ASTM C1899-21 PDF

SIGNIFICANCE AND USE 5.1 This test method may be used for material development, material comparison, quality assurance, characterization, and design data generation. 5.2 Continuous fiber-reinforced ceramic composites (CFCCs) may be composed of continuous ceramic-fiber directional (1D, 2D, and 3D) reinforcements which are often contained in a fine-grain-sized ( 5.3 CFCC components have distinctive and synergistic combinations of material properties, interface coatings, porosity control, composite architecture (1D, 2D, and 3D), and geometric shape that are generally inseparable. Prediction of the mechanical performance of CFCC tubes (particularly with braid and 3D weave architectures) may not be possible by applying measured properties from flat CFCC plates to the design of tubes. This is because fabrication/processing methods may be unique to tubes and not replicable to flat plates, thereby producing compositionally similar but structurally and morphologically different CFCC materials. In particular, tubular components comprised of CFCC material form a unique synergistic combination of material, geometric shape, and reinforcement architecture that is generally inseparable. In other words, prediction of mechanical performance of CFCC tubes generally cannot be made by using properties measured from flat plates. Strength tests of transversely loaded CFCC tubes provide information on mechanical behavior and strength for a material subjected to a uniaxial, nonuniform stress. 5.4 Unlike monolithic advanced ceramics that fracture catastrophically from a single dominant flaw, CMCs generally experience “graceful” fracture from a cumulative damage process. Therefore, while the volume of material subjected to a nonuniform, uniaxial flexural stress for transversely loaded tube test may be a significant factor for determining matrix cracking stress, this same volume may not be as significant a factor in determining the ultimate strength of a CMC. However, the probabilistic nature of the stre... SCOPE 1.1 This test method covers the determination of flexural strength, including stress-strain response, under monotonic loading of continuous fiber-reinforced advanced ceramic tubes at ambient temperature. This test method addresses tubular test specimen geometries, test specimen/grip fabrication methods, testing modes (force, displacement, or strain-control), testing rates (force rate, stress rate, displacement rate, or strain rate), and data collection and reporting procedures. 1.2 In this test method, an advanced ceramic composite tube/cylinder with a defined gage section and a known wall thickness is subjected to four-point flexure while supported in a four-point loading system utilizing two force-application points spaced an inner span distance that are centered between two support points located an outer span distance apart. The applied transverse force produces a constant moment in the gage section of the tube and results in uniaxial flexural stress-strain response of the composite tube that is recorded until failure of the tube. The flexural strength and the flexural fracture strength are determined from the resulting maximum force and the force at fracture, respectively. The flexural strains, the flexural proportional limit stress, and the flexural modulus of elasticity in the longitudinal direction are determined from the stress-strain data. Note that flexural strength as used in this test method refers to the maximum tensile stress produced in the longitudinal direction of the tube by the introduction of a monotonically applied transverse force, where ‘monotonic’ refers to a continuous, nonstop test rate without reversals from test initiation to final fracture. The flexural strength is sometimes used to estimate the tensile strength of the material. 1.3 This test method is intended for advanced ceramic matrix composite tubes with continuous fiber reinforcement: unidirectional (1D, filament wound and tape l...