Symmetry and warp
A stack that is not a mirror image about its mid-plane couples stretching to bending: a [0/90] laminate curls as it cools from cure (CLT: radius about 34 mm for two 0.127 mm plies and a 156 °C drop) and bends when pulled. [0/90]s stays flat. AddPly checks symmetry live.
Predict · at 0:46 in the video
Two laminates, cured flat. Zero, ninety. And zero, ninety, ninety, zero. Which one comes out flat?
Zero, ninety, ninety, zero. Its two halves pull equally, so it stays flat. The plain zero, ninety curls.
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.
