Modulus tensile secant

Plate analysis Maximum deflection Modulus (tensile, secant, tensile creep) Poisson s ratio... 

Many designers have already used or calculated a safety factor on material, perhaps without recognizing it such as deciding what approach is used in determining the tensile secant modulus. The process appears to be simple and straightforward, but unfortunately things are never quite that simple. 

Buckling analysis Critical stress Modulus (compressive, tensile, secant) Poisson s ratio Compression strength Tfensile stress at 5deld... 

Secant modulus Tensile creep ruptm stress... 

Fig, 3-21 shows the variation of 100-s 0.5% tensile secant modulus with temperature. The results indicate the significant improvement in properties by reinforcing the polymer matrices with glass fibers. The stiffness between reinforced and unreinforced thermoplastics remains fairly constant over the temperature range fi om 20 to 100 C. The most outstanding thermoplastic material in terms of stiffness is the 30% glass-filled Noryl (J). 

An interesting fact, not brought out by singlepoint testing, is revealed in Fig. 3-22 which shows the variation of the 100-s tensile secant modulus with strain. This indicates that at strains, not high by normal plastics standards, the modulus values of the reinforced materials have dropped considerably. This presumably indicates that the bond between the fibers and the matrix has failed and the material has yielded. Some materials are better than others. These results indicate caution when using reinforced thermoplastics at strains greater than 0.01. 

Figure 3-21. lOO-s 0.5% Tensile Secant Modulus vs Temperature (Designations as in Fig. 3-11) ... 

Material Percent neutralized Melt index at 190°C, dg/min Secant modulus, % extension, MPa Ultimate tensile strength, MPa Elongation at break, %... 

J7 In a tensile test on a plastic, the material is subjected to a constant strain rate of 10 s. If this material may have its behaviour modelled by a Maxwell element with the elastic component f = 20 GN/m and the viscous element t) = 1000 GNs/m, then derive an expression for the stress in the material at any instant. Plot the stress-strain curve which would be predicted by this equation for strains up to 0.1% and calculate the initial tangent modulus and 0.1% secant modulus from this graph. 

For materials that deviate from the proportionality law even well below the elastic limit, the slope of the tangent to the stress-strain curve at a low stress level is taken as the tensile modulus. When the stress-strain curve displays no proportionality at any stress level, the secant modulus is employed instead of the tensile modulus (Fig. 2-2). The secant modulus is the ratio of stress to corresponding strain, usually at 1% strain or 85% from the initial tangent modulus. 

Uniaxial tensile tests were carried out to determine the stress-strain curves and document the damage growth on a computer-controlled Instron model 8516 servo hydraulic testing machine operating at a strain rate of 5% min . The macroscopic tensile yield stress was considered equal to the maximum stress on the loading curve. The Young s modulus was determined as the plateau value of a plot of the secant modulus as a function of the strain. 

Source of HDPE Melt index (g/10 min) Density (g/cm ) Tensile strength (psi) Secant modulus (psi)... 

Elongation at break, 71 Secant modulus, 71 Tensile strength at yield, 71 Branched MDPE, 71 Elongation at break, 71 Secant modulus, 71 Tensile strength at yield, 71 Branched polyethylene plastics, 52, 54, 67 Break load, 16, 231, 241, 243, 252, 255, 287, 289, 311... 

ETEE/TPE 0.64 RT air aac, 0-100 aac Tensile strength, elongation, secant modulus, solvent resistance, heat aging, cold impact brittleness temperature, blocking, volume resistivity, flex durability 68... 

The standard test methods, calculate the tensile modulus by drawing a tangent to the initial linear part of the stress-strain curve and calculating the slope of the line. In cases where no clearly defined linear portion exists, the secant modulus should be determined. 

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