An alternative method to reduce process-induced deformation of CFRP by introducing prestresses

Zhendong LIU,Xito ZHENG,Wenjing FAN,Fei WANG,Sohil AHMED,Leilei YAN

a School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China

b Unmanned System Research Institute, Northwestern Polytechnical University, Xi’an 710072, China

KEYWORDS Curing deformation;Prestressing;Pre-tension;Process-induced deforamtion;Residual stress

Abstract Process-induced deformation is an important limiting factor to the application of high performance composite structures. An alternative method to reduce process-induced deformation is proposed by introducing prestress to a single layer or part of the layers instead of all the applicable layers.In this method, the necessary prestress level that applied to the single layer was in the reasonable range. Two kinds of unsymmetric laminates are manufactured at varying prestress levels. The experimental results described that the curing deformation is changed rapidly with the growing prestress level and flipped after a certain prestress level. Moreover, there is a good linear relationship between prestress level and final curing deformation, which gives a convenient way to calculate the prestress level that can fully counteract the curing deformation. The numerical model to predict the curing deformation was built. A good agreement between the numerical and the experimental results shows the effectiveness of the numerical model.To predict the prestress level that can fully counteract the curing deformation, an analytical model is also proposed. Theoretically,the prestress method can fully counteract the curing deformation of the specimens,while the experimental results show that the prestressing layer reduces more than 80%of the curing deformation.

1. Introduction

The use of high performance Carbon Fiber Reinforced Polymers (CFRPs) increased significantly in aeronautical structures. The aeronautical structure usually requires