Abstract. In this paper, a new synthesis method of 2R3T (R denotes rotation and T denotes translation) overconstrained and non-overconstrained parallel mechanisms (PMs) with three branched chains based on the displacement sub-manifold method is presented. Firstly, the displacement sub-manifolds of mechanisms were determined based on 2R3T motions. Subsequently, the displacement sub-manifolds of the branched chains were derived using the displacement sub-manifold theory, and their corresponding motion diagrams were provided. Additionally, a comprehensive analysis of non-overconstrained 2R3T PMs with a single-constraint branched chain was conducted, and the type synthesis of overconstrained 2R3T PMs with two or three identical constraints was also performed, accompanied by the presentation of partial mechanism diagrams. Finally, the number of DOF (degrees of freedom) of the mechanism was calculated using the modified Kutzbach–Grübler equation for a new PMs,and the screw theory was used to verify the kinematic characteristics, proving this new method's correctness.
{"title":"Type synthesis of non-overconstrained and overconstrained two rotation and three translation (2R3T) parallel mechanisms with three branched chains","authors":"Yu Rong, X. Zhang, Tianci Dou, Hongbo Wang","doi":"10.5194/ms-14-567-2023","DOIUrl":"https://doi.org/10.5194/ms-14-567-2023","url":null,"abstract":"Abstract. In this paper, a new synthesis method of 2R3T (R denotes rotation and T denotes translation) overconstrained and non-overconstrained parallel mechanisms (PMs) with three branched chains based on the displacement sub-manifold method is presented. Firstly, the displacement sub-manifolds of mechanisms were determined based on 2R3T motions. Subsequently, the displacement sub-manifolds of the branched chains were derived using the displacement sub-manifold theory, and their corresponding motion diagrams were provided. Additionally, a comprehensive analysis of non-overconstrained 2R3T PMs with a single-constraint branched chain was conducted, and the type synthesis of overconstrained 2R3T PMs with two or three identical constraints was also performed, accompanied by the presentation of partial mechanism diagrams. Finally, the number of DOF (degrees of freedom) of the mechanism was calculated using the modified Kutzbach–Grübler equation for a new PMs,and the screw theory was used to verify the kinematic characteristics, proving this new method's correctness.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"101 3","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139170901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In the machining of monolithic components, machining distortion is a severe issue. The presence of initial residual stress is a major contributor to machining distortion. This paper proposes an approach to control the machining distortion of long beam parts by optimizing the workpiece structure before the start of the finishing stage, i.e. the transition structure. The first step is to establish a machining distortion analytical model for long beam parts with an identical cross-section, which is based on reasonable assumptions such as material linear elasticity and ignoring the influence of cutting heat. Then, an optimization model for the cross-section of the transition structure is developed, with the objective function defined as the minimum difference between the predicted distortion of the final part and the transition structure. Finally, a U-shaped beam is designed, followed by numerical simulation and machining experiments for verification. The theoretical maximum distortion of the optimized transition structure and the final part are −0.174 and −0.1782 mm, respectively, with a relative error of 2.9 %. The results of machining experiments and finite-element simulation demonstrate the effectiveness of the proposed model.
