Rolling bearings are crucial components of rotating machinery, and their health states directly affect the overall performance of the machinery. Therefore, it is exceedingly necessary to detect and diagnose bearing faults. Numerous bearing fault diagnosis methods have been successfully used for ensuring the safe operation of rotating machinery. However, in practical working environments, there is a considerable amount of noise, resulting in traditional methods incapable of achieving accurate fault diagnosis. This paper proposes a new multi-head attention residual network (MARNet) for rolling bearing fault diagnosis under noisy condition. MARNet optimizes residual units by simplifying multi-layer convolutions into a single-layer convolution and replaces the rectified linear unit (ReLU) function with the exponential linear unit (ELU) function to obtain a more appropriate activation function. Additionally, the multi-head attention mechanism is introduced into the residual block to capture correlation information between any two time sequences, enhancing the network’s feature extraction capability. The effectiveness and superiority of the MARNet in noisy environments are demonstrated through conducting the two bearing datasets from Case Western Reserve University (CWRU) and Paderborn University (PU). The experiment results show that the proposed method exhibits anti-noise characteristics and generalization capability compared with several up-to-date deep learning methods for fault diagnosis of rolling bearings.
{"title":"MARNet: Multi-head attention residual network for rolling bearing fault diagnosis under noisy condition","authors":"Linfeng Deng, Guojun Wang, Cheng Zhao, Yuanwen Zhang","doi":"10.1177/09544062241259614","DOIUrl":"https://doi.org/10.1177/09544062241259614","url":null,"abstract":"Rolling bearings are crucial components of rotating machinery, and their health states directly affect the overall performance of the machinery. Therefore, it is exceedingly necessary to detect and diagnose bearing faults. Numerous bearing fault diagnosis methods have been successfully used for ensuring the safe operation of rotating machinery. However, in practical working environments, there is a considerable amount of noise, resulting in traditional methods incapable of achieving accurate fault diagnosis. This paper proposes a new multi-head attention residual network (MARNet) for rolling bearing fault diagnosis under noisy condition. MARNet optimizes residual units by simplifying multi-layer convolutions into a single-layer convolution and replaces the rectified linear unit (ReLU) function with the exponential linear unit (ELU) function to obtain a more appropriate activation function. Additionally, the multi-head attention mechanism is introduced into the residual block to capture correlation information between any two time sequences, enhancing the network’s feature extraction capability. The effectiveness and superiority of the MARNet in noisy environments are demonstrated through conducting the two bearing datasets from Case Western Reserve University (CWRU) and Paderborn University (PU). The experiment results show that the proposed method exhibits anti-noise characteristics and generalization capability compared with several up-to-date deep learning methods for fault diagnosis of rolling bearings.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782886","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241259611
Siddharth Kumar, Sarthak S Singh
Epoxy resin controls the mechanical behavior of fiber-reinforced epoxy composites, which are extensively deployed in the aerospace and automotive industries. For numerical simulations to accurately predict the mechanical deformations of these components under multi-axial loading, matrix characteristics must account for tension, compression, and shear loads at varying strain rates. The existing literature lacks a comprehensive approach to predicting the experimental outcomes across all three loading conditions in a polymer matrix simultaneously using a unified set of viscoelastic or viscoplastic model parameters. In this study, the Three-Network (TN) viscoplastic model was successfully applied to concurrently predict the tension, compression, and shear experimental data of an epoxy resin, published by Littel et al. ( Journal of Aerospace Engg., 2008). The elastic modulus, strain softening-hardening response after yield for tension-compression deformation, and post-yield stress saturation under shear deformation are all accurately predicted by the model at different rates of loading conditions. The predicted and simulated results matched well when the TN viscoplastic model predicted parameters were employed as material property in Abaqus (a commercial finite element software) to simulate the deformation modes. This integrated approach highlights the potential of the TN model in enabling precise predictions for epoxy-based composites, which is crucial for optimizing their performance and reliability in aerospace engineering.
