In the reliability life evaluation of CRH_(3C) brake pads,the evaluation model of reliability life is put forward based on the Bayes method in the small sample. The correctness of evaluation model is validated by comp...In the reliability life evaluation of CRH_(3C) brake pads,the evaluation model of reliability life is put forward based on the Bayes method in the small sample. The correctness of evaluation model is validated by comparing and analyzing with the evaluation results based on Bootstrap simulation. Also by comparing the result with the semi-empirical method,the life evaluation results of the brake pads which are based on the Bayes method are more actual. The results which are based on the Bayes method can provide the theoretical basis and guidance for the repair and replacement of brake pads.展开更多
Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Haw...Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Hawaii, of particulate matter (PM) PM = 60, PM = 10, and PM = 2.5. In order to do a rock magnetic characterization we have performed low field susceptibility vs. temperature [k-T] experiments to determine the Curie points of small particles collected from exhaust pipes, as well as from brake pads of four different types of car engines using gasoline octane ratings of 87, 89, and 92. The Curie point determinations are very well defined and range from 292<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C through 393<span style="white-space:normal;"><span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span></span>C and up to 660<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C. In addition, we have conducted magnetic granulometry experiments on raw tobacco, burnt tobacco ashes, as well as on automotive engine exhaust, and brake pads in question. The results of the experiments show ferro and ferrimagnetic hysteresis loops with magnetic grain sizes ranging from superparamagnetic-multidomain [SP-MD], multidomain [MD] and pseudo-single domain [PSD] shown on the modified Day et al., diagram of <a href="#ref3">Dunlop (2002)</a>. Thus far, the results we have obtained from this pilot study are in agreement with other studies conducted from cigarette ashes from Bulgaria. Our results could be correlated to the traffic-related PM in Rome, Italy where the SP fraction mainly occurs as coating of MD particles originated by localized stress in the oxidized outer shell surrounding the un-oxidized core of magnetite-like grains. All these magnetic particles have been reported to be very harmful to our human bodies (i.e. brain, lungs, heart, liver etc.).展开更多
To enhance the high-temperature adaptability of copper-based composite materials and C–C/SiC discs,this article innovatively introduces a method of replacing graphite with sepiolite,resulting in the successful fabric...To enhance the high-temperature adaptability of copper-based composite materials and C–C/SiC discs,this article innovatively introduces a method of replacing graphite with sepiolite,resulting in the successful fabrication of samples with exceptional mechanical and friction properties.The results reveal that moderate incorporation(less 6%)of sepiolite provides a particle reinforcement effect,resulting in an improvement of mechanical properties.Interestingly,the addition of sepiolite causes a change in the traditional saddle-shaped friction curve due to high temperature lubrication.Meanwhile,the primary advantage of sepiolite lies in its superior abrasion resistance,evident in the increased friction coefficient and altered wear mechanisms with higher sepiolite content.The wear resistance is optimal at 200 Km/h(400℃).Particularly,the unique composition of the friction layer(outermost layer:a composite film consisting of B2O3,sepiolite,graphite,and metal oxide films;intermediate layer:metal oxide films)plays a pivotal role in improving friction stability.Finally,there are significant optimizations in the GA algorithm,especially GA-GB model has the best prediction effect on the maximum friction temperature.展开更多
Research into converting waste into viable eco-friendly products has gained global concern.Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscri...Research into converting waste into viable eco-friendly products has gained global concern.Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscriminately occupying the land.This study reviews the literature in the broad area of green composites in search of materials that can be used in automotive brake pads.Materials made by biocomposite,rather than fossil fuels,will be favoured.A database containing the tribo-mechanical performance of numerous potential components for the future green composite was established using the technical details of bio-polymers and natural reinforcements.The development of materials with diverse compositions and varying proportions is now conceivable,and these materials can be permanently connected in fully regulated processes.This explanation demonstrates that all of these variables affect friction coefficient,resistance to wear from friction and high temperatures,and the operating life of brake pads to varying degrees.In this study,renewable materials for the matrix and reinforcement are screened to determine which have sufficient strength,coefficient of friction,wear resistance properties,and reasonable costs,making them a feasible option for a green composite.The most significant,intriguing,and unusual materials used in manufacturing brake pads are gathered in this review,which also analyzes how they affect the tribological characteristics of the pads.展开更多
