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Keywords = normal–tangential contact

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13 pages, 1746 KiB  
Article
Calibration of DEM Parameters and Microscopic Deformation Characteristics During Compression Process of Lateritic Soil with Different Moisture Contents
by Chao Ji, Wanru Liu, Yiguo Deng, Yeqin Wang, Peimin Chen and Bo Yan
Agriculture 2025, 15(14), 1548; https://doi.org/10.3390/agriculture15141548 - 18 Jul 2025
Viewed by 300
Abstract
Lateritic soils in tropical regions feature cohesive textures and high specific resistance, driving up energy demands for tillage and harvesting machinery. However, current equipment designs lack discrete element models that account for soil moisture variations, and the microscopic effects of water content on [...] Read more.
Lateritic soils in tropical regions feature cohesive textures and high specific resistance, driving up energy demands for tillage and harvesting machinery. However, current equipment designs lack discrete element models that account for soil moisture variations, and the microscopic effects of water content on lateritic soil deformation remain poorly understood. This study aims to calibrate and validate discrete element method (DEM) models of lateritic soil at varying moisture contents of 20.51%, 22.39%, 24.53%, 26.28%, and 28.04% by integrating the Hertz–Mindlin contact mechanics with bonding and JKR cohesion models. Key parameters in the simulations were calibrated through systematic experimentation. Using Plackett–Burman design, critical factors significantly affecting axial compressive force—including surface energy, normal bond stiffness, and tangential bond stiffness—were identified. Subsequently, Box–Behnken response surface methodology was employed to optimize these parameters by minimizing deviations between simulated and experimental maximum axial compressive forces under each moisture condition. The calibrated models demonstrated high fidelity, with average relative errors of 4.53%, 3.36%, 3.05%, 3.32%, and 7.60% for uniaxial compression simulations across the five moisture levels. Stress–strain analysis under axial loading revealed that at a given surface displacement, both fracture dimensions and stress transfer rates decreased progressively with increasing moisture content. These findings elucidate the moisture-dependent micromechanical behavior of lateritic soil and provide critical data support for DEM-based design optimization of soil-engaging agricultural implements in tropical environments. Full article
(This article belongs to the Section Agricultural Technology)
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22 pages, 5702 KiB  
Article
Calibration and Experimental Validation of Discrete Element Parameters of Fritillariae Thunbergii Bulbus
by Hang Zheng, Zhaowei Hu, Xianglei Xue, Yunxiang Ye, Tian Liu, Ning Ren, Fanyi Liu and Guohong Yu
Appl. Sci. 2025, 15(14), 7951; https://doi.org/10.3390/app15147951 - 17 Jul 2025
Viewed by 226
Abstract
The development of slicing equipment for Fritillariae Thunbergii Bulbus (FTB) has been constrained by the absence of precise and reliable simulation model parameters, which has hindered the optimization of structural design through simulation techniques. Taking FTB as the research object, this study aims [...] Read more.
