Enhanced mechanical energy absorption via localized viscoplasticity of nano-cellular polymer coating under supersonic impact loading
Enhanced mechanical energy absorption via localized viscoplasticity of nano-cellular polymer coating under supersonic impact loading
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DOI：
10.1016/j.giant.2023.100180
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发表时间：
2023-07
期刊：
影响因子：
7
通讯作者：
Zongling Ren;Robert Green-Warren;Noah McAllister;Ara Kim;Asaad Shaikh;A. Pelegri;J. Singer;
中科院分区：
文献类型：
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作者：
Zongling Ren;Robert Green-Warren;Noah McAllister;Ara Kim;Asaad Shaikh;A. Pelegri;J. Singer;
材料在1000应变率（> 106 s −1）下的粘塑性变形通常会表现出由于热和应力局部化而导致的异常性质。作为一个模型系统，热塑性纳米蜂窝材料（NCM）涂层是通过巩固微观聚苯乙烯壳的纳米级薄壁使用自限制电喷雾沉积。由于空间和时间表征尺度是至关重要的，NCM的特征在于激光诱导弹丸冲击试验（LIPIT），以了解其超高应变率塑性起源于其多孔结构。在LIPIT中，刚性微球的超音速碰撞在微观尺度上创造了这些极端的物理条件。无泊松效应的粘塑性垂直致密化是NCM涂层超高速塑性变形的首要过程。当粘塑性变形的极端性质通过增加孔隙率和减小NCM涂层的厚度来促进时，由于绝热塑性变形和热软化之间的局部反馈，在没有更多材料的情况下观察到显著更多的能量耗散。尽管NCM的随机和各向同性的结构架构，NCM的比能量吸收高达170 kJ/kg，在400 m/s的变形速度，这是由于纳米效应从NCM涂层的薄壁厚度。研究结果表明，一般的设计规则，提高比能量吸收的冲击载荷下创建粘塑性热点。
Materials under viscoplastic deformation at ultrahigh strain rates (>106s−1) often demonstrate anomalous properties due to thermal and stress localization. As a model system, thermoplastic nano-cellular material (NCM) coatings are produced by consolidating microscopic polystyrene shells of nanoscale thin walls using self-limiting electrospray deposition. As both the spatial and temporal characterization scales are crucial, the NCMs are characterized by laser-induced projectile impact test (LIPIT) for understanding their ultrahigh-strain-rate plasticity originating from their porous structures. In LIPIT, supersonic collisions of rigid microspheres create these extreme physical conditions at the microscale. Viscoplastic vertical densification without the Poisson effect is the foremost process in the ultrahigh-rate plastic deformation of the NCM coatings. When the extreme nature of the viscoplastic deformation is promoted by increasing the porosity and reducing the thickness of NCM coatings, significantly more energy dissipation is observed without more material due to the localized feedback between adiabatic plastic deformation and thermal softening. Despite the stochastic and isotropic structural architecture of the NCM, the specific energy absorption of the NCM is high as 170 kJ/kg at the deformation speed of 400 m/s, which is attributed to the nanoscale effects from the thin wall thickness of NCM coatings. The findings suggest the general design rule for enhancing specific energy absorption by creating viscoplastic hot spots under impact loading.