Luke Jurmu, D. Robinette, Jason Blough, Craig Reynolds
A unique torque converter test setup was used to measure the torque transmissibility frequency response function of four torque converter clutch dampers using a stepped, multi-sine-tone, excitation technique. The four torque converter clutch dampers were modeled using a lumped parameter technique, and the damper parameters of stiffness, damping, and friction were estimated using a manual, iterative parameter estimation process. The final damper parameters were selected such that the natural frequency and damping ratio of the simulated torque transmissibility frequency response functions were within 10% and 20% error, respectively, of the experimental modal parameters. This target was achieved for all but one of the tested dampers. The damper models include stiffness nonlinearities, and a speed-dependent friction torque due to centrifugal loading of the damper springs. Recommendations include further testing to separate the coulomb friction mechanism from the viscous damping mechanism, testing with the torque converter operating in open mode, and tests on a series of customized dampers with centrifugal pendulum absorber hardware.
{"title":"Torque Converter Dynamic Characterization Using Torque\u0000 Transmissibility Frequency Response Functions: Locked Clutch\u0000 Operation","authors":"Luke Jurmu, D. Robinette, Jason Blough, Craig Reynolds","doi":"10.4271/15-17-02-0010","DOIUrl":"https://doi.org/10.4271/15-17-02-0010","url":null,"abstract":"A unique torque converter test setup was used to measure the torque\u0000 transmissibility frequency response function of four torque converter clutch\u0000 dampers using a stepped, multi-sine-tone, excitation technique. The four torque\u0000 converter clutch dampers were modeled using a lumped parameter technique, and\u0000 the damper parameters of stiffness, damping, and friction were estimated using a\u0000 manual, iterative parameter estimation process. The final damper parameters were\u0000 selected such that the natural frequency and damping ratio of the simulated\u0000 torque transmissibility frequency response functions were within 10% and 20%\u0000 error, respectively, of the experimental modal parameters. This target was\u0000 achieved for all but one of the tested dampers. The damper models include\u0000 stiffness nonlinearities, and a speed-dependent friction torque due to\u0000 centrifugal loading of the damper springs. Recommendations include further\u0000 testing to separate the coulomb friction mechanism from the viscous damping\u0000 mechanism, testing with the torque converter operating in open mode, and tests\u0000 on a series of customized dampers with centrifugal pendulum absorber\u0000 hardware.","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aerodynamic performance of automobile especially drag and lift was largely determined by the wake flow, which is three-dimensional, unsteady, and turbulent. The styling of the rear back of the vehicle body has much influence on the wake flow structure, typically including squareback, notchback, and hatchback. Bi-stability of the wake flow of vehicle body makes the aerodynamic force oscillating, which affects the energy consumption and driving stability. This article investigates the bi-stability of wake flow of a hatchback SUV in full-scale automotive wind tunnel. Both aerodynamic force and surface pressure on the rear back of the vehicle were measured. Time series of aerodynamic force and pressure footprint are used to confirm the existence of bi-stability. The effects of some sensitive factors on the bi-stability have been analyzed. The results show that for the given condition with bi-stability phenomenon existing, the change of drag and lift can be 6.36% and 111%, respectively. The bi-stability of wake of the tested hatchback SUV is related to the change of flow structure in the wake of the vehicle, which can be explained by the drag crisis of hatchback vehicle under critical slant angle.