To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produce...To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produced and tested using a scale dynamometer under various initial braking speeds(IBS).The results showed that at IBS lower than 250 km/h,both TiC and Al_(2)O_(3) particles acted as hard points and exhibited similar friction-increasing behavior,where the increase in friction was not only enhanced as IBS increased,but also enhanced by increasing the volume fraction of the abrasives.However,at higher IBS,the friction increase was limited by the bonding behavior between the matrix and abrasives.Under these conditions,the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al_(2)O_(3) because of its superior particle-matrix bonding and coefficient of thermal expansion(CTE)compatibility.Because of the poor interface bonding between the matrix and Al_(2)O_(3),a transition phenomenon exists in the Al_(2)O_(3)-reinforced composite,in which the friction-increasing effect diminished when IBS exceeded a certain value.展开更多
In order to predict the remaining service life of brake pads accurately and efficiently,and to achieve intelligent warning,this paper proposes a CNN-LSTM brake pad remaining life prediction model based on an attention...In order to predict the remaining service life of brake pads accurately and efficiently,and to achieve intelligent warning,this paper proposes a CNN-LSTM brake pad remaining life prediction model based on an attention mechanism.The model constructs a non-linear relationship between brake pad features such as brake temperature,brake oil pressure and brake speed and brake pad wear data through convolutional neural network(CNN)and long and short term memory network(LSTM),as well as capturing the time dependence that exists in the brake pad wear sequence.The attention mechanism is also introduced to assign different weight values to the features output from multiple historical moments,highlighting the features with high saliency and avoiding the influence of invalid features,so as to improve the prediction effect of the remaining brake pad life.The results show that the proposed CNN-LSTM-Attention model can effectively predict the remaining life of brake pads,with the mean absolute error MAE value of 0.0048,root mean square error RMSE value of 0.0059 and coefficient of determination R2 value of 0.9636;and compared with the BP model,CNN model,LSTM model and CNN-LSTM model,the coefficient of determination R2 values are closest to 1,with an improvement of 8.26%,5.25%,3.99%and 1.85%respectively,enabling more effective monitoring and intelligent warning of the remaining brake pad life.展开更多
In order to improve the performance of non-asbestos composite auto brake pads that are composed of matrix resin, reinforced material and fillers, a novel method with new technology of self-heal microcapsules was propo...In order to improve the performance of non-asbestos composite auto brake pads that are composed of matrix resin, reinforced material and fillers, a novel method with new technology of self-heal microcapsules was proposed. Nano reinforced fillers＇ effects were also considered in the experiment project. Five recipe designs for new composite auto brake pads were carried out and cor-responding samples were prepared as well. The friction coefficient and wearing properties at certain temperature, impact intensity and hardness were comparatively studied. Investigations indicate that properties of such composite auto brake pads meet the requirements of the national standards while microcapsule＇s weight content varies from 5.5wt%-1.09wt% of matrix resin and microcapsule＇s loca-tion varies in the pads. Nano reinforced fillers have the effects of increasing composites＇ impact in-tensity and hardness. Application of self-healing microcapsules in auto brake pads is feasible.展开更多
Abrasives,such as oxides of alumina(Al),silica(Si),zirconia(Zr),chromium(Cr)etc.,are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during b...Abrasives,such as oxides of alumina(Al),silica(Si),zirconia(Zr),chromium(Cr)etc.,are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during braking and will contribute to maintain the desired friction level.However,these inorganic particles have less adhesion with the resin/binder and hence are easily dug out during wearing process contributing to higher wear.If efforts are made to enhance the filler‐matrix adhesion,not only the wear of friction material(FM)should reduce,the particles may stay for a longer time on the tribo‐surface of the pads to contribute fully towards controlling the coefficient of friction(μ).In the present study,alumina particles were selected for siloxane treatment to improve the filler‐matrix adhesion.Two types of eco‐friendly(free from asbestos and Cu)brake‐pads were developed using alumina as a theme ingredient(treated and untreated)keeping all the parent formulation identical.An additional type of brake‐pads without alumina particles was also developed to observe the effect of abrasive particles on the tribo‐performance.The performance properties(physical,mechanical,and tribological)of brake‐pads were compared when evaluated in identical conditions.The tribotesting was done on full‐scale brake inertia dynamometer following the procedure in Japanese automobile standard(JASO C 406).It was observed that siloxane treatment affected both friction and wear of brake‐pads in a beneficial way.Wear resistance got increased 35%for siloxane treated pads.Worn surfaces were analysed using scanning electron microscopy(SEM)and energy dispersive X‐ray(EDAX)technique.展开更多
