Microstructures of laminates produced by epoxy/carbon fibers with different fiber volume fraction were studied by analyzing the composite cross-sections.The main result of the compaction of reinforcement is the flatti...Microstructures of laminates produced by epoxy/carbon fibers with different fiber volume fraction were studied by analyzing the composite cross-sections.The main result of the compaction of reinforcement is the flatting of bundle shape,the reducing of gap and the embedment of bundles among each layer.The void content outside the bundle decreased sharply during the compaction until it is less than that inside the bundle when the fiber volume fraction is over 60%.The resin flow velocity in the fiber tow is 102-104 times greater than the flow velocity out the fiber tow no matter the capillary pressure is taken into account or not.展开更多
A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The...A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.展开更多
基金The Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,Science and Technology Commission of Shanghai Municipality,China(No.06QA14001)
文摘Microstructures of laminates produced by epoxy/carbon fibers with different fiber volume fraction were studied by analyzing the composite cross-sections.The main result of the compaction of reinforcement is the flatting of bundle shape,the reducing of gap and the embedment of bundles among each layer.The void content outside the bundle decreased sharply during the compaction until it is less than that inside the bundle when the fiber volume fraction is over 60%.The resin flow velocity in the fiber tow is 102-104 times greater than the flow velocity out the fiber tow no matter the capillary pressure is taken into account or not.
基金This research work was funded by the National Natural Science Foundation of China(Grant No.51975260)Jiangsu Provincial Key Research and Development Program(Grant No.BE2018372),Jiangsu Natural Science Foundation(Grant No.BK20181443)+1 种基金Zhenjiang City Key Research and Development Program(Grant No.NY2018001)Qing Lan Project of Jiangsu Province,the Priority Academic Program Development(PAPD)of the Jiangsu Higher Education Institutions,China.The authors would like to acknowledge the other colleagues of the team for providing assistance in the experiment.
文摘A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.
