Composite Materials Research Progress

Multi-scale Analysis of Fiber-Reinforced Composite Parts… 25
4.4. Examples of Multi-scale Stresses Estimations in Composite Structures:
T300-N5208 Composite Pipe Submitted to Environmental Conditions
4.4.1. Macroscopic Analysis
4.4.1.1. Moisture Concentration
Consider an initially dry, thin uni-directionally reinforced composite pipe, whose inner and
outer radii are a and b respectively, and let the laminate be exposed to an ambient fluid with
boundary concentration c0. The macroscopic moisture concentration, c I (r,t), is solution of the
following system with Fick's equation (45), where D I is the transverse diffusion coefficient of
the composite. Boundary and initial conditions are described in (46):
I
∂c
∂t
⎪⎧
c
⎨
⎪⎩ c
I
I
= D
⎡ 2
∂ c
⎢ 2
⎣ ∂r
I
( a,
t)
( r,
0)
= c
= 0
0
I
+
I
1 ∂c
r ∂r
and c
I
⎤
⎥
⎦
( b,
t)
, a