slightly wedge shaped bricks/stones used to build an arch

the basic condition for the safety of masonry is that the thrust line is kept within the middle third of a wall or column

building out masonry step-wise from each side until the stones meet in the middle (precursor to an arch)

that’s why it softens

a line passing down the wall of a building from the top to bottom which defines the position at which vertical thrust can be thought to act on each joint

distortion in material over time

when people are exposed to prolonged, strong vibrations (such as from using chainsaws), their arteries can elongate

the horizontal tension member or tie-bar across the bottom of a truss

french for “built-in”

beam one end of which is ‘built in’ to some rigid support

shearing load / area

a measure of the tendency for one part of a solid to slide past the neighboring part

angle through which material is distorted as a result of shear stress (in radians)

stiffness of a material in shear (shear stress / shear strain). equivalent of Young’s modulus.

different in different directions (aka aelotropic)

same in all directions (from greek)

English longbows were made from Spanish Yew, which grows in the Medit. But yew bows are unrealiable above 35 C.

area under stress/strain curve (¹⁄₂ * s * e for Hookean materials)

after he was confined to his home. He figured it was unlikely to be controversial and get him in more trouble.

Proportional increase in length due to stress (e = increase/original = I/L)

Force / Area that the force acts over (s = load/area = P/A)

defined as the stress required to break it

roughly stiffness, E = s/e

specified by Inglis: s(1 + 2*sqrt(L/r))

number of times material strength is higher than expected working load

so they could assess the tensions of the ropes by ear

that’s how strong muscles are compared to bones

due more to loss of nervous control than weakened bones (only a 22% reduction in bone strengh)

L-sub-G: Point at which cracking system goes from consuming energy to releasing. ¹⁄₂ * 2 * WE / (strain energy)^2

form of fracture where material deforms plastically before breaking in tension

or “fracture energy”: “toughness”, quantity of energy required to break a given cross-section of material

the amount of strain energy that may be stored in a structure without causing permanent damage.

made from springy wood and only four spokes. worked like a bow to absorb shock.

it expands and spreads the shearing forces across a larger area.

any triangulated lattice girder

at 45 degrees to the warp/weft of a fabric

the yacht America won the race (which was then named for it) largely because American sail makers used tighter woven fabrics with the weave arranged to align tensions with the fibres while the brits used loose woven flax sails arranged haphazardly. The American sails allowed the yacht to sail in higher winds and turn in a tighter radius. When the Queen was told that America had come in first, she asked who came in second and was informed that no other ships were yet in sight.

the point at which a load must be applied so as to cause no twisting

if a wing isn’t rigid enough, an aileron can cause the wing to twist to such an extent that the opposite effect is achieved

the outside wood is tensioned to 4,000 psi while the inner wood is compressed

two rigid outer layers with a porous lightweight interior sandwiched between them

shell structure in which the load is carried in more or less continuous panels (think exoskeleton)

4’ 8.5” standard railway gauge derived from roman chariots. proved to be a major handicap (trains would be more stable and better able to go fast with a wider base)