LESSON 4.3 · 2:04 · CHAPTER 4 · LAYER TIME AND THE WELD
Healing goes as the fourth root of time
Polymer chains have to wriggle across the interface to weld it; strength grows only as the fourth root of contact time, fracture energy as the square root.
Predict · at 0:43 in the video
An interface gets one sixteenth of the time it needs to heal completely. What fraction of full strength does it reach, and of full fracture energy?
Half the strength, and a quarter of the fracture energy. The fourth root of a sixteenth is a half. The square root is a quarter.
Further reading
This course is our own. These books go deeper.
- The economics of Big Area Additive Manufacturing, Post et al., Solid Freeform Fabrication Symposium, 2016
- Additively manufactured carbon fibre-reinforced composites: state of the art and perspective, van de Werken et al., Composites Part A, 2020
About the numbers
Simulations in this lesson are our own. Where a number rests on an assumption or a single source, the video marks it with an asterisk and says where it comes from.
Up next · 4.4 · 2:01Near Tg, time almost stops