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Chirality plays a crucial role in biology, as it is highly conserved and fundamentally important in the developmental process. To better understand the relationship between the chirality of individual cells and that of tissues and organisms, we develop a generalized mechanics model of chiral polarized particles to investigate the swirling dynamics of cell populations on substrates. Our analysis reveals that cells with the same chirality can form distinct chiral patterns on ring-shaped or rectangular substrates. Interestingly, our studies indicate that an excessively strong or weak individual cellular chirality hinders the formation of such chiral patterns. Our studies also indicate that there exists the influence distance of substrate boundaries in chiral patterns. Smaller influence distances are observed when cell-cell interactions are weaker. Conversely, when cell-cell interactions are too strong, multiple cells tend to be stacked together, preventing the formation of chiral patterns on substrates in our analysis. Additionally, we demonstrate that the interaction between cells and substrate boundaries effectively controls the chiral distribution of cellular orientations on ring-shaped substrates. This research highlights the significance of coordinating boundary features, individual cellular chirality, and cell-cell interactions in governing the chiral movement of cell populations and provides valuable mechanics insights into comprehending the intricate connection between the chirality of single cells and that of tissues and organisms. [ABSTRACT FROM AUTHOR]

In response to the growing demand for robotic interventions to mitigate the profound physical strain experienced by caregivers during transfers, dual-arm robotic systems have emerged as a focal point of interest in the caregiving community due to their adaptability and versatility. However, the accuracy of existing human--robot mechanics model is insufficient, impacting the execution of transfer tasks. To enhance the model's precision, an improved model is proposed, integrating hip torque identification. This proposed methodology involves the simplification of the human structure based on the kinematic attributes associated with the embrace of individuals by robotic arms and the subsequent computation of its inertial parameters. Accordingly, the application of D'Alembert's principle is employed to analyze the impact of embracing motion, human posture, and the position of human--robot contact on the forces exerted on the human. This culminates in the establishment of a model. Considering the static indeterminacy predicament inherent in the model, a biomechanical data set is curated for the dual-arm transfer scenario. Leveraging this data set, a deep neural network utilizing multilayer perceptron is trained to accurately identify hip torque, thereby improving the model. Accordingly, a robotic transfer platform featuring dual arms is developed and trailed on six subjects with varying anatomical profiles. The results show that the constructed model has high accuracy. This study provides critical mechanics insights for dual-arm transfer tasks, offering potential application value in the field of nursing and rehabilitation. [ABSTRACT FROM AUTHOR]

Clogging is a major geohazards risk in mechanized tunnelling through cohesive soils. Clay clogging results from the high adhesion between the clay and metal. Based on the water film theory and Reynolds fluid equation, the interfacial adhesion between metal and soil is simplified in this study as viscous hydrodynamic behavior between planes. Considering the influence of capillary force and the viscous force of water film at the interface between metal and soil, a theoretical calculation model of interfacial adhesion between metal and soil is established. The influence of water film thickness and separation rate on the interfacial adhesion between metal and soil is qualitatively analyzed. Then, the adhesion stress between the clay and the metal surface was tested with a pullout test and the influence of moisture content, pullout rates and types of clay minerals on the adhesion stress was analyzed. Finally, the calculation model of adhesion force was compared with the experimental results. The calculation model of soil adhesion stress established in this paper can quantitatively describe the relationship between soil adhesion force and moisture content and can also qualitatively reveal the influence mechanism of soil moisture content on adhesion stress.

ABSTRACTCotton is a crucial raw material for the textile industry, and the quality of its initial product greatly affects the properties of the yarn and fabric. However, the impact of low temperature and moisture regain during ginning on the mechanical properties has not been extensively studied. This paper aims to address this gap by designing and analyzing a strategy for evaluating the mechanical properties of machine-harvested cotton fibers pretreated at different moisture regain levels and temperatures. Regression models for the relationship between temperature and mechanical properties under different moisture regain conditions were also established, showing good consistency. Additionally, the study examines the mechanical damage mechanism of cotton fibers during the harvesting and ginning process by observing the fiber fracture interface of different samples. Especially, those with low moisture regain exhibit a V-type fracture, while those with high moisture regain display significant fibrils exposed on the fiber body, resulting in a tearing morphology at the fracture interface. In conclusion, this study provides theoretical support for optimizing the harvesting process in cotton processing enterprises in terms of moisture regain and low temperature and makes a significant toward sustainable cotton fiber harvesting and processing technology.

