Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this stud...Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.展开更多
Reliable foot-to-ground contact state detection is crucial for the locomotion control of quadruped robots in unstructured environments.To improve the reliability and accuracy of contact detection for quadruped robots,...Reliable foot-to-ground contact state detection is crucial for the locomotion control of quadruped robots in unstructured environments.To improve the reliability and accuracy of contact detection for quadruped robots,a detection approach based on the probabilistic contact model with multi-information fusion is presented to detect the actual contact states of robotic feet with the ground.Moreover,a relevant control strategy to address unexpected early and delayed contacts is planned.The approach combines the internal state information of the robot with the measurements from external sensors mounted on the legs and feet of the prototype.The overall contact states are obtained by the classification of the model-based predicted probabilities.The control strategy for unexpected foot-to-ground contacts can correct the control actions of each leg of the robot to traverse cluttered environments by changing the contact state.The probabilistic model parameters are determined by testing on the single-leg experimental platform.The experiments are conducted on the experimental prototype,and results validate the contact detection and control strategy for unexpected contacts in unstructured terrains during walking and trotting.Compared with the body orientation under the time-based control method regardless of terrain,the root mean square errors of roll,pitch,and yaw respectively decreased by 60.07%,54.73%,and 64.50%during walking and 73.40%,61.49%,and 61.48%during trotting.展开更多
Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterial...Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterials due to the lack of efficient contact-friction models.This paper introduces an original contact-friction model that leverages twin mesh and potential function principles within PD to model rock cracking under tensile and compressive stresses.The contact detection algorithm,based on space segmentation axis-aligned bounding box(AABB)tree data structure,is used to address the significant challenge of highly efficient contact detection in compression and shear problems.In this method,the twin mesh and potential function are utilized to quantify contact detection and contact degree,as well as friction behavior.This is in contrast to the distance and circular contact area model,which lacks physical significance in the classical PD method.As demonstrated by the tests on specimens containing cracks,the proposed model can capture 8 types of secondary fractures,reduce the contact detection error by about 29%e56%,and increase the contact retrieval efficiency by over 1600 times compared to the classic PD models.This significantly enhances the capability of PD to simulate the initiation,expansion,and coalescence of intricate compression-shear cracks.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation st...Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.展开更多
This paper describes a virtual environment, which can present dynamic force transformation during the control of objects. A 5-DOF haptic interface with the capability to generate kinesthetic effect is combined. In thi...This paper describes a virtual environment, which can present dynamic force transformation during the control of objects. A 5-DOF haptic interface with the capability to generate kinesthetic effect is combined. In this system, the operator manipulates an object in a virtual environment by using the 5-DOF master arm. When contacting with the virtual object, the contact force can be calculated and shown in the graphic interface. The contact response and deformation of the virtual object, which are usually called haptic rendering, also can be performed. The study supplies an approach to improve the operator’s immersion and can be used in many tele-robot control fields.展开更多
As fundamental components of consumer electronics,medical devices,and aerospace precision instruments,cir-cuit modules require fault detection analysis to ensure operational stability and safety,which remains a critic...As fundamental components of consumer electronics,medical devices,and aerospace precision instruments,cir-cuit modules require fault detection analysis to ensure operational stability and safety,which remains a critical challenge.Conventional contact-based electrical signal detection methods for printed circuit board(PCB)fault analysis often induce contact damage and suffer from slow detection and analysis speeds due to massive redundant data transmission and processing.Here,we propose a diamond-neural-network quantum magnetic sensor that enables non-contact circuit fault analysis by detecting far-field weak magnetic signals from PCBs.The sensor comprises a diamond array where each diamond functions as a nitrogen-vacancy(NV)center quantum magnetic sensor with tunable responsivity regulated by positive and negative voltage follower units.This diamond array inherently constitutes an artificial neural network(ANN),capable of simultaneous magnetic signal detection and real-time processing with ultra-low latency.Through training the sensor for fault classification,we achieve a response time superior to 137.1 ns.展开更多