摘要在整体部件的加工过程中，加工变形是一个严重的问题。初始残余应力的存在是造成加工变形的主要原因。本文提出了一种通过优化精加工阶段开始前的工件结构（即过渡结构）来控制长梁零件加工变形的方法。第一步是建立横截面相同的长梁零件的加工变形分析模型，该模型基于合理的假设，如材料线弹性和忽略切削热的影响。然后，建立过渡结构横截面的优化模型，目标函数定义为最终零件与过渡结构预测变形之间的最小差值。最后，设计了一个 U 形梁，并进行了数值模拟和加工实验验证。优化后的过渡结构和最终零件的理论最大变形分别为-0.174 毫米和-0.1782 毫米，相对误差为 2.9%。加工实验和有限元模拟的结果证明了所提模型的有效性。
{"title":"Machining distortion control of long beam parts based on optimal design of transition structure","authors":"Long-Xin Fan, Ning Han, Yi Zhang","doi":"10.5194/ms-14-557-2023","DOIUrl":"https://doi.org/10.5194/ms-14-557-2023","url":null,"abstract":"Abstract. In the machining of monolithic components, machining distortion is a severe issue. The presence of initial residual stress is a major contributor to machining distortion. This paper proposes an approach to control the machining distortion of long beam parts by optimizing the workpiece structure before the start of the finishing stage, i.e. the transition structure. The first step is to establish a machining distortion analytical model for long beam parts with an identical cross-section, which is based on reasonable assumptions such as material linear elasticity and ignoring the influence of cutting heat. Then, an optimization model for the cross-section of the transition structure is developed, with the objective function defined as the minimum difference between the predicted distortion of the final part and the transition structure. Finally, a U-shaped beam is designed, followed by numerical simulation and machining experiments for verification. The theoretical maximum distortion of the optimized transition structure and the final part are −0.174 and −0.1782 mm, respectively, with a relative error of 2.9 %. The results of machining experiments and finite-element simulation demonstrate the effectiveness of the proposed model.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"4 3","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139001069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In the context of non-standard blade geometries of knife-like tools with tapered cutting edges where the width of the blade surface varies with feed, there is limited research on predicting grinding forces considering the changing contact line. To enhance the accuracy of predicting grinding forces during the blade surface grinding of knife-like tools, a novel analytical-regression correction method is proposed. This method employs an analytical approach to analyze the varying contact line between the grinding wheel and the tool during grinding, enabling the determination of irregularly shaped grinding contact zones. By introducing exponential coefficients related to the grinding contact line, a regression analysis is employed to refine a variable edge-width grinding force model. In comparison to the conventional constant contact line blade surface grinding force prediction, this model is better suited for non-standard blade geometries of knife-like tools in grinding processes. Results indicate that the average relative error between the predicted values from the variable edge-width grinding force model and the actual measurements remains within 9 %, thereby validating the model's effectiveness in predicting grinding forces.
{"title":"Study on a grinding force model of a variable grinding contact area during knife-edge surface grinding","authors":"Baohua Yu, Tianfeng Lou, Dongwei Chen, Jie Rui, Wenliang Li, Yuepeng Chen","doi":"10.5194/ms-14-531-2023","DOIUrl":"https://doi.org/10.5194/ms-14-531-2023","url":null,"abstract":"Abstract. In the context of non-standard blade geometries of knife-like tools with tapered cutting edges where the width of the blade surface varies with feed, there is limited research on predicting grinding forces considering the changing contact line. To enhance the accuracy of predicting grinding forces during the blade surface grinding of knife-like tools, a novel analytical-regression correction method is proposed. This method employs an analytical approach to analyze the varying contact line between the grinding wheel and the tool during grinding, enabling the determination of irregularly shaped grinding contact zones. By introducing exponential coefficients related to the grinding contact line, a regression analysis is employed to refine a variable edge-width grinding force model. In comparison to the conventional constant contact line blade surface grinding force prediction, this model is better suited for non-standard blade geometries of knife-like tools in grinding processes. Results indicate that the average relative error between the predicted values from the variable edge-width grinding force model and the actual measurements remains within 9 %, thereby validating the model's effectiveness in predicting grinding forces.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"60 7","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139004156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. The stochastic stability of a gyro-pendulum system parametrically excited by a real noise is investigated by the moment Lyapunov exponent in the paper. Using the spherical polar and non-singular linear stochastic transformations and combining these with Khasminskii's method, the diffusion process and the eigenvalue problem of the moment Lyapunov exponent are obtained. Then, applying the perturbation method and Fourier cosine series expansion, we derive an infinite-order matrix whose leading eigenvalue is the second-order expansion g2(p) of the moment Lyapunov exponent. Thus, an infinite sequence for g2(p) is constructed, and its convergence is numerically verified. Finally, the influences of the system and noise parameters on stochastic stability are given such that the stochastic stability is strengthened with the increased drift coefficient and the diffusion coefficient has the opposite effect; among the system parameters, only the increase in k and A0 strengthens moment stability.