The development of slicing equipment for Fritillariae Thunbergii Bulbus (FTB) has been constrained by the absence of precise and reliable simulation model parameters, which has hindered the optimization of structural design through simulation techniques. Taking FTB as the research object, this study aims to resolve this issue by conducting the calibration and experimental validation of the discrete element parameters for FTB. Both intrinsic and contact parameters were obtained through physical experiments, on the basis of which a discrete element model for FTB was established by using the Hertz–Mindlin with bonding model. To validate the calibrated bonding parameters of this model, the maximum shear force was selected as the evaluation index. Significant influencing factors were identified and analyzed through a single-factor test, a two-level factorial test, and the steepest ascent method. Response surface methodology was then applied for experimental design and parameter optimization. Finally, shear and compression tests were conducted to verify the accuracy of calibrated parameters. The results show that the mechanical properties of FTB are significantly affected by the normal stiffness per unit area, the tangential stiffness per unit area, and the bonding radius, with optimal values of 1.438 × 108 N·m−3, 0.447 × 108 N·m−3, and 1.362 mm, respectively. The relative errors in the shear and compression tests were all within 5.18%. The maximum error between the simulated and measured maximum shear force under three different types of blades was less than 5.11%. The percentages of the average shear force of the oblique blade were reduced by 52.23% and 29.55% compared with the flat and arc blades, respectively, while the force variation trends for FTB remained consistent. These findings confirm the reliability of the simulation parameters and establish a theoretical basis for optimizing the structural design of slicing equipment for FTB. Full article
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19 pages, 12875 KiB  
Article
Numerical Study of Wear Characteristics of Vertical Shaft Planetary Mixer Blades
by Shoubo Jiang, Hongwei Zhang, Qingliang Zeng, Qian Du and Xiaopeng Liu
Materials 2025, 18(13), 3137; https://doi.org/10.3390/ma18133137 - 2 Jul 2025
Viewed by 323
Abstract
The wear failure of vertical shaft planetary mixer blades under complex working conditions directly affects the quality and productivity of concrete. Given that it is time-consuming and labor-intensive to obtain the wear characteristics of mixer blades by experimental methods, this study used numerical [...] Read more.
The wear failure of vertical shaft planetary mixer blades under complex working conditions directly affects the quality and productivity of concrete. Given that it is time-consuming and labor-intensive to obtain the wear characteristics of mixer blades by experimental methods, this study used numerical simulation to analyze the effects of different factors on the wear characteristics of mixer blades based on the Hertz–Mindlin with JKR cohesive contact model and the Archard wear model. The results of this study show that under the influence of different factors, the blade is subjected to tangential cumulative contact energy and contact force is significantly larger than that in the normal direction, the wear of the blade is judged to be the form of abrasive wear accompanied by impacts, and the wear on the outer middle and lower edge regions of the blade is the most serious. Specifically, for every 5 rpm increase in mixing speed, the blade wear rate increases by 24.14% on average; for every 5° increase in blade angle, the blade wear rate decreases by 2.9% on average; for every 10% increase in the mass ratio of stone aggregate, the blade wear rate increases by 5.95% on average; conical aggregates have the most serious effect on blade wear, while spherical aggregates have the most minor effect. This study provides the theoretical basis and numerical support for understanding the reasons for blade wear loss and enhancing the service life of mixer blades. Full article
(This article belongs to the Section Mechanics of Materials)
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23 pages, 6736 KiB  
Article
Parameter Calibration and Experimental Study of a Discrete Element Simulation Model for Yellow Cinnamon Soil in Henan, China
by Huiling Ding, Mengyang Wang, Qiaofeng Wang, Han Lin, Chao Zhang and Xin Jin
Agriculture 2025, 15(13), 1365; https://doi.org/10.3390/agriculture15131365 - 25 Jun 2025
Viewed by 359
Abstract
To investigate the interaction mechanism between agricultural tillage machinery and soil, this study established a precise simulation model by integrating physical and numerical experiments using typical yellow cinnamon soil collected from western Henan Province, China. The discrete element parameters for soils with varying [...] Read more.
