Torsional stiffness tests

A torsional stiffness test measures the modulus of rigidity of an elastomer composition over a broad temperature range. There are two commonly used tests ASTM D 1043,... 

Torsional Stiffness - Torsional stiffness tests measure the modulus of rigidity of an elastomer composition over a broad temperature range. Two widely-used tests are ASTM D-1043, which uses the Clash-Berg Tester, and the ASTM D-1053, which uses the Gehman Torsional Stiffness Tester. In both tests, the sample is chilled to a preset temperature, then twisted with a known force. The amount of twist is measured and related to the stiffness (modulus of rigidity) of the sample. The test temperature is then changed and the test is repeated, until a complete curve of stiffness vs. temperature is plotted. The temperature which produces a stiffness of 69 MPa (10000 psi) is sometimes taken as the Stiffness Temperature. 

In-Plane Shear Properties. The basic lamina in-plane shear stiffness and strength is characterized using a unidirectional hoop-wound (90°) 0.1 -m nominal internal diameter tube that is loaded in torsion. The test method has been standardized under the ASTM D5448 test method for in-plane shear properties of unidirectional fiber-resin composite cylinders. D5448 provides the specimen and hardware geometry necessary to conduct the test. The lamina in-plane shear curve is typically very nonlinear [51]. The test yields the lamina s in-plane shear strength, t12, in-plane shear strain at failure, y12, and in-plane chord shear modulus, G12. 

Creep testing was performed on a Clash-Berg Torsion Stiffness Tester. Silicone oil was used as the heat transfer medium. Temperatures were held constant to within + 1... 

Hardness increase, differential scanning calorimetry (DSC), differential thermal analysis (125-127), low temperature compression set, and Gehman torsional stiffness are tests normally employed to measure crystallization properties. The heat of fusion of the crystalline phase of polychloroprene homopoljuner is approximately 96 kJ/kg (23 kcal mol ) and the activation energy for crystallization is 104 kJ/mol (25 kcal mol ). The extent of crystallization can be calculated from... 

The relationship between torsional stiffness, aspect ratio and compression ratio and the fatigue life of rubber bushings for military vehicle track systems is discussed. Results are presented of tests conducted on traditional and prototype bushing designs using a laboratory endurance simulation machine, and which suggest that the endurance life is more sensitive to changes in torsional stiffness (shear strain) than radial stiffness (compressive stress). 5 refs. 

Modulus can be obtained from rotational stiffness by using the formula for static torsion of a strip test piece ... 

ASTM D1043, Stiffness properties of plastics as a function of temperature by means of a torsion test, 1992. 

Wang SS, Chim ES-M, Socie DF. Stiffness degradation of fiber-reinforced composites under uniaxial tensile, pure torsional, and biaxial fatigue at cryogenic temperature. In Composite materials testing and design. ASTM STP 787 EB 1982. pp. 287-301. 

ASTM D1043-02 Standard Test Method for Stiffness Properties of Plastics as a Function of Temperature by Means of a Torsion Test... 

Shear modulus can be determined by a static torsion test or by a dynamic test using primarily a torsional pendulum (ASTM D 2236). Also used is an oscillatory rheometer test. The torsional pendulum is applicable to virtually all plastics and uses a simple specimen readily fabricated by all commercial fabricating processes or easily cut from fabricated part. The moduli of elasticity, G for shear and E for tension, are ratios of stress to strain as measured within the proportional limits of the material. Thus the modulus is really a measure of the rigidity for shear of a material or its stiffness in tension and compression. For shear or torsion, the modulus analogous to that for tension is called the shear modulus or the modulus of rigidity, or sometimes the transverse modulus. 

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