汽车的空气动力性能，尤其是阻力和升力，在很大程度上取决于尾流，而尾流是三维的、不稳定的和湍流的。车身后部的造型对尾流结构有很大影响，通常包括方背式、槽背式和掀背式。车身尾流的双稳态会使空气动力产生振荡，从而影响能量消耗和行驶稳定性。本文在全尺寸汽车风洞中研究了掀背式 SUV 车身尾流的双稳定性。测量了车辆后部的空气动力和表面压力。空气动力和压力足迹的时间序列用于证实双稳态的存在。分析了一些敏感因素对双稳定性的影响。结果表明，在存在双稳态现象的给定条件下，阻力和升力的变化分别为 6.36% 和 111%。被测掀背式越野车尾流的双稳态现象与车辆尾流的流动结构变化有关，这可以用临界斜角下掀背式车辆的阻力危机来解释。
{"title":"Bi-stability of the Wake Flow of a Hatchback Car under Zero Yaw Angle\u0000 Condition","authors":"Haidong Yuan, Haiyang Wang, Guangjun Fan","doi":"10.4271/15-17-02-0007","DOIUrl":"https://doi.org/10.4271/15-17-02-0007","url":null,"abstract":"The aerodynamic performance of automobile especially drag and lift was largely\u0000 determined by the wake flow, which is three-dimensional, unsteady, and\u0000 turbulent. The styling of the rear back of the vehicle body has much influence\u0000 on the wake flow structure, typically including squareback, notchback, and\u0000 hatchback. Bi-stability of the wake flow of vehicle body makes the aerodynamic\u0000 force oscillating, which affects the energy consumption and driving stability.\u0000 This article investigates the bi-stability of wake flow of a hatchback SUV in\u0000 full-scale automotive wind tunnel. Both aerodynamic force and surface pressure\u0000 on the rear back of the vehicle were measured. Time series of aerodynamic force\u0000 and pressure footprint are used to confirm the existence of bi-stability. The\u0000 effects of some sensitive factors on the bi-stability have been analyzed. The\u0000 results show that for the given condition with bi-stability phenomenon existing,\u0000 the change of drag and lift can be 6.36% and 111%, respectively. The\u0000 bi-stability of wake of the tested hatchback SUV is related to the change of\u0000 flow structure in the wake of the vehicle, which can be explained by the drag\u0000 crisis of hatchback vehicle under critical slant angle.","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139010705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhipeng Liu, Zhiming Cui, Wonhyck Lee, Jeongmu Heo, Jihun Park, Jaehyung Ju
The nonreciprocal elastic behavior of flexible spokes is essential for designing a top-loading condition of nonpneumatic wheels to distribute the vehicle load throughout the upper circumferential region of a wheel to replicate the loading mode of their pneumatic counterparts. However, most ad hoc spoke designs had been conducted without considering the top-loading mechanics. Moreover, minimizing the stress concentration on the spokes is also significant for preventing potential failures; however, modification of the geometry to reduce the local stress on the spokes has not yet been studied. In this work, we investigate the effect of nonreciprocal elastic behaviors of curved spokes on the top-loading distribution of nonpneumatic wheels. We also study the geometric effect of nonuniform curved spokes on reducing the local stress concentration. Curved beam spokes with greater curvature can contribute to a high top-loading ratio of nonpneumatic wheels. The nonuniform thickness of curved spokes with the spoke’s ends and center regions can reduce the local stress level by up to 24%. Our design method with varying curvature and nonuniformity of the curved spokes can provide significant design guidelines for nonpneumatic wheels for determining the top-loading ratio, tuning the vertical stiffness, and minimizing local stress on the spokes.
{"title":"Nonreciprocal Elasticity and Nonuniform Thickness of Curved Spokes on\u0000 the Top-Loading Ratio, Vertical Stiffness, and Local Stress of Nonpneumatic\u0000 Wheels","authors":"Zhipeng Liu, Zhiming Cui, Wonhyck Lee, Jeongmu Heo, Jihun Park, Jaehyung Ju","doi":"10.4271/15-17-02-0008","DOIUrl":"https://doi.org/10.4271/15-17-02-0008","url":null,"abstract":"The nonreciprocal elastic behavior of flexible spokes is essential for designing\u0000 a top-loading condition of nonpneumatic wheels to distribute the vehicle load\u0000 throughout the upper circumferential region of a wheel to replicate the loading\u0000 mode of their pneumatic counterparts. However, most ad hoc spoke designs had\u0000 been conducted without considering the top-loading mechanics. Moreover,\u0000 minimizing the stress concentration on the spokes is also significant for\u0000 preventing potential failures; however, modification of the geometry to reduce\u0000 the local stress on the spokes has not yet been studied. In this work, we\u0000 investigate the effect of nonreciprocal elastic behaviors of curved spokes on\u0000 the top-loading distribution of nonpneumatic wheels. We also study the geometric\u0000 effect of nonuniform curved spokes on reducing the local stress concentration.\u0000 Curved beam spokes with greater curvature can contribute to a high top-loading\u0000 ratio of nonpneumatic wheels. The nonuniform thickness of curved spokes with the\u0000 spoke’s ends and center regions can reduce the local stress level by up to 24%.\u0000 Our design method with varying curvature and nonuniformity of the curved spokes\u0000 can provide significant design guidelines for nonpneumatic wheels for\u0000 determining the top-loading ratio, tuning the vertical stiffness, and minimizing\u0000 local stress on the spokes.","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138598451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