Discontinuous deformation analysis （DDA） provides a powerful numerical tool for the analysis of discontinuous media. This method has been widely applied to the 2D analysis of discontinuous deformation. However, it i...Discontinuous deformation analysis （DDA） provides a powerful numerical tool for the analysis of discontinuous media. This method has been widely applied to the 2D analysis of discontinuous deformation. However, it is hindered from analyzing 3D rock engineering problems mainly due to the lack of reliable 3D contact detection algorithms for polyhedra. Contact detection is a key in 3-D DDA analysis. The limitations and advantages of existing contact detection schemes are discussed in this paper, and a new approach, called the incision body （IB）, is proposed, taking into account the advantages of the existing methods. A computer code 3DIB, which uses the IB scheme as a 3D contact detection algorithm, was programmed with Visual C^＋＋. Static and dynamic stability analysis for three realistic engineering problems has been carried out. Furthermore, the focus is on studying the stability of a gravity dam on jointed rock foundation and dynamic stability of a fractured gravity dam subject to earthquake shaking. The simulation results show that the program 3DIB and incision body scheme are capable of detecting 3D block contacts correctly and hence simulating the open-close and slide process of jointed block masses. In addition, the code 3DIB could provide an effective tool for evaluating the safety of 3D dam structures, which is quite important for engineering problems.展开更多
The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor...The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor signals or damages devices,and detecting hundred-pascal-level contact forces under tens-of-megapascal hydrostatic pressures presents a critical challenge that hinders the advancement of underwater tactile sensing technology.Inspired by deep-sea sponges’hydrostatic skeletal supporting mechanisms,we developed a fully open-pore hydrophobic ionogel as the sensing layer to construct a biomimetic deep-sea tactile sensor.The contact force is converted into electrical signals for object classification and non-destructive manipulation of marine organisms.This innovative sensing layer features aquatic stability and a pore structure balancing internal-external hydrostatic pressure,reducing environmental disturbances.The sensor maintains stable contact force detection under 50 MPa hydrostatic pressure,and accurately classify objects of varying hardness with an overall recognition accuracy of 95.5%,holding great potential for deep-sea exploration and sustainable resource exploitation.展开更多
基金financially supported by the National Key R&D Program of China(Grant No.2023YFC3081200)the National Natural Science Foundation of China(Grant Nos.U21A20159 and 52179117).
文摘Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.
基金supported by the National Natural Science Foundation of China(Grant Nos.52205059 and 52175050)the Graduate Innovation Special Fund Project of Jiangxi Province,China(Grant No.YC2021-B031).
文摘Reliable foot-to-ground contact state detection is crucial for the locomotion control of quadruped robots in unstructured environments.To improve the reliability and accuracy of contact detection for quadruped robots,a detection approach based on the probabilistic contact model with multi-information fusion is presented to detect the actual contact states of robotic feet with the ground.Moreover,a relevant control strategy to address unexpected early and delayed contacts is planned.The approach combines the internal state information of the robot with the measurements from external sensors mounted on the legs and feet of the prototype.The overall contact states are obtained by the classification of the model-based predicted probabilities.The control strategy for unexpected foot-to-ground contacts can correct the control actions of each leg of the robot to traverse cluttered environments by changing the contact state.The probabilistic model parameters are determined by testing on the single-leg experimental platform.The experiments are conducted on the experimental prototype,and results validate the contact detection and control strategy for unexpected contacts in unstructured terrains during walking and trotting.Compared with the body orientation under the time-based control method regardless of terrain,the root mean square errors of roll,pitch,and yaw respectively decreased by 60.07%,54.73%,and 64.50%during walking and 73.40%,61.49%,and 61.48%during trotting.
基金supported by the National Natural Science Foundation of China(Grant No.52278333)the China Scholarship Council(CSC)and the Science and Technology Department of Liaoning Province(Grant No.2024JH2/102500069).
文摘Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterials due to the lack of efficient contact-friction models.This paper introduces an original contact-friction model that leverages twin mesh and potential function principles within PD to model rock cracking under tensile and compressive stresses.The contact detection algorithm,based on space segmentation axis-aligned bounding box(AABB)tree data structure,is used to address the significant challenge of highly efficient contact detection in compression and shear problems.In this method,the twin mesh and potential function are utilized to quantify contact detection and contact degree,as well as friction behavior.This is in contrast to the distance and circular contact area model,which lacks physical significance in the classical PD method.As demonstrated by the tests on specimens containing cracks,the proposed model can capture 8 types of secondary fractures,reduce the contact detection error by about 29%e56%,and increase the contact retrieval efficiency by over 1600 times compared to the classic PD models.This significantly enhances the capability of PD to simulate the initiation,expansion,and coalescence of intricate compression-shear cracks.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
基金the National Basic Research Program of the Ministry of Science and Technology of China (Grant No. 2010CB731506)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAK10B01)the Youth Science Fund of National Natural Science Foundation of China (Grant No. 11302230)
文摘Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.
