https://doi.org/10.1351/goldbook.C00833
Carbon fibres type HM (high modulus) are @C00831@ with a value of @Y06733@ (tensile modulus) larger than \(300\ \text{GPa}\) (nearly 30% of the \(C_{11}\) elastic constant of a @G02684@ single crystal).
Note:
The level of the tensile modulus of carbon fibres is controlled by the degree of preferred orientation of the layer planes in the direction parallel to the fibre axis. \(C_{11}\), the elastic constant of @G02684@ single crystals in the direction of the layer planes, is \(1060\ \pm 20\ \text{GPa}\). In general, the ratio of tensile strength to tensile modulus is smaller than \(1 \times 10^{-2}\) for carbon fibres type HM (but the tensile strength is influenced by flaws in the fibres and may be improved in the future). Carbon fibres type UHM (ultra-high modulus) have moduli of elasticity in excess of \(600\ \text{GPa}\), surpassing 50% of the theoretical \(C_{11}\) number. Such high values of @Y06733@ can be achieved most readily in @M03851@ (@M04038@).
The level of the tensile modulus of carbon fibres is controlled by the degree of preferred orientation of the layer planes in the direction parallel to the fibre axis. \(C_{11}\), the elastic constant of @G02684@ single crystals in the direction of the layer planes, is \(1060\ \pm 20\ \text{GPa}\). In general, the ratio of tensile strength to tensile modulus is smaller than \(1 \times 10^{-2}\) for carbon fibres type HM (but the tensile strength is influenced by flaws in the fibres and may be improved in the future). Carbon fibres type UHM (ultra-high modulus) have moduli of elasticity in excess of \(600\ \text{GPa}\), surpassing 50% of the theoretical \(C_{11}\) number. Such high values of @Y06733@ can be achieved most readily in @M03851@ (@M04038@).