Civil structural health monitoring (CSHM) tracks different aspects of an infrastructure system's service and safety condition by utilizing reliably measured data and physics-based model simulations. Data and physical models are coupled with heuristic experience to proactively represent current and expected future performance. In the past two decades, more bridges and dams have been instrumented and monitored during and after construction to determine their performances and responses to various loading, material, boundary, and environmental conditions. Furthermore, bridge and dam owners increasingly utilize civionics systems to obtain essential data for developing data-driven asset management programs and addressing the state of good repair requirements. [ABSTRACT FROM AUTHOR]

The incidence of oral malocclusion is increasing and is seriously damaging the oral health of human beings. The Kitchon root‐controlled auxiliary archwire is an individualized orthodontic arch. It is used clinically for the treatment of tooth‐lingual tilt/root‐lip tilt phenomenon of the central incisors. However, the bending parameters of the Kitchon root‐controlled auxiliary archwire used in different patients are based on the clinical experience of the dentists. Therefore, this orthodontic treatment has a high risk and unpredictability. In this paper, the loading performance and orthodontic process of Kitchon root‐controlled auxiliary archwire are analyzed. And the prediction model of support resistance and correction torque are established. The bending parameters of the Kitchon root‐controlled auxiliary archwire, as well as the effect of the bending parameters on the support resistance and the correction torque, are all quantified. And the prediction models for the support resistance and the correction torque are calculated separately. The correlation coefficients of calculated data and experimental data are ξT1 >.97 and ξA1 >.96, respectively; the correlation coefficients of simulated data and experimental data are ξT2 >.96 and ξA2 >.96, respectively. The accuracy and reliability of the established prediction models are verified. It provides an effective theoretical guide for dentists to safely and efficiently perform root‐controlled rotation orthodontic treatment on patients' central incisors. [ABSTRACT FROM AUTHOR]

In order to explore the development path of Hunan embroidery under the vision of artificial intelligence, promote the digital regeneration and database construction of Hunan embroidery stitches, the communication, and interaction between Hunan embroidery brands and the public, and create more possibilities for revitalizing the culture and industrial development of non-heritage Hunan embroidery. In this paper, a mechanics model of Hunan embroidery stitch is established based on the finite element idea under the view of artificial intelligence. The single yarn in the yarn is regarded as a frictionless articulation of some rows of elastic rods with a circular cross-section. The elastic rod can only be subjected to axial force without a moment, and it is a uniform, continuous, and completely elastic isotropic body. Using the displacement method, the displacement of the unit node is taken as the basic unknown quantity, the displacement in the unit is assumed to be linearly distributed, and the displacement of any node in the unit is obtained by linear interpolation. The strain, stress, and stiffness matrices of the elastic rod unit are derived, the equilibrium equations are given, and a database is established. The results of the study showed that consumers of all age levels thought that the patterns representing Hunan embroidery mainly include Hunan characteristic landscapes, portraits of Hunan great men, traditional flowers, birds and animals, and totems of Chu culture, etc., among which Hunan characteristic landscape accounted for 54% of the largest proportion. It provides a development direction for the inheritance and protection of Hunan embroidery skills.

Civil structural health monitoring (CSHM) tracks different aspects of an infrastructure system’s service and safety condition by utilizing reliably measured data and physics-based model simulations. Data and physical models are coupled with heuristic experience to proactively represent current and expected future performance. In the past two decades, more bridges and dams have been instrumented and monitored during and after construction to determine their performances and responses to various loading, material, boundary, and environmental conditions. Furthermore, bridge and dam owners increasingly utilize civionics systems to obtain essential data for developing data-driven asset management programs and addressing the state of good repair requirements.

Granite binary structure slopes and residual soil slopes containing spheroidal boulders formed by differential weathering are widely distributed along the southeast coast of China. Field studies demonstrate that the failure of differentially weathered granite slopes mainly occurs at soil–rock interfaces. Only few studies have been conducted on the shear characteristics of the interfaces between rocks and granite residual soil. Moreover, mechanics models describing the engineering properties of the interfaces have not been developed. In this study, the ring shear tests are conducted on a granite residual soil–rock interface using the orthogonal design method and considering factors such as the roughness of granite, water content and initial dry density, shear rate, and number of drying–wetting cycles. A mechanics model that can precisely demonstrate the shear characteristics of the interface is also developed, and its validity is verified using test results. The findings indicate that the roughness of granite and the water content of the residual soil are the main factors affecting the interface shear stress. As the increase of granite roughness, the peak internal friction angle, residual internal friction angles, and peak cohesion of soil–rock interface increase. The residual cohesion of the interface, however, decreases as the roughness of granite increases. As the water content of the soil increases, both the interface shear stress and internal friction angle initially start to increase and then decrease. With the increase of the number of drying–wetting cycles, the internal friction angle and peak cohesion of the interface decrease. [ABSTRACT FROM AUTHOR]

