For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and...For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and noise for car body panels is useful for engineering.Analysis and active control of booming noise in car is researched by using a new active damping vibration reduction technology named smart constrained layer damping(SCLD).According to the vibration characters of body roof,an optimal placement of actuators is distributed.Based on dSPACE hardware in loop environment,an adaptive active control system is designed.Selecting vibration signals of engine mounting point as the reference input of adaptive controller,an active control experiment of booming noise for mini-car is carried out.Experimental results show that,when the engine speed is at 3700 RPM and4250RPM,the interior booming noise decreases 4.2dB(A),and 3.5dB(A) separately.It proposes new methods and techniques for intelligent control of car body NVH in the future.展开更多
A comprehensive model that included mechanical dynamics of the shock absorber coupled with its thermal properties was proposed innovatively.Moreover a thermal-mechanical coupled model which reflected the closed-loop p...A comprehensive model that included mechanical dynamics of the shock absorber coupled with its thermal properties was proposed innovatively.Moreover a thermal-mechanical coupled model which reflected the closed-loop positive feedback system was established by using MATLAB/SIMULINK,and some curves of shock absorber temperature rising characteristic were obtained by simulation ＆computation under several operating modes and different parameters conditions.Research results show that：shock absorber design parameters,external excitations,and thermo-physical properties parameter,such as oil density have effect on the shock absorber temperature rising characteristic.However other thermo-physical properties parameters,such as oil specific heat,cylinder density,cylinder specific heat,and cylinder thermal conductivity,have no effect on it.The results may be used for studying reliability design of the shock absorber.展开更多
Lithium-ion batteries(LIBs)are widely employed in electric vehicles owing to their high power density,long cycle life,and environmental friendliness.However,LIBs are hazardous in the event of a crash,leading to therma...Lithium-ion batteries(LIBs)are widely employed in electric vehicles owing to their high power density,long cycle life,and environmental friendliness.However,LIBs are hazardous in the event of a crash,leading to thermal runaway.In this study,the basic structure of a battery module is analyzed to improve the crashworthiness of LIBs.A simplified finite element model of the battery module structure,which is a battery unit composed of two pouch cells and a cooling fin,is set up and verified by conducting module-level simulations.The simulation results reveal that the cooling fin in the battery module has the potential to absorb energy.Six sandwich configurations are introduced to modify the cooling fin.With a unidirection-ally stiffened double hull USDH structure serving as an example,a parametric analysis is conducted,demonstrating that the sandwich height does not influence the areal density;a small height of 3 mm can make the material work sufficiently while avoiding early buckling of the structure.Further,the crashworthiness of different sandwich configurations with the same areal density and height is compared,leading to three deformation modes.USDH and circular core structures are found to be able to effectively reduce the peak force and improve the energy absorption ability.展开更多
Car-to-pedestrian collision(CPC)accidents occur frequently,and pedestrians often suffer serious head/brain injuries.One major cause is the primary impact with the windshield.Here,we use an umerical sim ulation method ...Car-to-pedestrian collision(CPC)accidents occur frequently,and pedestrians often suffer serious head/brain injuries.One major cause is the primary impact with the windshield.Here,we use an umerical sim ulation method to study the influence of the windshield in-clination angle of a passenger car on pedestrian head/brain injury due to CPC accidents.The range of the windshield inclination angle was set at 24°-50°,with an interval of 2°.The results show that the windshield angle significantly affects the pedestrian kine-matics and exerts different effects on the head injury when evaluating with various head injury criteria.Regarding the head peak linear/rotational acceleration and acceleration-based head injury criterion(HIC)/rotational injury criterion(RIC),the predictions at the secondary impact stage have no clear relationship with the windshield angle(R^(2)=0.04,0.07,0.03 and 0.26,respectively)and their distributions are scattered.In the primary impact,the peak linear acceleration and HIC show a weak trend of first decreasing and then increasing with the increasing of the windshield angle,and the rotational acceleration and RIC tend to remain relatively con-stant.Regarding the cum ulative strain dama ge measure(CSDM)criterion,the predictions at the primary impact are slightly lower than those at the secondary impact,and the trend of first decreasing and then increasing with the increase in the windshield angle is observed at both impact stages.When the windshield inclination angle is approximately 32°-40°,the head injury severity in both impact phases is generally lower than that predicted at other windshield angles.展开更多
The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parame...The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.展开更多
