濕手糊威諾納州立大學(xué)

1、(WET) HAND LAY-UPCOMBINING OF REINFORCING FIBER AND RESIN AT THE TIME OF PART FABRICATION1REINFORCING FIBERE-glass, S-glass, Aramid, Carbon/GraphiteE-glass most common (process inherently produces lower quality composite laminate due to lack of tight resin content control and low compaction pressure

2、)mat materialconsists of randomly oriented chopped fibers or swirled continuous fibers which are held together loosely by a binder0.5 oz/sq ft - 3 oz/sq ftwoven fabric materialavailable on rolls in widths from 36 in. to 60 in. typicallyterminology and basic weave patterns (reference manufacturers fa

3、bric book and plied yarn construction figure)unidirectional fabricvery fine filling (stitching) yarnbiaxial fabric2RESINSpolyestersvinyl estersepoxies3MOLD/TOOL PREPARATIONprocedure to some degree dependent on:tooling materialwhether tool is being used in first cycle or subsequent cycleclean toolsco

4、tch brite padwipe with a clean cloth dampened with solvent (i.e. Acetone)mold release agentswaxes (carnuba-based)spray releasesrelease films (sheet, PVA)internal releases (added to gel coat or resin system)4APPLYING A MOLD RELEASE AGENTpreheat moldapply release agentallow period of time for release

5、agent to set up (for wax) or flash offbuff with clean clothrepeat application (particularly for first cycle) alternating patterncure5THE WET LAY-UP PROCESS OFTEN BEGINS WITH A GEL COATtypically polyester, mineral filled (clays and carbonates), pigmented (different than mold color), non-reinforced la

6、yer or coatingproduces decorative, high protective, glossy, colored surfacelittle or no additional finishing requiredcan paint on, roll on, or spray onallow gel coat to set (gel) barely tacky, but not release to the finger6CUTTING THE FABRICcut desired patterntools: shears and/or utility knife7WEIGH

7、ING OUT THE RESINweigh out resin components in specified proportions to achieve desired resin content (desired fiber volume of finished part)epoxy curing agents/hardeners often expressed in parts per hundred by weight (phr) of epoxy resin or parts by weightsee West System epoxy resin systemsresin co

8、ntent expressed as percent by weightepoxy resins typically 25% - 35% by weight (part fiber volume?, dependent on ability to wet out fiber, amount of resin bleeding out during cure, etc.)need to account for process wasteresin bleeding out, remaining on brushes, .dependent on size of part (i.e. the sm

9、aller the part the greater the proportion of process waste)draw quantity of resin components, in separate containersthoroughly mix resin components (combine resin into curing agent container, move from container to container)tools: containers, stirrers8RESIN SYSTEM QUANTITIES FOR THE DEMONSTRATION P

10、ART11 in x 11 in panel made of 16 plies of 120 E-glass clothresin system is West System epoxy resin systemdesired fiber volume in panel is 50%account for process wastebring back container showing amount of resin system needed (using water)9APPLY RESIN TO FABRICapply resin to fabric on mold surface o

11、r, preferably, wet out fabric with resin on separate surface and transfer to moldresin may be sprayed, poured or brushed on, and spread with brush and/or squeegeeapplying resin on mold surface prior to laying of fabric facilitates removal of entrapped air during compaction process - resin is forced

12、up through the fabric along with the airapplying resin to fabric on separate surface prevents resin rich (female curvature) and resin starved (male curvature) areastools: paint brush, spray equipment, squeegee10COMPACTIONresin should be applied and the plies compacted on mold surface from the center

13、 to the outside to facilitate removal of entrapped air, visually able to see air movingpressure can be applied with a squeegee and/or serrated rollerbridging on female contours (radii) must be avoidedtools: squeegee, serrated rollers11VACUUM BAGGING SEQUENCE (VERTICAL BLEED)12PEEL PLYplaced immediat

14、ely on top of or under the composite laminateremoved just before bonding or painting operations to provide clean, bondable surfacewoven fabric (nylon, polyester, or fiberglass) treated with nontransferable release agent13SEPARATOR (RELEASE FILM)nonperforated film is placed between laminate (and peel

15、 ply, if used) and tool (tool surface preparation may make film unnecessary)porous or perforated film is placed on top of laminate (and peel ply, if used, or peel ply alone may serve this function)porous or perforated film allows volatiles to escape from laminate and excess resin to bleed from lamin

16、ate into bleeder plies during curespacing of perforations or porosity of material determines amount of resin flow from laminate surface14BLEEDERabsorb excess resin from laminate during cure (resulting in desired fiber volume)fiberglass fabric or other absorbent materials or fabrics are usedamount of

17、 bleeder used is a function offinished part fiber volume desiredresin contentabsorbency of material15BARRIERbetween bleeder plies and breather nonperforated, nonadhering (release) filmresins which produce excessive volatile by-products during cure (must be vented) by using film with small perforatio

18、ns and large spacing to prevent breather from becoming clogged with resin16BREATHERon top of barrier film to allow uniform application of vacuum pressure over laminate and removal of entrapped air or volatiles during curedrapeable, loosely woven fabric, or felt17CAUL PLATESsteel, aluminum, otherused

19、 to maintain same heating and cooling rate as moldbetween barrier and breathermore uniform application of pressureensure a smooth, non-wavy surface18DAMlocated peripherally to minimize edge bleedingmay be integral part of tool or rubber, metal bars, etc. 19VACUUM BAGGINGvacuum bagused to contain any

20、 vacuum pressure appliedapplication of the vacuum bag extremely criticalbag perforation must be prevented no sharp edges on toolproperly sealed on edgeno bridging (requires folds in bag)folds must be properly made or undesirable wrinkles may occur in partbag sealant tapevacuum valvesvacuum hosesvacu

21、um source (effects of improper use )20CURINGfollow cure schedule recommended by resin suppliereither room temperature or elevated temperature cure resin system21PREIMPREGNATED MATERIALS (PREPREGS)reinforcements impregnated with predetermined amounts of uniformly distributed resinprocessed to obtain optimum handling characteristics and reproducible cured laminate propertiesthermoset (and thermoplastic) resin systems (specify by % resin content by weight)reinforcing fibe