36
4 Mechanical characterization on constituent level
served as reference for the base materials. Therefore, the constituent material properties are derived in top-down manner using the results of macroscopic core tests. This is
done for the two core modelling approaches detailed meso-scale and homogenized 3Dcontinuum elements. In the following, the performed experimental and numerical studies are described.
4.1.1 Materials
In the framework of the present thesis, Nomex honeycomb cores with a cell size of
3.2 mm and a density of 48 kg/mm³ manufactured by EURO-COMPOSITES [EUR10] are
investigated. This core is typical for aircraft interior applications and complies with the
Airbus specification ABS 5035 [Air14]. In honeycomb manufacturing, Nomex of the Type
412 is usually applied. Due to the dipping process during fabrication (see 2.1.2), Nomex
honeycomb is a bonded composite material comprising two constituents, Nomex paper
and phenolic resin as coating. Both constituents are described in the following before
the analysis of the bonded honeycomb core is presented.
Nomex T412
Nomex paper retains the typical asymmetric stress-strain behavior of its aramid fiber
components, with high tensile strength and comparably low compressive strength
[War01]. The mechanical material properties of Nomex T412 were provided on request
by its manufacturer DuPont. They are summarized in Table 3 for different paper thicknesses. The indices in Table 3 refer to the material directions of the Nomex paper as
described in Figure 4 on page 8. There are only few additional references for the mechanical properties of Nomex paper. One of which being the work of Roy et al. [Roy14],
who investigated Nomex T410. When comparing both sources some differences become
evident in particular when it comes to the material strength. This may be attributed to
the fact that different Nomex Types are compared. Regarding Poisson’s ratio, Roy et al.
determined η Nomex = 0.193, while DuPont did not provide any reference.
Table 3 Material properties of Nomex T412 in compliance with ASTM D828 [AST97] acc. to DuPont
Nomex
Type
Thick.
[µm]
Density
[g/cc]
E1
[MPa]
E2
[MPa]
s1
[N/mm]
s2
[N/mm]
d1
[%]
d2
[%]
2T412
47 - 65
0.54-0.94
3000
1700
3.63
1.23
6.1
3.5
3T412
71 - 91
0.67-0.91
3000
2000
6.01
2.33
6.7
5.1
4T412
94 - 117
0.72-0.94
3100
2200
6.13
1.70
8.0
5.3
Phenolic resin
Phenolic resin is a brittle synthetic polymer with low tensile strength if compared to its
compressive strength [Pil10]. The literature provides a limited number of references for
4 Mechanical characterization on constituent level
served as reference for the base materials. Therefore, the constituent material properties are derived in top-down manner using the results of macroscopic core tests. This is
done for the two core modelling approaches detailed meso-scale and homogenized 3Dcontinuum elements. In the following, the performed experimental and numerical studies are described.
4.1.1 Materials
In the framework of the present thesis, Nomex honeycomb cores with a cell size of
3.2 mm and a density of 48 kg/mm³ manufactured by EURO-COMPOSITES [EUR10] are
investigated. This core is typical for aircraft interior applications and complies with the
Airbus specification ABS 5035 [Air14]. In honeycomb manufacturing, Nomex of the Type
412 is usually applied. Due to the dipping process during fabrication (see 2.1.2), Nomex
honeycomb is a bonded composite material comprising two constituents, Nomex paper
and phenolic resin as coating. Both constituents are described in the following before
the analysis of the bonded honeycomb core is presented.
Nomex T412
Nomex paper retains the typical asymmetric stress-strain behavior of its aramid fiber
components, with high tensile strength and comparably low compressive strength
[War01]. The mechanical material properties of Nomex T412 were provided on request
by its manufacturer DuPont. They are summarized in Table 3 for different paper thicknesses. The indices in Table 3 refer to the material directions of the Nomex paper as
described in Figure 4 on page 8. There are only few additional references for the mechanical properties of Nomex paper. One of which being the work of Roy et al. [Roy14],
who investigated Nomex T410. When comparing both sources some differences become
evident in particular when it comes to the material strength. This may be attributed to
the fact that different Nomex Types are compared. Regarding Poisson’s ratio, Roy et al.
determined η Nomex = 0.193, while DuPont did not provide any reference.
Table 3 Material properties of Nomex T412 in compliance with ASTM D828 [AST97] acc. to DuPont
Nomex
Type
Thick.
[µm]
Density
[g/cc]
E1
[MPa]
E2
[MPa]
s1
[N/mm]
s2
[N/mm]
d1
[%]
d2
[%]
2T412
47 - 65
0.54-0.94
3000
1700
3.63
1.23
6.1
3.5
3T412
71 - 91
0.67-0.91
3000
2000
6.01
2.33
6.7
5.1
4T412
94 - 117
0.72-0.94
3100
2200
6.13
1.70
8.0
5.3
Phenolic resin
Phenolic resin is a brittle synthetic polymer with low tensile strength if compared to its
compressive strength [Pil10]. The literature provides a limited number of references for