Composite Materials Research Progress

176
Giangiacomo Minak and Andrea Zucchelli
the corresponding experimental values, while in table 3 the ultimate strain and stress values
are reported.
Table 2. Theoretical calculation and experimental measure of Elastic modulus of each
laminate type
Ex (MPa)
Theoretical Experimental
ID M.V. M.V. S.D.
UD 197000 190000 16000
AP 23000 22000 3000
QI1 75000 74000 6000
QI2 75000 76000 3000
QI3 77000 78000 3000
Table 3. Ultimate strain and stress values of tested laminates
Ultimate Strain Ultimate Stress (MPa)
ID M.V. S.D. M.V. S.D.
UD 0.019 0.001 2157 104
AP 0.084 0.008 62 7
QI1 0.012 0.002 571 35
QI2 0.010 0.001 600 44
QI3 0.012 0.001 322 19
The main acoustic parameters that have been considered are: counts per AE event and AE
event energy (Ea). Both parameters have been related by means of double entry diagram with
the stress-strain behaviour. In the following figures 6-10 examples of these diagrams, one for
each type of laminate, are reported.