Ultimate tensile strain

Sulfur dioxide was the major volatile product and was used as a probe to correlate the radiation resistance with polymer structure. The use of biphenol in the polymer reduced G(SO ) by 60% compared with bisphenol A based systems (Bis-A PSF). Surprisingly, the isopro-pylidene group was shown to be remarkably radiation resistant. The ultimate tensile strain decreased with dose for all polysulfones investigated and the rate of decrease correlated well with the order of radiation resistance determined from volatile product measurements. The fracture toughness (K ) of Bis-A PSF also decreased with irradiation dose, but the biphenol based system maintained its original ductility. 

Fig. 28. The ultimate tensile strain vs. T403 concentration for DGEBA-T403 epoxies, at 23 °C...

Vuf is the final chip up-curl radius, fimax is the ultimate tensile strain of the chip material. 

Fibre type Density (kg/m ) Tensile strength (MPa) Young modulus (GPa) Ultimate tensile strain (%) Thermal expansion coefficient (10- /°C) Poisson s coefficient... 

The fracture controlled strain is smaller than the ultimate tensile strain of the FRP, because of stress concentrations at, for example, rounded corners (Triantafillou 1998). 

Interface coating Fiber lay-up Fiber volume.% Proportional limit stress, % MPa Proportional limit strain. % Elastic modulus, GPa Ultimate tensile strength, MPa Ultimate tensile strain,%... 

Modulus Ultimate tensile Strain at ultimate (MPa) strength (MPa) tensile strength (%) Source... 

Strength data Ultimate tensile strain (x-direction) (%) 2.0... 

The cracking processes develop when a system of stresses of any origin is applied to a solid and its tensile strength is exceeded or, in other words, when the ultimate tensile strain is exceeded. 

Further information on the effect of ply construction on the initial modulus, ultimate tensile strength and ultimate tensile strain, of a [ 0]s glass fibre composite is shown in Figures 5.2, 5.3 and 5.4. 

Fig. 3. Ratio of dynamic to static ultimate tensile strains vs strain rate e at 77 K. Key PE = polyethylene PC = polycarbonate EP = epoxy resin.

Thus, fibreswhichdonot lead toan increase in tensile strength, but which enhance the post-cracking ductility, can lead to an increase in the load-bearing capacity of the composite in bending. Hannant [77] has estimated that in order to achieve the stress distribution in Figure 4.43, which gave the factor of 2.44 in Eq. 4.96, the ultimate tensile strain of the composite must be about 0.9%. In composites with a lower strain capacity, a y will be reduced. That is, the factor 2.44 in Eq. 4.96 is an upper limit. 

PVA fibres tend to rupture instead of pull-out of a cementitious matrix, due to the strong chemical bonding and the resulting slip-hardening response during pullout [133]. Li etal. [134] were able to produce composites with an ultimate tensile strain exceeding 4% and a tensile strength of 4.5 MPa, with a fibre volume of only... 

Another factor which was found to be of significance for maximizing the ductility for a given fibre content is the distribution of the fibres [77]. Uneven distribution was found to reduce the ultimate strain for the composite, and a linear relation could be established between the distribution factor (a value between 0 and 1, with 1 being ideally uniform distribution) for 2% PVA fibre composite in a 0.42 w/c ratio matrix, the ultimate tensile strain varied in the range of about 2-7% with a change in the distribution factor from about 0.64 to 0.79 (ultimate strain increased linearly with the distribution coefficient). 

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