复合材料的损伤.docVIP

TCO D Module – Recognize Composite Damage Types and Sources D1: Identify Sources and Characteristics of Damage to Composite Sandwich and Laminate Stiffened Structures Sources of damages to composite structures can be roughly sorted into three types: Processing anomalies and in-process handling damages Incorrect processing can result in defects in composite parts, and carelessness during post-cure handling and assembly can also result in damages. The anomalies resulting from these kinds of processing mistakes are usually discovered by rigorous inspections by the OEM; however some can go undetected and may show up during routine maintenance. Similar mistakes during repair processing or careless handling in the maintenance depot can result in the same kind of anomalies or damages that can occur during the original manufacturing process. Some of the defects listed below may exacerbate in-service damages, or grow as a result of temperature excursions or mechanical loadings. They also can grow as a result of, or lead to, to moisture ingression. a) Processing anomalies such as voids, delaminations and porosity typically occur during the cure process, and may be the result of poor tooling, insufficient ply consolidation, low autoclave pressure, or loss of vacuum. Poorly designed or installed cure tooling can lead to bridging and lack of proper pressure. This can result in areas of porosity, voids and delaminations. Some of the latest, tougher materials require ply consolidation prior to the cure cycle. This is due in part to the material viscosity, and depending on the number of plies in a layup, several compaction cycles may be necessary. In these cases, insufficient ply consolidation or compaction prior to cure can lead to voids, porosity and delaminations. During the cure cycle, any loss of vacuum, autoclave pressure or temperature can result in anomalies such as voids and porosity. An improperly cured part may also have lower than required thermal stability in