To investigate the interaction mechanism between agricultural tillage machinery and soil, this study established a precise simulation model by integrating physical and numerical experiments using typical yellow cinnamon soil collected from western Henan Province, China. The discrete element parameters for soils with varying moisture contents were calibrated based on the Hertz–Mindlin (no slip) contact model. Through Plackett–Burman screening, steepest ascent optimization, and Box–Behnken response surface methodology, a predictive model correlating moisture content, parameters, and repose angle was developed, yielding the optimal contact parameter combination: interparticle static friction coefficient (0.6), soil–65Mn static friction coefficient (0.69), and interparticle rolling friction coefficient (0.358). For the Bonding model, orthogonal experiments coupled with NSGA-II multi-objective optimization determined the optimal cohesive parameters targeting maximum load (673.845 N) and displacement (9.765 mm): normal stiffness per unit area (8.8 × 107 N/m3), tangential stiffness per unit area (6.85 × 107 N/m3), critical normal stress (6 × 104 Pa), critical tangential stress (3.15 × 104 Pa), and bonding radius (5.2 mm). Field validation using rotary tillers and power harrows demonstrated less than 6% deviation in soil fragmentation rates between simulations and actual operations, confirming parameter reliability and providing theoretical foundations for constructing soil-tillage machinery interaction models. Full article
(This article belongs to the Section Agricultural Technology)
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18 pages, 3602 KiB  
Article
Modeling and Analysis of Torsional Stiffness in Rehabilitation Robot Joints Using Fractal Theory
by Shuaidong Zou, Wenjie Yan, Guanghui Xie, Renqiang Yang, Huachao Xu and Fanwei Sun
Materials 2025, 18(12), 2866; https://doi.org/10.3390/ma18122866 - 17 Jun 2025
Viewed by 290
Abstract
The torsional stiffness of rehabilitation robot joints is a critical performance determinant, significantly affecting motion accuracy, stability, and user comfort. This paper introduces an innovative traction drive mechanism that transmits torque through friction forces, overcoming mechanical impact issues of traditional gear transmissions, though [...] Read more.
The torsional stiffness of rehabilitation robot joints is a critical performance determinant, significantly affecting motion accuracy, stability, and user comfort. This paper introduces an innovative traction drive mechanism that transmits torque through friction forces, overcoming mechanical impact issues of traditional gear transmissions, though accurately modeling surface roughness effects remains challenging. Based on fractal theory, this study presents a comprehensive torsional stiffness analysis for advanced traction drive joints. Surface topography is characterized using the Weierstrass–Mandelbrot function, and a contact mechanics model accounting for elastic–plastic deformation of micro-asperities is developed to derive the tangential stiffness of individual contact pairs. Static force analysis determines load distribution, and overall joint torsional stiffness is calculated through the integration of individual contact contributions. Parametric analyses reveal that contact stiffness increases with normal load, contact length, and radius, while decreasing with the tangential load and roughness parameter. Stiffness exhibits a non-monotonic relationship with fractal dimension, reaching a maximum at intermediate values. Overall system stiffness demonstrates similar parameter dependencies, with a slight decrease under increasing output load when sufficient preload is applied. This fractal-based model enables more accurate stiffness prediction and offers valuable theoretical guidance for design optimization and performance improvement in rehabilitation robot joints. Full article
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16 pages, 18412 KiB  
Article
Research on the Influence of Surface Defects Under the Influence of Rail Corrosion on the Fatigue Damage of Wheel Rolling Contact
by Longzhi Zhao, Minghui Mou, Daoyun Chen and Minshi Zhong
Coatings 2025, 15(5), 589; https://doi.org/10.3390/coatings15050589 - 15 May 2025
Cited by 1 | Viewed by 444
Abstract
Heavy rolling contact fatigue (RCF) may be caused by wheel surface defects under the influence of rail corrosion, which threatens the operational safety of rail vehicles. To investigate the role of surface defects on wheel RCF damage under the influence of rail corrosion, [...] Read more.
Heavy rolling contact fatigue (RCF) may be caused by wheel surface defects under the influence of rail corrosion, which threatens the operational safety of rail vehicles. To investigate the role of surface defects on wheel RCF damage under the influence of rail corrosion, a salt spray tester was used to corrode the rails, an impact testing machine was employed to create surface defects, and RCF tests were completed. The role of surface defects on wheel RCF damage was studied by monitoring the wheel defect surface and cross-section. The results indicate that the tendencies of the RCF crack extension of surface defects of different sizes are similar, and they all extend in a C-shape along the tangential force direction. However, the larger the defect size, the later the crack is initiated. The leading edge material is continuously squeezed into the defect by the tangential force, and a larger plastic deformation layer is formed, which causes the RCF at the leading edge to crack more severely. Meanwhile, under the effect of combined normal force and shear stress, the leading edge crack intersects with the middle edge crack, and the leading edge material is spalled off first. Wheel RCF damage and wear are aggravated by rail corrosion, the longer the corrosion time, the more serious the RCF damage and wear, and the earlier the material spalling time, the lower the fatigue life. Full article
(This article belongs to the Special Issue Advancements in Surface Engineering, Coatings and Tribology)
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19 pages, 10219 KiB  
Article
Research on the Grinding Force Modeling of Herringbone Gear Tooth Surface Formation Based on the Microscopic Mechanism of Wear Particles
by Rongyi Li, Chenglong Kan, Zemin Zhao, Xianbin Li, Xianli Liu and Zhaochi Li
Coatings 2025, 15(4), 395; https://doi.org/10.3390/coatings15040395 - 27 Mar 2025
Viewed by 460
Abstract
In the process of herringbone gear grinding, excessive grinding force leads to a large increase in grinding specific energy. A large increase in the specific grinding energy can easily lead to an increase in the transient cutting load. It leads to grinding burn, [...] Read more.
