There is an increasing awareness of the need to reduce traffic accidents and fatality due to vehicle collision.Post-impact hazards can be more serious as the driver may fail to maintain effective control after collisi...There is an increasing awareness of the need to reduce traffic accidents and fatality due to vehicle collision.Post-impact hazards can be more serious as the driver may fail to maintain effective control after collisions.To avoid subsequent crash events and to stabilize the vehicle,this paper proposes a post-impact motion planning and stability control method for autonomous vehicles.An enabling motion planning method is proposed for post-impact situations by combining the polynomial curve and artificial potential field while considering obstacle avoidance.A hierarchical controller that consists of an upper and a lower controller is then developed to track the planned motion.In the upper controller,a time-varying linear quadratic regulator is presented to calculate the desired generalized forces.In the lower controller,a nonlinear-optimization-based torque allocation algorithm is proposed to optimally coordinate the actuators to realize the desired generalized forces.The proposed scheme is verified under comprehensive driving scenarios through hardware-in-loop tests.展开更多
探究了不同碳纤维/玄武岩纤维(carbon fiber/basalt fiber,CF/BF)配比的混杂层合板在弹道冲击及冲击后压缩(compression after impact,CAI)性能方面的表现,结果表明,玄武岩纤维显著提升了混杂层合板的能量吸收能力。采用C扫描、电子显...探究了不同碳纤维/玄武岩纤维(carbon fiber/basalt fiber,CF/BF)配比的混杂层合板在弹道冲击及冲击后压缩(compression after impact,CAI)性能方面的表现,结果表明,玄武岩纤维显著提升了混杂层合板的能量吸收能力。采用C扫描、电子显微镜和扫描电镜分析了材料的损伤机制,揭示了材料性能提升的内在机理。另一方面,混杂层合板的初始压缩强度随玄武岩纤维含量的增加而下降。在混杂层合板的能量吸收能力增强与初始压缩强度下降的共同作用下,CAI测试中受损层合板的残余压缩强度呈局部波动趋势。研究结果可为轻量化、高抗冲击复合材料的结构设计提供指导。展开更多
This study investigates the low-velocity impact and post-impact flexural properties of 3D integrated woven spacer composites,focusing on their orthotropic behavior when tested along two principal directions,i.e.,warp(...This study investigates the low-velocity impact and post-impact flexural properties of 3D integrated woven spacer composites,focusing on their orthotropic behavior when tested along two principal directions,i.e.,warp(X-type)and weft(Y-type)directions.The same composite material was tested in these orientations to evaluate the differences in impact resistance and residual bending strength.Specimens were fabricated via vacuum-assisted molding and tested at 2,3,5,and 7 J impact energies using an Instron Ceast 9350 drop-weight impact testing machine,in accordance with ASTM D7136.Post-impact flexural tests were performed using a four-point bending method in accordance with ASTM D7264.The absorbed energy increased from 1.97 to 6.98 J,and the panel damage area ranged from 121 to 361 mm^(2) as impact energy roses.Specimens tested in the weft direction(Y-type)showed greater residual strength(up to 15.83 N)and displacement(up to 0.538 mm)than those tested in the warp direction(X-type).Ultrasonic C-scan imaging revealed localized matrix cracking and fiber failure damage patterns.Results emphasize the directional differences in impact resistance and residual bending properties,highlighting the importance of material orientation in structural applications.This study provides a foundation for utilizing 3D woven spacer composites in lightweight,damage-tolerant structural components.展开更多
基金Beijing Municipal Science and Technology Commission via the Beijing Nova Program(Grant No.Z201100006820007).
文摘There is an increasing awareness of the need to reduce traffic accidents and fatality due to vehicle collision.Post-impact hazards can be more serious as the driver may fail to maintain effective control after collisions.To avoid subsequent crash events and to stabilize the vehicle,this paper proposes a post-impact motion planning and stability control method for autonomous vehicles.An enabling motion planning method is proposed for post-impact situations by combining the polynomial curve and artificial potential field while considering obstacle avoidance.A hierarchical controller that consists of an upper and a lower controller is then developed to track the planned motion.In the upper controller,a time-varying linear quadratic regulator is presented to calculate the desired generalized forces.In the lower controller,a nonlinear-optimization-based torque allocation algorithm is proposed to optimally coordinate the actuators to realize the desired generalized forces.The proposed scheme is verified under comprehensive driving scenarios through hardware-in-loop tests.
文摘探究了不同碳纤维/玄武岩纤维(carbon fiber/basalt fiber,CF/BF)配比的混杂层合板在弹道冲击及冲击后压缩(compression after impact,CAI)性能方面的表现,结果表明,玄武岩纤维显著提升了混杂层合板的能量吸收能力。采用C扫描、电子显微镜和扫描电镜分析了材料的损伤机制,揭示了材料性能提升的内在机理。另一方面,混杂层合板的初始压缩强度随玄武岩纤维含量的增加而下降。在混杂层合板的能量吸收能力增强与初始压缩强度下降的共同作用下,CAI测试中受损层合板的残余压缩强度呈局部波动趋势。研究结果可为轻量化、高抗冲击复合材料的结构设计提供指导。
基金funded by Open Foundation of the State Key Laboratory of Advanced Inorganic Fibers and Composites(Grant No.KF2024SYS02)the Jiangsu Province Special Fund for Carbon Peaking and Carbon Neutrality Technology Innovation(Grant No.BE2022008)the Prioritized Academic Program Development for Higher Education Institutions in Jiangsu.
文摘This study investigates the low-velocity impact and post-impact flexural properties of 3D integrated woven spacer composites,focusing on their orthotropic behavior when tested along two principal directions,i.e.,warp(X-type)and weft(Y-type)directions.The same composite material was tested in these orientations to evaluate the differences in impact resistance and residual bending strength.Specimens were fabricated via vacuum-assisted molding and tested at 2,3,5,and 7 J impact energies using an Instron Ceast 9350 drop-weight impact testing machine,in accordance with ASTM D7136.Post-impact flexural tests were performed using a four-point bending method in accordance with ASTM D7264.The absorbed energy increased from 1.97 to 6.98 J,and the panel damage area ranged from 121 to 361 mm^(2) as impact energy roses.Specimens tested in the weft direction(Y-type)showed greater residual strength(up to 15.83 N)and displacement(up to 0.538 mm)than those tested in the warp direction(X-type).Ultrasonic C-scan imaging revealed localized matrix cracking and fiber failure damage patterns.Results emphasize the directional differences in impact resistance and residual bending properties,highlighting the importance of material orientation in structural applications.This study provides a foundation for utilizing 3D woven spacer composites in lightweight,damage-tolerant structural components.
