Sheet metal and non-metallic structures Flashcards
What is the grip length of a Rivet
Combine thickness of the materials to be joined by the rivet
Where are special rivets, such as huck or cherry lock rivets used
We’re access to both sides of the rivet structure is impossible, or where limited space will not permit the use of a bucking bar
Also known as blind rivets
What is the bonded honeycomb construction
It is a laminar Construction consisting of a combination of alternating dissimilar materials, Assembled and fixed in relation to each other so that the properties of each can be used to attain specific structural advantages for the whole assembly While reducing weight
What type of materials are used in honeycomb construction
May employ stainless steel, titanium, magnesium, plywood, resin impregnated paper, E glass, nylon, or cotton cloth
Where are sandwich construction assemblies used
Bulkheads, control surfaces, fuselage panels, wing panels, radomes, empennage skins, or shear webs
What procedures should be used to prevent damage to the whole when drilling through plexiglass
Plexiglass should be backed with wood and fed slowly as the drill point breaks through the underside of the sheet. The drillbit to be used should be modified to a 60° tip angle, and the edge to a zero rank angle, and the back lip clearance angle increased to 12-15°
What calculations must be made when bending sheet metal
Bend allowance and setback must be determined
Setback depends on two factors one radius to thickness. And allowance depends on four factors the degree of band, the radius of the band, the thickness of the material, the type of metal used.
Bending the strip of metal compresses the material on the inside of the curve and stretches the material on the outside of the curve
When making a band to exact dimensions, the length of the neutral line must be calculated so enough material can be allowed for the bend
What factors are used to determine setback
The radius of the band and the thickness of the material. Setback equals radius plus thickness
When bending sheet metal, how should The grain be in relation to the bend
The grain should be perpendicular to the bend
What is the bend Tangent line
The line at which the Metal starts to bend
What is a joggle
A joggle is an offset near the edge of a piece of sheet metal to allow clearance for a sheet or extrusion
What are several methods used in forming sheet metal
Folding, bumping, crimping, shrinking, and stretching
What kind of material forming is done by bumping
Compound curves
What is crazing and how does it occur
Hairline cracks in the surface of plastics
A form of heat damage caused by uneven heating. One side expanding more than the other causing excessive stress. Subjecting plastic to a large stresses and exposure to harmful solvents which caused crazing
Briefly describe the anodizing process and what purpose it serves
Aluminum alloy’s are placed an electric bath which causes a thin film of hydroxide to form on the surface of aluminum. This anodized coating Not only provides excellent resistance to corrosion, but it also is an excellent bond for pain
What are the proper dimensions for the shop head of a rivet
1 and 1 1/2 times The diameter in width and 1/2 times the diameter in height after bucking
When inspecting plexiglass what should you look for
Crazing and discoloration
What causes honeycomb Structures to deteriorate
Moisture
What are the acceptable repair methods for bonded honeycomb structures that has been damaged
One is potted repair method. The other is the laminated glass fabric cloth overlay which is applied to the honeycomb damage which exceeds the repair limitations of the potted compound method
What size drill should be used for the common Shank rivet diameters of 3/32 of an inch, 4/32 inch, and 5/32 of an inch
For a 3/32 rivet, a number 40. For a 4/32 Rivet, a number 30. For a 5/32 rivet, number 21
What is used for a hole filling in a bonded honeycomb repair
Potting compound
What is a lightning whole
They are cut into rib sections, fuselage frames, and other structural parts to decrease weight. Flanges are pressed around the holes for strength
What special precautions should be observed when repairing a radome
The repair must remain its strength and electrical transparency
What is a warp line
A highlighted strand in the fabric used for ply orientation
What does pot life mean
The length of time a resin will remain workable after the catalyst has been added
What is Barcol hardness tester
A device that pushes a spike into material such as composite. The depth of penetration can be measured to determine if the resin’s in the composite have cured