In the process of herringbone gear grinding, excessive grinding force leads to a large increase in grinding specific energy. A large increase in the specific grinding energy can easily lead to an increase in the transient cutting load. It leads to grinding burn, tooth surface crack and other undesirable phenomena, which ultimately affect the surface quality and service performance of the workpiece. This paper is based on the contact mechanics of workpiece materials. The number of dynamic effective abrasive particles is considered. Combined with the mechanism of grinding force, the model is developed. Based on the consideration of the wear characteristics of the grinding wheel and the structure parameters of the gear itself, the grinding force model was modified. The accuracy of grinding force model is improved by dividing the effective contact angle of grinding grains into four cases. The experimental results show that the normal grinding force error reaches 10.73% and the tangential grinding force error reaches 10.34%. The model reveals the grinding mechanism, optimizes grinding parameters and improves grinding efficiency. It provides a new way for high-precision machining of aerospace precision herringbone gear. Full article
(This article belongs to the Special Issue Cutting Performance of Coated Tools)
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17 pages, 12733 KiB  
Article
Effects of Contact Characteristics on Dynamic Response of Planar Mechanical Systems with Lubricated Revolute Joint
by Xu Peng, Haoran Zhu, Yang Guo, Xuze Wu and Yu Chen
Lubricants 2025, 13(3), 124; https://doi.org/10.3390/lubricants13030124 - 14 Mar 2025
Cited by 1 | Viewed by 533
Abstract
In this study, a dynamic response model that incorporates lubricated clearance is developed to examine the evolution of contact and friction in a mechanical system. The dynamic model of a lubricated clearance joint is established by considering the contact, friction, and hydrodynamics. The [...] Read more.
In this study, a dynamic response model that incorporates lubricated clearance is developed to examine the evolution of contact and friction in a mechanical system. The dynamic model of a lubricated clearance joint is established by considering the contact, friction, and hydrodynamics. The expression of contact force in normal and tangential directions is developed using elastic contact theory. The lubrication characteristics of a revolute joint are obtained using hydrodynamic theory, which is introduced into the simulation model. This case study is conducted to investigate the effects of design parameters on the dynamic stability of a mechanical system with a lubricated clearance joint. The results elucidate the relationship between lubrication characteristics and vibration response, offering valuable insights for the optimization of mechanical systems. Full article
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11 pages, 948 KiB  
Article
Contact Interaction of a Rigid Stamp and a Porous Elastic Cylinder of Finite Dimensions
by Mikhail I. Chebakov, Elena M. Kolosova and Maria D. Datcheva
Mathematics 2025, 13(1), 104; https://doi.org/10.3390/math13010104 - 30 Dec 2024
Viewed by 579
Abstract
This article investigates an axisymmetric contact problem involving the interaction between a rigid cylindrical stamp and a poroelastic cylinder of finite dimensions, based on the Cowin–Nunziato theory of media with voids. The stamp is assumed to have a flat base and to be [...] Read more.