In order to explore the fracture law and structural evolution characteristics of overlying strata in deep high-stress mining, according to the geometric characteristics and mechanical causes of overlying strata in different mining stages of the stope, four stages of overlying strata structure model are established and analyzed in turn. According to the characteristics of the overburden load transfer path in the deep high-stress stope, the fracture law and macroscopic mechanical response of overburden are analyzed by MATLAB and PFC2D numerical simulation method. The evolution model of overburden structure and load transfer in 'four stages and three modes' of the deep high-stress stope is constructed, and the stage fracture effect of 'beam, plate and arch' is put forward. The results show that the overburden rock is a fixed beam structure before the initial weighting. After the initial weighting, it evolves into a plate structure with three sides fixed and one side simply supported. After the periodic weighting, the overburden rock structure further evolves into a plate structure with one side fixed and three sides simply supported. After full mining, the overburden rock forms an arch structure, and the load is transmitted by the beam–plate–arch path. The findings of the study provide an important basis for exploring the nature of overburden transport and load transfer in deep high-stress quarries and strengthening overburden prevention and control. [ABSTRACT FROM AUTHOR]

Herein, we developed a bead-spring model to predict the Poisson's ratios of two-dimensional hexagonal materials under finite strains. The predicted strain-dependent Poisson's ratios were supported by simulations. The bounds on the Poisson's ratios of two-dimensional hexagonal materials under finite strains (-1/3, +∞) were established. The underlying mechanism for the strain-dependent Poisson's ratios was uncovered as the interplay between bond stretching and angle bending during the stretching. These findings indicate that, even for the simplified material system under finite strains, there is no upper bound on the Poisson's ratios, and that there is plenty of room for strain-engineering the Poisson's ratios. [ABSTRACT FROM AUTHOR]

Recycled Glass Concrete (RGC) exhibits low mechanical strength due to the loose structure of its interfacial transition zone. Adding supplementary cementitious materials is an effective approach to address the issues of low mechanical performance and durability in RGC. In order to improve the performance of recycled glass concrete, three series of tests were prepared for mechanical testing, drying shrinkage testing and microstructure analysis: single-doped limestone powder (RGC-L), single-doped metakaolin (RGC-M), and limestone-metakaolin mix (RGC-LM). The mechanical results demonstrate that RGC, with the addition of 5 % limestone powder and 5 % metakaolin, exhibits optimal strength improvement. Specifically, compressive strength increased by 23.3 %, splitting tensile strength by 38.1 %, and flexural strength by 7.3 %. Additionally, a mechanical prediction model for RGC was proposed, yielding relational equations for splitting tensile strength (f t), flexural strength (f r), and compressive strength (f c): f t = 0.14 f c 0.93 , f r = 0.72 f c 0.56 . The drying shrinkage results indicate that RGC containing 10 % limestone powder and 20 % metakaolin exhibits the best performance, with a 32.5 % reduction in shrinkage rate. Microstructural analysis revealed that the reaction between Al₂O₃ in metakaolin and limestone powder produces CO₃-AFm, which results in a denser structure in the interfacial transition zone of the recycled glass concrete. Ultimately, this study elucidates the micro-mechanisms and drying shrinkage mechanisms of limestone powder and metakaolin in RGC, offering a promising approach for the effective utilization of construction waste. • The reaction mechanisms of Limestone Powder and Metakaolin within Recycled Glass Concrete were explored. • The auxiliary cementing material is used to improve the interfacial transition zone of Recycled Glass Concrete. • A mechanical model for Recycled Glass Concrete was proposed. [ABSTRACT FROM AUTHOR]

