The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varyi...The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varying degrees of degradation and damage to the main cable,necessitating regular inspections to prevent catastrophic failures.Traditional manual inspection methods not only suffer from low efficiency but also pose significant safety risks to personnel.To address these challenges and ensure the safe and effective inspection of suspension bridge main cables,this study introduces a novel cooperative climbing robot,designated as Main Cable Robot Version II(CCRobot-M-II),inspired by the locomotion of the inchworm.The robot employs an alternating opening and closing mechanism of four gripper sets,mimicking the inchworm's movement to achieve efficient crawling along the suspension bridge handrails.This paper provides a comprehensive analysis of the structural design,key components,and motion mechanisms of CCRobot-M-II.A detailed force analysis of the robot's crawling process is also presented,followed by the design of the control system and the development of an efficient motion control algorithm.Laboratory experiments demonstrate that the robot achieves a positional error of 00.64%during crawling,with a maximum average crawling speed of 7.6 m/min.Furthermore,the biomimetic design enables the robot to overcome obstacles up to 30 mm in height and possess the capability to handle suspension bridge cables with spans ranging from 740 to 1100 mm.Finally,CCRobot-M-II successfully conducted an inspection of the main cable on a suspension bridge,marking the world's first successful deployment of a climbing robot for main cable inspection on a suspension bridge.展开更多
The rapid growth of foreign investment in China will continue and may even accelerate after the country enters the World Trade Organization (WTO), analysts said. "More fields are opening to foreign investors and ...The rapid growth of foreign investment in China will continue and may even accelerate after the country enters the World Trade Organization (WTO), analysts said. "More fields are opening to foreign investors and market regulations are becoming more transparent, which encourages foreign companies to increase their presence in China," said Sun Xiaohua, a senior researcher at the Chinese Academy of International Trade and展开更多
一、请根据录音,填写单词。二、听对话,选择正确的答案。1.Where did Lucy go for her summer vacation?A.She stayed in the city.B.She went to the science museum.C.She went to Beijing.2.What did Tom think about climbing the G...一、请根据录音,填写单词。二、听对话,选择正确的答案。1.Where did Lucy go for her summer vacation?A.She stayed in the city.B.She went to the science museum.C.She went to Beijing.2.What did Tom think about climbing the Great Wall?展开更多
Dear Xu Yan,How is everything going these days?I am writing to invite you to an outing I will organize on Sunday,May 10th.We will start at 6:30 in the morning at the school gate and then go to Yongfeng Mountain by bus...Dear Xu Yan,How is everything going these days?I am writing to invite you to an outing I will organize on Sunday,May 10th.We will start at 6:30 in the morning at the school gate and then go to Yongfeng Mountain by bus.We will climb the mountain there in the morning and then have a picnic at 12 o’clock at noon.If you can come,you don’t need to bring food but it’s best for you to wear sports shoes and suitable clothes.展开更多
My hometown is Linqu.It is a small county in Weifang.It is very beautiful and peaceful,and I love it very much.There is a famous place called Shimenfang.In autumn,the mountains turn red.The leaves look like red flower...My hometown is Linqu.It is a small county in Weifang.It is very beautiful and peaceful,and I love it very much.There is a famous place called Shimenfang.In autumn,the mountains turn red.The leaves look like red flowers on the hills.Many people come here to climb the mountains and take photos of the beautiful views.展开更多
Reticular structures are the basis of major infrastructure projects,including bridges,electrical pylons and airports.However,inspecting and maintaining these structures is both expensive and hazardous,traditionally re...Reticular structures are the basis of major infrastructure projects,including bridges,electrical pylons and airports.However,inspecting and maintaining these structures is both expensive and hazardous,traditionally requiring human involvement.While some research has been conducted in this field of study,most efforts focus on faults identification through images or the design of robotic platforms,often neglecting the autonomous navigation of robots through the structure.This study addresses this limitation by proposing methods to detect navigable surfaces in truss structures,thereby enhancing the autonomous capabilities of climbing robots to navigate through these environments.The paper proposes multiple approaches for the binary segmentation between navigable surfaces and background from 3D point clouds captured from metallic trusses.Approaches can be classified into two paradigms:analytical algorithms and deep learning methods.Within the analytical approach,an ad hoc algorithm is developed for segmenting the structures,leveraging different techniques to evaluate