{"title":"Concurrent predictions of tension, compression, and shear characteristics of epoxy using three-network viscoplastic model","authors":"Siddharth Kumar, Sarthak S Singh","doi":"10.1177/09544062241259611","DOIUrl":"https://doi.org/10.1177/09544062241259611","url":null,"abstract":"Epoxy resin controls the mechanical behavior of fiber-reinforced epoxy composites, which are extensively deployed in the aerospace and automotive industries. For numerical simulations to accurately predict the mechanical deformations of these components under multi-axial loading, matrix characteristics must account for tension, compression, and shear loads at varying strain rates. The existing literature lacks a comprehensive approach to predicting the experimental outcomes across all three loading conditions in a polymer matrix simultaneously using a unified set of viscoelastic or viscoplastic model parameters. In this study, the Three-Network (TN) viscoplastic model was successfully applied to concurrently predict the tension, compression, and shear experimental data of an epoxy resin, published by Littel et al. ( Journal of Aerospace Engg., 2008). The elastic modulus, strain softening-hardening response after yield for tension-compression deformation, and post-yield stress saturation under shear deformation are all accurately predicted by the model at different rates of loading conditions. The predicted and simulated results matched well when the TN viscoplastic model predicted parameters were employed as material property in Abaqus (a commercial finite element software) to simulate the deformation modes. This integrated approach highlights the potential of the TN model in enabling precise predictions for epoxy-based composites, which is crucial for optimizing their performance and reliability in aerospace engineering.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782930","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241259612
Congpeng Chen, Jiangmin Mao, Yingdan Zhu, Guanjun Bao
The dynamic behavior of the mechanism is subject to the influence of the clearance in the joints. Existing methods for improving the mechanism’s performance usually focus on one type of clearance joint, ignoring the interaction among multiple different types of clearance joints. To address this gap, an optimization method is proposed to lower adverse impact forces and vibrations in planar conjugate cam linkage mechanisms with cam and revolute clearance joints. The contact force model of the clearance joint is formulated using the Flores contact force model and the modified Coulomb friction model. Based on these models and Lagrange’s equation of the first kind, the dynamic equations of the mechanism describe its behavior during operation. The optimization method is aimed at minimizing the peak of the mechanism’s maximum absolute acceleration by employing the whale optimization algorithm (WOA) to optimize the length of the linkages and the initial angles between them. Additionally, the slider stroke serves as a constraint function. Finally, the effectiveness of the approach is validated using an example of a planar conjugate cam linkage mechanism. Simulation results show a reduction of 65.8% in acceleration peaks and 64.2% in the clearance revolute joint maximum contact force.
{"title":"Reducing the undesirable effects of the planar conjugate cam linkage mechanism with multiple clearances","authors":"Congpeng Chen, Jiangmin Mao, Yingdan Zhu, Guanjun Bao","doi":"10.1177/09544062241259612","DOIUrl":"https://doi.org/10.1177/09544062241259612","url":null,"abstract":"The dynamic behavior of the mechanism is subject to the influence of the clearance in the joints. Existing methods for improving the mechanism’s performance usually focus on one type of clearance joint, ignoring the interaction among multiple different types of clearance joints. To address this gap, an optimization method is proposed to lower adverse impact forces and vibrations in planar conjugate cam linkage mechanisms with cam and revolute clearance joints. The contact force model of the clearance joint is formulated using the Flores contact force model and the modified Coulomb friction model. Based on these models and Lagrange’s equation of the first kind, the dynamic equations of the mechanism describe its behavior during operation. The optimization method is aimed at minimizing the peak of the mechanism’s maximum absolute acceleration by employing the whale optimization algorithm (WOA) to optimize the length of the linkages and the initial angles between them. Additionally, the slider stroke serves as a constraint function. Finally, the effectiveness of the approach is validated using an example of a planar conjugate cam linkage mechanism. Simulation results show a reduction of 65.8% in acceleration peaks and 64.2% in the clearance revolute joint maximum contact force.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782925","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}
Tower cranes are widely applied in outdoor environments with inevitable external disturbances, which can reduce transportation efficiency and safety. To improve the transient control performance of the tower crane when transporting goods and to guarantee good robustness, this paper designs an adaptive sliding mode Anti-swing control method based on a nonlinear disturbance observer. Firstly, a 4-DOF tower crane error dynamics model considering external disturbances and air friction is established, and then, a nonlinear disturbance observer is designed to estimate the aggregate disturbance. Further, a disturbance effect indicator (DEI) is set to judge the advantages and disadvantages of the disturbance effect on the tower crane system from a new perspective. Finally, beneficial disturbance effects are organically combined with a sliding mode control method possessing an adaptive mechanism to eliminate payload swing by introducing favorable interference. Using Lyapunov stability analysis in conjunction with the LaSalle invariance principle, the closed-loop system is shown to be asymptotically stable. Simulation results show that the controller proposed in this paper achieves accurate positioning by driving the trolley and the jib, and at the same time, can keep the payload swing angle slight during the working process and eliminate the payload swing angle after accurate positioning. Moreover, it is also robust in the face of external disturbances and system parameter variations.
