Lightweight structure is an important method to increase vehicle fuel efficiency. High strength steel is applied for replacing mild steel in automotive structures to decrease thickness of parts for lightweight. Howeve...Lightweight structure is an important method to increase vehicle fuel efficiency. High strength steel is applied for replacing mild steel in automotive structures to decrease thickness of parts for lightweight. However, the lightweight structures must show the improved capability for structural rigidity and crash energy absorption. Advanced high strength steels are attractive materials to achieve higher strength for energy absorption and reduce weight of vehicles. Currently, many research works focus on component level axial crash testing and simulation of high strength steels. However, the effects of high strength steel parts to the impact of auto body are not considered. The goal of this research is to study the application of hot forming high strength steel（HFHSS） in order to evaluate the potential using in vehicle design for lightweight and passive safety. The performance of HFHSS is investigated by using both experimental and analytical techniques. In particular, the focus is on HFHSS which may have potential to enhance the passive safety for lightweight auto body. Automotive components made of HFHSS and general high strength steel（GHSS） are considered in this study. The material characterization of HFHSS is carried out through material experiments. The finite element method, in conjunction with the validated model is used to simulate the side impact of a car with GHSS and HFHSS parts according to China New Car Assessment Programme（C-NCAP） crash test. The deformation and acceleration characteristics of car body are analyzed and the injuries of an occupant are calculated. The results from the simulation analyses of HFHSS are compared with those of GHSS. The comparison indicates that the HFHSS parts on car body enhance the passive safety for the lightweight car body in side impact. Parts of HFHSS reduce weight of vehicle through thinner thickness offering higher strength of parts. Passive safety of lightweight car body is improved through reduction of crash deformation on car body by the application of HFHSS parts. The experiments and simulation are conducted to the HFHSS parts on auto body. The results demonstrate the feasibility of the application of HFHSS materials on automotive components for improved capability of passive safety and lightweight.展开更多
Based on multi-body dynamics, the simulation models of auto-side structures and occupant＇s dynamic responses are set up, using the occupant injury simulation software MADYMO3D. These models include auto-body structur...Based on multi-body dynamics, the simulation models of auto-side structures and occupant＇s dynamic responses are set up, using the occupant injury simulation software MADYMO3D. These models include auto-body structure, impact barrier, seat and dummy. Definitions of multi-body and joints and dynamics properties of joints based on FE combination models, of model setup are introduced. Kelvin element of MADYMO is introduced to show the force action between non-adjoining rigid bodies, too. Then all examples of the methods mentioned are given. By the comparison of simulation and real test, the contract curves between simulation and real test for main structures and biology mechanics properties of dummy are obtained. The result shows the accuracy and validity of the models.展开更多
Neck injury is a severe problem in traffic accidents.While most studies are focused on the neck injury in rear and front impacts,few are conducted in side impact.This study focuses on the difference of neck injury und...Neck injury is a severe problem in traffic accidents.While most studies are focused on the neck injury in rear and front impacts,few are conducted in side impact.This study focuses on the difference of neck injury under different postures and the difference of 7 cervical vertebras under the same posture using the method of prescribed structure motion（PSM）.The analytical results show that the maximum changes of mean force and mean moment of 7 cervical vertebras under 8 different postures are 20% and 47% respectively.The variation of each cervical vertebra is different under different neck postures.Up cervical vertebras （C1-C4） and low cervical vertebras （C5-C7） suffer different forces and moments under the same neck posture.Generally speaking,No.6 （neck right leaning 40°） is the posture with lowest neck injury risk.展开更多
In the development of side-impact safety performance in automobiles,the injury conditions of far-side occupants have gradually been incorporated into the evaluation system of automotive safety in China.This study,base...In the development of side-impact safety performance in automobiles,the injury conditions of far-side occupants have gradually been incorporated into the evaluation system of automotive safety in China.This study,based on three side-impact conditions in the Chinese automotive safety assessment system,employs the finite element method to analyze the injury and motion characteristics of far-side occupants under various impact scenarios.The results indicate that in the C-NCAP 75°POLE condition,certain impact areas of the far-side dummy sustain more severe injuries.These findings provide data references for the development of safety performance measures aimed at protecting far-side occupants.展开更多