The design of a multiple-segment notched tube is distinctively appropriate for miniature surgical robots, attributing to its superior structural compliance and the provision of a substantial lumen within a constrained diameter. However, the cable-driven mechanism commonly adopted in this design naturally leads to inter-segment motion coupling, limiting its clinical potential. This study introduces a model-based design optimization method aimed at concurrently minimizing the coupled motion of a two-segment notched flexible robot and meeting diverse design and performance criteria. In the design optimization framework, a single-segment mechanics model, a 3-dimensional (3D) coupled mechanics model, and a 3D stiffness model have been developed and integrated to simultaneously minimize the coupled bending angle and satisfy surgery-specific performance requirements. A back propagation neural network (BPNN) has also been adopted to achieve computationally efficient optimization process. A case study is conducted on two-segment notched flexible robot optimization design for maxillary sinus surgery, with the mechanics models being verified experimentally. Ultimately, the optimized robot demonstrates its ability to provide visualization of the maxillary sinus cavity, including the blind spots. The proposed robot design optimization approach offers a systematic and efficient methodology to minimize motion coupling without compromising robot performance, thus fundamentally enabling procedure-specific design of multi-segment flexible surgical robots. [Display omitted] • Established a mechanics model with coupled motion of a 2-segment flexible robot. • Established a stiffness model that considers the tip payload. • Proposed a model-based design optimization method for 2-segment flexible robot. • Introduced a back propagation neural network to approximate the mechanics model. • Demonstrated effectiveness of the design optimization method in sinus surgery. [ABSTRACT FROM AUTHOR]

Aiming at the vibration reduction problems of pipeline systems under high temperature, a high temperature mechanics model of the metal rubber coated damping structure of the pipe-lines was established by equivalent linearization method. The model was used for analyzing the stiffness and response amplitude of metal rubber treated with different temperatures. The thermal-vibration joint test system of the pipelines was set up firstly. Then the damping performance of the coated damping structure of the pipelines was verified with different ambient temperatures and metal rubber densities, where the insertion loss was taken as the evaluation index. The results show that reducing he density of metal rubber may effectively increase the vibration attenuation effectiveness of the pipelines. At the same time, the effect of the ambient temperature on the metal rubber coated damping structure is negligible, indicating that the coated damping structure may work well in a high temperature environment. [ABSTRACT FROM AUTHOR]

To conduct a comfortable lift for the care-receiver, it takes a lot of time and operations to design the motion trajectory for each care-receiver before transfer tasks. To solve this problem, this paper proposed a method to design a lift trajectory for a piggyback transfer robot. The robot, which can lift and move a person from a wheelchair to a bed or a pedestal pan, has been developed. The trajectory obtained by this method could make the robot conduct a comfort lift for the care-receiver, according to the weight and height of the care-receiver. A human-robot mechanics model and the relationship between the comfortable lift trajectory and the care-receiver's weight and height were also contributed. According to the test results of 20 subjects, the force parameters used for trajectory design were determined, and the trajectory design method was optimized. The results of three subjects demonstrated that this method could conveniently and quickly provide a robot lift trajectory based on the subject's weight and height, and this trajectory also achieved a similar lift as the trajectory designed by relying on the opinion of the subject. This method can be used for the design of the reference trajectory in the compliant control of the piggyback robot, which realizes the comfortable lifting of the care-receiver. [ABSTRACT FROM AUTHOR]

In order to explore the fracture law and structural evolution characteristics of overlying strata in deep high-stress mining, according to the geometric characteristics and mechanical causes of overlying strata in different mining stages of the stope, four stages of overlying strata structure model are established and analyzed in turn. According to the characteristics of the overburden load transfer path in the deep high-stress stope, the fracture law and macroscopic mechanical response of overburden are analyzed by MATLAB and PFC2D numerical simulation method. The evolution model of overburden structure and load transfer in ‘four stages and three modes’ of the deep high-stress stope is constructed, and the stage fracture effect of ‘beam, plate and arch’ is put forward. The results show that the overburden rock is a fixed beam structure before the initial weighting. After the initial weighting, it evolves into a plate structure with three sides fixed and one side simply supported. After the periodic weighting, the overburden rock structure further evolves into a plate structure with one side fixed and three sides simply supported. After full mining, the overburden rock forms an arch structure, and the load is transmitted by the beam–plate–arch path. The findings of the study provide an important basis for exploring the nature of overburden transport and load transfer in deep high-stress quarries and strengthening overburden prevention and control.

Understanding the contact mechanics of rough tooth surfaces is critical in order to understand phenomena such as tooth surface flash temperature, tooth surface wear, and gear vibration. In this paper, the contact behavior between the meshing tooth surfaces of beveloid gear pairs with elliptical asperities is the focus. The contact area distribution function of the elliptical asperity was proposed for the point contact of curved surfaces by transforming the elastic contact problem between gear meshing surfaces into the contact between elastic curved surfaces with an arbitrary radius of curvature. In addition, a fractal contact mechanics model for the rough surface of a beveloid gear with elliptical asperities was established. The influence of tooth surface topography on the contact load and contact stiffness under different fractal parameters was investigated, and the results demonstrated that the real contact load and the contact stiffness of curved surfaces increase with the increase in the fractal dimension D and the contact coefficient λ. Conversely, the real contact load and normal contact stiffness decrease with the increase in the fractal roughness G and eccentricity e. [ABSTRACT FROM AUTHOR]

