Volume 21 - Composites Part 10 pdf

Secondary Adhesive Bonding of Polymer-Matrix Composites Flake C.. 3 Load paths to avoid in adhesive use Secondary Adhesive Bonding of Polymer-Matrix Composites Flake C.. References cite

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Introduction to Post-Processing and Assembly

Introduction

Flake C Campbell, The Boeing Company

Polymer-Matrix Composites

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Flake C Campbell, The Boeing Company

Metal-Matrix and Ceramic-Matrix Composites

Machining, Trimming, and Routing of Matrix Composites

Polymer-Introduction

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Machining, Trimming, and Routing of Polymer-Matrix Composites

Lawrence F Kuberski, Fischer U.S.A

Machining Operations

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μ

Cutting Tools For Machining

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Fig 1 Typical diamond brazed cutting tool

Fig 2 Solid carbide end mill with thin film diamond coating

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Peripheral Milling

Fig 3 Typical machined surface of carbon/epoxy composite

Face Milling

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Table 1 Typical face-milling parameters for carbon fiber-reinforced epoxy composites

Tool diam Speed (a) Axial depth of cut Radial depth of cut Feed rate

mm in m/min sfm mm in mm in mm/min in./min

Trimming

μ

Material thickness Feed rate

mm in mm/min in./min

50–70 25.4–50.8 1–2 127–152 5–6 50–70

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Fig 4 Typical abrasive waterjet head configuration

Fig 5 Waterjet cutting

Table 2 Partial list of materials cut with abrasive waterjet

718 Inconel

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625 Inconel

6AL-4V titanium alloy (3.2 mm, or 0.125 in., thick)

Commercially pure titanium

Hastelloy

321 CRES (75 mm, or 3 in., thick)

15-7 PH CRES

301 half hard CRES

301 full hard CRES

Chromoloy

ESCO 49M-high nickel/high chrome alloy (170 mm, or 6.75 in., thick) Mild steels

Glass (25 mm, or 1 in., thick)

Aluminum (140 mm, or 5.5 in., thick)

Peel shim stock

304L CRES (13 mm, or 0.5 in., thick)

Fig 6 Typical router bit

Selected References

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Secondary Adhesive Bonding of Polymer-Matrix Composites

Flake C Campbell, The Boeing Company—St Louis

Adhesive Joint Design

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Fig 1 Typical secondary adhesively bonded joint configurations (a) Single lap joint (b) Tapered single lap joint (c) Single strap joint (d) Double lap joint (e) Double strap joint (f) Tapered double strap joint (g) Scarf joint

Fig 2 Typical bondline shear stress distribution

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Fig 3 Load paths to avoid in adhesive use

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Table 1 Typical characteristics of adhesive types

temperature,°C (°F)

Maximum use temperature,°C (°F)

Advantages

Not generally as strong or

environmentally resistant as typical heat-cured epoxies

Store at 18 °C (0

°F); short shelf life; high- temperature cure; brittle and low peel strength

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Strong, objectionable odor; limited pot life

Moisture sensitive before and after cure

High cost; low strength

Poor heat resistance; special equipment

required; poor creep resistance; low strength; high melt temperature Brittle and low peel

High cost; low peel strength; high cure and postcure temperatures; volatiles for some forms

Phenolic-based

One-part films

163–177 (325–

350)

To 177 (350)

High-temperature use

Low peel strength

Table 2 Use-temperature guide to structural adhesives

216 (420)

…

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…

Highly Loaded Joint Considerations

Fig 4 Single lap shear specimen P, load

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Fig 5 KGR-1 extensometer with thick adherend specimen Source: Ref 1

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Fig 6 Adhesive shear stress distribution for skin-doubler specimen E, tensile modulus of adherends; G, shear modulus of adhesive Source: Ref 2

Fig 7 Some general properties of adhesives relative to shear stress and strain LL, end of straight line region; KN, maximum rate loss of stiffness; UL, ultimate strength

