Damage evaluation and lifetime prediction of CFRP composites initiated from microdefects

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14047
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Tokyo Metropolitan University
• Principal Investigator: Oshima Sota 東京都立大学, システムデザイン研究科, 助教 (90885112)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 複合材料 / 欠陥 / 亀裂 / 破壊力学 / 疲労破壊 / 有限要素解析

Outline of Final Research Achievements

Carbon fiber composite polymers (CFRPs) are widely used in the aerospace industry because of their strength and weight. The presence of defects is inevitable during the manufacturing process of CFRPs. In this study, the damage progression behavior was evaluated initiated from defects. Artificial defects with different sizes were introduced in CFRPs. The minimum size of the artificial defects was as small as 2.5 μm. Cracks initiation and propagation from the defects were observed using a high-magnification optical microscope. A trigger system synchronized with the testing machine was developed to capture crack growth behavior under cyclic (fatigue) loading. In addition, the stress distribution around the defects was visualized using a numerical approach.

Free Research Field

材料強度学

Academic Significance and Societal Importance of the Research Achievements

炭素繊維複合材料中の欠陥は寸法や位置、分布を制御できないため従来は欠陥を起点とする亀裂進展挙動を定量的に評価することは困難とされてきた。本研究では位置と大きさが制御された欠陥をひとつだけ材料中に導入できるため、欠陥の影響を定量的に評価することが可能となった。これにより、これまでは「材料のばらつき」として取り扱われてきた積層板の寿命をより正確に予測できるようになることが期待される。これは航空宇宙分野をはじめとした複合材料の信頼性が求められる分野で重要な知見である。