Fruit particle shedding can be often caused by the vibration excitation of broken stems in the clip-cut grape picking. In this study, a dynamic model of the fruit-stem-dividing plane pendulum in the vertical plane was first established, according to the actual growth of grapes. The theoretical angular velocity of fruit shedding was then deduced under the excitation force of the broken stem. After that, the critical condition was determined for the separation of the fruit-stalk swing and falling off, where the swing trajectory was actually a part of the circular motion. In research objects, the freshly picked round grapes were collected to survey with a similar appearance, maturity, and no damage on the surface. The main physical characteristics of the grapes were also measured at the ripening stage in turn. Specifically, the average length of the main stalk of grapes was 214.44 mm, and the width was 85.51 mm; the average longitudinal diameter of the grape berries was 28.99 mm and the equatorial diameter was 26.45 mm; the average weight was 20.01 g; the average hardness was 9.44 kg/cm2; the weight of the stalk was 7.53 g. In a simulation, a SolikWorks2020 three-dimensional modeling software was utilized to model the grapes. Then the ABAQUS software was used to analyze the dynamic response and swing trend of a single grape under the excitation of broken stems. As such, the swing and deformation trends of a single grape were determined under the excitation of broken stems without squeezing. Since there was much squeezing between the grape particles, the model was simplified to 14 independent, isotropic, and uniform linear elastic spherical particles. The main shearing stem was also applied for the simplified clamping model, thereby collecting the input information, such as the shear force, and the clamping force under the excitation of the broken stem. The simulation test showed that the shear force was 6.454 N when cutting the main stem, and the clamping force changed from the initial 2.6 N to the maximum 6.4 N. The finite element analysis was then performed on the vibration using the simplified model of cluster grapes. A dataset was thus obtained, including the displacement, velocity, acceleration, as well as the stress and strain of the grape fruit relative to the junction of the fruit stalk at the moment before falling off. An optimal combination of parameters was achieved to determine the critical vibration shedding of the grapes. In the 18-order modal analysis, the vibration excitation was transmitted to the vibrated fruit via the main stem-sub-stem-fruit three levels, where the fruit particles appeared the indefinite anisotropic torsional swing. Specifically, the 0-20 Hz sweep frequency was selected for the whole bunch of grapes under modal superposition. Consequently, the frequency of the vibrated fruit suddenly changed to a peak frequency of 4 Hz, and then rapidly attenuated to 0 under the excitation. The maximum swing amplitude of the vibrated fruit was 49.88 mm, the peak velocity was 0.92 mm/s, and the acceleration peak was 39.08 mm/s2, ranging from the shedding and then gradually decay to 0 in a picking cycle. The vibration frequency of the fruit particles presented a great mutation over their own natural frequency. At this time, the tertiary fruit-stalk junction was broken to cause the particles to fall off. The trend of vibration was the same under the same excitation, although the position of each fruit was different. The finding can provide a theoretical basis for the parameter design of anti-shedding picking. [ABSTRACT FROM AUTHOR]

Chirality plays a crucial role in biology, as it is highly conserved and fundamentally important in the developmental process. To better understand the relationship between the chirality of individual cells and that of tissues and organisms, we develop a generalized mechanics model of chiral polarized particles to investigate the swirling dynamics of cell populations on substrates. Our analysis reveals that cells with the same chirality can form distinct chiral patterns on ring-shaped or rectangular substrates. Interestingly, our studies indicate that an excessively strong or weak individual cellular chirality hinders the formation of such chiral patterns. Our studies also indicate that there exists the influence distance of substrate boundaries in chiral patterns. Smaller influence distances are observed when cell-cell interactions are weaker. Conversely, when cell-cell interactions are too strong, multiple cells tend to be stacked together, preventing the formation of chiral patterns on substrates in our analysis. Additionally, we demonstrate that the interaction between cells and substrate boundaries effectively controls the chiral distribution of cellular orientations on ring-shaped substrates. This research highlights the significance of coordinating boundary features, individual cellular chirality, and cell-cell interactions in governing the chiral movement of cell populations and provides valuable mechanics insights into comprehending the intricate connection between the chirality of single cells and that of tissues and organisms., Competing Interests: Competing interests statement:The authors declare no competing interest.

