Assembly (exc monm)

adherends

When using adhesives to connect two parts together, what is the name of the parts being joined?

curing

when the adhesive changes from liquid to solid - often requires a catalyst

where would u ideally want failure in an adhesive joint?

in the adherends not adhesive

adhesives are strongest under which forces?

tension and shear but fail under peeling

main methods of adhesive application

brushing

spraying

flowing (hot glue)

roller - like paint roller

what is the only permanent mechanical assembly we know

rivets

main advantages of mechanical fasteners

cheap

standardised universally - thus easily repairable

requires little to no training/tools

self-tapping screw purpose

ability to create the reverse thread into a PRE DRILLED HOLE.

(for extra security)

pitch

is the distance between adjacent threads - presented next to diameter.

what force is a bolt under once fastened

tension - ensure direction correct in calculations

ISO standard for Area for stress calculations

D = diameter

p = pitch

ANSI standard for area for stress calculations

IN SQUARE INCHES ETC

n = number of threads per inch

stall-motor (wrench)

designed to stall/stop when correct torque/tightness reached

rivet how they work

1 head and tube initially

passed through hole

pulled from initial side from the inside of the pole causing it to flatten

second head created - permanent

eyelets

rings usually used in fabrics to form holes and prevent fraying - click in place under force

main interference fits (those that require mechanical interference to function

press fitting

shrink and expansion fits

snap fits

retaining rings.

stress calculations for interferance fits

pf = radial pressure

i = interferance between pin and collar

…

C = collar therefore outer radius - inner radius just gonna be pins radius!

Y = yield strength NOTE not same as UTS but in design u dont ever want product going past Y - never reaching UTS so use context of qs.

IF PIN JUST IN HOLE OF METAL AND NO OUTER RADIUS THEN SAY Dc = infinite.

press fitting

i.e. dowel joints

fitting in which both parts have an interference fit

shrink and expansion fits (kinda counter intuitive)

SHRINK FIT = ENLARGE OUTER then let it shrink

EXPANSION = SHRINK INNER (by cooling) then let it expand

snap fit

obv - but main advantage is speed and simplicity but weak.

retaining ring

snaps around diameter of shaft and acts as a shoulder to prevent movement.