为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数...为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数值模型,并通过鸟撞试验验证计算模型的准确性。最后,以试验修正后的机翼前缘数值模型为依托,研究分析鸟体俯仰和偏航12种撞击姿态下机翼前缘的损伤变形情况和冲击响应规律。结果表明,仿真分析和试验结果通过一致性验证;蒙皮凹坑和凹陷范围随鸟体姿态角增大而增大,鸟体剩余能量随之降低;俯仰角增大,前缘结构吸收的能量更多,蒙皮高应力区增大,结构更易破坏。因此对于鸟撞威胁影响更大的重要飞机结构的抗鸟撞安全评估应计入鸟体姿态的影响。研究结果可在飞机抗鸟撞设计与适航评估方面提供重要参考。展开更多
This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethy...This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethylene(Al/PTFE).A challenge in current modeling efforts is accurately capturing the complex physical and chemical coupling under extreme loading,especially the influence of rapidly forming gaseous products in Al/PTFE mixtures on material integrity.To address this,a wide-range numerical model based on the Smoothed Particle Hydrodynamics(SPH)method was developed.This mesh-free approach manages large deformations and incorporates elastic-plastic flow,heat transfer,component diffusion,and chemical kinetics simulated using both zero-and first-order reaction schemes,favoring the latter for surface-reaction mechanisms.The proposed model takes into account gaseous reaction products,specifically aluminum fluoride(AlF3)to assess their impact on ampoule fracture dynamics.Numerical simulations,validated against experimental data,demonstrated that reaction rate,local pressure,and temperature are the primary controlling factors governing energy release and structural response.Comparative analysis revealed that although Al/CuO initiates reaction more readily(lower critical pressure/temperature),the Al/S mixture exhibits superior overall reaction efficiency under shock-wave loading,highlighting the significance of post-initiation kinetic factors.Furthermore,simulations using the conical ampoule geometry confirmed its effectiveness in generating a continuous pressure gradient,enabling systematic characterization of pressure-dependent reaction kinetics.This validated SPH model provides a powerful and predictive tool for understanding the complex behavior of energetic materials under shock-wave loading and aids in optimizing material composition for desired performance characteristics.展开更多
文摘泥石流作为高破坏性混合流体,其携带的块石对框架结构的冲击机制尚未得到充分研究。为揭示含块石泥石流冲击框架结构的动力响应与损伤机制,基于光滑粒子流体动力学-离散元法-有限元法(smoothed particle hydrodynamics-discrete element method-finite element method,SPH-DEM-FEM)耦合数值方法,构建流体-块石-结构的多耦合数值模型,模拟不同冲击速度和角度下框架结构的损伤过程,并结合两相溃坝试验来验证模型有效性。研究表明:泥石流冲击导致结构损伤经历“接触-扩散-反弹-堆积/冲击”四个阶段,当冲击速度超过6.00 m/s时,结构产生不可恢复损伤,且块石阻隔作用使流体上部冲击力大于下部,引发结构中部最先发生集中损伤;此外,冲击力峰值随速度和角度增大呈非线性增长,10.00 m/s与90°工况下框架柱底冲击力达497.17 kN,超过结构抗冲击承载力;最后,数值模拟与经验公式所得冲击力结果误差在13.95%~29.00%,数量级一致,验证了模型可靠性。研究结果可为泥石流高发区框架结构的抗冲击设计提供参考。
文摘为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数值模型,并通过鸟撞试验验证计算模型的准确性。最后,以试验修正后的机翼前缘数值模型为依托,研究分析鸟体俯仰和偏航12种撞击姿态下机翼前缘的损伤变形情况和冲击响应规律。结果表明,仿真分析和试验结果通过一致性验证;蒙皮凹坑和凹陷范围随鸟体姿态角增大而增大,鸟体剩余能量随之降低;俯仰角增大,前缘结构吸收的能量更多,蒙皮高应力区增大,结构更易破坏。因此对于鸟撞威胁影响更大的重要飞机结构的抗鸟撞安全评估应计入鸟体姿态的影响。研究结果可在飞机抗鸟撞设计与适航评估方面提供重要参考。
基金conducted under the public contract for the Tomsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences(Project No.FWRF-2024-0009).
文摘This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethylene(Al/PTFE).A challenge in current modeling efforts is accurately capturing the complex physical and chemical coupling under extreme loading,especially the influence of rapidly forming gaseous products in Al/PTFE mixtures on material integrity.To address this,a wide-range numerical model based on the Smoothed Particle Hydrodynamics(SPH)method was developed.This mesh-free approach manages large deformations and incorporates elastic-plastic flow,heat transfer,component diffusion,and chemical kinetics simulated using both zero-and first-order reaction schemes,favoring the latter for surface-reaction mechanisms.The proposed model takes into account gaseous reaction products,specifically aluminum fluoride(AlF3)to assess their impact on ampoule fracture dynamics.Numerical simulations,validated against experimental data,demonstrated that reaction rate,local pressure,and temperature are the primary controlling factors governing energy release and structural response.Comparative analysis revealed that although Al/CuO initiates reaction more readily(lower critical pressure/temperature),the Al/S mixture exhibits superior overall reaction efficiency under shock-wave loading,highlighting the significance of post-initiation kinetic factors.Furthermore,simulations using the conical ampoule geometry confirmed its effectiveness in generating a continuous pressure gradient,enabling systematic characterization of pressure-dependent reaction kinetics.This validated SPH model provides a powerful and predictive tool for understanding the complex behavior of energetic materials under shock-wave loading and aids in optimizing material composition for desired performance characteristics.