{"title":"Adaptive sliding mode anti-swing control of 4-DOF tower crane based on a nonlinear disturbance observer","authors":"Chen Zhao, Qin He, Jibin Zhang, Xiangshuai Zhu, Qinglin Meng","doi":"10.1177/09544062241260710","DOIUrl":"https://doi.org/10.1177/09544062241260710","url":null,"abstract":"Tower cranes are widely applied in outdoor environments with inevitable external disturbances, which can reduce transportation efficiency and safety. To improve the transient control performance of the tower crane when transporting goods and to guarantee good robustness, this paper designs an adaptive sliding mode Anti-swing control method based on a nonlinear disturbance observer. Firstly, a 4-DOF tower crane error dynamics model considering external disturbances and air friction is established, and then, a nonlinear disturbance observer is designed to estimate the aggregate disturbance. Further, a disturbance effect indicator (DEI) is set to judge the advantages and disadvantages of the disturbance effect on the tower crane system from a new perspective. Finally, beneficial disturbance effects are organically combined with a sliding mode control method possessing an adaptive mechanism to eliminate payload swing by introducing favorable interference. Using Lyapunov stability analysis in conjunction with the LaSalle invariance principle, the closed-loop system is shown to be asymptotically stable. Simulation results show that the controller proposed in this paper achieves accurate positioning by driving the trolley and the jib, and at the same time, can keep the payload swing angle slight during the working process and eliminate the payload swing angle after accurate positioning. Moreover, it is also robust in the face of external disturbances and system parameter variations.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782934","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241258909
Yongjun Shi, Yongzhuo Gao, Weiqi Lin, Long He, Xiwang Mao, Yi Long, Wei Dong
In the field of rehabilitation engineering, wearable robots for upper limbs tend to help powerless arms of patients smoothly complete daily activities. Compared with traditional rigid exoskeleton, soft exosuit takes the advantage of high movement flexibility and relatively compact structure so that it could be a more adaptive and compliant alternative for the elder and the disabled. In this study, a novel dual-arm exosuit is proposed to provide active assistance for multiple joints through bidirectional cable-driven modules. Several Bowden cables achieve power transmission from actuators mounted on the back to shoulders and elbows. The actuator is designed with reference to the principle of differential mechanism, in order to automatically preload both cables wrapped around it, generate assistive torque in two opposite rotation directions of a joint, and keep the human-robot interaction as safe as possible. This study adopts the constant torque control to assist in the pre-tightening process, and develop a model-based control strategy for bidirectional joint motion enhancement according to mathematical models of the human-robot system. The experimental results demonstrate that the prototype can impose pretension on each cable, and offer enough support on the joint according to the wearers’ demands.
