Article
Low-Velocity Impact Resistance of Al/Gf/PP Laminates with
Different Interface Performance
Yanyan Lin
1
, Huaguan Li
2,
*, Zhongwei Zhang
3
and Jie Tao
1,4,
*
Citation: Lin, Y.; Li, H.; Zhang, Z.;
Tao, J. Low-Velocity Impact Resistance
of Al/Gf/PP Laminates with Different
Interface Performance. Polymers 2021,
13, 4416. https://doi.org/10.3390/
polym13244416
Academic Editors: Alberto
Campagnolo and Alberto Sapora
Received: 19 November 2021
Accepted: 15 December 2021
Published: 16 December 2021
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4.0/).
1
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics,
Nanjing 211106, China; linyanyan@nuaa.edu.cn
2
Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of
Technology, Nanjing 211167, China
3
State Key Laboratory of Explosion & Impact and Disaster Prevention & Mitigation, Army Engineering
University of PLA, Nanjing 210007, China; zhangzhongwei.cn@gmail.com
4
Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites,
Nanjing 210016, China
* Correspondence: lihuaguan@njit.edu.cn (H.L.); taojie@nuaa.edu.cn (J.T.); Tel./Fax: +86-025-5211-2911 (J.T.)
Abstract:
The weak interface performance between metal and composite (IPMC) makes the composite
materials susceptible to impact load. Aluminum/glass fiber/polypropylene (Al/Gf/PP) laminates
were manufactured with the aluminum alloy sheets modified by nitrogen plasma surface treatment
and the phosphoric acid anodizing method, respectively. FEM models of Al/Gf/PP laminates under
low-velocity impact were established in ABAQUS/Explicit based on the generated data including
the model I and II interlaminar fracture toughness. Low-velocity impact tests were performed to
investigate the impact resistance of Al/Gf/PP laminates including load traces, failure mechanism,
and energy absorption. The results showed that delamination was the main failure mode of two
kinds of laminates under the impact energy of 20 J and 30 J. When the impact energy was between
40 J and 50 J, there were metal cracks on the rear surface of the plasma pretreated specimens, which
possessed higher energy absorption and impact resistance, although the integrity of the laminates
could not be preserved. Since the residual compressive stress was generated during the cooling
process, the laminates were more susceptible to stretching rather than delamination. For impact
energy (60 J) causing the through-the-thickness crack of two kinds of laminates, plasma pretreated
specimens exhibited higher SEA values close to 9 Jm
2
/kg due to better IPMC. Combined with the
FEM simulation results, the interface played a role in stress transmission and specimens with better
IPMC enabled the laminates to absorb more energy.
Keywords:
Al/Gf/PP laminates; low-velocity impact; interface performance; plasma surface treatment;
fracture toughness
1. Introduction
Fiber metal laminates (FMLs) have been designed to improve the fatigue life and
damage tolerance of the metal in aerospace applications [
1
–
3
]. Glass fiber reinforced alu-
minum laminates (GLARE) are one of the most representative and have been successfully
applied in A380 due to their contribution to reducing weight and saving costs [
4
,
5
]. The
consolidation of traditional thermoset-based FMLs requires a simultaneous combination of
high temperature, high pressure, and long process cycle time. Nevertheless, thermoplastic-
based (TP-based) FMLs have the advantage of better toughness, high production efficiency,
excellent recyclability, and thermal deformation [
6
,
7
]. With the continuous development
of the public transportation industry, TP-based FMLs have attracted attention from many
experts and scholars. A glass fiber reinforced thermoplastic layer alternatively laminated
with an aluminum alloy sheet has great application prospects, mainly in new energy ve-
hicles and rail transit industries. These high-performance composites with the benefit of
Polymers 2021, 13, 4416. https://doi.org/10.3390/polym13244416 https://www.mdpi.com/journal/polymers
