Testing methods flexural

The impact of thermal shock on the properties of a ceramic or a CMC is assessed by means of both destructive and non-destructive testing methods. Flexural or tensile (mainly for CMCs) tests of suitably-sized thermally shocked specimens are usually employed to measure retained mechanical properties as a function of the temperature difference. The temperature differential for which a significant drop in property values is observed is the A A- For monolithic ceramics and particle- or whisker-reinforced CMCs the property under investigation is usually strength, whereas in fibre-reinforced CMCs a drop in Young s modulus is usually a better indication of the onset of damage. 

Data for thermal movement of various bitumens and felts and for composite membranes have been given (1). These describe the development of a thermal shock factor based on strength factors and the linear thermal expansion coefficient. Tensile and flexural fatigue tests on roofing membranes were taken at 21 and 18°C, and performance criteria were recommended. A study of four types of fluid-appHed roofing membranes under cycHc conditions showed that they could not withstand movements of <1.0 mm over joiats. The limitations of present test methods for new roofing materials, such as prefabricated polymeric and elastomeric sheets and Hquid-appHed membranes, have also been described (1). For evaluation, both laboratory and field work are needed. 

ASTM Standard C651-91, Standard Test Method for Flexural Strength of Manufactured Carbon And Graphite Articles Using Four-Point Loading at Room Temperature, American Society for Testing and Materials, 1991... 

Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. D790-84a. American Society for Testing and Materials Philadelphia, 1985, Vol 8.01, p 397. 

Compare flexural and tensile modulus testing methods. Why is it reasonable to say that both methods describe the rigidity of a material ... 

ASTM D2990, a, Test Methods for Tensile, Compressive and Flexural Creep and Creep Rupture of Plastics, Vol. 8.02, ASTM, Philadelphia, Pa., 1993. 

D 1184 Test Method for Flexural Strength of Adhesive Bonded Laminated Assemblies... 

The strength properties more often specified for plastics materials are (1) tensile strength and elongation, (2) flexural strength, (3) Izod and Gardner impact, and (4) heat deflection temperature under load. Our purpose here is not to describe each test in detail but to point out some of the known effects that colorants and other formulation ingredients can have on these properties. Table 22.1 lists the ISO and ASTM test methods for most of the physical properties, and ref. 1 (pp. 7-112) describes each of the methods in detail. Table 22.2 lists typical values of the above cite four properties for selected thermoplastics. 

Testing of ceramic composites has been around since the earliest fabrication of these materials. For particulate- and whisker-reinforced composites, testing methods which are suitable for monolithic ceramics are generally used. These methods include three- and four-point flexure, uniaxial tension and compression, and many others. For fiber-reinforced ceramic composites, flexural testing was also used initially. However, as was recognized in the polymer composites area, flexural testing alone could not provide the type of... 

Whilst test methods to measure the mode I fracture resistance of polymer fibre-composites [1] and stmctural adhesive joints [2,3] have now proceeded to full standards, the efforts to standardise a mode II method have been beset by a number of problems. Firstly, there exist a number of competing tests e.g. the end-loaded split (ELS), the end-notched flexure (ENF), the four point end-notched flexure (4-ENF) and the stabilised end-notched flexure (S-ENF) have all been proposed and have been subjected to various inter-laboratory evaluations. However, the results of these programmes have always revealed a very large scatter in the values of Gnc measured e.g, [4], and this scatter has been variously attributed to friction... 

ASTM D 1565, a specification, outlines a test method for dynamic flexing of flexible vinyl cellular materials. This test uses a flexing machine which oscillates at 1 Hz. A minimum of 250,000 flexes are applied. After alternate compression and relaxation the effect on the structure and thickness of the foam is observed. The percentage loss of thickness is reported. Flexural modulus of microcellular urethane is described in ASTM D 3489. This method uses the general procedure in ASTM D 790, Method I. ASTM D 3768 outlines a procedure for determining flexural recovery of microcellular urethanes. The method is used to indicate the ability of a material to recover after a 180° bend around a 12.7-mm (0.5 in.) diameter mandrel at room temperature. 

ASTM C 203-91 Standard Test Methods fox Breaking Load and Flexural Properties of Block-Type Thermal Insulation, 6 pp (DOD Adopted) (Comm C-16)... 

ASTM C 480-62 (1988) Standard Test Method for Flexure-Creep of Sandwich Constructions, 2 pp (Comm F-7)... 

Bending test JIS A 1106 (Method of Test for Flexural Strength of Concrete). 

Rigid plastic for purpose of general classification, a plastic that has a modulus of elasticity, either in flexure or in tension, greater than 700 MPa (100,000 psi) at 23°C and 50% relative humidity when tested in accordance with Test Methods D 747, D 790, D 638, or D 882. 

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