{"title":"A cable-driven exosuit for upper limbs: design, control, and evaluation","authors":"Yongjun Shi, Yongzhuo Gao, Weiqi Lin, Long He, Xiwang Mao, Yi Long, Wei Dong","doi":"10.1177/09544062241258909","DOIUrl":"https://doi.org/10.1177/09544062241258909","url":null,"abstract":"In the field of rehabilitation engineering, wearable robots for upper limbs tend to help powerless arms of patients smoothly complete daily activities. Compared with traditional rigid exoskeleton, soft exosuit takes the advantage of high movement flexibility and relatively compact structure so that it could be a more adaptive and compliant alternative for the elder and the disabled. In this study, a novel dual-arm exosuit is proposed to provide active assistance for multiple joints through bidirectional cable-driven modules. Several Bowden cables achieve power transmission from actuators mounted on the back to shoulders and elbows. The actuator is designed with reference to the principle of differential mechanism, in order to automatically preload both cables wrapped around it, generate assistive torque in two opposite rotation directions of a joint, and keep the human-robot interaction as safe as possible. This study adopts the constant torque control to assist in the pre-tightening process, and develop a model-based control strategy for bidirectional joint motion enhancement according to mathematical models of the human-robot system. The experimental results demonstrate that the prototype can impose pretension on each cable, and offer enough support on the joint according to the wearers’ demands.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782928","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241260713
Pham Van Lieu, Nguyen Trong Hai
The article combines the finite element method with the novel-type sinusoidal hyperbolic shear strain hypothesis to study the static bending response and dynamics of nanoplates subjected to simultaneous mechanical, thermal, and voltage loads. The plate equilibrium equation is developed from the concept of potential work, which takes into account the impact of the flexoelectricity effect. The formula for the electric field that is operating on the plate becomes more complicated when the new strain theory is used; nonetheless, its complexity adequately displays both the mechanical and electrical components, as well as the electromechanical components, that are acting on the nanoplate. The computational theory is also verified through comparison with previously published data. The article also investigates the influence of some material factors, temperature, and external voltage on displacement response and charge polarization of nanoplates in the case of subjecting to static and time-varying loads. The results demonstrate that the thermomechanical-electrical response of nanoplates is dependent on numerous factors, which serve as the foundation for the practical design and application of nanostructures.
{"title":"Bending and linear dynamic response of nanoplates in thermal environment","authors":"Pham Van Lieu, Nguyen Trong Hai","doi":"10.1177/09544062241260713","DOIUrl":"https://doi.org/10.1177/09544062241260713","url":null,"abstract":"The article combines the finite element method with the novel-type sinusoidal hyperbolic shear strain hypothesis to study the static bending response and dynamics of nanoplates subjected to simultaneous mechanical, thermal, and voltage loads. The plate equilibrium equation is developed from the concept of potential work, which takes into account the impact of the flexoelectricity effect. The formula for the electric field that is operating on the plate becomes more complicated when the new strain theory is used; nonetheless, its complexity adequately displays both the mechanical and electrical components, as well as the electromechanical components, that are acting on the nanoplate. The computational theory is also verified through comparison with previously published data. The article also investigates the influence of some material factors, temperature, and external voltage on displacement response and charge polarization of nanoplates in the case of subjecting to static and time-varying loads. The results demonstrate that the thermomechanical-electrical response of nanoplates is dependent on numerous factors, which serve as the foundation for the practical design and application of nanostructures.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782929","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241257086
Xing Han, Lei Feng, Chang Li, Han Sun
Laser-MIG hybrid welding is an energy-saving welding process. It is of great significance to quantitatively investigate the instantaneous evolution of temperature and stress in the process of hybrid welding to reveal the mechanism of hybrid welding and improve welding quality. Existing studies lack systematic analysis of temperature field and thermal stress field of laser-MIG hybrid welding of stainless steel, and there are relatively few literatures comparing traditional MIG welding and hybrid welding process. In this paper, the thermal mechanical coupling model of laser-MIG hybrid welding of SUS301L-HT stainless steel was established by numerical simulation. The temperature field, thermal stress field, and residual stress field distribution of the hybrid welding were quantitatively revealed, and compared with traditional MIG welding. The calculation results show that compared with the traditional single-heat source MIG welding, the center temperature of the laser-MIG hybrid welding pool is higher, and the peak temperature can reach 3386 K. Compared with the traditional MIG arc welding, the thermal stress distribution of laser-MIG hybrid welding is more uniform and the thermal stress value is lower at the same time. The distribution trend of residual stress in the two welding processes is similar. The overall residual stress in hybrid welding is relatively small, and the transverse residual stress and the thickness residual stress both have peak values in the heat affected zone. The research can provide theoretical reference and guidance for optimizing stainless steel hybrid welding process and improving welding quality and efficiency.