Efficient detection of performance limits is critical to autonomous driving.As autonomous driving is difficult to be realized under complicated scenarios,an improved genetic algorithm-based evolution test is proposed ...Efficient detection of performance limits is critical to autonomous driving.As autonomous driving is difficult to be realized under complicated scenarios,an improved genetic algorithm-based evolution test is proposed to accelerate the evaluation of performance limits.It conducts crossover operation at all positions and mutation several times to make the high-quality chromosome exist in candidate offspring easily.Then the normal offspring is selected statistically based on the scenario com-plexity,which is designed to measure the difficulty of realizing autonomous driving through the Analytic Hierarchy Process.The benefits of modified cross/mutation operators on the improvement of scenario complexity are analyzed theoretically.Finally,the effectiveness of improved genetic algorithm-based evolution test is validated after being applied to evaluate the collision avoidance performance of an automatic parallel parking system.展开更多
The existing beamforming with aliasing elimination in the spherical harmonics domain usually adopts a single design goal,making it challenging to adapt to diverse application scenarios.Therefore,we propose optimal bea...The existing beamforming with aliasing elimination in the spherical harmonics domain usually adopts a single design goal,making it challenging to adapt to diverse application scenarios.Therefore,we propose optimal beamforming with aliasing cancellation in the spherical harmonics domain and establish a corresponding multiply constrained convex optimization model with a second-order cone programming form.Benefiting from this model,we further propose a maximum directivity beamformer with sidelobe constraint and aliasing cancellation,a robust maximum directivity beamformer with aliasing cancellation,a minimum variance distortionless response beamformer with aliasing elimination,and a maximum directivity beamformer with null constraint and aliasing elimination.The proposed method not only inherits the aliasing-cancellation capability of the existing aliasing cancellation beamforming,but also achieves a proper trade-off among multiple conflicting performance measures such as directivity factor,white noise gain,and sidelobe level.Hence,the proposed optimal beamforming provides users with the flexibility to adjust the constraint parameters according to actual application requirements and thus obtain a beamformer with the best all-around performance in a specific scenario.展开更多
基金Supported by the State Key Development Program for Basic Research of China(No.2010CB736104)the National High Technology Research and Development Program of China(No.2012AA111803)
文摘For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and noise for car body panels is useful for engineering.Analysis and active control of booming noise in car is researched by using a new active damping vibration reduction technology named smart constrained layer damping(SCLD).According to the vibration characters of body roof,an optimal placement of actuators is distributed.Based on dSPACE hardware in loop environment,an adaptive active control system is designed.Selecting vibration signals of engine mounting point as the reference input of adaptive controller,an active control experiment of booming noise for mini-car is carried out.Experimental results show that,when the engine speed is at 3700 RPM and4250RPM,the interior booming noise decreases 4.2dB(A),and 3.5dB(A) separately.It proposes new methods and techniques for intelligent control of car body NVH in the future.
基金Supported by Central Universities Fundamental Research Projects Foundation(11QG22)State Key Laboratory of Automobile Noise Vibration and Safety Projects Foundation(NVHSKL-201105)
文摘A comprehensive model that included mechanical dynamics of the shock absorber coupled with its thermal properties was proposed innovatively.Moreover a thermal-mechanical coupled model which reflected the closed-loop positive feedback system was established by using MATLAB/SIMULINK,and some curves of shock absorber temperature rising characteristic were obtained by simulation ＆computation under several operating modes and different parameters conditions.Research results show that：shock absorber design parameters,external excitations,and thermo-physical properties parameter,such as oil density have effect on the shock absorber temperature rising characteristic.However other thermo-physical properties parameters,such as oil specific heat,cylinder density,cylinder specific heat,and cylinder thermal conductivity,have no effect on it.The results may be used for studying reliability design of the shock absorber.
基金This study is supported by the National Natural Science Foundation of China(Grant Nos.51675294 and U1564205)the International Science and Technology Cooperation Program of China(Grant No.2016YFE0102200)the State Key Laboratory of Vehicle NVH and Safety Technology(Contract No.NVHSKL-201907).
文摘Lithium-ion batteries(LIBs)are widely employed in electric vehicles owing to their high power density,long cycle life,and environmental friendliness.However,LIBs are hazardous in the event of a crash,leading to thermal runaway.In this study,the basic structure of a battery module is analyzed to improve the crashworthiness of LIBs.A simplified finite element model of the battery module structure,which is a battery unit composed of two pouch cells and a cooling fin,is set up and verified by conducting module-level simulations.The simulation results reveal that the cooling fin in the battery module has the potential to absorb energy.Six sandwich configurations are introduced to modify the cooling fin.With a unidirection-ally stiffened double hull USDH structure serving as an example,a parametric analysis is conducted,demonstrating that the sandwich height does not influence the areal density;a small height of 3 mm can make the material work sufficiently while avoiding early buckling of the structure.Further,the crashworthiness of different sandwich configurations with the same areal density and height is compared,leading to three deformation modes.USDH and circular core structures are found to be able to effectively reduce the peak force and improve the energy absorption ability.
