Tensile strength and fracture surface analysis of PAN-based carbon fibres

摘要

In high-strength fibre, there is no obvious flaw or flaws combination that initiates catastrophic failure in the fracture surface, so the fracture isn't plane. While in low-strength fibre, a flaw or several small flaws in the same cross section cause catastrophic failure. Except the size of the flaws, the number of the flaws within very short fibre length is also very important, so we can enhance the tensile strength of carbon fibres by decrease the number of the flaws inside the carbon fibre. Most of the stress concentrators causing the failure of carbon fibres at low strength are surface defects. Surface deposits, surface pits, surface crack are the most popular defects. This work was partially supported by National Nature Science Foundation of China(grant number 50333050).