This study aims to clarify the effects of different structural arrangements on the axial vibration of the sugarcane cutting system. A vibration characteristic test was performed on an experimental rig of a sugarcane harvester. Mechanics and mathematical models were also established for the sugarcane harvester platform. Some impact parameters were determined on the axial vibration of the cutting system, including the installing positions of hydraulic cylinders, the engine, and the logistics frame. The results showed 1) The vibration amplitude of axial cutter with the HP3 position of hydraulic cylinders (1.28 mm) was reduced by 63% under complicated excitations, compared with the HP1 position (3.52 mm). The excitation source presented the least influences on the vibration of the cutter frame when the hydraulic cylinder was installed at the position HP3 (720, 375, 1,880), that is, in the positive direction of X axis near the front wheel 535 mm. 2) The vibration amplitude of axial cutter with the EP2 position of the engine was reduced by 49% under complicated excitations, compared with the EP5 position. The excitation source presented the least influences on the vibration of the cutter frame, when the engine was installed at the position EP2 (12 400,1 800), that is, in the positive direction of X axis near the front wheel 1 055 mm. 3) The vibration amplitude of axial cutter with the No. LP3 position of logistics frame was reduced by 43% under complicated excitations, compared with the LP1 position. The excitation source behaved the least influences on the vibration of the cutter frame when the logistics frame was installed at the position LP3 (1 800, 537, 1 255), that is, in the positive direction of X axis near the front wheel 1 615 mm. There was the greatest significance of logistics frame on the vibrations of cutting system, followed closely by hydraulic cylinders. Nevertheless, there was the least significant effect of engine installation position on the vibrations of the cutting system. An orthogonal experiment was carried out to verify the parameters. An optimal configuration was then achieved for the sugarcane harvester, where the logistics frame was installed on the position LP3, while the hydraulic cylinder was on the position HP3, and the engine was on the position EP2. In this case, the vibration amplitude of the axial cutter was reduced by 40.8%, compared with that before optimization. Consequently, some suggestions can be addressed during this time, where the installation position of hydraulic cylinder, engine, and logistics frame should avoid the position above the front and rear wheels as far as possible, particularly on the sugarcane harvesting machinery suitable for hilly areas. The vibration isolation or damping device should also be added to reduce the vibration of the cutting system for better performance of sugarcane cutting. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To conduct a comfortable lift for the care-receiver, it takes a lot of time and operations to design the motion trajectory for each care-receiver before transfer tasks. To solve this problem, this paper proposed a method to design a lift trajectory for a piggyback transfer robot. The robot, which can lift and move a person from a wheelchair to a bed or a pedestal pan, has been developed. The trajectory obtained by this method could make the robot conduct a comfort lift for the care-receiver, according to the weight and height of the care-receiver. A human-robot mechanics model and the relationship between the comfortable lift trajectory and the care-receiver’s weight and height were also contributed. According to the test results of 20 subjects, the force parameters used for trajectory design were determined, and the trajectory design method was optimized. The results of three subjects demonstrated that this method could conveniently and quickly provide a robot lift trajectory based on the subject’s weight and height, and this trajectory also achieved a similar lift as the trajectory designed by relying on the opinion of the subject. This method can be used for the design of the reference trajectory in the compliant control of the piggyback robot, which realizes the comfortable lifting of the care-receiver.

Understanding the contact mechanics of rough tooth surfaces is critical in order to understand phenomena such as tooth surface flash temperature, tooth surface wear, and gear vibration. In this paper, the contact behavior between the meshing tooth surfaces of beveloid gear pairs with elliptical asperities is the focus. The contact area distribution function of the elliptical asperity was proposed for the point contact of curved surfaces by transforming the elastic contact problem between gear meshing surfaces into the contact between elastic curved surfaces with an arbitrary radius of curvature. In addition, a fractal contact mechanics model for the rough surface of a beveloid gear with elliptical asperities was established. The influence of tooth surface topography on the contact load and contact stiffness under different fractal parameters was investigated, and the results demonstrated that the real contact load and the contact stiffness of curved surfaces increase with the increase in the fractal dimension D and the contact coefficient λ. Conversely, the real contact load and normal contact stiffness decrease with the increase in the fractal roughness G and eccentricity e.