the eigendecomposition of planar patches within the point cloud.In parallel,widely used and advanced deep learning models,including PointNet,PointNet++,MinkUNet34C,and PointTransformerV3,are trained and evaluated for the same task.A comparative analysis of these paradigms reveals some key insights.The analytical algorithm demonstrates easier parameter adjustment and comparable performance to that of the deep learning models,despite the latter’s higher computational demands.Nevertheless,the deep learning models stand out in segmentation accuracy,with PointTransformerV3 achieving impressive results,such as a Mean Intersection Over Union(mIoU)of approximately 97%.This study highlights the potential of analytical and deep learning approaches to improve the autonomous navigation of climbing robots in complex truss structures.The findings underscore the trade-offs between computational efficiency and segmentation performance,offering valuable insights for future research and practical applications in autonomous infrastructure maintenance and inspection.展开更多
Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to s...Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.展开更多
To achieve high-precision trajectory following during helicopter maneuver tasks and reduce the disruptive influences of unknown variabilities,this study introduces a cascaded-loop helicopter trajectory tracking contro...To achieve high-precision trajectory following during helicopter maneuver tasks and reduce the disruptive influences of unknown variabilities,this study introduces a cascaded-loop helicopter trajectory tracking controller,whose parameters are set using an Ant Colony OptimizationSlime Mould Algorithm(ACO-SMA).Initially,a nonlinear flight dynamics model of the helicopter is constructed.Observer gain functions and nonlinear feedback from a vibrational suppression function to improve the tracking performance of the controller,addressing issues in disturbance estimation and compensation of the Active Disturbance Rejection Control(ADRC).Simultaneously,a cascaded loop system,comprising an internal attitude loop and an external position loop,is created,and the ant colony-slime mold hybrid algorithm optimizes the system parameters of the trajectory tracking controller.Finally,helicopter trajectory tracking simulation experiments are conducted,including spiral ascending and“8”shape climbing maneuvers.The findings indicate that the ADRC employed for helicopter trajectory tracking exhibits outstanding performance in rejecting disturbances caused by gusts and accurately tracking trajectories.The trajectory tracking controller,whose parameters are optimized by the ACO-SMA,shows higher tracking precision compared to the conventional PID and ADRC,thereby substantially improving the precision of maneuver tasks.展开更多
This paper presents a novel 6-degree-of-freedom(DOF)inchworm-like robot inspired by bionics,designed to perform pipe inspection tasks with high flexibility in complex,unstructured environments.To determine the optimal...This paper presents a novel 6-degree-of-freedom(DOF)inchworm-like robot inspired by bionics,designed to perform pipe inspection tasks with high flexibility in complex,unstructured environments.To determine the optimal dimensions of each link,a Nash bargaining solution-based multi-objective optimization framework is developed,evaluating performance indicators such as reachable workspace,global manipulability,and acceleration capability.Inspired by the inchworm locomotion,three distinct climbing gaits are designed to enhance adaptability in confined and irregular spaces.To ensure safe and reliable operation,transition analysis is conducted and the operational workspace is systematically calculated.Moreover,a novel global path planning algorithm specially designed for the inchworm-like robot,termed inchworm-like robot rapidly-exploring random tree(ICHRRT*),is proposed.As an improved algorithm of RRT*,this method integrates gait planning and transition analysis to generate feasible and collision-free paths tailored to the robot’s unique structure and motion characteristics.A physical prototype is developed,and trusscrossing experiments are conducted in a truss environment.Experimental results validate the robot’s superior climbing capability and its effectiveness in navigating obstacles.展开更多
On April 30,the 22nd China Xiza ng Mountai neering Conventi on in 2025 comme need.As its flagship eve nt,the Luodui Peak Mountaineering Expedition took place from May 2 to 3 in Yangbajain Town of Lhasa,attracting more...On April 30,the 22nd China Xiza ng Mountai neering Conventi on in 2025 comme need.As its flagship eve nt,the Luodui Peak Mountaineering Expedition took place from May 2 to 3 in Yangbajain Town of Lhasa,attracting more than 160 mountain climbing enthusiasts from all over the country.展开更多