To clearly understand passenger car structure＇s crashworthiness in typical side impacts of pole and moving deformable barrier （MDB） impact modes, which could assist the establishment of Chinese vehicle side impact ...To clearly understand passenger car structure＇s crashworthiness in typical side impacts of pole and moving deformable barrier （MDB） impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the p01e side impact according to European New Car Assessment Program （EuroNCAP） and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger＇s head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.展开更多
Side impact accidents of passenger cars with fixed poles may result in severe injuries to the vehicle occupants. In this paper, side structure intrusion was considered as the criterion for passenger cars crashworthine...Side impact accidents of passenger cars with fixed poles may result in severe injuries to the vehicle occupants. In this paper, side structure intrusion was considered as the criterion for passenger cars crashworthiness during side impact with a pole. The relationship between side intrusions and the side structure stiffness was analyzed. The acceleration of the unstruck side vehicle body was selected as the criterion for studying the influence of different side structure components on the side structure stiffness during passenger car pole side impacts. The behavior was analyzed using finite element simulations. The results show that the rocker and the lower part of the B-pillar are the key parts of the side structures in determining the passenger car side stiffness. Passenger car pole side impact crashworthiness is, therefore, most sensitive to these two components.展开更多
A version of an electric vehicle was developed and designed for the US market on the basis of the required domestic body structure.When compared with the original car,the new car body design leads to two major technic...A version of an electric vehicle was developed and designed for the US market on the basis of the required domestic body structure.When compared with the original car,the new car body design leads to two major technical difficulties.First,the installation of high-voltage components such as the battery pack and other new energy sources increases the vehicle weight and occupies a great deal of its structural space;this limits the impact paths and the use of traditional structural designs,which greatly increases the design difficulty.Second,the USA,as an advanced automobile-using country,has well-developed laws and regulations for collision standards,vehicle operating conditions and evaluation standards.Using a combination of butterfly diagram analysis,bending moment management,section forces and other computer-aided simulation and analysis techniques,this paper presents a body structure design that can achieve a“GOOD”evaluation under the US Insurance Institute for Highway Safety(IIHS)side impact body structure conditions by optimizing the force transfer path,the B-pillar deformation mode and the threshold support structure.The threshold support structure supports realization of the“GOOD”rating for IIHS side impact and helps the body to meet the crash requirements of the Federal Motor Vehicle Safety Standard FMVSS214 and the US New Car Assessment Program(NCAP)requirements for side impact at 32 km/h and 75°angular pole impact.展开更多
The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio...The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio compared to traditional steel, using fiber-reinforcement composite materials in automobile bodies has emerged as the most effective strategy for improving fuel efficiency while maintaining safety standards. This research paper examined the utilization of fiber-reinforced composite materials in car bodies to meet the increasing consumer demand for fuel-efficient and eco-friendly vehicles. It particularly focused on a carbon-aramid fiber-reinforced composite impact beam for passenger car side door impact protection. Despite the encouraging prospects of the carbon-aramid fiber-reinforced beam, the research uncovered substantial defects in the fabrication process, resulting in diminished load-bearing capacity and energy absorption. As a result, the beam was un-successful in three-point bending tests. This was accomplished by using an I cross-section design with varying thickness because of the higher area moment of inertia. Vacuum-assisted resin transfer molding (VARTM) manufacturing process was used and the finished beam underwent to three-point bending tests.展开更多
