Fibers elastic modulus values

Fibers would not be so relevant, despite their high strength and elastic modulus values, without a stable shape of the member to be designed. This task is performed by the matrix, which incorporates the fibers and ensures that a shape is given to the manber... 

The axial elastic modulus of PET fibers E) depends, as with other kinds of fibers, on the value of the elastic modulus of crystalline material ) and amorphous fiber... 

When a - 1 ( perfect adhesion) the elasticity modulus of the interphase decreases continuously from the fiber value to the matrix value, the interphase layer modulus being higher than that of the matrix. When a < 1, the interphase layer modulus assumes, some distance off the fiber surface, a minimum value smaller than the matrix value, and then increases tending asymptotically to the matrix modulus. 

Assume that the conductivity of a undirectional, continuous fiber-reinforced composite is a summation effect just like elastic modulus and tensile strength that is, an equation analogous to Eq. (5.88) can be used to describe the conductivity in the axial direction, and one analogous to (5.92) can be used for the transverse direction, where the modulus is replaced with the corresponding conductivity of the fiber and matrix phase. Perform the following calculations for an aluminum matrix composite reinforced with 40 vol% continuous, unidirectional AI2O3 fibers. Use average conductivity values from Appendix 8. 

The graphitic layer planes are held together only by weak van der Waals forces, whereas strong covalent sp bonding is present within the layers. The elastic modulus of the fiber is assumed to be determined mainly by the size, and the orientation in the fiber axis, of these graphitic layers, which both increase with increasing temperature of carbonization. Carbon fibers (<1600 °C) have modulus values in the order of 200-300 GN/m, whereas graphite fibers may attain up to ca 700 GN/m (Diefendorf and Tokarsky )-... 

Table 5.2-3. Average values for Density, Tensile Strength and Elasticity Modulus of Fibers.

Tensile properties of hair fibers at 55 to 65% RH and at 100% RH (in water) show greater extensibility at the higher humidity (Figure 8-2) and a lower elastic modulus (Table 8-1) and lower work and force values in general [26]. 

For DR values between 10 and 50, a decrease in elastic modulus with DR is observed. In the case of a polymer blend, such as PA6/LDPE, there is an almost independent behavior of the tensile properties in the MD of noncompatibilized blends as a function of the dispersed phase concentration. However, in the TD, a clear dependence of the elastic modulus is observed. It is also observed that compatibilized films have higher modulus compared to noncompatibilized films. For the films presented in Table 24.4, PA6 particulate fibers... 

The elastic modulus can be derived directly from the shape of the stress-strain curve and is equal to its initial, constant slope. Its value equals that of the stress that would be required to double the length of the fiber at the initial conditions it is therefore measured in units of stress or specific stress. The work of rupture, a measure of the toughness of the fiber, is defined as the energy needed to break the fiber and may be represented by the following equation ... 

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