{"title":"Stochastic stability and the moment Lyapunov exponent for a gyro-pendulum system driven by a bounded noise","authors":"Shenghong Li, Junting Lv","doi":"10.5194/ms-14-545-2023","DOIUrl":"https://doi.org/10.5194/ms-14-545-2023","url":null,"abstract":"Abstract. The stochastic stability of a gyro-pendulum system parametrically excited by a real noise is investigated by the moment Lyapunov exponent in the paper. Using the spherical polar and non-singular linear stochastic transformations and combining these with Khasminskii's method, the diffusion process and the eigenvalue problem of the moment Lyapunov exponent are obtained. Then, applying the perturbation method and Fourier cosine series expansion, we derive an infinite-order matrix whose leading eigenvalue is the second-order expansion g2(p) of the moment Lyapunov exponent. Thus, an infinite sequence for g2(p) is constructed, and its convergence is numerically verified. Finally, the influences of the system and noise parameters on stochastic stability are given such that the stochastic stability is strengthened with the increased drift coefficient and the diffusion coefficient has the opposite effect; among the system parameters, only the increase in k and A0 strengthens moment stability.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"23 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139003624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. The cell-mapping method, due to its global optimality, has been applied to solve multi-objective optimization problems (MOPs) and optimal control problems. However, the curse of dimensionality limits its application in high-dimensional systems. In this paper, the multi-parameter sensitivity analysis is investigated to reduce the parameter space dimension, which broadens the application of cell mapping to MOPs in high-dimensional parameter space. A post-processing algorithm for MOPs is introduced to help choose proper control parameters from the Pareto set. The proposed scheme is applied successfully in the control parameter optimization of an adaptive nonsingular terminal sliding-mode control for an antenna servo system on a disturbed carrier. Moreover, as the existing global optimal tracking control with an adjoining cell-mapping method may generate tracking-phase differences, an optimal-sliding-mode combined-control strategy is proposed. By using the combined-control strategy, the azimuth and pitch angles of the antenna system are controlled to catch up to a target trajectory with the minimum cost function and to keep high-precision tracking after that.
{"title":"Application of cell mapping to control optimization for an antenna servo system on a disturbed carrier","authors":"Zhui Tian, Yongdong Cheng","doi":"10.5194/ms-14-519-2023","DOIUrl":"https://doi.org/10.5194/ms-14-519-2023","url":null,"abstract":"Abstract. The cell-mapping method, due to its global optimality, has been applied to solve multi-objective optimization problems (MOPs) and optimal control problems. However, the curse of dimensionality limits its application in high-dimensional systems. In this paper, the multi-parameter sensitivity analysis is investigated to reduce the parameter space dimension, which broadens the application of cell mapping to MOPs in high-dimensional parameter space. A post-processing algorithm for MOPs is introduced to help choose proper control parameters from the Pareto set. The proposed scheme is applied successfully in the control parameter optimization of an adaptive nonsingular terminal sliding-mode control for an antenna servo system on a disturbed carrier. Moreover, as the existing global optimal tracking control with an adjoining cell-mapping method may generate tracking-phase differences, an optimal-sliding-mode combined-control strategy is proposed. By using the combined-control strategy, the azimuth and pitch angles of the antenna system are controlled to catch up to a target trajectory with the minimum cost function and to keep high-precision tracking after that.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139223215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. At present, research on bionic jumping robots mainly focuses on imitating various jumping animals, such as kangaroos, frogs, or locusts. These bionic objects have good jumping ability. The goat, as one of these with a moderate size and a strong jumping ability, is very suitable as a prototype to imitate jumping. In this study, first, a simplified serial joint model that imitates a goat's hindlimb is proposed with a comparison analysis of its physiological structure. Then, a jumping leg mechanism that imitates a goat's hindlimb was designed. Second, the kinematics of the goat-inspired jumping leg were constructed to describe the relationship between joint angles and foot positions. Additionally, we used a cubic polynomial to plan the trajectory of the jumping process to achieve a smooth jumping movement based on the characteristics of the goat's jumping, with position and speed constraints during the jump. Thus, we established a smooth jumping trajectory model of the goat-inspired jumping leg. Finally, experiments on the jumping of the goat-inspired jumping leg were conducted. The goat-inspired jumping leg has good jumping performance. In this study, we took the goat's hindlimbs as the bionic model, proposed the goat-inspired jumping leg mechanism, and presented the jumping trajectory planning theory for smooth jumping of the goat-inspired jumping leg. These provide new ideas for the study of bionic jumping legs and can effectively promote further development of bionic jumping robots.
