Fatigue life prediction method for notched 3D woven composites based on progressive damage and field intensity

Jiaming Xue,Haitao Cui,Weidong Wen

doi:10.1177/1558925020978326

Abstract

To solve the problem of fatigue life prediction of notched 3D woven composites, a novel fatigue life prediction method based on progressive damage and field intensity theory is proposed. By analyzing the initial loading process of 3D woven composite structure based on progressive damage method, the stress field when the fatigue damage develops gently and the dangerous area where the fatigue damage occurs first are obtained. Then combining with the concept of notch field intensity function, the failure criteria of composites and the three-dimensional space vector stress field intensity method, the fatigue damage degree field intensity of the fiber yarns in the dangerous area is analyzed and the most damaged fiber yarn is found. The fatigue life of the structure is calculated with the field intensity equivalent stress and the S-N curve of this fiber yarn. In order to verify the effectiveness of this method, the fatigue life of notched 3D woven composites under several stress levels is predicted and compared with the existing experimental data. The compared results show that the fatigue life prediction values are all within the two-fold error bounds of the experimental data, which are in good agreement with experimental results. Compared with the progressive damage fatigue life prediction method of woven composites, the prediction accuracy of the method proposed in this paper is improved by 31.5% on average, and the calculation efficiency is also greatly improved.

Highlights

Woven composite is a high-performance composite material
Based on the fatigue damage development law of 3-dimensional woven composites (3DWC), PDFIM is mainly divided into three parts: in the first part, prediction method (PDM) is used to analyze the stress in the initial loading process of the composite structure
It can be seen that under various stress levels, the prediction results of the warp direction tension-tension fatigue life of centrally notched 3DWC plates by PDFIM are all within twofold error bounds of the experimental data, which indicates that this method can predict the fatigue life well

Summary

Introduction

Woven composite is a high-performance composite material. It is composed of several groups of fiber yarns interwoven along with their respective directions and compounded with the matrix material.[1]. Qiu et al.[15] and Song et al.[16] established the progressive damage fatigue life prediction method (PDM) of 3DWC based on the degradation laws of component material properties, combined with failure criteria and stiffness reduction method. This structure makes the stress field intensity calculation area discontinuous, and makes the stress of fiber yarn too large under the condition of stress concentration, which makes it difficult to predict the fatigue life with SFI.

Results

Conclusion