Moduli of elasticity

The modulus of elasticity, often referred to as the modulus, is the stress required on the unit strain. The modulus of elasticity is called tensile modulus (E), shear modulus (G), and 

Modulus is the characterization of a rigid material. The elasticity modulus of plastic products made from pure resin is low, even for polyesters and polyamides with relatively higher elastic moduli, which is only 2.5%-10% of the metal elasticity modulus. The modulus of elasticity of filled plastics always increases with the addition of filler because the filler modulus is much larger than the modulus of polymers. For example, when 40 phr of magnesium sulfate whiskers are added to PVC, the breaking strength of the composite material increases by 62.43% and the modulus of elasticity increases by 52.38%.2o 

Curves of uniaxial compressive stress against strain for hep are non-linear and vary somewhat with the strain rate. Caution is therefore needed in comparing values of Young s modulus obtained in different investigations, results obtained at very low stresses by the dynamic method in which a resonance frequency of vibration is determined being higher than ones given 

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Special software (HILLGUS) was also developed for material characterizations such as the determination of the modulus of elasticity for building materials. 

The ratio of stress to strain in the initial linear portion of the stress—strain curve indicates the abiUty of a material to resist deformation and return to its original form. This modulus of elasticity, or Young s modulus, is related to many of the mechanical performance characteristics of textile products. The modulus of elasticity can be affected by drawing, ie, elongating the fiber environment, ie, wet or dry, temperature or other procedures. Values for commercial acetate and triacetate fibers are generally in the 2.2—4.0 N/tex (25—45 gf/den) range. 

Stiffness of the films and sheeting can be measured as the tensile modulus of elasticity. Droop or drape tests may be used, particularly for multilayer products. The stiffness is strongly influenced by thickness (to the third power) and temperature, and is important to the processing of film in printing, coating, or end use appHcations where it affects the "hand" of the product. 

Ultrasonic Microhardness. A new microhardness test using ultrasonic vibrations has been developed and offers some advantages over conventional microhardness tests that rely on physical measurement of the remaining indentation size (6). The ultrasonic method uses the DPH diamond indenter under a constant load of 7.8 N (800 gf) or less. The hardness number is derived from a comparison of the natural frequency of the diamond indenter when free or loaded. Knowledge of the modulus of elasticity of the material under test and a smooth surface finish is required. The technique is fast and direct-reading, making it useful for production testing of similarly shaped parts. 

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. 

Molybdenum, a typical transition element, has the maximum number, five, of unpaired Ad electrons, which account for its high melting point, strength, and high modulus of elasticity. There are many similarities between molybdenum and its horizontal and vertical neighbors in the periodic system. 

Because of its high modulus of elasticity, molybdenum is used in machine-tool accessories such as boring bars and grinding quills. Molybdenum metal also has good thermal-shock resistance because of its low coefficient of thermal expansion combined with high thermal conductivity. This combination accounts for its use in casting dies and in some electrical and electronic appHcations. 

Material Tensile strength, MPa Shear strength, MPa Elongation, % Modulus of elasticity, GPa Specific gravity Hardness... 

Laminate T °C GTE below ppm/°C Water uptake, MIL-P-13949F, mg Dielectric constant at IMH2 Dissipation factor at 1 MH2 Tensde strength, MPa " Modulus of elasticity, GPa Thermal conductivity, W/(m-K)... 

The critical property for conformal coatings is resistance to chemicals, moisture, and abrasion. Other properties, such as the coefficient of thermal expansion, thermal conductivity, flexibiHty, and modulus of elasticity, are significant only in particular appHcations. The dielectric constant and loss tangent of the conformal coating are important for high speed appHcations. 

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