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the requirements of pneumatic soft manipulators working in remote unstructured environments, a teleoperation system of pneumatic soft manipulators was built. Based on the principle of "fast pneumatic network" and modular disassembly, a flexible bending actuator was designed and manufactured. A hand-like flexible manipulator was assembled according to the experimental requirements. The mechanics model of the soft actuator was established based on Yeoh model, and was revised by simulation analysis, which provided a theoretical basis for the control of the soft actuator. The architecture of the teleoperation system was designed, the driving mode and control strategy of the pneumatic soft manipulators were put forward. The client software interface was created in the C# windows application. Based on skinning technology, the soft actuator was modeled in 3D Max software, and a virtual working scene was built in Unity3D. The motion control of the soft manipulators and the collision and picking of the target objects were realized by remote feedback information through script programming. Experiments for finding the relationship between the bending angle of the soft actuator and pressure were carried out to verify the accuracy of the analytics mechanics model. And the teleoperation gesture mapping experiments were carried out to analyze the feasibility of the teleoperation systems, and the further research and applications were discussed. [ABSTRACT FROM AUTHOR]

Drilling mechanics model has always been the key and difficult point in the research field of gun drilling. In this paper, through theoretical analysis and processing experiments, the gun drilling mechanics model of Ti6Al4V titanium alloy is studied. On the one hand, based on the Oxley cutting model and the Johnson-Cook flow stress model, this paper takes Ti6Al4V titanium alloy as the research object and use the "microelement" method to establish the mechanical model of gun drilling, which includes cutting parameters, tool geometric parameters and material mechanical properties. On the other hand, the drilling model considers the influence of process damping and verified by experiments. The results show the calculated value of the model is consistent with the experimental value and the error is within the acceptable range. The model provides a theoretical basis for the prediction of drilling force, tool analysis and straightness error analysis. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Referencing special energy model, a new gun drill mechanics model was established and the influence of the cutting parameters on axial force and torque was based on 15-5PH solid solution stainless steel through theoretical analysis and cutting tests. On the basis of the existing model, the model coefficients were modified under various cutting conditions and the integral area of the cutting edge was enlarged. The eccentricity at the bottom of the drill groove was taken into account in the integral area of the cutting edge. In the meanwhile, the torque calculation was simplified reasonably according to the theoretical analysis. The feasibility of the model was verified by experiments and the influence of cutting parameters on the axial force and torque was analyzed. The experiment data had shown that the relative error between the calculated values and the experimental values were within the acceptable range. The axial force and torque increased with the increase in cutting speed and feed rate. [ABSTRACT FROM AUTHOR]

• Solved the stress field of rock based on Boussinesq stress solution. • Revealed the formation mechanism of dense cores. • Proposed new force model for cutter based on dense core position. • The side force and normal force model is corrected by cutter spacing. • The influence of parameters on dense core position and cutter force is discussed. Based on the solution of Boussinesq problem, this paper studied the stress field beneath contact surface during the Constant Cross-Section (CCS) type disc cutter cutting. The feature of stress field indicated that dense core formed under the contact surface at a depth approximately equal to the half-length of contact surface. And the penetration and cutter thickness significant influence the dense core position. Based on Mohr-Coulomb criterion and the dense core position, a new cutter force model is proposed. And the side force and normal force model is corrected by cutter spacing according to linear correlation assumption. The accuracy and suitability for proposed model was compared with classic CSM model and numerous full-scale linear cutting machine (LCM) database collecting from the others' researches. The research indicated that the proposed model can accurately predict cutting force in a wide range of rock mechanics parameters, especially on the rock with USC ≥ 40 MPa. In addition, the influence of main parameters on cutting force was discussed. This research offered fundamental insights into dense core forming and provided a theoretical basis for disc cutter design. [ABSTRACT FROM AUTHOR]

The mechanics model of crossed cylindrical roller slewing bearing under combined radial,axial and tilting moment loads was established,this model considers the clearance parameter of the slewing bearing. The mechanics model was numerically solved by using Newton-Raphson method. Two carrying capacity indexes that are safety factor and fatigue life of the slewing bearing were calculated,and the influence law of slewing bearing clearance on the internal load distribution,safety factor and fatigue life of the slewing bearing was analyzed. The results show that the change of slewing bearing clearance has significant influence on the internal load distribution and carrying capacity of the slewing bearing. With the increase of axial clearance of slewing bearing,the number of rollers inside the slewing bearing undertaking the external load decreases gradually,the load of the heaviest loaded rollers increases correspondingly. During the process of the axial clearance increase of the slewing bearing from 0 mm to 0. 24 mm,the carrying capacity safety factor of the slewing bearing decreases by 16 percent,the fatigue life decreases by 26 percent.