文摘This paper describes a virtual environment, which can present dynamic force transformation during the control of objects. A 5-DOF haptic interface with the capability to generate kinesthetic effect is combined. In this system, the operator manipulates an object in a virtual environment by using the 5-DOF master arm. When contacting with the virtual object, the contact force can be calculated and shown in the graphic interface. The contact response and deformation of the virtual object, which are usually called haptic rendering, also can be performed. The study supplies an approach to improve the operator’s immersion and can be used in many tele-robot control fields.
基金National Natural Science Foundation of China(62175219,52275576,U21A20141)Natural Science Foundation of Shanxi Province(202403021223007)Sanjin Talent Program of Shanxi Province.
文摘As fundamental components of consumer electronics,medical devices,and aerospace precision instruments,cir-cuit modules require fault detection analysis to ensure operational stability and safety,which remains a critical challenge.Conventional contact-based electrical signal detection methods for printed circuit board(PCB)fault analysis often induce contact damage and suffer from slow detection and analysis speeds due to massive redundant data transmission and processing.Here,we propose a diamond-neural-network quantum magnetic sensor that enables non-contact circuit fault analysis by detecting far-field weak magnetic signals from PCBs.The sensor comprises a diamond array where each diamond functions as a nitrogen-vacancy(NV)center quantum magnetic sensor with tunable responsivity regulated by positive and negative voltage follower units.This diamond array inherently constitutes an artificial neural network(ANN),capable of simultaneous magnetic signal detection and real-time processing with ultra-low latency.Through training the sensor for fault classification,we achieve a response time superior to 137.1 ns.
基金Key Program of National Natural Science Foundation of China Under Grant No.90510018 and Natural Science Foundation of Liaoning Province of China Under Grant No.20041077.
文摘Discontinuous deformation analysis （DDA） provides a powerful numerical tool for the analysis of discontinuous media. This method has been widely applied to the 2D analysis of discontinuous deformation. However, it is hindered from analyzing 3D rock engineering problems mainly due to the lack of reliable 3D contact detection algorithms for polyhedra. Contact detection is a key in 3-D DDA analysis. The limitations and advantages of existing contact detection schemes are discussed in this paper, and a new approach, called the incision body （IB）, is proposed, taking into account the advantages of the existing methods. A computer code 3DIB, which uses the IB scheme as a 3D contact detection algorithm, was programmed with Visual C^＋＋. Static and dynamic stability analysis for three realistic engineering problems has been carried out. Furthermore, the focus is on studying the stability of a gravity dam on jointed rock foundation and dynamic stability of a fractured gravity dam subject to earthquake shaking. The simulation results show that the program 3DIB and incision body scheme are capable of detecting 3D block contacts correctly and hence simulating the open-close and slide process of jointed block masses. In addition, the code 3DIB could provide an effective tool for evaluating the safety of 3D dam structures, which is quite important for engineering problems.
基金support from the National Key R&D Program of China(No.2024YFB4707300)the National Natural Science Foundation of China(No.52550004,52188102,52475018)+3 种基金the Fundamental Research Funds for the Central Universities(HUST:YCJJ20242101)the STAR Project by the School of Mechanical Science and Engineering of Huazhong University of Science and Technologysupport from Flexible Electronics Research Center and Analytical and Testing Center of HUST for providing experiment facilitysupport from the National University of Singapore Presidential Young Professorship.
文摘The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor signals or damages devices,and detecting hundred-pascal-level contact forces under tens-of-megapascal hydrostatic pressures presents a critical challenge that hinders the advancement of underwater tactile sensing technology.Inspired by deep-sea sponges’hydrostatic skeletal supporting mechanisms,we developed a fully open-pore hydrophobic ionogel as the sensing layer to construct a biomimetic deep-sea tactile sensor.The contact force is converted into electrical signals for object classification and non-destructive manipulation of marine organisms.This innovative sensing layer features aquatic stability and a pore structure balancing internal-external hydrostatic pressure,reducing environmental disturbances.The sensor maintains stable contact force detection under 50 MPa hydrostatic pressure,and accurately classify objects of varying hardness with an overall recognition accuracy of 95.5%,holding great potential for deep-sea exploration and sustainable resource exploitation.
