8. Forces and stresses Flashcards
What is compression?
Forces that are trying to crush or shorten
What is tension?
forces pulling in opposite directions
What is bending?
flexing force
What is torsion?
twisting force
What is shear?
a strain produced when an object is subjected to opposing forces
What is a fair test for tension?
apply the same weight to each material and suspended in the same manner
What is a fair test for compression?
insert materials into a vice/clamp and apply the same amount of twists to the handle
What is a fair test for bending?
flexing force
What is a fair test for torsion?
twisting force
What is a fair test for shear?
place the material between a tool that works in opposite directions e.g shears
How can a material/object be adapted to resist tension?
concrete can have steel bars inserted to reinforce
How can a material/object be adapted to resist compression?
composite panels can have a honeycomb structure sandwiched in the middle to resist
How can a material/object be adapted to resist bending?
steel beams have an I profile to resist bending
How can a material/object be adapted to resist torsion?
the diagonals on a tower crane help the structure against torsion
How can a material/object be adapted to resist shear?
bolts are hardened and have unthreaded shanks to help stop shearing
What is lamination?
layering of thin materials
What is bending/folding?
Folding a 90 degree edge on a sheet metal plastic
What is webbing?
Modern Polymer fabrics woven together
What is fabric interfacing?
a strengthening material added to the unseen face of a fabric
What is the result of lamination?
it can make boards stiffer or actually more flexible, depending on the direction of lamination
What is the result of bending/folding?
makes the panel more rigid
What is the result of webbing?
extremely strong and durable fabric
What is the result of fabric interfacing?
adds strength/shape
What is an example of where lamination is used?
plywood
What is an example of where bending/folding is used?
body panels on cars
What is an example of where webbing is used?
seat belts
What is an example of where fabric interfacing is used?
shirt collars
What does the seasoning of timber do?
removes the moisture content so that the timber will not shrink, warp and twist
What does the annealing (heating) of copper do?
softens the copper to make it more malleable
What does the addition of stabilisers in PVC do?
stops plastic becoming brittle with exposure to the sun