The continuously variable transmission can significantly improve the dynamic performance of automotive,which is the development direction of automobile transmission. The metal belt is the main transmission component of automotive continuously variable transmission,the four layers metal band analysis model is established,and the force and change of velocity of each layer of metal belt in different working conditions are analyzed. The results show that when the metal belt between the friction rate is small,the major tension used for transmission torque is in the first layer of metal band,with the friction rate between each layer of metal band belt increase,the four layers of metal band relative slip decreases and the velocity difference becomes small.The friction between metal bands belt can be effective delivery of torsional moment,the final metal belt tension began to evenly distribute to the four layers of metal belt. With the metal bands belt outward,the operating speed of band gradually decreases on the driver pulley,through the mechanical analysis of automotive continuously variable transmission,which provides an important reference for the design and dynamic characteristics study.

The high-speed train transmission system is a complex electromechanical coupling system, which consists of a motor, a universal shaft, a gearbox, and a wheel set. In order to solve dynamic problems such as torsion vibration caused by a high-speed train transmission system, the simplified model and equivalent mechanics model of the system were established, the natural vibration frequency was solved, and the simulation results of the system under a fixed torque input were analysed. The results showed that the natural vibration frequency of the universal shaft was 4.19 Hz, the natural vibration frequency of the pinion was 7.54 Hz, the natural vibration frequency of the big gear was 35.6 Hz, and the natural vibration frequency of the wheel set was 107.45 Hz. The natural vibration frequency of each part of the system increased gradually during the transmission from the motor to the wheel set. A fixed torque was added to the input end of the simulation model. The simulation results showed that the change amplitude of the torsion angle displacement of the big gear and the wheel set decreases. It is known that the angular displacement caused by the torsional vibration is weakened by the larger torsion stiffness of the axle.

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Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper is devoted to the problem of modeling and trajectory tracking for stochastic nonholonomic dynamic systems in the presence of unknown parameters. Prior to tracking controller design, the rigorous derivation of stochastic nonholonomic dynamic model is given. By reasonably introducing so-called internal state vector, a reduced dynamic model, which is suitable for control design, is proposed. Based on the backstepping technique in vector form, an adaptive tracking controller is then derived, guaranteeing that the mean square of the tracking error converges to an arbitrarily small neighborhood of zero by tuning design parameters. The efficiency of the controller is demonstrated by a mechanics system: a vertical mobile wheel in random vibration environment.

[Display omitted] • A new model for honeycomb cutting is derived based on the mechanical model and analytical analysis. • The interaction state between cutter and honeycomb wall is revealed by modeling the material structure. • The function of entry and exit angles are developed to describe various types of thin-walled edges. • The analytical results are verified by comparison with the experimental data. The structural characteristics of the material and dynamic changes in the entry and exit angles are of great significance for the accurate prediction of the cutting force during milling of the aluminum honeycomb core. In this study, an instantaneous cutting force prediction model for the aluminum honeycomb core that comprehensively considers the porous structural characteristics of the material and dynamic changes in the entry and exit angles during the machining process was developed. A unified structural model for an aluminum honeycomb core with a regular hexagonal cell structure and excellent mechanical property was established. Based on the structural characteristics of the aluminum honeycomb core, three types of thin-walled edges were considered, and the dynamic changes in their entry and exit angles were investigated by considering the cutter radius, cutting width, honeycomb core wall thickness, and relative position between the cutter and thin-walled edge. An orthogonal-to-oblique cutting transformation approach that can effectively reflect the cutting characteristics of the material was adopted to calibrate the cutting force coefficients in which cutting experiments using different cutter geometries and parameters were conducted. The aluminum honeycomb core was fixed using green, high-efficiency cryogenic liquid nitrogen. To verify the reliability of the proposed model, a series of milling experiments were carried out and the experimental and simulation results were compared. It was found that the simulated cutting force is highly consistent with the experimental result. The proposed model can accurately predict the peak values of the cutting force in the x , y , and z directions, with an average prediction error of less than 10%. [ABSTRACT FROM AUTHOR]

A natural biomaterial has been discovered with bactericidal activities, which is mainly attributed to its nanopatterned surface structure. The surface of Clanger cicada ( Psaltoda claripennis ) wings has been identified as a natural bactericidal material, which has lead to the emergence of research on the development of novel antibacterial surfaces. From the interactions between bacterial biofilms and nanopatterned surface structures, a new mechanical model is proposed that investigates the rupture of bacterial cells within the framework of the “stretching” theory. The effect of surface nanoroughness on the survival of bacterial cells is evaluated by determining the stretching ability of their cell walls. The results, calculated using Gram-positive and Gram-negative bacteria as examples, show a correlation between the stretching of the cell wall and the geometric parameters of the surface structures. The theoretical results indicate that for a given cell rigidity, the bactericidal nature of the surface is determined by the geometric parameters of the surface structures. [ABSTRACT FROM AUTHOR]