【国外标准】 Standard Practice for Radiographic Examination of Flat Panel Composites and Sandwich Core Materials Used in Aerospace Applications

5.1 Radiographic examination may be used during product and process design optimization, on line process control, after manufacture inspection, and in service inspection. In addition to verifying structural placement, radiographic examination can be used in the case of honeycomb core materials to detect node bonds, core-to-core splices, and core-to-structure splices. Radiographic examination is especially well suited for detecting sub-surface flaws. The general types of defects detected by radiographic examination include blown core, core corrosion, damaged filaments, density variation, entrapped fluid, fiber debonding, fiber misalignment, foreign material, fractures, inclusions, micro-cracks, node bond failure, porosity/voids, and thickness variation.5.2 Factors that influence image formation and X-ray attenuation in radiographic examination, and which are relevant to interpreting the images for the conditions of interest, should be included in the examination request. Examples include, but not limited to, the following: laminate (matrix and fiber) material, lay-up geometry, fiber volume fraction (flat panels); facing material, core material, facing stack sequence, core geometry (cell size); core density, facing void content, adhesive void content, and facing volume percent reinforcement (sandwich core materials); overall thickness, specimen alignment, and specimen geometry relative to the beam (flat panels and sandwich core materials).5.3 Information regarding discontinuities that are detectable using radiographic examination methods can be found in Guide E2533.1.1 This practice is intended to be used as a supplement to Practices E1742, E1255, E2033, and E2698.1.2 This practice describes procedures for radiographic examination of flat panel composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. Radiographic examination is: a) Film Radiography (RT), b) Computed Radiography (CR) with Imaging Plate, c) Digital Radiography (DR) with Digital Detector Array’s (DDA), and d) Radioscopic (RTR) Real Time Radiography with a detection system such as an Image Intensifier. The composite materials under consideration typically contain continuous high modulus fibers (> 20 GPa), such as those listed in 1.4.1.3 This practice describes established radiographic examination methods that are currently used by industry that have demonstrated utility in quality assurance of flat panel composites and sandwich core materials during product process design and optimization, process control, after manufacture inspection, in service examination, and health monitoring. Additional guidance can be found in E2533, Guide for Nondestructive Testing of Polymer Matrix Composites Used in Aerospace.1.4 This practice has utility for examination of flat panel composites and sandwich constructions containing, but not limited to, bismaleimide, epoxy, phenolic, poly(amide imide), polybenzimidazole, polyester (thermosetting and thermoplastic), poly(ether ether ketone), poly(ether imide), polyimide (thermosetting and thermoplastic), poly(phenylene sulfide), or polysulfone matrices; and alumina, aramid, boron, carbon, glass, quartz, or silicon carbide fibers. Typical as-fabricated geometries include uniaxial, cross ply and angle ply laminates; as well as honeycomb core sandwich constructions.1.5 This practice does not specify accept-reject criteria and is not intended to be used as a means for approving flat panel composites or sandwich core materials for service.1.6 To ensure proper use of the referenced standards, there are recognized nondestructive testing (NDT) specialists that are certified according to industry and company NDT specifications. It is recommended that a NDT specialist be a part of any composite component design, quality assurance, in service maintenance or damage examination.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.