Slope climbing of urban expansion(SCE),as a form of urbanization,has increasingly significant impacts on urban development.Unsustainable slope climbing of urban expansion can harm the natural environment,thereby affec...Slope climbing of urban expansion(SCE),as a form of urbanization,has increasingly significant impacts on urban development.Unsustainable slope climbing of urban expansion can harm the natural environment,thereby affecting human production and living conditions.Using a coupled coordination model and the geographically weighted regression(GTWR)model,leveraging night light remote sensing data and ecological environment quality index model,this study investigated the coupling relationship between urban expansion and ecological environment quality and its influencing factors in the Yangtze River Economic Belt of China from 2000 to 2020.The results indicate that from 2000 to 2020,the intensity of urban slope climbing in the Yangtze River Economic Belt showed a fluctuating upward trend,with the slope climbing intensity being most significant in Chongqing Municipality and Kunming of Yunnan Province.Overall,the ecological environment quality exhibited an upward trend,with over 80%of the study area maintaining stable or improved ecological quality.There is a certain spatial correspondence between ecological environment quality and urban slope climbing.Although these two aspects of development demonstrate a high degree of coordination,fluctuations still occur during the development process.Further research on the coupling coordination relationship between the two revealed that population density has a negative impact on coupling coordination in the eastern region,and technology expenditure in eastern coastal cities has shown a negative trend over time.To ensure the continued increase in the proportion of highly coordinated areas in the future,eastern coastal cities in the study region could prioritize ecological civilization construction,strengthen urban construction and development planning,adjust influencing factors,and ensure the coordinated development of urban growth with ecological environment quality.展开更多
To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of...To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.展开更多
In order to well understand the elementary mechanisms that govern the hot working process of a V？5Cr？5Ti alloy （mass fraction, %）, thermal activation parameters under compression were measured in a temperature ran...In order to well understand the elementary mechanisms that govern the hot working process of a V？5Cr？5Ti alloy （mass fraction, %）, thermal activation parameters under compression were measured in a temperature range of 1373？1673 K by a Gleeble？3800 system. The results show that the stress exponentn is 4.87 and the activation energyQis 375.89 kJ/mol for the power law equation. The activation energy is determined as 288.34 kJ/mol, which is close to the self-diffusion energy of alloy （270？300 kJ/mol） by introducing a threshold stress（σ0） variable. The typical values of physical activation volume （Vp） and strain rate sensitivity （m） are measured as （120？700）b3 and 0.075？0.122, respectively, by the repeated stress relaxation tests. These activation parameters indicate that the rate controlling mechanism for V？5Cr？5Ti alloy compressed in ranges of 1373？1673 K and 0.001？1.0 s？1 is the dislocation climb by overcoming of forest dislocations.展开更多
基金Shenzhen Science and Technology Program(Grant No.20220817171811004)(Grant No.RCBS20231211090816033)+4 种基金the Major Key Project of PCL,China under Grant PCL2025A13Longgang District,Shenzhen's"Ten-Action Plan"for Supporting Innovation Projects(Grant No.LGKCSDPT2024002,LGKCSDPT2024003,LGKCSDPT2024004)the"Zhiguo"Action of Guangxi Science and Technology Program(Grant No.ZG2503980003)Guangdong S&T Program under(Grant No.2025B0909040003)Guangdong Provincial Leading Talent Program(Grant No.2024TX08Z319).
文摘The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varying degrees of degradation and damage to the main cable,necessitating regular inspections to prevent catastrophic failures.Traditional manual inspection methods not only suffer from low efficiency but also pose significant safety risks to personnel.To address these challenges and ensure the safe and effective inspection of suspension bridge main cables,this study introduces a novel cooperative climbing robot,designated as Main Cable Robot Version II(CCRobot-M-II),inspired by the locomotion of the inchworm.The robot employs an alternating opening and closing mechanism of four gripper sets,mimicking the inchworm's movement to achieve efficient crawling along the suspension bridge handrails.This paper provides a comprehensive analysis of the structural design,key components,and motion mechanisms of CCRobot-M-II.A detailed force analysis of the robot's crawling process is also presented,followed by the design of the control system and the development of an efficient motion control algorithm.Laboratory experiments demonstrate that the robot achieves a positional error of 00.64%during crawling,with a maximum average crawling speed of 7.6 m/min.Furthermore,the biomimetic design enables the robot to overcome obstacles up to 30 mm in height and possess the capability to handle suspension bridge cables with spans ranging from 740 to 1100 mm.Finally,CCRobot-M-II successfully conducted an inspection of the main cable on a suspension bridge,marking the world's first successful deployment of a climbing robot for main cable inspection on a suspension bridge.
