Book: 20231016 to 20231208, "Structures" by J.E.Gordon
20231016 - 1 The structures in our lives — or how to communicate with engineers
I never thought about the world this way.There are so many things that we are so used to them, and then we don't pay attention to them.
Does this understanding help our lives anyway?
20231019 - Part One - The difficult birth of the science of elasticity
Force applys to molecules and atoms, which cause completely different effect on different material.
Small cracks are everywhere in big structure, such as buildings, bridges and ships. Because of that, mild steel is much more important that high tensile steel. Big parts use mild steel, and small parts prefer to use high tensile steel.
20231108 - Part Two - Tension structures
20231115 - Part Three - Compression and bending structures
These are mainly about compression. If we only have wood and rock, then there is no other choice.
20231206 - Part Four - And the consequence was…
When AGI is invented, it would emulate the whole structure with hundreds of different material and millions of different structure. Structure could be combined with different scales, from micrometer to hundreds of meters. The new design would need much more energy but should be much more grace and safer.
20231113 - Appendix 2 Beam theory
20231019 - Part One - The difficult birth of the science of elasticity
20231019 - 2 Why structures carry loads — or the springiness of solids
Force applys to molecules and atoms, which cause completely different effect on different material.The world is amazing.
Stress is the force per unit area, strain is the shape change per stress.
Strength is the stress need to damage the material, stiffness is capability to maintain the shape after stress.
20231019 - 3 The invention of stress and strain — or Baron Cauchy and the decipherment of Young’s modulus
Stress and strain; strength and stiffness.Stress is the force per unit area, strain is the shape change per stress.
Strength is the stress need to damage the material, stiffness is capability to maintain the shape after stress.
In old days, the progress of technology, is more about natural selection. People don't know why something works, so they don't allow any changes.
20231027 - 4 Designing for safety — or can you really trust strength calculations?
Small crack can cause some material collapse, such as glass, stone and rubber. It change the force per unit area in certain area, around the tip point of the crack.Glass and rubber are quite different, but both are vulnerable to small cracks or holes. Why?
20231028 - 5 Strain energy and modem fracture mechanics — with a digression on bows, catapults and kangaroos
Ancient people cannot make long distance weapon, mainly because they don't have good material and energy source.
That's the reason the size of boat, bridge, and animal are limited.
In the future, is it possible to make glass with high strain energy storage capacity?
How can we improve the nerve system of eld people to avoid bone fracture? Does big muscle help?
20231108 - Part Two - Tension structures
20231108 - 6 Tension structures and pressure vessels — with some remarks on boilers, bats and Chinese junks
Good to know that pipe shell needs to hold double strength of the one pushing liquid forward.
The sails on Chinese junk is more likely to survive storm, but it's less flexible. Maybe it's inspired by the swing of bats.
Membrane is so different from rubber. It needs to become the base components of humanoids. But, is it possible to make it with inorganic material?
Is there something similar to feathers being used in modern machine?
20231108 - 7 Joints, fastenings and people — also about creep and chariot wheels
Riveted lapped joint is heavier and more expensive than other solutions, such as welding. But it's more consistent to common sense.When moulding something(such as nails) into other material(such as concrete), we need to compare their rigidness and strength. Insert hard stuff into soft material, is quite different from soft stuff in hard block(such as an earthworm in soil).
Creeping is interesting. What happens at micro level when spring is always under heavy load?
20231108 - 8 Soft materials and living structures — or how to design a worm
Billions of years of natural selection did good job. It's hard to imagine how that organism is designed so well.From physics point of view, all creatures are some solid and liquid stuff in a container. For human, this container is our skin, and each of our organ is some other stuff in containers. Even each cell is some stuff in a container.
Can nano tech implement similar feature with inorganic matter?
20231115 - Part Three - Compression and bending structures
20231115 - 9 Walls, arches and dams — or cloud-capp’d towers and the stability of masonry
These are mainly about compression. If we only have wood and rock, then there is no other choice.Everything is elastic. This is the key to understand all structures.
20231115 - 10 Something about bridges — or Saint Bénezèt and Saint Isambard
Different structure suits different situation.Material, skill, labour cost, span distance, etc.
Not sure about joints. There must be many different joints apart from riveted lapped joint and welding.
Maybe I should be a book about how to build house or boat.
20231116 - 11 The advantage of being a beam — with observations on roofs, trusses and masts
Beam can drastically reduce the cost and weight of truss, thanks for the invention of low cost steel. Maybe it's still too heavy?If build a skycrape framework mainly by steel, how tall it could be? Concrete can support up to 2000 meters, surely that steel can support 10 kilometer, right?
20231125 - 12 The mysteries of shear and torsion — or Polaris and the bias-cut nightie
Shear and torsion are actually caused by sliding at atom or molecule level. If the material is surrounded by stiff material completely, then any material can support extreme high compression.This is the reason that bottom of earth shell can support more than 30km thick rock layer. If we seal melted silicon in steel container, can this container resist much higher compression?
Many structure such as the wing of plane, takes different compression and tension at different position. Designing structure is perfect job for computer simulation.
20231126 - 13 The various ways of failing in compression — or sandwiches, skulls and Dr Euler
This chapter explains why structure is part of material.Wood is quite different from other material. Most materials are with unequal tensil and compression strengths. For some material we can sacrifice tensile to get better compression strengths, such as wood.For most of other material, we sacrificecompression for better tensile.
We need to think about all position of the material to make perfect structure.
Will Nano Tech build much better material?
20231206 - Part Four - And the consequence was…
20231206 - 14 The philosophy of design — or the shape, the weight and the cost
When AGI is invented, it would emulate the whole structure with hundreds of different material and millions of different structure. Structure could be combined with different scales, from micrometer to hundreds of meters. The new design would need much more energy but should be much more grace and safer.AGI would consider everything following the first principle.
20231207 - 15 A chapter of accidents — a study in sin, error and metal fatigue
Is it possible to solve metal fatigue by applying some special structure at micro scale? Can we make glass with great ductility?
Probability is something that no one can conquer, or else the cost is too high. I think, if we seal the complicated details into black boxes, there will be much less accidents. Computer chip is a good example.
We need to tolerate different, especially unpopular opinions.We need to encourage technical arguments, no matter how ridiculous it may sounds.
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