This article investigates an axisymmetric contact problem involving the interaction between a rigid cylindrical stamp and a poroelastic cylinder of finite dimensions, based on the Cowin–Nunziato theory of media with voids. The stamp is assumed to have a flat base and to be in frictionless contact with the cylinder. The cylinder, in turn, rests on a rigid base without friction, with no normal displacements or tangential stresses on its lateral surface. Under an applied vertical force, the stamp undergoes displacement, compressing the poroelastic cylinder. The mathematical formulation of this problem involves expressing the unknown displacements within the cylinder and the variation in pore volume fraction as a series of Bessel functions. This representation reduces the problem to an integral equation of the first kind, describing the distribution of contact stresses beneath the stamp. The kernel of the integral equation is explicitly provided in its transformed form. The collocation method is employed to solve the integral equation, enabling the determination of contact stresses and the relationship between the indenter’s displacement and the applied force. A comparative model parameter analysis is performed to examine the effects of different material porosity parameters and model geometrical characteristics on the results. Full article
(This article belongs to the Section E2: Control Theory and Mechanics)
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19 pages, 18714 KiB  
Article
Hardware Implementation for Triaxial Contact-Force Estimation from Stress Tactile Sensor Arrays: An Efficient Design Approach
by María-Luisa Pinto-Salamanca, Wilson-Javier Pérez-Holguín and José A. Hidalgo-López
Sensors 2024, 24(23), 7829; https://doi.org/10.3390/s24237829 - 7 Dec 2024
Viewed by 1509
Abstract
This paper presents a contribution to the state of the art in the design of tactile sensing algorithms that take advantage of the characteristics of generalized sparse matrix-vector multiplication to reduce the area, power consumption, and data storage required for real-time hardware implementation. [...] Read more.
This paper presents a contribution to the state of the art in the design of tactile sensing algorithms that take advantage of the characteristics of generalized sparse matrix-vector multiplication to reduce the area, power consumption, and data storage required for real-time hardware implementation. This work also addresses the challenge of implementing the hardware to execute multiaxial contact-force estimation algorithms from a normal stress tactile sensor array on a field-programmable gate-array development platform, employing a high-level description approach. This paper describes the hardware implementation of the proposed sparse algorithm and that of an algorithm previously reported in the literature, comparing the results of both hardware implementations with the software results already validated. The calculation of force vectors on the proposed hardware required an average time of 58.68 ms, with an estimation error of 12.6% for normal forces and 7.7% for tangential forces on a 10 × 10 taxel tactile sensor array. Some advantages of the developed hardware are that it does not require additional memory elements, achieves a 4× reduction in processing elements compared to a non-sparse implementation, and meets the requirements of being generalizable, scalable, and efficient, allowing an expansion of the applications of normal stress sensors in low-power tactile systems. Full article
(This article belongs to the Special Issue Recent Development of Flexible Tactile Sensors and Their Applications)
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18 pages, 3616 KiB  
Article
Theoretical Analysis of Shaft Wall Damage and Failure Under Impacting of Ore-Rock Falling in Vertical Ore Pass
by Qiangying Ma, Chi Ma, Jiaoqun Li, Zengxiang Lu and Zhiguo Xia
Appl. Sci. 2024, 14(22), 10695; https://doi.org/10.3390/app142210695 - 19 Nov 2024
Viewed by 830
Abstract
The impact of ore-rock blocks on the shaft wall of a vertical ore pass is a crucial cause of shaft wall damage and failure. Based on the structure and parameters of the ore pass in a case mine, the first collision’s position of [...] Read more.