All two-wheeler industries validate their product’s fatigue life on proving track before heading for mass production. Proving test tracks are made to simulate the end-user environment in order to find out the possible fatigue failures during each development stage of vehicle design, which in turn helps the CAE analysts to verify the design before it goes to the end-user hands. In this article we present the design and failure analysis of sub-frame assembly of motorbike observed during the accelerated fatigue test on proving track. Sub-frame main rod was found broken exactly between two weld endings during fatigue test before reaching 6% of the target fatigue life. Possible causes of sub-frame failures have been identified/analyzed in detail using fish bone diagram. A finite element analysis (FEA) model of sub-frame assembly was developed and a random response analysis was carried out on initial design. Acceleration input loads measured from test track have been given at the sub-frame mounting points to calculate output responses. Output responses show a high magnitude of amplitude stresses on the sub-frame main rod exactly where track test failure occurred. Fishbone diagram analysis indicates that the improper design of the stay bracket, stress concentrations regions in the design, improper weld/tool fixture, and method of welding could be reasons for failure. FEA on the final design concept shows a reduction of amplitude stress to 49% and an increase of fatigue life to an infinite limit as compared to initial design.
{"title":"Design and Failure Analysis of Motorbike Sub-frame Using Finite\u0000 Element Analysis","authors":"Ashish Sharma, Saharash Khare","doi":"10.4271/15-17-02-0006","DOIUrl":"https://doi.org/10.4271/15-17-02-0006","url":null,"abstract":"All two-wheeler industries validate their product’s fatigue life on proving track\u0000 before heading for mass production. Proving test tracks are made to simulate the\u0000 end-user environment in order to find out the possible fatigue failures during\u0000 each development stage of vehicle design, which in turn helps the CAE analysts\u0000 to verify the design before it goes to the end-user hands. In this article we\u0000 present the design and failure analysis of sub-frame assembly of motorbike\u0000 observed during the accelerated fatigue test on proving track. Sub-frame main\u0000 rod was found broken exactly between two weld endings during fatigue test before\u0000 reaching 6% of the target fatigue life. Possible causes of sub-frame failures\u0000 have been identified/analyzed in detail using fish bone diagram. A finite\u0000 element analysis (FEA) model of sub-frame assembly was developed and a random\u0000 response analysis was carried out on initial design. Acceleration input loads\u0000 measured from test track have been given at the sub-frame mounting points to\u0000 calculate output responses. Output responses show a high magnitude of amplitude\u0000 stresses on the sub-frame main rod exactly where track test failure occurred.\u0000 Fishbone diagram analysis indicates that the improper design of the stay\u0000 bracket, stress concentrations regions in the design, improper weld/tool\u0000 fixture, and method of welding could be reasons for failure. FEA on the final\u0000 design concept shows a reduction of amplitude stress to 49% and an increase of\u0000 fatigue life to an infinite limit as compared to initial design.","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138601062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philipp Uhl, Alexander Schell, Roland Ewert, Jan Delfs
The broadband aeroacoustics of a side mirror is investigated with a stochastic noise source method and compared to scale-resolving simulations. The setup based on an already existing work includes two geometrical variants with a plain series side mirror and a modified mirror with a forward-facing step mounted on the inner side. The aeroacoustic near- and farfield is computed by a hydrodynamic–acoustic splitting approach by means of a perturbed convective wave equation. Aeroacoustic source terms are computed by the Fast Random Particle-Mesh method, a stochastic noise source method modeling velocity fluctuations in time domain based on time-averaged turbulence statistics. Three RANS models are used to provide input data for the Fast Random Particle-Mesh method with fundamental differences in local flow phenomena. Results of aeroacoustics simulations excited by the Fast Random Particle-Mesh method based on well-matching RANS data are in good agreement to the scale-resolving simulations in the integral acoustic Delta on the side window induced by the different side mirror geometries. For relative levels in between the variations, the robustness of the Fast Random Particle-Mesh method can be shown with secondary influences on the choice of the integral length scale. Absolute levels are only achieved with an adaptation of the length scale from literature. Two different RANS models with a missing separation bubble on the mirror or an overestimated wake flow show a good agreement with the plain series side mirror. However, they fail at computing the Delta to the step variant due to the missing amplification of the local turbulent kinetic energy interacting with the step and downstream mirror surfaces. Computational aeroacoustics simulations excited by the Fast Random Particle-Mesh method method based on RANS data only needs 14% of the computational effort compared to the conventional hybrid RANS-LES approach. This reveals its enormous potential for aeroacoustic broadband noise optimization purposes.