文摘The rapid growth of foreign investment in China will continue and may even accelerate after the country enters the World Trade Organization (WTO), analysts said. "More fields are opening to foreign investors and market regulations are becoming more transparent, which encourages foreign companies to increase their presence in China," said Sun Xiaohua, a senior researcher at the Chinese Academy of International Trade and
文摘一、请根据录音,填写单词。二、听对话,选择正确的答案。1.Where did Lucy go for her summer vacation?A.She stayed in the city.B.She went to the science museum.C.She went to Beijing.2.What did Tom think about climbing the Great Wall?
文摘Dear Xu Yan,How is everything going these days?I am writing to invite you to an outing I will organize on Sunday,May 10th.We will start at 6:30 in the morning at the school gate and then go to Yongfeng Mountain by bus.We will climb the mountain there in the morning and then have a picnic at 12 o’clock at noon.If you can come,you don’t need to bring food but it’s best for you to wear sports shoes and suitable clothes.
文摘My hometown is Linqu.It is a small county in Weifang.It is very beautiful and peaceful,and I love it very much.There is a famous place called Shimenfang.In autumn,the mountains turn red.The leaves look like red flowers on the hills.Many people come here to climb the mountains and take photos of the beautiful views.
基金funded by the spanish Ministry of Science,Innovation and Universities as part of the project PID2020-116418RB-I00 funded by MCIN/AEI/10.13039/501100011033.
文摘Reticular structures are the basis of major infrastructure projects,including bridges,electrical pylons and airports.However,inspecting and maintaining these structures is both expensive and hazardous,traditionally requiring human involvement.While some research has been conducted in this field of study,most efforts focus on faults identification through images or the design of robotic platforms,often neglecting the autonomous navigation of robots through the structure.This study addresses this limitation by proposing methods to detect navigable surfaces in truss structures,thereby enhancing the autonomous capabilities of climbing robots to navigate through these environments.The paper proposes multiple approaches for the binary segmentation between navigable surfaces and background from 3D point clouds captured from metallic trusses.Approaches can be classified into two paradigms:analytical algorithms and deep learning methods.Within the analytical approach,an ad hoc algorithm is developed for segmenting the structures,leveraging different techniques to evaluate the eigendecomposition of planar patches within the point cloud.In parallel,widely used and advanced deep learning models,including PointNet,PointNet++,MinkUNet34C,and PointTransformerV3,are trained and evaluated for the same task.A comparative analysis of these paradigms reveals some key insights.The analytical algorithm demonstrates easier parameter adjustment and comparable performance to that of the deep learning models,despite the latter’s higher computational demands.Nevertheless,the deep learning models stand out in segmentation accuracy,with PointTransformerV3 achieving impressive results,such as a Mean Intersection Over Union(mIoU)of approximately 97%.This study highlights the potential of analytical and deep learning approaches to improve the autonomous navigation of climbing robots in complex truss structures.The findings underscore the trade-offs between computational efficiency and segmentation performance,offering valuable insights for future research and practical applications in autonomous infrastructure maintenance and inspection.
基金supported by the National Key Research&Development Program of China(Grant No.2020YFB1313504)the State Key Laboratory of Mechanics and Control for Aerospace Structures of Nanjing University of Aeronautics and Astronautics.
文摘Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.
基金support of the National Natural Science Foundation of China(No.12032012)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China。
文摘To achieve high-precision trajectory following during helicopter maneuver tasks and reduce the disruptive influences of unknown variabilities,this study introduces a cascaded-loop helicopter trajectory tracking controller,whose parameters are set using an Ant Colony OptimizationSlime Mould Algorithm(ACO-SMA).Initially,a nonlinear flight dynamics model of the helicopter is constructed.Observer gain functions and nonlinear feedback from a vibrational suppression function to improve the tracking performance of the controller,addressing issues in disturbance estimation and compensation of the Active Disturbance Rejection Control(ADRC).Simultaneously,a cascaded loop system,comprising an internal attitude loop and an external position loop,is created,and the ant colony-slime mold hybrid algorithm optimizes the system parameters of the trajectory tracking controller.Finally,helicopter trajectory tracking simulation experiments are conducted,including spiral ascending and“8”shape climbing maneuvers.The findings indicate that the ADRC employed for helicopter trajectory tracking exhibits outstanding performance in rejecting disturbances caused by gusts and accurately tracking trajectories.The trajectory tracking controller,whose parameters are optimized by the ACO-SMA,shows higher tracking precision compared to the conventional PID and ADRC,thereby substantially improving the precision of maneuver tasks.
