SLM钛合金蜂窝结构的面内压缩力学行为

doi:10.12382/bgxb.2022.0585

摘要/Abstract

摘要：

为探究增材制造金属蜂窝结构在防护领域的潜在应用，采用激光选区融化(SLM) 技术制备钛合金蜂窝试样，进行单轴面内压缩力学实验，在平台段出现了周期压溃卸载现象，这不同于传统的塑性/脆性材料蜂窝平台段特征；结合数字摄像机和扫描电子显微镜，分析结构变形模式与断口破坏机理；基于参数化有限元数值分析，研究壁厚对蜂窝结构压溃卸载的影响规律。研究结果表明：SLM技术制备的钛合金蜂窝试样打印精度高，力学性能差异小；钛合金蜂窝结构面内受压时，结构剪切带区域蜂窝边连接处断裂造成结构应力-应变曲线周期性压溃卸载；破坏处断口可观察到明显的韧窝，呈现明显的塑性破坏形貌；壁厚减薄可以有效增大破坏时蜂窝短边的旋转角度，降低最小弯曲半径，从而显著改善压溃卸载现象，提升结构承载稳定性。

关键词: 蜂窝, 钛合金, 激光选区融化, 面内压缩, 有限元模拟

Abstract:

In order to explore the potential application of additively manufactured metal honeycomb structures in the field of protection, titanium alloy honeycomb samples were prepared by selective laser melting (SLM), and uniaxial in-plane compressive mechanical experiments were carried out. Periodic crushing and unloading phenomena appeared in the platform section, which was different from the features of the platform section of traditional plastic/brittle materials honeycomb. Using the digital camera and scanning electron microscope, the structural deformation modes and fracture failure mechanism were analyzed. Based on the parametric finite element analysis, the influence of wall thickness on the crushing and unloading of honeycomb structures was studied. The results showed that: the titanium alloy honeycomb samples prepared by SLM had high printing accuracy and small difference in mechanical properties; when the titanium alloy honeycomb structure was compressed in the plane, the fracture of the honeycomb edge connection in the structural shear zone results in the periodic crushing and unloading in the stress-strain curve of the structure; obvious dimples could be observed on the fracture surface at the failure site, showing an obvious plastic failure morphology; the wall thickness thinning can effectively increase the rotation angle of the short side of the honeycomb during failure and reduce the minimum bending radius, thus significantly improving the crushing and unloading phenomena and enhancing the bearing stability of the structure.

Key words: honeycomb, titanium alloy, selective laser melting, in-plane compression, finite element modeling

乔扬, 赵至诚, 谢晶, 陈鹏万. SLM钛合金蜂窝结构的面内压缩力学行为[J]. 兵工学报, 2023, 44(3): 629-637.

QIAO Yang, ZHAO Zhicheng, XIE Jing, CHEN Pengwan. In-plane Compressive Mechanical Behavior of SLM Titanium Alloy Honeycomb Structure[J]. Acta Armamentarii, 2023, 44(3): 629-637.

图/表 14

图1 SLM技术原理

Fig. 1 Principle diagram of SLM technique

表1 元素质量分数

Table 1 Element mass fraction %

Al	V	C	Fe	O	N	H
5.5~6.75	3.5-4.5	0.08	0.3	0.2	0.05	0.015

表2 蜂窝试样尺寸

Table 2 Honeycomb specimen size

高/mm	宽/mm	厚/mm	横截面积/mm²
50±0.06	44.7±0.04	9.5±0.08	424.65±4

图2 蜂窝试样

Fig. 2 Honeycomb specimen

表3 钛合金材料模型参数[21]

Table 3 Titanium alloy material model parameters[21]

参数	数值	参数	数值
杨氏模量E/GPa	109.778	D₁	-0.09
泊松比μ	0.31	D₂	0.27
密度ρ/(kg·m^-3)	4 428	D₃	0.48
A/MPa	862	D₄	0.014
B/MPa	331	D₅	3.87
n	0.34	T_r/K	293
$\dot{\varepsilon}_0$/s^-1	1	T_m/K	1 189
C	0.012
m	0.8

图3 钛合金蜂窝SEM图像

Fig. 3 SEM image of the titanium alloy honeycomb

图4 SLM钛合金蜂窝准静态压缩实验与仿真对比

Fig. 4 Comparison of the quasi-static in-plane compression of SLM titanium alloy honeycomb in the experiment and simulation

图5 SLM钛合金蜂窝准静态压缩实验应力-应变曲线图

Fig. 5 Experimental stress-strain curves of quasi-static in-plane compression of SLM titanium alloy honeycomb

图6 长边单元微观表征

Fig. 6 Microstructural characterization of long edge elements

图7 短边单元微观表征

Fig. 7 Microstructural characterization of short edge elements

图8 蜂窝胞元变形过程示意图

Fig. 8 Schematic diagram of the honeycomb cell’s deformation process

图9 等效峰值力-应变曲线

Fig. 9 Equivalent peak force-strain curves

图10 不同壁厚的CLE对比

Fig. 10 CLE comparison under different wall thicknesses

图11 不同壁厚的吸能效率对比

Fig. 11 Comparison of energy absorption efficiencies under different wall thicknesses

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