{"title":"Numerical simulation of thermo-mechanical coupling in laser-MIG hybrid welding utilizing dual volume heat sources","authors":"Xing Han, Lei Feng, Chang Li, Han Sun","doi":"10.1177/09544062241257086","DOIUrl":"https://doi.org/10.1177/09544062241257086","url":null,"abstract":"Laser-MIG hybrid welding is an energy-saving welding process. It is of great significance to quantitatively investigate the instantaneous evolution of temperature and stress in the process of hybrid welding to reveal the mechanism of hybrid welding and improve welding quality. Existing studies lack systematic analysis of temperature field and thermal stress field of laser-MIG hybrid welding of stainless steel, and there are relatively few literatures comparing traditional MIG welding and hybrid welding process. In this paper, the thermal mechanical coupling model of laser-MIG hybrid welding of SUS301L-HT stainless steel was established by numerical simulation. The temperature field, thermal stress field, and residual stress field distribution of the hybrid welding were quantitatively revealed, and compared with traditional MIG welding. The calculation results show that compared with the traditional single-heat source MIG welding, the center temperature of the laser-MIG hybrid welding pool is higher, and the peak temperature can reach 3386 K. Compared with the traditional MIG arc welding, the thermal stress distribution of laser-MIG hybrid welding is more uniform and the thermal stress value is lower at the same time. The distribution trend of residual stress in the two welding processes is similar. The overall residual stress in hybrid welding is relatively small, and the transverse residual stress and the thickness residual stress both have peak values in the heat affected zone. The research can provide theoretical reference and guidance for optimizing stainless steel hybrid welding process and improving welding quality and efficiency.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782924","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}
Natural or buoyant convection flow is an exemplary heat transfer phenomenon, with growing applications in various industries. This article develops a new algorithm, which models and solves the buoyancy-driven turbulent flows in enclosures more accurately than the past similar solvers. A careful literature review shows that the past existing approaches have mostly had serious limitations to apply their algorithms to buoyancy-driven flows with high temperature differences magnitude because of employing the classical Boussinesq approximation. As the novelty of this study, it benefits from a momentum-based variable approach in the context of the semi-implicit method for the pressure linked equations (SIMPLE) algorithm, which lets it accurately solve the strong compressible buoyant flows with high temperature differences. The algorithm is applied to both the Navier-Stokes and the accompanied turbulent flow governing equations using OpenFOAM 4.1 as the platform. To validate the developed algorithm, the current results are compared with experimental data in both square and tall cavities considering low (8.6 × 105), high (1.43 × 106), and very high (1.58 × 109) Rayleigh numbers. As the major contribution of this work, it improves the accuracy of the thermo-buoyant turbulent flow prediction at both low and high Rayleigh numbers. All test cases are carried out employing two different turbulence models of k-ω and k-ε. Furthermore, comparing the results of the present non-Boussinesq algorithm and those of the past developed methods with the experimental data, it is shown that the present algorithm provides a more accurate prediction for the temperature field, that is, <10% differences with the experimental data. Moreover, the present maximum velocity results surpass the solution of the past numerical methods and show <3% differences with the experimental data.
{"title":"Applying a momentum-based variable formulation in the SIMPLE algorithm to numerically solve thermo-buoyant turbulent flow in enclosures","authors":"Farshad Rahimi, Davood Rashtchian, Masoud Darbandi","doi":"10.1177/09544062241261191","DOIUrl":"https://doi.org/10.1177/09544062241261191","url":null,"abstract":"Natural or buoyant convection flow is an exemplary heat transfer phenomenon, with growing applications in various industries. This article develops a new algorithm, which models and solves the buoyancy-driven turbulent flows in enclosures more accurately than the past similar solvers. A careful literature review shows that the past existing approaches have mostly had serious limitations to apply their algorithms to buoyancy-driven flows with high temperature differences magnitude