Crash worthiness is the most significant variable during lightweight design of vehicle struc tures.However,crashworthiness studies using the single substructure-based method are limited due to the negligence of intera...Crash worthiness is the most significant variable during lightweight design of vehicle struc tures.However,crashworthiness studies using the single substructure-based method are limited due to the negligence of interactions among substructures.Thus,a whole structure-based study was conducted for the lightweight design of a body-side structure.In this study,a full finite element model was firstly created and then modified into a simplified model for structural improvements,where the major load-carrying subassemblies were improved from the perspectives of crashworthiness and manufacturing costs.Finally,sensitivity analyses were conducted to further optimize the strength distribution,based on which an adaptive response surface method was employed for thickness optimization of the structure.It is found that through the structural improvements and optimizations,the weight of the structure was significantly reduced even when its crashworthiness was improved.This indicates that the whole structure-based method is effective for lightweight design of vehicle structures.展开更多
基金supported by National Natural Science Foundation of China(Grant No.19832020)National Science Fund of Outstanding Youths of China (Grant No.10125208)+1 种基金Chongqing Municipal Programs for Science and Technology Development of China(Grant No.CSTC, 2007AA4008)National Key Technology R&D Program of China(Grant No.2006BA104B04-2)
文摘Lightweight structure is an important method to increase vehicle fuel efficiency. High strength steel is applied for replacing mild steel in automotive structures to decrease thickness of parts for lightweight. However, the lightweight structures must show the improved capability for structural rigidity and crash energy absorption. Advanced high strength steels are attractive materials to achieve higher strength for energy absorption and reduce weight of vehicles. Currently, many research works focus on component level axial crash testing and simulation of high strength steels. However, the effects of high strength steel parts to the impact of auto body are not considered. The goal of this research is to study the application of hot forming high strength steel（HFHSS） in order to evaluate the potential using in vehicle design for lightweight and passive safety. The performance of HFHSS is investigated by using both experimental and analytical techniques. In particular, the focus is on HFHSS which may have potential to enhance the passive safety for lightweight auto body. Automotive components made of HFHSS and general high strength steel（GHSS） are considered in this study. The material characterization of HFHSS is carried out through material experiments. The finite element method, in conjunction with the validated model is used to simulate the side impact of a car with GHSS and HFHSS parts according to China New Car Assessment Programme（C-NCAP） crash test. The deformation and acceleration characteristics of car body are analyzed and the injuries of an occupant are calculated. The results from the simulation analyses of HFHSS are compared with those of GHSS. The comparison indicates that the HFHSS parts on car body enhance the passive safety for the lightweight car body in side impact. Parts of HFHSS reduce weight of vehicle through thinner thickness offering higher strength of parts. Passive safety of lightweight car body is improved through reduction of crash deformation on car body by the application of HFHSS parts. The experiments and simulation are conducted to the HFHSS parts on auto body. The results demonstrate the feasibility of the application of HFHSS materials on automotive components for improved capability of passive safety and lightweight.
基金This project is supported by 985-Automotive Engineering of Jilin University,China, Provincial Science and Technology Development Program of Jilin,China(No.20050583) and Key Lab of Modern Auto-body Techniques of Ministry of Education of China.
文摘Based on multi-body dynamics, the simulation models of auto-side structures and occupant＇s dynamic responses are set up, using the occupant injury simulation software MADYMO3D. These models include auto-body structure, impact barrier, seat and dummy. Definitions of multi-body and joints and dynamics properties of joints based on FE combination models, of model setup are introduced. Kelvin element of MADYMO is introduced to show the force action between non-adjoining rigid bodies, too. Then all examples of the methods mentioned are given. By the comparison of simulation and real test, the contract curves between simulation and real test for main structures and biology mechanics properties of dummy are obtained. The result shows the accuracy and validity of the models.
基金Sponsored by the National High Technology Research and Development Program of China("863"Program) (2006AA110102)
文摘Neck injury is a severe problem in traffic accidents.While most studies are focused on the neck injury in rear and front impacts,few are conducted in side impact.This study focuses on the difference of neck injury under different postures and the difference of 7 cervical vertebras under the same posture using the method of prescribed structure motion（PSM）.The analytical results show that the maximum changes of mean force and mean moment of 7 cervical vertebras under 8 different postures are 20% and 47% respectively.The variation of each cervical vertebra is different under different neck postures.Up cervical vertebras （C1-C4） and low cervical vertebras （C5-C7） suffer different forces and moments under the same neck posture.Generally speaking,No.6 （neck right leaning 40°） is the posture with lowest neck injury risk.
