Autoclave cure cycle

S.2.2.2. Composite adherends. Composite adherends are bonded in both the cured and uncured states. Wherever possible the adhesive and all adherends are cured simultaneously to avoid the added cost of additional autoclave cure cycles. In many cases this is not practical due to part size and complexity. Cured parts can be bonded to uncured parts, which is known as cobonding, and fully cured parts can be bonded together, which is known as secondary bonding. Adhesives for composites are formulated to be compatible with matrix resins in either cured or uncured states. 

First part qualification. First part qualification is a process performed the first time a new bonded assembly is manufactured or the first time a new tool is used to manufacture a bonded assembly. First part qualification provides assurance that all of the aspects that control bond assembly quality, such as the design dimensions, detail part manufacturing techniques, tool dimensions, layup procedures and autoclave cure cycle parameters are correct and will produce a bond assembly that meets the engineering requirements. 

Because it considers no analytical model, QPA does not make explicit use of heat transfer dynamics. Nonetheless, QPA does reduce the autoclave curing cycle durations in several experimental autoclave curing runs. 

The objective of the Springer KBES is twofold To ensure a high-quality part in the shortest autoclave curing cycle duration. This KBES is similar to QPA in that sensor outputs are combined with heuristics not with an analytical curing model. The rules for compaction dictate that dielectrically measured resin viscosity be held Constant during the First temperature hold in the autoclave curing run. The autoclave temperature is made to oscillate about the target hold temperature in an attempt to attain constant viscosity. Full pressure is applied from the cure cycle start. 

Part heat-up rate during autoclave processing can dramatically influence final part quality. At least three variables can affect the autoclave heat-up rate for composite parts (1) tool material and design, (2) the actual placement of the tool within the autoclave, and (3) the autoclave cure cycle used. Recommendations for the design of an individual tool are fairly obvious and well understood in industry (e.g., thin tools heat faster than thick tools materials with a high thermal conductivity heat faster than those with lower thermal conductivity and tools with well-designed gas flow paths heat-up faster than those with restricted flow paths [e.g., tools... 

Dave, R., Kardos, J., Dudukovic, M. Process Modeling of Thermosetting Matrix Composites A Guide For Autoclave Cure Cycle Selection, American Society for Composites, First Technical Conference, Dayton, OH, Oct. 1986... 

The autoclave cure of advanced composites serves as a good illustration of this sort of complex control problem. A typical autoclave cure cycle is shown in Figure 15.1. The temperature is usually increased in stages until some maximum cure temperature is reached. It is then held at maximum cure temperature until complete cure is certain. During this temperature cycle, the pressure is applied to achieve compaction. The 11 items capitalized in Figure 15.1 are all variables. It is clearly not possible to perform an exhaustive study of all variations of all of these variables with finite time and money. In addition, although the preceding template is common, it is not the only possibility. It would also be possible to heat... 

Figure 9.12 Typical autoclave cure cycle for a graphite/epoxy composite (TGDDM-DDS). 

Figure 6.2a Autoclave curing cycle for soft rubber lining...

Table 6.46. Epoxy Oven (Autoclave) Cure Cycle ...

A typical vacuum bag lay-up is shown in Figures 21.76 and 21.77, whilst Figure 21.78 depicts a characteristic autoclave cure cycle. 

In a standard autoclave cure cycle, dwell is an intermediate step in which the resin is held at a temperature below the cure temperature for a specified period of time sufficient to produce a desired degree of cross-linking. It is used primarily to control resin flow. 

Garschke C, Weimer C, Parlevliet P Fox B (2012), Out-of-autoclave cure cycle study of a resin film infusion process using in situ process monitoring . Composites A, 43, 935-944... 

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