because of employing the classical Boussinesq approximation. As the novelty of this study, it benefits from a momentum-based variable approach in the context of the semi-implicit method for the pressure linked equations (SIMPLE) algorithm, which lets it accurately solve the strong compressible buoyant flows with high temperature differences. The algorithm is applied to both the Navier-Stokes and the accompanied turbulent flow governing equations using OpenFOAM 4.1 as the platform. To validate the developed algorithm, the current results are compared with experimental data in both square and tall cavities considering low (8.6 × 10<jats:sup>5</jats:sup>), high (1.43 × 10<jats:sup>6</jats:sup>), and very high (1.58 × 10<jats:sup>9</jats:sup>) Rayleigh numbers. As the major contribution of this work, it improves the accuracy of the thermo-buoyant turbulent flow prediction at both low and high Rayleigh numbers. All test cases are carried out employing two different turbulence models of k-ω and k-ε. Furthermore, comparing the results of the present non-Boussinesq algorithm and those of the past developed methods with the experimental data, it is shown that the present algorithm provides a more accurate prediction for the temperature field, that is, <10% differences with the experimental data. Moreover, the present maximum velocity results surpass the solution of the past numerical methods and show <3% differences with the experimental data.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782931","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}
Pub Date : 2024-07-25DOI: 10.1177/09544062241260718
Christopher Bock, Brett D Ellis, Masoud Rais-Rohani
Process-induced deviation from the intended geometry is a challenge in additive manufacturing, particularly with increasing part size. To address this problem, a modeling workflow was created for polymer-extrusion Big Area Additive Manufacturing (BAAM) using sequentially-coupled thermal and mechanical finite element simulations with focus on stress state and component deformation. Thermal simulations oriented and placed material via an Abaqus/Standard user subroutine and accounted for conductive, convective, and radiative heat transfer to calculate thermal evolution. Mechanical simulations utilized the calculated thermal evolution to calculate thermally-induced stresses and deformations. Simulations were validated via experimental thermal and geometric data from a 3319.1 mm × 235.0 mm × 1016.0 mm corrugated wall printed from carbon fiber reinforced PETg (cfrPETg). Simulated and experimental temperatures were within [Formula: see text] K; simulated and experimental deformations of the lower surface were within 5% (i.e. 2.74 and 2.62 mm, respectively) after accounting for a 0.20-mm ridge attributable to an experimental build plate discontinuity. Lastly, a first-order sensitivity analysis examined the influence of different material properties on warpage and residual stress. For the factors and levels considered, coefficient of thermal expansion (CTE) had the greatest influence on warpage, thus identifying the characterization and tailoring of CTEs as important research topics.
在增材制造过程中，尤其是在零件尺寸不断增大的情况下，工艺引起的几何形状偏差是一个挑战。为了解决这个问题，我们为聚合物挤压大面积增材制造（BAAM）创建了一个建模工作流程，使用顺序耦合的热和机械有限元模拟，重点关注应力状态和部件变形。热仿真通过 Abaqus/Standard 用户子程序确定材料的方向和位置，并考虑传导、对流和辐射传热以计算热演化。机械模拟利用计算出的热演变来计算热引起的应力和变形。模拟结果通过一个由碳纤维增强 PETg（cfrPETg）打印而成的 3319.1 mm × 235.0 mm × 1016.0 mm 波纹壁的实验热和几何数据进行了验证。模拟温度和实验温度都在 [公式：见正文] K 以内；在考虑了因实验构建板不连续性造成的 0.20 毫米脊之后，下表面的模拟变形和实验变形都在 5% 以内（即分别为 2.74 毫米和 2.62 毫米）。最后，一阶敏感性分析检验了不同材料特性对翘曲和残余应力的影响。在所考虑的因素和水平中，热膨胀系数（CTE）对翘曲的影响最大，因此，CTE 的表征和定制成为重要的研究课题。
{"title":"Process-informed simulation of Big-Area Additive Manufacturing (BAAM) of polymers","authors":"Christopher Bock, Brett D Ellis, Masoud Rais-Rohani","doi":"10.1177/09544062241260718","DOIUrl":"https://doi.org/10.1177/09544062241260718","url":null,"abstract":"Process-induced deviation from the intended geometry is a challenge in additive manufacturing, particularly with increasing part size. To address this problem, a modeling workflow was created for polymer-extrusion Big Area Additive Manufacturing (BAAM) using sequentially-coupled thermal and mechanical finite element simulations with focus on stress state and component deformation. Thermal simulations oriented and placed material via an Abaqus/Standard user subroutine and accounted for conductive, convective, and radiative heat transfer to calculate thermal evolution. Mechanical simulations utilized the calculated thermal evolution to calculate thermally-induced stresses and deformations. Simulations were validated via experimental thermal and geometric data from a 3319.1 mm × 235.0 mm × 1016.0 mm corrugated wall printed from carbon