{"title":"Stochastic Noise Sources for Computational Aeroacoustics of a Vehicle Side Mirror","authors":"Philipp Uhl, Alexander Schell, Roland Ewert, Jan Delfs","doi":"10.4271/15-17-01-0005","DOIUrl":"https://doi.org/10.4271/15-17-01-0005","url":null,"abstract":"<div>The broadband aeroacoustics of a side mirror is investigated with a stochastic noise source method and compared to scale-resolving simulations. The setup based on an already existing work includes two geometrical variants with a plain series side mirror and a modified mirror with a forward-facing step mounted on the inner side. The aeroacoustic near- and farfield is computed by a hydrodynamic–acoustic splitting approach by means of a perturbed convective wave equation. Aeroacoustic source terms are computed by the Fast Random Particle-Mesh method, a stochastic noise source method modeling velocity fluctuations in time domain based on time-averaged turbulence statistics. Three RANS models are used to provide input data for the Fast Random Particle-Mesh method with fundamental differences in local flow phenomena. Results of aeroacoustics simulations excited by the Fast Random Particle-Mesh method based on well-matching RANS data are in good agreement to the scale-resolving simulations in the integral acoustic Delta on the side window induced by the different side mirror geometries. For relative levels in between the variations, the robustness of the Fast Random Particle-Mesh method can be shown with secondary influences on the choice of the integral length scale. Absolute levels are only achieved with an adaptation of the length scale from literature. Two different RANS models with a missing separation bubble on the mirror or an overestimated wake flow show a good agreement with the plain series side mirror. However, they fail at computing the Delta to the step variant due to the missing amplification of the local turbulent kinetic energy interacting with the step and downstream mirror surfaces. Computational aeroacoustics simulations excited by the Fast Random Particle-Mesh method method based on RANS data only needs 14% of the computational effort compared to the conventional hybrid RANS-LES approach. This reveals its enormous potential for aeroacoustic broadband noise optimization purposes.</div>","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135290523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the use of a road weather model (RWM) as a virtual sensing technique to assist autonomous vehicles (AVs) in driving safely, even in challenging winter weather conditions. In particular, we investigate how the AVs can remain within their operational design domain (ODD) for a greater duration and minimize unnecessary exits. As the road surface temperature (RST) is one of the most critical variables for driving safety in winter weather, we explore the use of the vehicle’s air temperature (AT) sensor as an indicator of RST. Data from both Road Weather Information System (RWIS) stations and vehicles measuring AT and road conditions were used. Results showed that using only the AT sensor as an indicator of RST could result in a high number of false warnings, but the accuracy improved significantly with the use of an RWM to model the RST. ROC-curve analysis resulted in an AUC value of 0.917 with the AT sensor and 0.985 with the RWM, while the true positive rate increased from 67% to 94%. The study also highlights the limitations of relying on dashboard cameras to detect slippery driving conditions, as it may not be accurate enough to distinguish between, for example, wet and icy road conditions. As winter maintenance often prevents slippery roads, the vehicles often measured wet or moist roads, despite RST < 0°C. Our calculations indicate that the vehicle should be able to detect 93% of slippery occasions but the rate of false warnings will be as high as 73%, if using a dashboard camera along with the AT sensor. There are clear benefits of using a RWM to improve road safety and reduce the risk of accidents due to slippery conditions, allowing AVs to safely extend their time within their ODD. The findings of this study provide valuable insights for the development of AVs and their response to slippery road conditions.
