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Friday, December 3, 2010

Lamina and Laminate, What Is That?

So, what is lamina? What is laminate? What is the different?
Let us talk about lamina first.

A lamina is a flat (or sometimes curved) arrangement of unidirectional (or woven) fibers suspended in a matrix material. A lamina is generally assumed to be orthotropic, and its thickness depends on the material from which it is made.

For example, a graphite/epoxy (graphite fibers suspended in an epoxy matrix) lamina may be on the order of 0.127 mm thick. For the purpose of analysis, a lamina is typically modeled as having one layer of fibers through the thickness. This is only a model and not a true representation of fiber arrangement. Both unidirectional and woven laminas are schematically shown below.


Schematic illustration of lamina composite

While a laminate is a stack of lamina, as illustrated below, oriented in a specific manner to achieve a desired result. Individual lamina is bonded together by a curing procedure that depends on the material system used. The mechanical response of a laminate is different from that of the individual lamina that forms it. The laminate’s response depends on the properties of each lamina, as well as the order in which the lamina are stacked.


Schematic of laminate composite

So, to construct a product (laminate) we have to use a several lamina with determined orientation to achieve properties that we want. Usually, lamina is not used without stacking it to create a laminate. These lamina is being hold together thanks to the resin that we choose depending on service conditon of the product.

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