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Fig 8 Shear stress and strain at various temperatures for a typical structural adhesive

RT, room temperature

Fig 9 Exaggerated deformation of composite plies and adhesive when bonded to metal

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τ

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Fig 10 Various bonded joint configurations (a), (b), and (c) Shear (d) Scarf (e) Tension (f) Peel

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References cited in this section

Epoxy Adhesives

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Surface Preparation

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Sandwich Structures

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Fig 11 Components of a honeycomb panel

Honeycomb Core

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Fig 12 Corrosion-resistant honeycomb core

Honeycomb Processing

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Fig 13 Core splicing

Fig 14 Machined honeycomb parts

Syntactic Core

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Foam Core

Adhesive-Bonding Process

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μ μ

Fig 15 Prefit fixture used for a complex-contour aircraft door

Adhesive Application

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Fig 16 Robot used for spraying adhesive

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Fig 18 Detail of a pressure bag bonding fixture

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Fig 19 Autoclave bonding fixture

Fig 20 Flat and contoured bonding fixtures mounted on a platen

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Fig 21 Fiberglass assembly bonded using clamps and temporary fasteners

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Fig 22 Honeycomb splicing fixture using screw jacks to apply load

Fig 23 Flat-panel bonding press Courtesy of M.C Gill Corporation

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Inspection

Acknowledgments

References

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Processing and Joining of Thermoplastic Composites

Douglas A McCarville and Henry A Schaefer, Boeing Military Aircraft & Missile Systems

Economic Considerations

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Table 1 Candidate matrix resins for thermoplastic advanced composites

Glass transition temperature Polymer

780

Slit tape woven into rattanlike broadgood rolls to improve drapability

Tacky unidirection fiber Tape that is slit to width Yarnlike fiber bundles Fabric Woven tow

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Fig 1 Advanced thermoplastic aerospace components

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Material Options

Fig 2 Ply Stacking/orientating TTP, true thermoplastic; PUTP, pseudothermoplastic;

TP, thermoplastic

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Fig 3 Pseudothermoplastic processing

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Tape is butted together and seam welded to wider widths with a handheld iron Also, ply stacks can be tack melted together

Equipment takes multiple 30 cm (12 in.), 0° tape rolls and butt seams them to wide (i.e., 300 cm, or 118 in.) 0° or 45° roll stock

Wide roll 0° and 45° roll stocks are stacked together and melt fused into sheet stock

Material is laid to shape, vacuum bagged; autoclave heats TP to melt, applies pressure, and cools to consolidate

Slit tape stacks are pulled through a heated pressure die to generate continuous cross section Ts, Js, etc

Similar to pultruding, but uses rollers to shape, consolidate, and cool the material 0.5 cm (0.2 in.) wide slit tape rolls are placed and melt fused to prior layers on a contoured mold tool (may autoclave after to get full compaction)

Similar to FL, but uses wider slit tape (7 cm, or 2.75 in.), better for large gentle contour parts such as wing skins

Induction Similar to diaphragm, but an electromagnet field is used to heat the extendable

plates, not the tool, thereby reducing cycle time

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Fig 4 Thermoplastic laminating IR, infrared Source: Ref 10

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Fig 5 Thermoplastic cycle times TS, thermoset; TP, thermoplastic; NIDF, nonisothermal diaphragm forming; IDF, induction diaphragm forming; TTP, true thermoplastic, PITP, postimpregnated thermoplastic; PUTP, pseudothermoplastic

Fig 6 Wing rib production cost comparison

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Fig 7 Thermoplastic press forming

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Fig 8 Thermoplastic diaphragm forming

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Joining

Joint Types

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Fig 9 Comparison of lap shear strength for various bond types/methods Source: Ref 21,

