An Empirical Study on Ballistic Resistance of Sandwich Targets with Aluminum Facesheets and Composite Core

Figure 7
The curve for variations of residual velocity versus the initial velocity for sandwich structures with foam core density of 248 kg/m³ (blunt-head projectile and conical-nose projectile).

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Figure 8
Variations of residual velocity versus the initial velocity for AP63 and AP37 sandwich structures.

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Figure 9
Variation of absorbed energy versus initial velocity of the projectile for sandwich specimen P248B.

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Figure 10
Comparison of absorbed energy by sandwich structures with different core densities impacted by blunt-head projectile.

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Figure 11
variation of ballistic limit velocity versus foam density in sandwich specimens.

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Figure 12
Comparison of energy dissipation versus core density of sandwich structures at impact velocity of 234.3 m/s.

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Figure 13
The energy absorption versus the initial velocity for specimens with different percentages of aluminum pins

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Figure 14
The rear facesheets damage in specimen AP63C1 tested at initial velocity of 243 m/s.

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Figure 15
Damage at the rear facesheet for specimen with density of 248kg/m3 at different velocities.

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Figure 16
Images of damage to rear facesheet of sandwich specimens with foam core.

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Figure 17
Effect of initial velocity on the rear face-sheet damage at P248B7 sample.

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Figure 18
Compare damage and petals shape of the rear face-sheet of sandwich panels with 37% pin tested with blunt and conical nose projectiles at the same initial velocities

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Figure 19
Compare damage and petals shape of the rear face-sheet of sandwich panels with 63% pin tested with blunt and conical nose projectiles at the same initial velocities.

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Figure 20
The damage zone and petals in different density foam core sandwich specimens impacted by blunt and conical nose projectiles.

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Table 1
Material properties of the projectiles.

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Table 2
Material properties of the facesheets.

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Table 3
Material properties of the foams.

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Table 4
The codes assigned to each specimen with polyurethane core.

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Table 5
The codes assigned to each specimen with composite core.

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Table 6
Comparison of predictive relationship for behavior of sandwich structures versus the density of core foam.

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Table 7
Effect of projectile nose shape on the ballistic limit velocity.

Mechanical properties	Data
ρ (kg/m³)	7860
E (GPa)	210
ν	0.3

Material	Thickness, h_f (mm)	Density, ρ (kg/m³ )	Young's modulus, E (GPa)	Poisson's ratio, ν	Tensile strength, σ_y (MPa)	Fracture strain, ε_f
Al-5005H16	1.5	2700	70.04	0.3	145.5	0.009

Density, ρ (kg/m³ )	Young's modulus, E (MPa)	Poisson's ratio, ν	Plateau stress, σ_pl (MPa)	Densification strain, ε_D
248	102	0.33	5.75	0.57
359	154.2	0.33	7.96	0.53
600	370.6	0.33	17.72	0.36

Specimen name	Core density (kg/m³ )	Core thickness (mm)	Facesheet thickness (mm)
P248B, P248C	248	50	1.5
P359B, P359C	359	35	1.5
P600B, P600C	600	22	1.5

Specimen name	Core density (kg/m³ )	Mass of foam in core (gr)	Mass of aluminum pin in core (gr)
AP37B, AP37C	460	79	46
AP63B, AP63C	457	46	79

Data used	R-square			RSME
Data used	Present	[Hou et al., 2010Hou, W., F. Zhu, G. Lu and D.-N. Fang (2010). "Ballistic impact experiments of metallic sandwich panels with aluminium foam core." International journal of impact engineering 37(10): 1045-1055.]	[Ghalami & Sadighi, 2014Ghalami-Choobar, M. and M. Sadighi (2014). "Investigation of high velocity impact of cylindrical projectile on sandwich panels with fiber-metal laminates skins and polyurethane core." Aerospace Science and Technology 32(1): 142-152.]	Present	[Hou et al., 2010Hou, W., F. Zhu, G. Lu and D.-N. Fang (2010). "Ballistic impact experiments of metallic sandwich panels with aluminium foam core." International journal of impact engineering 37(10): 1045-1055.]	[Ghalami & Sadighi, 2014Ghalami-Choobar, M. and M. Sadighi (2014). "Investigation of high velocity impact of cylindrical projectile on sandwich panels with fiber-metal laminates skins and polyurethane core." Aerospace Science and Technology 32(1): 142-152.]
Linear law (ax + b)	0.9894	0.9436	0.9866	10.30	10.93	9.074
Power low (ax^b + c)	0.9954	0.9805	1.0000	0.108	0.3426	0.0013

Core density	Ballistic limit		Difference (%)
Core density	Conicalc-nose projectile	Blunt-head projectile	Difference (%)
248	172	182	5.5%
360	184	195	5.6%
600	216	220.2	1.9%

[1] *Corresponding author: kazemii.m@gmail.com

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An Empirical Study on Ballistic Resistance of Sandwich Targets with Aluminum Facesheets and Composite Core

Abstract