{"title":"Structural design and jumping motion planning of the jumping leg inspired by a goat's hindlimb","authors":"Gang Chen, Longxin He, Zhihan Zhao, Yuwang Lu, Jiajun Tu, Xiangying Ren, Hanzhi Lv","doi":"10.5194/ms-14-493-2023","DOIUrl":"https://doi.org/10.5194/ms-14-493-2023","url":null,"abstract":"Abstract. At present, research on bionic jumping robots mainly focuses on imitating various jumping animals, such as kangaroos, frogs, or locusts. These bionic objects have good jumping ability. The goat, as one of these with a moderate size and a strong jumping ability, is very suitable as a prototype to imitate jumping. In this study, first, a simplified serial joint model that imitates a goat's hindlimb is proposed with a comparison analysis of its physiological structure. Then, a jumping leg mechanism that imitates a goat's hindlimb was designed. Second, the kinematics of the goat-inspired jumping leg were constructed to describe the relationship between joint angles and foot positions. Additionally, we used a cubic polynomial to plan the trajectory of the jumping process to achieve a smooth jumping movement based on the characteristics of the goat's jumping, with position and speed constraints during the jump. Thus, we established a smooth jumping trajectory model of the goat-inspired jumping leg. Finally, experiments on the jumping of the goat-inspired jumping leg were conducted. The goat-inspired jumping leg has good jumping performance. In this study, we took the goat's hindlimbs as the bionic model, proposed the goat-inspired jumping leg mechanism, and presented the jumping trajectory planning theory for smooth jumping of the goat-inspired jumping leg. These provide new ideas for the study of bionic jumping legs and can effectively promote further development of bionic jumping robots.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"14 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139251144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Robot-assisted rehabilitation has proven to improve a subject's upper-extremity motor function. However, it is still challenging to control the robot to provide minimal assistance based on the subject's performance. This paper proposes a motion-trend-based assistance control strategy to solve this problem. The control strategy provides the corresponding normal and tangential forces by constructing an adaptive virtual assistance force field around a predetermined training trajectory. In the normal direction, a performance function based on the position-tracking error and normal motion trend is established to adjust the normal assistance force field strength in real time; in the tangential direction, a performance function based on the tangential interaction force and tangential motion trend is established to adjust the tangential assistance force field strength in real time. Additionally, good motion trends can quickly reduce the assistance force field. The normal motion trend represents the state of the subject moving toward the target trajectory, and the tangential motion trend represents the state of increasing tangential interaction force. Finally, the performance of this control strategy was evaluated by training experiments with eight healthy subjects. Preliminary experiments showed that the normal assist force in the active movement phase was 92.48 % smaller than that in the poor phase, and the tangential assist force was 90.73 % smaller than that in the slack phase. And the normal assist force and tangential assist force will become zero within 0.2 s when the subject has a good tendency to move. This shows that the control strategy proposed in this paper can quickly adjust the assistance according to the subject's motor performance. In addition, the assistance can be quickly reduced when the subject has a good movement trend. Future work will incorporate OpenSim (muscle and bone simulation software) to develop a pathway suitable for the subject's arm rehabilitation.
