As damage initiation and growth and its effect on laminate properties are very important mechanisms prior to laminate failure, NPL has developed a software system known as PREDICT, which is an additional module to CoDA. PREDICT uses fibre and matrix properties, or ply properties, to predict the loading conditions for which ply cracks may form and grow across the laminate, and it can predict subsequent progressive cracking. General symmetric laminates may be considered subject to general in-plane loading, and the important effects of thermal residual stresses are considered.

Outputs from PREDICT may be any of the following list:

1. Effective ply properties, if fibre and matrix properties are available
2. Stress-strain plots showing onset of damage and the progressive degradation of the material during loading
3. Property variations with ply crack density, axial stress or axial strain

The outputs can be imported into FEA systems. The software has been extensively validated, both with other calculation methods (e.g. FEA and boundary element methods) and with experimental data. Other software, not included in PREDICT, has been developed to deal with combined biaxial in-plane loading (without shear) and biaxial bending.

Useful references

Physically based damage models for laminated composites
L N McCartney
Proc. Instn. Mech. Engrs. 2003, 217, Part L: J. Materials: Design & Applications, 163-199.

For more information: Neil McCartney