{"title":"Enhancing Autonomous Vehicle Safety in Cold Climates by Using a Road Weather Model: Safely Avoiding Unnecessary Operational Design Domain Exits","authors":"Esben Almkvist, Mariana Alves David, Jesper Landmér Pedersen, Rebecca Lewis-Lück, Yumei Hu","doi":"10.4271/15-17-01-0004","DOIUrl":"https://doi.org/10.4271/15-17-01-0004","url":null,"abstract":"<div>This study investigates the use of a road weather model (RWM) as a virtual sensing technique to assist autonomous vehicles (AVs) in driving safely, even in challenging winter weather conditions. In particular, we investigate how the AVs can remain within their operational design domain (ODD) for a greater duration and minimize unnecessary exits. As the road surface temperature (RST) is one of the most critical variables for driving safety in winter weather, we explore the use of the vehicle’s air temperature (AT) sensor as an indicator of RST. Data from both Road Weather Information System (RWIS) stations and vehicles measuring AT and road conditions were used. Results showed that using only the AT sensor as an indicator of RST could result in a high number of false warnings, but the accuracy improved significantly with the use of an RWM to model the RST. ROC-curve analysis resulted in an AUC value of 0.917 with the AT sensor and 0.985 with the RWM, while the true positive rate increased from 67% to 94%. The study also highlights the limitations of relying on dashboard cameras to detect slippery driving conditions, as it may not be accurate enough to distinguish between, for example, wet and icy road conditions. As winter maintenance often prevents slippery roads, the vehicles often measured wet or moist roads, despite RST &lt; 0°C. Our calculations indicate that the vehicle should be able to detect 93% of slippery occasions but the rate of false warnings will be as high as 73%, if using a dashboard camera along with the AT sensor. There are clear benefits of using a RWM to improve road safety and reduce the risk of accidents due to slippery conditions, allowing AVs to safely extend their time within their ODD. The findings of this study provide valuable insights for the development of AVs and their response to slippery road conditions.</div>","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136160709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reviewers","authors":"Mohamed El-Sayed","doi":"10.4271/15-16-03-0017","DOIUrl":"https://doi.org/10.4271/15-16-03-0017","url":null,"abstract":"<div>Reviewers</div>","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134909506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tiziano Alberto Giuliacci, Stefano Ballesio, Marco Fainello, Ulrich Mair, Julian King
A valuable quantity for analyzing the lateral dynamics of road vehicles is the side-slip angle, that is, the angle between the vehicle’s longitudinal axis and its speed direction. A reliable real-time side-slip angle value enables several features, such as stability controls, identification of understeer and oversteer conditions, estimation of lateral forces during cornering, or tire grip and wear estimation. Since the direct measurement of this variable can only be done with complex and expensive devices, it is worth trying to estimate it through virtual sensors based on mathematical models. This article illustrates a methodology for real-time on-board estimation of the side-slip angle through a machine learning model (SSE—side-slip estimator). It exploits a recurrent neural network trained and tested via on-road experimental data acquisition. In particular, the machine learning model only uses input signals from a standard road car sensor configuration. The model adaptability to different road conditions and tire wear levels has been verified through a sensitivity analysis and model testing on real-world data proves the robustness and accuracy of the proposed solution achieving a root mean square error (RMSE) of 0.18 deg and a maximum absolute error of 1.52 deg on the test dataset. The proposed model can be considered as a reliable and cheap potential solution for the real-time on-board side-slip angle estimation in serial cars.
