Energy absorption characteristics of axial series energy absorption tubes
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摘要: 针对工程技术领域的碰撞载荷削峰减载问题,采用数值模拟与试验相结合的方法研究了轴向串联式吸能管的吸能特性:首先基于材料高速拉伸试验,构建吸能管的材料Johnson-Cook动态本构参数,并对拟合参数有效性进行评估;随后通过数值模拟与高速冲击试验研究高速撞击过程中吸能管的缓冲吸能特性,评估仿真与试验的一致性;最终通过数值模拟对吸能管轴向串联构型与单管构型之间的吸能评价指标开展对比分析。分析研究表明:数值模拟与冲击试验的变形模式、载荷曲线、吸能评价指标均吻合较好,材料性能参数准确,仿真预示方法有效,高速冲击试验方案合理可信;与相同结构参数的串联构型吸能管相比,单管构型吸能管在压缩过程中会出现非轴对称、不稳定的扭曲变形,单管构型的有效压缩行程减小了13%,峰值载荷提高了33.4%,撞击瞬间载荷提高了15%,平均压缩力提高了13%,载荷峰均比提高了17.7%;吸能管的串联构型是更为理想的缓冲吸能结构。Abstract: To address the issue of peak load reduction for impact loads in engineering technology, the energy absorption characteristics of axial series energy absorbing tubes was investigated through a combination of numerical simulation and experimentation. Firstly, the Johnson-Cook dynamic constitutive parameters of the material 06Cr18Ni11Ti GB/T1220-2007 of energy absorbing tubes were established and evaluated based on high-speed tensile tests which indicates 06Cr18Ni11Ti has obvious strain rate hardening effect. Subsequently, numerical simulation and high-speed impact tests were conducted to examine the energy absorption characteristics of energy absorption tubes, with an evaluation of consistency between numerical simulation and test results. The numerical simulation was based on the time-step ABAQUS/Explicit finite element simulation platform. The high speed impact test system used the high pressure gas inside the air actuated piston cylinder as the power source, which could accelerate the mass block to a speed of 30 m/s. Finally, the energy absorption evaluation indexes between the axial series configuration and the single configuration of the energy absorption tube were compared and analyzed by numerical simulation. The analysis demonstrates that deformation mode, load curve, and energy absorption evaluation indexes from both numerical simulations and impact tests exhibit good agreement. The accuracy of material performance parameters confirms the effectiveness of simulation prediction methods while validating reasonability and reliability of high-speed impact test schemes. Compared to axial series configurations with identical structural parameters, single-tube configurations display asymmetric and unstable twist deformations during compression processes. Single-tube configurations experience a 13% reduction in effective compression stroke along with a 33.4% increase in peak load, 15% increase in instantaneous impact load, 13% increase in average compression force, as well as a 17.7% increase in peak-to-average load ratio. Consequently, axial series configurations prove to be more ideal energy absorbing structures.
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表 1 06Cr18Ni11Ti材料本构常数
Table 1. Material parameters of 06Cr18Ni11Ti
E/GPa ν ρ/(kg·m−3) A/MPa B/MPa n $ {\dot{\varepsilon }}_{0} $/s−1 C m 210 0.28 7800 297.7 1250 0.726 0.005 0.0231454 1 表 2 吸能评价指标
Table 2. Energy absorption evaluation indexes
指标 符号 定义 吸能效率 f $ f=\dfrac{1}{{F}_{\mathrm{m}\mathrm{a}\mathrm{x}}}{\displaystyle \int }_{0}^{S}F\left(s\right)\mathrm{d}s $ 有效压缩行程 Seff 吸能效率 f 最大值对应的压缩位移 有效行程比 Res $ {R}_{\text{es}}=S_{\rm{ eff}}/L $ 总吸能 Et $ {E}_{t}={\displaystyle \int }_{0}^{{S}_{\text{ eff}}}F\left(s\right)\mathrm{d}s $ 结构平均压缩力 Fm $ {F}_{\mathrm{m}}={E}_{\mathrm{t}}/{S}_{\text{ef}\text{f}} $ 比吸能 esa $ {e}_{\mathrm{s}\mathrm{a}}={E}_{\mathrm{t}}/M $ 载荷峰均比 Rpa $ {R}_{\text{pa}}={F}_{\text{peak}}/{F}_{\mathrm{m}} $ 注:S为压缩位移, F为压缩载荷, Fmax为[0, S]区间中最大的压缩载荷,L为吸能元件的原长,Fpeak为[0, Sef]区间中最大的压缩载荷。 表 3 吸能管仿真吸能评价指标
Table 3. Simulated performance indicators of the energy absorption tube
Seff Fpeak Res Et Fm esa Rpa 119.4 mm 40440 N59.7% 2788 J23350 N47.5 J/g 1.732 表 4 吸能管吸能评价指标
Table 4. Performance indicators of energy absorption tube
数据
来源Seff/mm Fpeak/N Res/% Et/J Fm/N esa/(J·g−1) Rpa 仿真 119.4 40440 59.70 2788 23350 47.5 1.732 试验 115.5 36599 57.75 2610 22597 44.5 1.575 表 5 吸能管吸能评价指标对比
Table 5. Comparision of performance indicators of energy absorption tube
参数 Seff/mm Fpeak/N Res/% Et/J Fm/N esa/(J·g−1) Rpa 轴向串联构型 119.4 40440 59.7 2788 23350 47.5 1.732 单管构型 103.6 53881 51.8 2739 26438 46.6 2.038 -
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