1. Composite Panels & Adhesives

2. Composite Panels Panels are fiberglass on both sides with a core in the middle consisting of either foam or a honeycomb structure

3. Core Options

4. Final Core Material HT Diab 61 - Wing Skins Ability to lay up curves of Airfoils Cheapest that met criteria of foams Aramid Core - Spar, Aft Spar, Rib Light Weight Cheapest per Pound

5. Adhesive Options DP 420 –3M, Two Part Epoxy »From 3M Epoxy Comparison

6. Adhesive Options (Cont.) PTM & W: –ES6292 Lightweight Tough Epoxy Adhesive Two Part Epoxy Designed for use in the structural assemblies involving composites Already used by Cirrus Design Center

7. Adhesive Testing Objectives: –Test Max Adhesive Loads Need to make sure adhesives aren’t effected by surfaces –Test surface preparation techniques

8. Adhesive Testing (Cont.) Materials Tested: –Adhesives: PTM & W ES6292 3M DP 420 –Composites: Aramid Core with Fiberglass Skin HT Diab Foam Core with Tencate Fiberglass

9. Adhesive Testing (Cont.) Tensile Test: –Load Bonds in Tension –Measure Load at Fracture –Calculate Lbs/In. Bond Strength Test Equipment: –Constant Strain Load Cell –Measures Load and displacement

10. Adhesive Testing (Cont.)

11. Tensile Load Justification: –Jaws: 2° freedom on both directions –Top & Bottom All samples were applied within 1 degree of perpendicular Therefore: Tension loads were perpendicular to bond

12. Adhesive Testing (Cont.) Surface Preparation: –All surfaces were lightly sanded to rough up surface –All surfaces were cleaned with to remove

13. Adhesive Testing (Cont.) Results: –Bond Strength per Inch of Bond (Lbs/In) PTM & W ES6292= 81.7 ± 4.1 Lbs/In 3M DP 420=87.1 ± 4.4 Lbs/In »Uncertainty Estimated at 5%

14. Adhesive Testing (Cont.) Conclusions: –Adhesives were comparable in Strength per Inch –Both Adhesives meet strength requirements for wing –PTM & W ES6292 Adhesive is better because of lower cost

15. Adhesive Testing (Cont.) Errors: –Improper preparation: Issue: Samples broke at surface Resolution: Better Surface Preparation –Sanding (possibly Sand Blasting) –Better Removal of oils from surface Effect: –Bonds Broke Prematurely –With Better Preparation Bonds could hold more Weight

16. Adhesive Testing (Cont.) –Test Equipment: Issue: Jaws Slipping Resolution: Better Transition from Material to Jaw –Adhere Aluminum Tab into Composite –External Clamp System with Aluminum Tab for Jaw »Allow Material to be secured by clamp and Jaw to attach to Aluminum Tab Effect: –Load might be underestimated. –Result: Bond Strength could be higher than reported

17. Adhesive Testing (Cont.) Further Testing: –Shear Test Side View:

18. Adhesive Testing (Cont.) –Shear Test Top View: (Load Pulling out from picture)

19. Adhesive Testing (Cont.) Shear Test:

20. Epoxy Safety Precautions Effects of Overexposure: –Eyes: Causes severe conjunctive irritation, Corneal injury and Iritis –Skin: May cause irritation, burns, ulceration, or skin sensitization –Inhalation: Vapors are irritating and cause tears, burning of nose and throat, coughing, wheezing nausea and vomiting

21. Epoxy Safety Precautions (Cont) –Ingestion: Moderately toxic, may cause mouth and throat burns, abdominal pain, weakness, thirst and coma. –Chronic: Amine vapors may cause liver and kidney injury. Eye, skin or lung may develop or be irritated by Amine vapors. [From MSDS of ES6292B with Beads]

22. Epoxy Handling Precautions Respiratory: –Not required unless process is creating dust, mist or vapor. Ventilation: –Breathing of vapor must be avoided. Hand Protection: –Impervious gloves, neoprene or rubber, must be worn

23. Epoxy Handling Precautions (Cont.) Eye Protection: –Splash proof Goggles or safety glasses Other: –Clean body covering clothing and shoes [From MSDS of ES6292B with Beads]

24. Aramid Core Handling Requirements Ventilation required when machining produces dust, mist or vapor Light Hand Cotton gloves for General Protection [From Aramid Core MSDS]