{"title":"Recurrent Neural Network Model for On-Board Estimation of the Side-Slip Angle in a Four-Wheel Drive and Steering Vehicle","authors":"Tiziano Alberto Giuliacci, Stefano Ballesio, Marco Fainello, Ulrich Mair, Julian King","doi":"10.4271/15-17-01-0003","DOIUrl":"https://doi.org/10.4271/15-17-01-0003","url":null,"abstract":"<div>A valuable quantity for analyzing the lateral dynamics of road vehicles is the side-slip angle, that is, the angle between the vehicle’s longitudinal axis and its speed direction. A reliable real-time side-slip angle value enables several features, such as stability controls, identification of understeer and oversteer conditions, estimation of lateral forces during cornering, or tire grip and wear estimation. Since the direct measurement of this variable can only be done with complex and expensive devices, it is worth trying to estimate it through virtual sensors based on mathematical models. This article illustrates a methodology for real-time on-board estimation of the side-slip angle through a machine learning model (SSE—side-slip estimator). It exploits a recurrent neural network trained and tested via on-road experimental data acquisition. In particular, the machine learning model only uses input signals from a standard road car sensor configuration. The model adaptability to different road conditions and tire wear levels has been verified through a sensitivity analysis and model testing on real-world data proves the robustness and accuracy of the proposed solution achieving a root mean square error (RMSE) of 0.18 deg and a maximum absolute error of 1.52 deg on the test dataset. The proposed model can be considered as a reliable and cheap potential solution for the real-time on-board side-slip angle estimation in serial cars.</div>","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136011449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, demands of flat wipers have rapidly increased in the vehicle industry due to their simpler structure compared to the conventional wipers. Procedures for evaluating the appropriate metallic flexor geometry, which is one of the major components of the flat wiper, were proposed in the authors’ previous study. However, the computational cost of the aforementioned procedures seems to be unaffordable to the industry. The discrete Winkler model regarding the flexor as the Euler–Bernoulli beam is established as the mathematical model in this study to simulate a flexor compressed against a surface at various wiping angles. The deflection of the beam is solved using a finite difference method, and the calculated contact pressure distributions agree fairly with those based on the corresponding finite element model. Flexor designs are paired with various windshield surfaces to accumulate a sufficiently large simulation database based on the mathematical model. An artificial neural network (ANN) approach is developed to predict contact pressure distributions of the flexor much faster than the mathematical model. Geometry of the curved surface is represented by a shape code obtained via a principal component analysis (PCA) and used in the ANN model. The ANN algorithm is also applied to efficiently evaluate the wiping patterns according to the simulated contact pressure distributions. These patterns are then classified by using a convolutional neural network (CNN) to identify several suitable flexor designs for the specific windshield. The flat wiper suggested by the current procedures is experimentally validated to justify its qualified wiping performances.
{"title":"Applications of Neural Networks to Metallic Flexor Geometry Optimization of Flat Wipers","authors":"Yi-Tzu Chu, Ting-Chuan Huang, Kuo-Chi Liao","doi":"10.4271/15-17-01-0002","DOIUrl":"https://doi.org/10.4271/15-17-01-0002","url":null,"abstract":"<div>In recent years, demands of flat wipers have rapidly increased in the vehicle industry due to their simpler structure compared to the conventional wipers. Procedures for evaluating the appropriate metallic flexor geometry, which is one of the major components of the flat wiper, were proposed in the authors’ previous study. However, the computational cost of the aforementioned procedures seems to be unaffordable to the industry. The discrete Winkler model regarding the flexor as the Euler–Bernoulli beam is established as the mathematical model in this study to simulate a flexor compressed against a surface at various wiping angles. The deflection of the beam is solved using a finite difference method, and the calculated contact pressure distributions agree fairly with those based on the corresponding finite element model. Flexor designs are paired with various windshield surfaces to accumulate a sufficiently large simulation database based on the mathematical model. An artificial neural network (ANN) approach is developed to predict contact pressure distributions of the flexor much faster than the mathematical model. Geometry of the curved surface is represented by a shape code obtained via a principal component analysis (PCA) and used in the ANN model. The ANN algorithm is also applied to efficiently evaluate the wiping patterns according to the simulated contact pressure distributions. These patterns are then classified by using a convolutional neural network (CNN) to identify several suitable flexor designs for the specific windshield. The flat wiper suggested by the current procedures is experimentally validated to justify its qualified wiping performances.