The impact of ore-rock blocks on the shaft wall of a vertical ore pass is a crucial cause of shaft wall damage and failure. Based on the structure and parameters of the ore pass in a case mine, the first collision’s position of the ore-rock block with respect to the ore pass wall and the angle between the impacting direction of the ore-rock block and the horizontal plane before and after the collision are investigated via a kinematic analysis. The normal and tangential analysis models of ore rock impacting the shaft wall are established and analyzed based on contact mechanics. The results show that: (1) based on the kinematic analysis of ore rock moving in the ore pass and on the colliding condition of the ore-rock block the first time that it collides with the ore pass wall, the coordinates and angles of the collision are proposed; (2) the impacting process of ore rock is categorized into elastic compression, elastic–plastic compression, and rebound of the shaft wall material. The relationship between the normal impact force and the penetrating depth is determined, and the slipping distance of the ore-rock block along the shaft wall and the lost volume of the shaft material are established. (3) The wall material’s normal, tangential, and total restitution coefficient is acquired. (4) The total lost volume during the collision is obtained through the analysis and solution of the model. (5) Based on the characteristics and parameters of the ore pass in the case mine, the influence of the impact velocity and angle of the ore-rock block on the restitution coefficient, maximum normal intrusion depth, maximum tangential displacement, and volume loss of the shaft wall are analyzed by using relevant formulas. Full article
(This article belongs to the Special Issue Advanced Methodology and Analysis in Coal Mine Gas Control)
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11 pages, 886 KiB  
Article
Energy Loss in Frictional Hertzian Contact Subjected to Two-Dimensional Cyclic Loadings
by Young Ju Ahn
Coatings 2024, 14(11), 1440; https://doi.org/10.3390/coatings14111440 - 13 Nov 2024
Viewed by 889
Abstract
We investigate the effect of three different harmonically varying loads as a function of the friction coefficient on energy loss in a three-dimensional discrete uncoupled frictional contact problem. Three loading cases include (1) a normal force is constant and a tangential force varies, [...] Read more.
We investigate the effect of three different harmonically varying loads as a function of the friction coefficient on energy loss in a three-dimensional discrete uncoupled frictional contact problem. Three loading cases include (1) a normal force is constant and a tangential force varies, (2) normal and tangential forces both vary, but the loading and unloading curves are identical, and (3) normal and tangential forces both vary, but the loading and unloading curves are different. For a higher coefficient of friction, three loading cases show different characteristics. If a normal force is constant and a tangential force varies, there is always some slip, but dissipation tends asymptotically to zero at large coefficient of friction. If normal and tangential forces both vary, but the loading and unloading curves are identical, there is no slip and no dissipation above a critical coefficient of friction. If the loading and unloading curves are different, dissipation occurs for all values of the coefficient of friction, and we expect that the dissipation is asymptotic to the relaxation damping value as the coefficient of friction approaches infinity. For lowering coefficient of friction, the three loading cases show similar behavior. Dissipation increases and reaches a maximum just before a state where gross slip is possible. Full article
(This article belongs to the Special Issue Advanced Wear-Resistant Materials and Coatings)
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10 pages, 2344 KiB  
Article
An Analysis of the Stress–Strain State of a Layer on Two Cylindrical Bearings
by Vitaly Miroshnikov, Oleksandr Denshchykov, Iaroslav Grebeniuk and Oleksandr Savin
Computation 2024, 12(9), 182; https://doi.org/10.3390/computation12090182 - 6 Sep 2024
Viewed by 925
Abstract
A spatial problem of elasticity theory is solved for a layer located on two bearings embedded in it. The bearings are represented as thick-walled pipes embedded in the layer parallel to its boundaries. The pipes are rigidly connected to the layer, and contact-type [...] Read more.
A spatial problem of elasticity theory is solved for a layer located on two bearings embedded in it. The bearings are represented as thick-walled pipes embedded in the layer parallel to its boundaries. The pipes are rigidly connected to the layer, and contact-type conditions (normal displacements and tangential stresses) are specified on the insides of the pipes. Stresses are set on the flat surfaces of the layer. The objective of this study is to obtain the stress–strain state of the body of the layer under different geometric characteristics of the model. The solution to the problem is presented in the form of the Lamé equation, whose terms are written in different coordinate systems. The generalized Fourier method is used to transfer the basic solutions between coordinate systems. By satisfying the boundary and conjugation conditions, the problem is reduced to a system of infinite linear algebraic equations of the second kind, to which the reduction method is applied. After finding the unknowns, using the generalized Fourier method, it is possible to find the stress–strain state at any point of the body. The numerical study of the stress state showed high convergence of the approximate solutions to the exact one. The stress–strain state of the composite body was analyzed for different geometric parameters and different pipe materials. The results obtained can be used for the preliminary determination of the geometric parameters of the model and the materials of the joints. The proposed solution method can be used not only to calculate the stress state of bearing joints, but also of bushings (under specified conditions of rigid contact without friction on the internal surfaces). Full article
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23 pages, 7759 KiB  
Article
Machine Learning Algorithms for Prediction and Characterization of Cohesive Zone Parameters for Mixed-Mode Fracture
by Arash Ramian and Rani Elhajjar
J. Compos. Sci. 2024, 8(8), 326; https://doi.org/10.3390/jcs8080326 - 17 Aug 2024
Cited by 1 | Viewed by 1764
Abstract
Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture [...] Read more.
Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture analysis of advanced composite sandwich structures. Experimental results often yield non-unique solutions, complicating the determination of cohesive parameters. Numerical determination can be time-consuming due to fine mesh requirements near the crack tip. This research evaluates the performance of Support Vector Regression (SVR), Random Forest (RF), and Artificial Neural Network (ANN) machine learning methods. The study uses features extracted from load–displacement responses during the fracture of the Asymmetric Double-Cantilever Beam (ADCB) specimen. The inputs include the displacement at the maximum load (δ*), the maximum load (Pmax), the total area under the load–displacement curve (At), and the initial slope of the linear region of the load–displacement curve (m). There are two objectives in this research: the first is to investigate which method performs best in identifying the interfacial cohesive parameters between the honeycomb core and carbon-epoxy facesheets, while the second objective is to reduce the dimensionality of the dataset by reducing the number of input features. Reducing the number of inputs can simplify the models and potentially improve the performance and interpretability. The results show that the ANN method produced the best results, with a mean absolute percentage error (MAPE) of 0.9578% and an R-squared (R²) value of 0.7932. These values indicate a high level of accuracy in predicting the four cohesive zone parameters: maximum normal contact stress (σI), critical fracture energy for normal separation (GI), maximum equivalent tangential contact stress (σII), and critical fracture energy for tangential slip (GII). Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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19 pages, 6835 KiB  
Article
Development and Investigation of a Grasping Analysis System with Two-Axis Force Sensors at Each of the 16 Points on the Object Surface for a Hardware-Based FinRay-Type Soft Gripper
by Takahide Kitamura, Kojiro Matsushita, Naoki Nakatani and Shunsei Tsuchiyama
Sensors 2024, 24(15), 4896; https://doi.org/10.3390/s24154896 - 28 Jul 2024
Cited by 1 | Viewed by 1477
Abstract
The FinRay soft gripper achieves passive enveloping grasping through its functional flexible structure, adapting to the contact configuration of the object to be grasped. However, variations in beam position and thickness lead to different behaviors, making it important to research the relationship between [...] Read more.
The FinRay soft gripper achieves passive enveloping grasping through its functional flexible structure, adapting to the contact configuration of the object to be grasped. However, variations in beam position and thickness lead to different behaviors, making it important to research the relationship between structure and force. Conventional research using FEM simulations has tested various virtual FinRay models but replicating phenomena such as buckling and slipping has been challenging. While hardware-based methods that involve installing sensors on the gripper and the object to analyze their states have been attempted, no studies have focused on the tangential contact force related to slipping. Therefore, we developed a 16-way object contact force measurement device incorporating two-axis force sensors into each of the 16 segmented objects and compared the normal and tangential components of the enveloping grasping force of the FinRay soft gripper under two types of contact friction conditions. In the first experiment, the proposed device was compared with a device containing a six-axis force sensor in one segmented object, confirming that the proposed device has no issues with measurement performance. In the second experiment, comparisons of the proposed device were made under various conditions: two contact friction states, three object contact positions, and two object motion states. The results demonstrated that the proposed device could decompose and analyze the grasping force into its normal and tangential components for each segmented object. Moreover, low friction conditions result in a wide contact area with lower tangential frictional force and a uniform normal pushing force, achieving effective enveloping grasping. Full article
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