23, 24, 25, 26, 27, 28, and 29

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Fig 10 Comparison of fracture toughness to lap shear strength for various bond types/methods PEEK, polyetheretherketone; PEI, polyetherimide Adhesive 1, Ciba Geigy AV138M, 100 °C (210 °F) cure; adhesive 2, Ciba Geigy AY103, 100 °C (210 °F) cure; adhesive 3, Ciba Geigy AV118, 180 °C (355 °F) cure Source: Ref 25

Table 4 Comparison of selected thermoplastic-joining methods

Requires heating of tool and entire part Requires dedicated tool

Requires heating of tool and entire part Long heatup and cool down

Hard to scale up Not practical on complex geometries

Foreign object in bondline Inconsistent heating as length increases

Induction

welding

Localized heating Can use room temperature fixturing Potential to make running long welds

Foreign object in bondline

Joining Methods

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Fig 11 Dual polymer bonded V-22 Osprey door

μ

Fig 12 Co-consolidated cockpit floor

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Fig 13 Schematic for ultrasonic welder and multiunit weld machine Source: Ref 30, 31

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Fig 14 Schematic for resistance weld of rib to spar

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Fig 15 Resistance welding wing substructure using copper foil and amorphous thermoplastic (Ultem, GE Company, Pittsfield, MA) resin

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Fig 16 Induction welder schematic

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Fig 17 Induction weld machine

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Fig 18 Induction welded K3B skin/stringer using Avimid K3A at the bond interface

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References

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Hole Drilling in Polymer-Matrix Composites

Introduction

Michael J Paleen and Jeffrey J Kilwin, The Boeing Company, St Louis

Part Fit-Up

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Drilling Considerations

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Fig 1 A flat flute drill for drilling carbon/epoxy composites

Fig 2 Four-flute drilling/reaming cutter for carbon/epoxy composites

Fig 3 Hand-feed drill motor with hydraulic dash pot for feed control

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Fig 4 Typical hole exit splintering damage from drilling without a backup

Fig 5 Clean hole exit condition when using a backup

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Fig 6 Power feed tool with hard tooling plates

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Fig 7 Peck drilling in which drill advances into material, retracts, cools, and cleans chips before repeating the process

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Fig 8 Automated system for drilling fastener holes in wings

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Fig 9 Automated system for drilling holes and installing fasteners in wings

Reaming

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Countersinking

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Fig 10 Optimal countersink cutter for aramid fiber-reinforced composites

Fig 11 Microstop cage for adjustable, controlled-depth countersinking

Hole Quality

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Mechanical Fastener Selection

Robert T Parker, Boeing Commercial Airplane Company

Corrosion Compatibility

Fastener Materials and Strength Considerations

Bolt Bending

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Fig 1 Example of plastic bending curves for nickel alloy 718 Ftu , ultimate tensile

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Fig 2 Blind fastener bolt bending and deflection (a) Smooth bore allows little resistance

to bolt bending in multiple piece fasteners such as blind fasteners The multiple pieces act

as axial laminates and slide over each other (b) The effect of the threads on the corebolt

“lock” the corebolt to the other components and improve stiffness of the joint However, the notches (threads) can be detrimental in fatigue if the loads are high enough to cause significant deflections

Head Configuration Selection

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Fig 3 Single fastener lap shear specimen in uniaxial tension

Fig 4 Reaction loads of a flush head fastener in uniaxial tension

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Fig 5 Development of 130° head for shear

Fig 6 Load distribution in fasteners joining thin and thick laminates

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Fig 7 Flush head applications for composite structures The fastener head height should

not exceed 70% of t, where t is the top sheet thickness Head diameter, A, is the same for 100° tension and 130° reduced shear fasteners Head diameter is 0.88 to 0.93A for 100°

shear head fasteners

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Clamp-Up

Fig 8 Slippage of composite plies under load

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Tiêu đề	Introduction to Post-Processing and Assembly
Tác giả	Flake C. Campbell
Trường học	The Boeing Company
Chuyên ngành	Polymer-Matrix Composites
Thể loại	Introduction

Định dạng
Số trang	160
Dung lượng	6,7 MB