基金Supported by National Natural Science Foundation of China(Grant No.62303095)Fundamental Research Funds for the Central Universities(Grant No.2682025CX080).
文摘This paper presents a novel 6-degree-of-freedom(DOF)inchworm-like robot inspired by bionics,designed to perform pipe inspection tasks with high flexibility in complex,unstructured environments.To determine the optimal dimensions of each link,a Nash bargaining solution-based multi-objective optimization framework is developed,evaluating performance indicators such as reachable workspace,global manipulability,and acceleration capability.Inspired by the inchworm locomotion,three distinct climbing gaits are designed to enhance adaptability in confined and irregular spaces.To ensure safe and reliable operation,transition analysis is conducted and the operational workspace is systematically calculated.Moreover,a novel global path planning algorithm specially designed for the inchworm-like robot,termed inchworm-like robot rapidly-exploring random tree(ICHRRT*),is proposed.As an improved algorithm of RRT*,this method integrates gait planning and transition analysis to generate feasible and collision-free paths tailored to the robot’s unique structure and motion characteristics.A physical prototype is developed,and trusscrossing experiments are conducted in a truss environment.Experimental results validate the robot’s superior climbing capability and its effectiveness in navigating obstacles.
文摘On April 30,the 22nd China Xiza ng Mountai neering Conventi on in 2025 comme need.As its flagship eve nt,the Luodui Peak Mountaineering Expedition took place from May 2 to 3 in Yangbajain Town of Lhasa,attracting more than 160 mountain climbing enthusiasts from all over the country.
基金Under the auspices of National Natural Science Foundation of China(No.42371191)Science and Technology Planning of NIGLAS(No.NIGLAS2022GS06,2022NIGLAS-CJH04)。
文摘Slope climbing of urban expansion(SCE),as a form of urbanization,has increasingly significant impacts on urban development.Unsustainable slope climbing of urban expansion can harm the natural environment,thereby affecting human production and living conditions.Using a coupled coordination model and the geographically weighted regression(GTWR)model,leveraging night light remote sensing data and ecological environment quality index model,this study investigated the coupling relationship between urban expansion and ecological environment quality and its influencing factors in the Yangtze River Economic Belt of China from 2000 to 2020.The results indicate that from 2000 to 2020,the intensity of urban slope climbing in the Yangtze River Economic Belt showed a fluctuating upward trend,with the slope climbing intensity being most significant in Chongqing Municipality and Kunming of Yunnan Province.Overall,the ecological environment quality exhibited an upward trend,with over 80%of the study area maintaining stable or improved ecological quality.There is a certain spatial correspondence between ecological environment quality and urban slope climbing.Although these two aspects of development demonstrate a high degree of coordination,fluctuations still occur during the development process.Further research on the coupling coordination relationship between the two revealed that population density has a negative impact on coupling coordination in the eastern region,and technology expenditure in eastern coastal cities has shown a negative trend over time.To ensure the continued increase in the proportion of highly coordinated areas in the future,eastern coastal cities in the study region could prioritize ecological civilization construction,strengthen urban construction and development planning,adjust influencing factors,and ensure the coordinated development of urban growth with ecological environment quality.
基金The National High Technology Research and Development Program of China (863Program) (No.2006AA04Z234)
文摘To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.
基金Project(11105127)supported by the National Natural Science Foundation of China
文摘In order to well understand the elementary mechanisms that govern the hot working process of a V？5Cr？5Ti alloy （mass fraction, %）, thermal activation parameters under compression were measured in a temperature range of 1373？1673 K by a Gleeble？3800 system. The results show that the stress exponentn is 4.87 and the activation energyQis 375.89 kJ/mol for the power law equation. The activation energy is determined as 288.34 kJ/mol, which is close to the self-diffusion energy of alloy （270？300 kJ/mol） by introducing a threshold stress（σ0） variable. The typical values of physical activation volume （Vp） and strain rate sensitivity （m） are measured as （120？700）b3 and 0.075？0.122, respectively, by the repeated stress relaxation tests. These activation parameters indicate that the rate controlling mechanism for V？5Cr？5Ti alloy compressed in ranges of 1373？1673 K and 0.001？1.0 s？1 is the dislocation climb by overcoming of forest dislocations.