文摘In the development of side-impact safety performance in automobiles,the injury conditions of far-side occupants have gradually been incorporated into the evaluation system of automotive safety in China.This study,based on three side-impact conditions in the Chinese automotive safety assessment system,employs the finite element method to analyze the injury and motion characteristics of far-side occupants under various impact scenarios.The results indicate that in the C-NCAP 75°POLE condition,certain impact areas of the far-side dummy sustain more severe injuries.These findings provide data references for the development of safety performance measures aimed at protecting far-side occupants.
文摘To clearly understand passenger car structure＇s crashworthiness in typical side impacts of pole and moving deformable barrier （MDB） impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the p01e side impact according to European New Car Assessment Program （EuroNCAP） and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger＇s head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.
文摘Side impact accidents of passenger cars with fixed poles may result in severe injuries to the vehicle occupants. In this paper, side structure intrusion was considered as the criterion for passenger cars crashworthiness during side impact with a pole. The relationship between side intrusions and the side structure stiffness was analyzed. The acceleration of the unstruck side vehicle body was selected as the criterion for studying the influence of different side structure components on the side structure stiffness during passenger car pole side impacts. The behavior was analyzed using finite element simulations. The results show that the rocker and the lower part of the B-pillar are the key parts of the side structures in determining the passenger car side stiffness. Passenger car pole side impact crashworthiness is, therefore, most sensitive to these two components.
文摘A version of an electric vehicle was developed and designed for the US market on the basis of the required domestic body structure.When compared with the original car,the new car body design leads to two major technical difficulties.First,the installation of high-voltage components such as the battery pack and other new energy sources increases the vehicle weight and occupies a great deal of its structural space;this limits the impact paths and the use of traditional structural designs,which greatly increases the design difficulty.Second,the USA,as an advanced automobile-using country,has well-developed laws and regulations for collision standards,vehicle operating conditions and evaluation standards.Using a combination of butterfly diagram analysis,bending moment management,section forces and other computer-aided simulation and analysis techniques,this paper presents a body structure design that can achieve a“GOOD”evaluation under the US Insurance Institute for Highway Safety(IIHS)side impact body structure conditions by optimizing the force transfer path,the B-pillar deformation mode and the threshold support structure.The threshold support structure supports realization of the“GOOD”rating for IIHS side impact and helps the body to meet the crash requirements of the Federal Motor Vehicle Safety Standard FMVSS214 and the US New Car Assessment Program(NCAP)requirements for side impact at 32 km/h and 75°angular pole impact.
文摘The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio compared to traditional steel, using fiber-reinforcement composite materials in automobile bodies has emerged as the most effective strategy for improving fuel efficiency while maintaining safety standards. This research paper examined the utilization of fiber-reinforced composite materials in car bodies to meet the increasing consumer demand for fuel-efficient and eco-friendly vehicles. It particularly focused on a carbon-aramid fiber-reinforced composite impact beam for passenger car side door impact protection. Despite the encouraging prospects of the carbon-aramid fiber-reinforced beam, the research uncovered substantial defects in the fabrication process, resulting in diminished load-bearing capacity and energy absorption. As a result, the beam was un-successful in three-point bending tests. This was accomplished by using an I cross-section design with varying thickness because of the higher area moment of inertia. Vacuum-assisted resin transfer molding (VARTM) manufacturing process was used and the finished beam underwent to three-point bending tests.
基金the National Natural Science Foundation of China(Nos.51775227 and 51375201)the National New Energy Vehicle Pilot Project(2016YFB0101601)the Jilin Scientific and Technological Development Program(No.20170101130JC)
文摘Crash worthiness is the most significant variable during lightweight design of vehicle struc tures.However,crashworthiness studies using the single substructure-based method are limited due to the negligence of interactions among substructures.Thus,a whole structure-based study was conducted for the lightweight design of a body-side structure.In this study,a full finite element model was firstly created and then modified into a simplified model for structural improvements,where the major load-carrying subassemblies were improved from the perspectives of crashworthiness and manufacturing costs.Finally,sensitivity analyses were conducted to further optimize the strength distribution,based on which an adaptive response surface method was employed for thickness optimization of the structure.It is found that through the structural improvements and optimizations,the weight of the structure was significantly reduced even when its crashworthiness was improved.This indicates that the whole structure-based method is effective for lightweight design of vehicle structures.