</div>","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136193746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the field of thermal protection, detailed three-dimensional computational fluid dynamics (3D-CFD) simulations are widely used to analyze the thermal behavior on a full vehicle level. One target is to identify potential violations of component temperature limits at an early stage of the development process. In battery electric vehicles (BEVs), transient load cases play an increasing role in evaluating components and vehicle systems close to real-world vehicle operation. The state-of-the-art 3D simulation methodologies require significant time and computational effort when running transient load scenarios. One main reason is the conjugate characteristic of the problem, meaning that conduction within the component and convection into the surrounding air occur simultaneously. This requires a detailed consideration of both the fluid and structural domains. Therefore, this article derives a time-efficient simulation methodology for transient component temperatures in electric vehicles. The approach is to extract heat transfer coefficients and reference temperatures from sample flow simulations and to construct convective meta-models. Solid component temperatures are then transiently computed whereby the low-dimensional meta-models provide the convective heat transfer. Dimensional analysis determines the smallest possible parameter space for the meta-modeling. Two different types of meta-models, a scalar regression model and a vector proper orthogonal decomposition (POD) approach, are tested and compared. The study examines at first the applicability of the heat transfer formulation under different flow and component temperature conditions using a generic flat plate test case. A low Biot number (Bi) is crucial to receive accurate temperature predictions as heat transfer coefficients are derived on uniform temperature walls. The methodology is subsequently applied to a sample component in the motor compartment. Measurements on a test rig and a transient load case comparison with a coupled simulation prove the validity of the numerical procedure. Scaling to full-vehicle applications is feasible. The new methodology delivers a highly accurate temperature prediction and increases computation efficiency, especially for sensitivity studies.
{"title":"Enhancing Simulation Efficiency and Quality of Transient Conjugate\u0000 Thermal Problems by Using an Advanced Meta-modeling Approach","authors":"Simon Peissner, B. Weigand","doi":"10.4271/15-16-03-0016","DOIUrl":"https://doi.org/10.4271/15-16-03-0016","url":null,"abstract":"In the field of thermal protection, detailed three-dimensional computational\u0000 fluid dynamics (3D-CFD) simulations are widely used to analyze the thermal\u0000 behavior on a full vehicle level. One target is to identify potential violations\u0000 of component temperature limits at an early stage of the development process. In\u0000 battery electric vehicles (BEVs), transient load cases play an increasing role\u0000 in evaluating components and vehicle systems close to real-world vehicle\u0000 operation. The state-of-the-art 3D simulation methodologies require significant\u0000 time and computational effort when running transient load scenarios. One main\u0000 reason is the conjugate characteristic of the problem, meaning that conduction\u0000 within the component and convection into the surrounding air occur\u0000 simultaneously. This requires a detailed consideration of both the fluid and\u0000 structural domains.\u0000\u0000 \u0000Therefore, this article derives a time-efficient simulation methodology for\u0000 transient component temperatures in electric vehicles. The approach is to\u0000 extract heat transfer coefficients and reference temperatures from sample flow\u0000 simulations and to construct convective meta-models. Solid component\u0000 temperatures are then transiently computed whereby the low-dimensional\u0000 meta-models provide the convective heat transfer. Dimensional analysis\u0000 determines the smallest possible parameter space for the meta-modeling. Two\u0000 different types of meta-models, a scalar regression model and a vector proper\u0000 orthogonal decomposition (POD) approach, are tested and compared.\u0000\u0000 \u0000The study examines at first the applicability of the heat transfer formulation\u0000 under different flow and component temperature conditions using a generic flat\u0000 plate test case. A low Biot number (Bi) is crucial to receive accurate\u0000 temperature predictions as heat transfer coefficients are derived on uniform\u0000 temperature walls. The methodology is subsequently applied to a sample component\u0000 in the motor compartment. Measurements on a test rig and a transient load case\u0000 comparison with a coupled simulation prove the validity of the numerical\u0000 procedure. Scaling to full-vehicle applications is feasible. The new methodology\u0000 delivers a highly accurate temperature prediction and increases computation\u0000 efficiency, especially for sensitivity studies.","PeriodicalId":29661,"journal":{"name":"SAE International Journal of Passenger Vehicle Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43216852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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