There are unidirectional, crossply and angle ply laminates.What is the use of quasi-isotropic laminates.
there are different stacking sequences in quasi-isotropic:
[0/+-45/90], [0/45/90/-45], [45/0/-45/90] etc.
Why these many number of stacking sequences?
In which application (aerospace,automotive etc) these quasi-isotropic laminates are used?
QI laminates are typically used as one-for-one replacements for metallic structures, where the lighter weight of the composite is an advantage. These are the so-called "black aluminium" structures.
There are many QI layups other than 0, 45, 90. [0/60/-60]s is another popular option.
Dear Manikanta,
the so-called quasi-isotropic (QI) stacking sequence can be obtained by exploiting the well-known Werren and Norris condition (see the book Anisotropic Elasticity by P. Vannucci for a deeper insight into the topic).
However, the Werren and Norris condition is just a sufficient condition to get a QI stack (recall that in this case the stack is isotropic only in membrane, while is completely anisotropic in bending).
Necessary and sufficient conditions for obtaining fully isotropic stacks (both in membrane and bending) as well as other general properties, like membrane or bending orthotropy, uncoupling, membrane or bending square symmetry, etc., can be obtained by using the so-called polar formalism. By means of the polar formalism, the membrane, bending and membrane/bending coupling tensors of the laminate are expressed in terms of tensor invariants (which are called polar parameters) which are directly related to the elastic symmetries of the laminate. You can find these general conditions for obtaining all kind of elastic symmetries in the following publications:
M. Montemurro. An extension of the Polar Method to the First-order Shear Deformation Theory of laminates. Composite Structures, v. 127, pp. 328-339, 2015.
M. Montemurro. Corrigendum to" An extension of the polar method to the First-order Shear Deformation Theory of laminates"[Compos. Struct. 127 (2015) 328-339]. Composite Structures, v.131, pp. 1143-1144, 2015.
M. Montemurro. The polar analysis of the Third-order Shear Deformation Theory of laminates. Composite Structures, v. 131, pp. 775-789, 2015.
T. Garulli, A. Catapano, M. Montemurro, J. Jumel, D. Fanteria. Quasi-trivial stacking sequences for the design of thick laminates. Composite Structures, v. 200, pp. 614-623, 2018.
Do not hesitate to contact me if you have further questions on the topic
Kind regards
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