{"title":"Assistance control strategy for upper-limb rehabilitation robot based on motion trend","authors":"Haojun Zhang, Tao Song, Leigang Zhang","doi":"10.5194/ms-14-503-2023","DOIUrl":"https://doi.org/10.5194/ms-14-503-2023","url":null,"abstract":"Abstract. Robot-assisted rehabilitation has proven to improve a subject's upper-extremity motor function. However, it is still challenging to control the robot to provide minimal assistance based on the subject's performance. This paper proposes a motion-trend-based assistance control strategy to solve this problem. The control strategy provides the corresponding normal and tangential forces by constructing an adaptive virtual assistance force field around a predetermined training trajectory. In the normal direction, a performance function based on the position-tracking error and normal motion trend is established to adjust the normal assistance force field strength in real time; in the tangential direction, a performance function based on the tangential interaction force and tangential motion trend is established to adjust the tangential assistance force field strength in real time. Additionally, good motion trends can quickly reduce the assistance force field. The normal motion trend represents the state of the subject moving toward the target trajectory, and the tangential motion trend represents the state of increasing tangential interaction force. Finally, the performance of this control strategy was evaluated by training experiments with eight healthy subjects. Preliminary experiments showed that the normal assist force in the active movement phase was 92.48 % smaller than that in the poor phase, and the tangential assist force was 90.73 % smaller than that in the slack phase. And the normal assist force and tangential assist force will become zero within 0.2 s when the subject has a good tendency to move. This shows that the control strategy proposed in this paper can quickly adjust the assistance according to the subject's motor performance. In addition, the assistance can be quickly reduced when the subject has a good movement trend. Future work will incorporate OpenSim (muscle and bone simulation software) to develop a pathway suitable for the subject's arm rehabilitation.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"97 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. The application of a self-adjusted strategy has received increasing attention in current transmission design. This paper proposes a gear injury equilibrium oriented self-adjusted shifting strategy (EASS), which can make injury of different gears consistent. First, the injury value of different gears was judged in real time, and the working time of the gear with the largest injury value was reduced by adjusting the shift curve. Second, by considering key points as constraints, an optimal displacement trajectory for a synchronizer was proposed, and then a compound control method using adaptive nonsingular global fast-terminal sliding-mode control (AN-GFTSMC) was developed, which enables a high tracking performance and a better parameter perturbation rejection ability. Finally, both the simulation and real-vehicle experimental results showed that, compared with conventional control, the designed control strategy had good performance: response time was decreased, gear injury tended to be consistent, and transmission reliability was improved.
{"title":"Gear injury equilibrium-oriented self-adjusted shifting strategy and advanced servo control","authors":"Zhichao Lyu, Guangqiang Wu, Qiming Wang, Heqi Yan","doi":"10.5194/ms-14-479-2023","DOIUrl":"https://doi.org/10.5194/ms-14-479-2023","url":null,"abstract":"Abstract. The application of a self-adjusted strategy has received increasing attention in current transmission design. This paper proposes a gear injury equilibrium oriented self-adjusted shifting strategy (EASS), which can make injury of different gears consistent. First, the injury value of different gears was judged in real time, and the working time of the gear with the largest injury value was reduced by adjusting the shift curve. Second, by considering key points as constraints, an optimal displacement trajectory for a synchronizer was proposed, and then a compound control method using adaptive nonsingular global fast-terminal sliding-mode control (AN-GFTSMC) was developed, which enables a high tracking performance and a better parameter perturbation rejection ability. Finally, both the simulation and real-vehicle experimental results showed that, compared with conventional control, the designed control strategy had good performance: response time was decreased, gear injury tended to be consistent, and transmission reliability was improved.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"3 4","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139255568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liyong Wang, Li Yang, Le Li, Jianpeng Wu, Qian Zou
Abstract. Fingertip friction perception characteristics have not formed a clear and complete theory, owing to the low repeatability and accuracy of related experiments. Given this, a novel experimental method is proposed based on ridged surfaces for investigating the fingertip friction perception characteristics. In this method, based on the Universal Mechanical Tester (UMT) TriboLab, the proposed experiment makes subjects touch ridged surfaces under different ridge sizes and lubrication conditions, aiming to obtain fingertip friction and subject judgment. Subsequently, the average friction force fluctuation degree and the tactile perception accuracy are calculated to analyze the friction characteristics. For this, the relationship between friction and perception characteristics is discussed further. The results show that the adhesive and the deformation friction forces, which mainly consist of the total friction force under incomplete contact conditions, decrease due to the lubricating oil. However, the adhesive friction force increases slightly as the ridge widens. In addition, when the ridge spacing is raised, the deformation friction force increases and becomes the dominant component, while the adhesive friction force is the opposite. While analyzing the friction characteristics, it is found that the tactile perception accuracy is enhanced by raising the average friction force fluctuation. Moreover, the tactile perception accuracy can be improved by changing the surface texture and lubrication conditions, due to the changes in fingertip friction characteristics.
