7: CAE Methods

Question 1

Why are CAE methods used in design?

Answer 1

-To calculate structural properties
-Optimise processing parameters
-To check manufacturability
-Compare available manufacturing options
-Verify manufacturing robustness
-Evaluate costs (cost mainly during manufacturing, but commitment occurs early so options must be evaluated)

Question 2

Show the general diagram for the CAE process chain for the design and production of a composite part

Answer 2

Question 3

What information does the ‘ply book’ contain?

Answer 3

-Ply layup sequences
-Ply fibre orientations
-Ramps (between ply layers)
-Shape of the plies
-Orientation of the ply relative to the tool surface
-Position of the ply relative to a feature on the tool surface
-Tolerances
-Log of any design changes

Question 4

What are the steps for creating a composites part using CPD (Catia Composites Part Designer)

Answer 4

-Geometry of the component is created using CAD
-Create a ply book using FEA (finite element analysis) to ensure structural requirements are met
-OML (Outer Mould Line) is defined showing the intersection of the outer surfaces
-A grid design is applied, where composite surfaces are divided into subsections (depends on the structure requirements of the component)
-Laminate properties are applied to each grid element
-Virtual stacking refines the layup sequence of predefined plies (optimised by the designer)
-Stacking sequence is further optimised, determining the optimal ply drop-off patterns and minimise ply overlaps
-Top surface geometry indicating ply stack thickness across the component is produced

Question 5

Explain the laminate analysis process

Answer 5

-Use micromechanical model to calculate the elastic properties of plies
-Determine the ply stiffness matrices in material coordinates
-Determine transformation matrices from ply angles
-Determine ply stiffness matrices in laminate coordinates
-Determine the laminate stiffness matrix from lay-up information
-Calculate inverse of laminate stiffness matrix
-Calculate mid-surface strains and curvatures for given loads
-Derive laminate strain
-Determine stresses in plies in laminate coordinates
-Determine stresses in plies in material coordinates
-Apply failure criterion