Fibre and resin, two jobs
A ply is stiff fibres (231 GPa) in soft resin (4.7 GPa): along the fibres they share the load side by side and the fibres take it; across, the load must pass through the resin, so the ply is closer to the resin (10 GPa against 141 along).
Predict · at 0:45 in the video
The fibre is about fifty times stiffer than the resin. Pull a ply across its fibres. Is it closer to the fibre's stiffness, or the resin's?
Much closer to the resin's. About 10 gigapascals, for AS4 in 8552. Along the fibres, the same ply is 141.
This course is our own. These books go deeper.
- Basic Mechanics of Laminated Composite Plates, A. T. Nettles, NASA Reference Publication 1351, 1994
- Mechanics of Composite Materials, R. M. Jones, Taylor & Francis, 2nd ed., 1999
- Engineering Mechanics of Composite Materials, I. M. Daniel & O. Ishai, Oxford University Press, 2nd ed., 2006
- Design and Analysis of Composite Structures, C. Kassapoglou, Wiley, 2nd ed., 2013
- Composite Materials Handbook (CMH-17), Volume 3, Rev. G, CMH-17, SAE International, 2012
The course designs in AddPly, our browser app for laminate design: regions, ply stacks with live stacking-rule checks, thickness, mass and the ply book. It does not do strength, failure or draping; where a lesson covers those, the simulation is our own.
Simulations in this lesson are our own. Ply data come from the datasheet or textbook named on screen; where a number rests on an assumption, the video says so.
