Significance and Use
Shearography is commonly used during product process design and optimization, process control, post manufacture inspection, and in service inspection, and can be used to measure static and dynamic axial (tensile and compressive) strain, as well as shearing, Poisson, bending, and torsional strains. The general types of defects detected by shearography include delamination, deformation under load, disbond/unbond, microcracks, and thickness variation.
Factors that influence shearography and therefore shall be reported include but are 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, and facing volume percent reinforcement (sandwich core materials); processing and fabrication methods, overall thickness, specimen alignment, specimen conditioning, specimen geometry, and test environment (flat panels and sandwich core materials).
Scope
1.1 This practice describes procedures for shearography of polymer matrix composites, sandwich core materials, and filament-wound pressure vessels made entirely or in part from fiber-reinforced polymer matrix composites. The composite materials under consideration typically contain continuous high modulus (greater than 20 GPa (3106 psi)) fibers, but may also contain discontinuous fiber, fabric, or particulate reinforcement.
1.2 This practice describes established shearography procedures that are currently used by industry and federal agencies that have demonstrated utility in quality assurance of polymer matrix composites, sandwich core materials, and filament-wound pressure vessels during product process design and optimization, manufacturing process control, post manufacture inspection, and in service inspection.
1.3 This practice has utility for testing of polymer matrix composites, sandwich core materials, and filament-wound pressure vessels containing but not limited to bismaleimide, epoxy, phenolic, poly(amideimide), 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 and foam core sandwich materials and structures.
1.4 This practice does not specify accept-reject criteria and is not intended to be used as a means for approving polymer matrix composites, sandwich core materials, or filament-wound pressure vessels for service. (Please note that a flaw does not become a defect until rejected by acceptance/rejection criteria.)
1.5 To ensure proper use of the referenced standards, there are recognized nondestructive testing (NDT) specialists that are certified in accordance with industry and company NDT specifications. It is recommended that an NDT specialist be a part of any composite component design, quality assurance, in service maintenance, or damage examination activity.
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 and health practices and determine the applicability of regulatory limitations prior to use.
