What is elastegrity?

©Comparison between force and energy. Stewart MacPherson. 25/12/15

Comparison between the concepts of Force and Energy.

Force Energy Dead-loads Living energy Loading Down Pushing Up Static Dynamic Vector Scalar Zero on the number-line A distance in the positive direction Long bow Composite bow Zero Stress and Strain Stored initial stress Denser elements 'lighter' elements

Through the concepts of force a structure 'reacts' against load by [essentially] stressing the molecular bonds and by straining elastically with the applied mass of dead loads. By replacing the concept of force (a vector magnitude) with energy (a scalar magnitude) we pre-stress the structure with a generous amount of elastic strain energy, similar to the idea of the palintonos bow (cupids bow). Which means we can deliver much more punch (power) to our structures and increased stability.

If we pre-stress our structures using the internal tension within the molecular lattice structure of the material/fabric we increase its resistance/reaction to the load, taking some of the sting out of the overall deformation of the structure.

Think of it as moving the slider/fulcrum along the scale, then loading the structure. Normally the fulcrum is at zero on the number-line, with negative numbers to the left and positive numbers to the right. By storing-up energy, like the palintonos bow, we move the slider/fulcrum further up to the right of the number-line, starting, if you like, from a 'position of strength'. When the structure is loaded the slider moves back down the number-line, passing zero (the static, dead-load concept of the force-vector and classic concept of the strength of materials) and hopefully comes to rest an equal and opposite distance from the pre-stressed starting point to the right of zero.

Now imagine both ends of the number-line are raised up, so that you now have the catenary or parabola familiar to mathematicians and to people like Antonio Gaudy, with his hanging chains? Now you begin to approach the ideas of 'form-finding self-stressed structures'?

If it helps elastegrity then, is a palintonos bow which being pre-stressed has the ability to react against increasing loads simply by making use of the inherent properties of the material/fabric. It achieves this through the concept of resilience and toughness, rather than the conventionally taught concepts of load-carrying capacity through the strength of materials, which are imagined as force-vectors, mass times gravitational acceleration.

Just like the English Long Bow structures designed with the classical notion of strength calculations rely on density and as such are much heavier. On the other hand, elastegrity, being analogous to the composite bow (the bow of Odysseus) carries no 'excess baggage', no excess dead weight. Therefore, it can be designed with less fabric. Consequently it is in effect 'lighter', because it makes use of the inherent internal elastic molecular tensions of the fabric (wood). If the fabric/material is a composite material analogous to the horn and tendon in the palintonos bow, its ability to resist the punishment of stress and strain should therefore improve 'measurably'…?

#isotropic