Gen.The Gebart formula was used to predict the internal permeability of the 3D woven preform yarn.On this basis,a finite element model of the unit cell inside the preform was created,and imported into ANSYS CFX 19.0 for simulation analysis to obtain the warp and latitude permeability of the preform.The comparison shows that there is a certain gap between the simulation results and the experimental results.Through analysis,possible reasons for the deviation are discussed in detail.