fiber reinforced PETg (cfrPETg). Simulated and experimental temperatures were within [Formula: see text] K; simulated and experimental deformations of the lower surface were within 5% (i.e. 2.74 and 2.62 mm, respectively) after accounting for a 0.20-mm ridge attributable to an experimental build plate discontinuity. Lastly, a first-order sensitivity analysis examined the influence of different material properties on warpage and residual stress. For the factors and levels considered, coefficient of thermal expansion (CTE) had the greatest influence on warpage, thus identifying the characterization and tailoring of CTEs as important research topics.","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782933","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}
Pub Date : 2024-07-24DOI: 10.1177/09544062241256589
Sarada Prasad Parida, Pankaj Charan Jena, Sudhansu Ranjan Das, Ali Basem, Ajit Kumar Khatua, Ammar H Elsheikh
Usually, the laminated-composite-plates (LCPs) are strengthened by altering the constituents. The use of nano-particles as filler is a new approach in this regard. Here, flyash and graphene are used as fillers in epoxy-based woven E-glass fabric-reinforced LCPs. The LCPs are often subjected to moving mass/load in use and it becomes necessary to study their stability. Further, foundation support has an important role in structural stability. Here, the response of LCPs resting on elastic foundations to a moving load is studied. A fifth-order plate-theory based on Eringen’s non-local model for LCPS with filler is followed and validated with finite-element-analysis (FEA) and other literature. The effect of the intensity of moving mass, its position on LCP, speed, the material variant, foundation constant, and damping ratio on the dynamicity of LCPs is then reported. It is observed that masses moving on the LCP induce instability with frequency loss (FL) and increased dynamic amplitude ratio (DAR) in vibration. LCPs with the least FL and maximum DAR are more stable. Further, LCP with flyash (FLCP) is highly unstable with 18.5% FL for 10% moving load and GLCP (LCP with graphene) is the most stable (6% loss). Meanwhile, the DAR for GLCP is maximum (16.13%) at 140 m/s critical velocity of moving mass. Increasing the Pasternak co-efficient increases foundation stiffness and frequency whereas Winkler’s parameter has a negligible effect. The foundation without damping oscillates more critically (with a maximized DAR of 1.92) in comparison to the foundation with a damping ratio of 0.1 (DAR of 1.17).
{"title":"Transverse vibration of laminated-composite-plates with fillers under moving mass rested on elastic foundation using higher order shear deformation theory","authors":"Sarada Prasad Parida, Pankaj Charan Jena, Sudhansu Ranjan Das, Ali Basem, Ajit Kumar Khatua, Ammar H Elsheikh","doi":"10.1177/09544062241256589","DOIUrl":"https://doi.org/10.1177/09544062241256589","url":null,"abstract":"Usually, the laminated-composite-plates (LCPs) are strengthened by altering the constituents. The use of nano-particles as filler is a new approach in this regard. Here, flyash and graphene are used as fillers in epoxy-based woven E-glass fabric-reinforced LCPs. The LCPs are often subjected to moving mass/load in use and it becomes necessary to study their stability. Further, foundation support has an important role in structural stability. Here, the response of LCPs resting on elastic foundations to a moving load is studied. A fifth-order plate-theory based on Eringen’s non-local model for LCPS with filler is followed and validated with finite-element-analysis (FEA) and other literature. The effect of the intensity of moving mass, its position on LCP, speed, the material variant, foundation constant, and damping ratio on the dynamicity of LCPs is then reported. It is observed that masses moving on the LCP induce instability with frequency loss (FL) and increased dynamic amplitude ratio (DAR) in vibration. LCPs with the least FL and maximum DAR are more stable. Further, LCP with flyash (FLCP) is highly unstable with 18.5% FL for 10% moving load and GLCP (LCP with graphene) is the most stable (6% loss). Meanwhile, the DAR for GLCP is maximum (16.13%) at 140 m/s critical velocity of moving mass. Increasing the Pasternak co-efficient increases foundation stiffness and frequency whereas Winkler’s parameter has a negligible effect. The foundation without damping oscillates more critically (with a maximized DAR of 1.92) in comparison to the foundation with a damping ratio of 0.1 (DAR of 1.17).","PeriodicalId":20558,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783017","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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