Young s modulus of elasticity

Magnesium alloys have a Young s modulus of elasticity of approximately 45 GPa (6.5 x 10 psi). The modulus of rigidity or modulus of shear is 17 GPa (2.4 X 10 psi) and Poisson s ratio is 0.35. Poisson s ratio is the ratio of transverse contracting strain to the elongation strain when a rod is stretched by forces at its ends parallel to the rod s axis. 

P = pressure of liquid Vl = volume of hquid Ey = Young s modulus of elasticity V = Poisson s ratio... 

Flexural strength (c direction), MPa 80-170 Tensile strength (ab direction), MPa 110 Young s modulus of elasticity, GPa 28-31... 

Young s Modulus of Elasticity 620-720 GPa Shear Modulus 262 GPa Poisson s Ratio 0.18 Transverse Rupture Strength 550 MPa... 

The variation in wall thickness and the development of cell wall rigidity (stiffness) with time have significant consequences when considering the flow sensitivity of biomaterials in suspension. For an elastic material, stiffness can be characterised by an elastic constant, for example, by Young s modulus of elasticity (E) or shear modulus of elasticity (G). For a material that obeys Hooke s law,for example, a simple linear relationship exists between stress, , and strain, a, and the ratio of the two uniquely determines the value of the Young s modulus of the material. Furthermore, the (strain) energy associated with elastic de-... 

For a Hookian material, the concept of minimum strain energy states that a material fails, for example cell wall disruption occurs, when the total strain energy per unit volume attains a critical value. Such an approach has been used in the past to describe a number of experimental observations on the breakage of filamentous micro-organisms [78,79]. Unfortunately, little direct experimental data are available on the Young s modulus of elasticity, E, or shear modulus of elasticity G representing the wall properties of biomaterial. Few (natural) materials behave in an ideal Hookian manner and in the absence of any other information, it is not unreasonable to assume that the mechanical properties of the external walls of biomaterials will be anisotropic and anelastic. 

The value of C in equation 10.39 depends on the way in which the pipe is restrained but for practical purposes a value of unity is adequate. In this equation, E is Young s modulus of elasticity of the pipe, d, the internal diameter of the pipe and tw its wall thickness. The value of E for steel is about 2 x 10s MPa and K for water is about 2 x 103 MPa thus K/E is about 10-2. It will be seen that the elasticity of the pipe has a negligible effect with thick-wall pipes but with thin-wall ones (say djtw > 40) the propagation speed a will typically be reduced to about 70 per cent of the speed of sound c in the liquid. 

Young s modulus of elasticity, or the tensile modulus, is the ratio of the stress applied to the strain within this linear region. It provides an indication of stiffness or how much a material or part will stretch under a given load. For example, a material that has a high tensile modulus is rigid and resists stretching. 

When there is no volume change, as when an elastomer is stretched, Poisson s ratio is 0.5. This value decreases as the Tg of the polymer increases and approaches 0.3 for rigid solids such as PVC and ebonite. For simplicity, the polymers dealt with here will be considered to be isotropic viscoelastic solids with a Poisson s ratio of 0.5, and only deformations in tension and shear will be considered. Thus, a shear modulus (G) will usually be used in place of Young s modulus of elasticity E Equation 14.2) where E is about 2.6G at temperatures below Tg. 

If, in case of solids, the elastic limit is exceeded, th en the hnrjy Hqpr not rcfurn to its original state when the stress is removed. The Young s Modulus of Elasticity (known also as Longitudinal Elasticity) is,... 

Determine Young s modulus of elasticity (E), which is the slope of the linear portion of the stress versus strain curve. Calculate the stiffness of the specimen from the force/deformation curve. 

Compressive measurements provide a means to determine specimen stiffness, Young s modulus of elasticity, strength at failure, stress at yield, and strain at yield. These measurements can be performed on samples such as soy milk gels (Kampf and Nussi-novitch, 1997) and apples (Lurie and Nussi-novitch, 1996). In the case of convex bodies, where Poisson s ratio is known, the Hertz model should be applied to the data in order to determine Young s modulus of elasticity (Mohsenin, 1970). It should also be noted that for biological materials, Young s modulus or the apparent elastic modulus is dependent on the rate at which a specimen is deformed. 

Metal Tensile strength (units of 10 Ib/in. ) Young s modulus of elasticity (units of 10 Ib/in. ) Melting point (°C) Density (g/cm ... 

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