{"title":"Experimental study on fingertip friction perception characteristics on ridged surfaces","authors":"Liyong Wang, Li Yang, Le Li, Jianpeng Wu, Qian Zou","doi":"10.5194/ms-14-463-2023","DOIUrl":"https://doi.org/10.5194/ms-14-463-2023","url":null,"abstract":"Abstract. Fingertip friction perception characteristics have not formed a clear and complete theory, owing to the low repeatability and accuracy of related experiments. Given this, a novel experimental method is proposed based on ridged surfaces for investigating the fingertip friction perception characteristics. In this method, based on the Universal Mechanical Tester (UMT) TriboLab, the proposed experiment makes subjects touch ridged surfaces under different ridge sizes and lubrication conditions, aiming to obtain fingertip friction and subject judgment. Subsequently, the average friction force fluctuation degree and the tactile perception accuracy are calculated to analyze the friction characteristics. For this, the relationship between friction and perception characteristics is discussed further. The results show that the adhesive and the deformation friction forces, which mainly consist of the total friction force under incomplete contact conditions, decrease due to the lubricating oil. However, the adhesive friction force increases slightly as the ridge widens. In addition, when the ridge spacing is raised, the deformation friction force increases and becomes the dominant component, while the adhesive friction force is the opposite. While analyzing the friction characteristics, it is found that the tactile perception accuracy is enhanced by raising the average friction force fluctuation. Moreover, the tactile perception accuracy can be improved by changing the surface texture and lubrication conditions, due to the changes in fingertip friction characteristics.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"3 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135216879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guangtao Xu, Zeyuan Qiao, Shaokang Wu, Tianyi Liu, Minghao Zhao, Gang Wang
Abstract. Surface topography is an important parameter for evaluating the quality of surface machining, and the stress concentrations produced at notches can have a profound effect on the fatigue life of notched components. The stress concentration factor (SCF, Kt) and relative stress gradient (RSG, χ) are important parameters used to quantitatively characterize stress concentration. In this study, a finite-element (FE) method was used to evaluate the surface SCF and RSG and determine the effect of microscopic surface topography on machined surfaces. An FE simulation of the static tension test of V-notched round-bar specimens was performed, and the stress due to the local surface topography was investigated. The FE method was used to analyze the stress concentration of round-bar specimens with Kt=1, and the reliability of the results was verified using a perturbation method. The FE method was used to calculate the surface SCF and RSG with high accuracy. The surface SCF and RSG values increased with the surface roughness, and the local maximum values of the surface SCF and RSG were at the bottom of the local topography. Therefore, the SCF and RSG could be estimated based on a linear relationship involving average roughness.
{"title":"Finite-element method for the analysis of surface stress concentration factor and relative stress gradient for machined surfaces","authors":"Guangtao Xu, Zeyuan Qiao, Shaokang Wu, Tianyi Liu, Minghao Zhao, Gang Wang","doi":"10.5194/ms-14-451-2023","DOIUrl":"https://doi.org/10.5194/ms-14-451-2023","url":null,"abstract":"Abstract. Surface topography is an important parameter for evaluating the quality of surface machining, and the stress concentrations produced at notches can have a profound effect on the fatigue life of notched components. The stress concentration factor (SCF, Kt) and relative stress gradient (RSG, χ) are important parameters used to quantitatively characterize stress concentration. In this study, a finite-element (FE) method was used to evaluate the surface SCF and RSG and determine the effect of microscopic surface topography on machined surfaces. An FE simulation of the static tension test of V-notched round-bar specimens was performed, and the stress due to the local surface topography was investigated. The FE method was used to analyze the stress concentration of round-bar specimens with Kt=1, and the reliability of the results was verified using a perturbation method. The FE method was used to calculate the surface SCF and RSG with high accuracy. The surface SCF and RSG values increased with the surface roughness, and the local maximum values of the surface SCF and RSG were at the bottom of the local topography. Therefore, the SCF and RSG could be estimated based on a linear relationship involving average roughness.","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135570215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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