基金supported by the National Natural Science Funds for Distinguished Young Sc holar(Gr ant No.52325211)National Natural Science Foundation of China(Grants No.52172399 and 52372348)+1 种基金Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Pro vince,Natural Science Foundation of Changsha(Grant No.KQ2208235)Chongqing Ph.D.‘Through Train’Scientific Research Project(Grant No.s1202100000528).
文摘Car-to-pedestrian collision(CPC)accidents occur frequently,and pedestrians often suffer serious head/brain injuries.One major cause is the primary impact with the windshield.Here,we use an umerical sim ulation method to study the influence of the windshield in-clination angle of a passenger car on pedestrian head/brain injury due to CPC accidents.The range of the windshield inclination angle was set at 24°-50°,with an interval of 2°.The results show that the windshield angle significantly affects the pedestrian kine-matics and exerts different effects on the head injury when evaluating with various head injury criteria.Regarding the head peak linear/rotational acceleration and acceleration-based head injury criterion(HIC)/rotational injury criterion(RIC),the predictions at the secondary impact stage have no clear relationship with the windshield angle(R^(2)=0.04,0.07,0.03 and 0.26,respectively)and their distributions are scattered.In the primary impact,the peak linear acceleration and HIC show a weak trend of first decreasing and then increasing with the increasing of the windshield angle,and the rotational acceleration and RIC tend to remain relatively con-stant.Regarding the cum ulative strain dama ge measure(CSDM)criterion,the predictions at the primary impact are slightly lower than those at the secondary impact,and the trend of first decreasing and then increasing with the increase in the windshield angle is observed at both impact stages.When the windshield inclination angle is approximately 32°-40°,the head injury severity in both impact phases is generally lower than that predicted at other windshield angles.
基金This work was financially supported by the State Key Laboratory of Vehicle NVH and Safety Technology(NVHSKL-202104)the innovation research group of universities in Chongqing(CXQT21030,CXQT19031).
文摘The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.
基金This work is supported by the Open Fund of State Key Laboratory of Vehicle NVH and Safety Technology under Grant NVHSKL-202009the Technological Plans of Chongqing under grant cstc2019jcyj-zdxm0022.
文摘Efficient detection of performance limits is critical to autonomous driving.As autonomous driving is difficult to be realized under complicated scenarios,an improved genetic algorithm-based evolution test is proposed to accelerate the evaluation of performance limits.It conducts crossover operation at all positions and mutation several times to make the high-quality chromosome exist in candidate offspring easily.Then the normal offspring is selected statistically based on the scenario com-plexity,which is designed to measure the difficulty of realizing autonomous driving through the Analytic Hierarchy Process.The benefits of modified cross/mutation operators on the improvement of scenario complexity are analyzed theoretically.Finally,the effectiveness of improved genetic algorithm-based evolution test is validated after being applied to evaluate the collision avoidance performance of an automatic parallel parking system.
基金supported by the Open Foundation of the State Key Laboratory of Noise,Vibration and Safety Technology of China(NVHSKL-202002)the National Natural Science Foundation of China(11704040)。
文摘The existing beamforming with aliasing elimination in the spherical harmonics domain usually adopts a single design goal,making it challenging to adapt to diverse application scenarios.Therefore,we propose optimal beamforming with aliasing cancellation in the spherical harmonics domain and establish a corresponding multiply constrained convex optimization model with a second-order cone programming form.Benefiting from this model,we further propose a maximum directivity beamformer with sidelobe constraint and aliasing cancellation,a robust maximum directivity beamformer with aliasing cancellation,a minimum variance distortionless response beamformer with aliasing elimination,and a maximum directivity beamformer with null constraint and aliasing elimination.The proposed method not only inherits the aliasing-cancellation capability of the existing aliasing cancellation beamforming,but also achieves a proper trade-off among multiple conflicting performance measures such as directivity factor,white noise gain,and sidelobe level.Hence,the proposed optimal beamforming provides users with the flexibility to adjust the constraint parameters according to actual application requirements and thus obtain a beamformer with the best all-around performance in a specific scenario.