In this study,we evaluated the wear properties of four brands of brake pad available in the Nigerian market.In particular,we assessed the tribo performance and service life of the brake pads.We purchased four commerci...In this study,we evaluated the wear properties of four brands of brake pad available in the Nigerian market.In particular,we assessed the tribo performance and service life of the brake pads.We purchased four commercial brands of brake pads used in light duty cars and coded them as AU,SN,TY and SM,respectively.A small piece of the brake pad lining materials was carefully chiseled from the back plates to obtain samples for the experiments.We conducted Brinell hardness tests using a tensometer and a pin-on-disc test rig to determine the coefficient of friction and the wear characteristics of the materials.We then correlated the wear on each set of brake pads with the running time and used Weibull’s equation to determine average service life.Sample TY exhibited the highest hardness value(29.09)and sample SN the lowest(10.05).The determined coefficients of friction ranged between 0.3-0.36,with sample AU exhibiting the lowest value and sample SM the highest.Sample SN showed the lowest wear rate of 3.53×10^(9) g/min,while the wear rates of samples TY,AU,and SM were 5.64×10^(8),8.19×10^(9),and 2.10×10^(8) g/min,respectively.The relative service life of samples SN,TY,and AU were similar,with average values of 2778.09,2725.41,and 2717.34 min,respectively,and SM had a relatively low service life(2017.82 min).We conclude that the overall performances of Nigerian brake pads do not meet all the specifications for friction materials used in road vehicle brake linings and pads.展开更多
基金National Natural Science Foundation of Liaoning Province,China(No.2014028020)Liaoning Province Education Administration Project,China(No.L2013182)Dalian Science and Technology Project,China(No.2015A11GX026)
文摘In the reliability life evaluation of CRH_(3C) brake pads,the evaluation model of reliability life is put forward based on the Bayes method in the small sample. The correctness of evaluation model is validated by comparing and analyzing with the evaluation results based on Bootstrap simulation. Also by comparing the result with the semi-empirical method,the life evaluation results of the brake pads which are based on the Bayes method are more actual. The results which are based on the Bayes method can provide the theoretical basis and guidance for the repair and replacement of brake pads.
文摘Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Hawaii, of particulate matter (PM) PM = 60, PM = 10, and PM = 2.5. In order to do a rock magnetic characterization we have performed low field susceptibility vs. temperature [k-T] experiments to determine the Curie points of small particles collected from exhaust pipes, as well as from brake pads of four different types of car engines using gasoline octane ratings of 87, 89, and 92. The Curie point determinations are very well defined and range from 292<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C through 393<span style="white-space:normal;"><span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span></span>C and up to 660<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C. In addition, we have conducted magnetic granulometry experiments on raw tobacco, burnt tobacco ashes, as well as on automotive engine exhaust, and brake pads in question. The results of the experiments show ferro and ferrimagnetic hysteresis loops with magnetic grain sizes ranging from superparamagnetic-multidomain [SP-MD], multidomain [MD] and pseudo-single domain [PSD] shown on the modified Day et al., diagram of <a href="#ref3">Dunlop (2002)</a>. Thus far, the results we have obtained from this pilot study are in agreement with other studies conducted from cigarette ashes from Bulgaria. Our results could be correlated to the traffic-related PM in Rome, Italy where the SP fraction mainly occurs as coating of MD particles originated by localized stress in the oxidized outer shell surrounding the un-oxidized core of magnetite-like grains. All these magnetic particles have been reported to be very harmful to our human bodies (i.e. brain, lungs, heart, liver etc.).
基金the National Key Research and Development Program of China(Grant No.2021YFB3703803)National Natural Science Foundation of China(Grant No.52075555)for their financial support.
文摘To enhance the high-temperature adaptability of copper-based composite materials and C–C/SiC discs,this article innovatively introduces a method of replacing graphite with sepiolite,resulting in the successful fabrication of samples with exceptional mechanical and friction properties.The results reveal that moderate incorporation(less 6%)of sepiolite provides a particle reinforcement effect,resulting in an improvement of mechanical properties.Interestingly,the addition of sepiolite causes a change in the traditional saddle-shaped friction curve due to high temperature lubrication.Meanwhile,the primary advantage of sepiolite lies in its superior abrasion resistance,evident in the increased friction coefficient and altered wear mechanisms with higher sepiolite content.The wear resistance is optimal at 200 Km/h(400℃).Particularly,the unique composition of the friction layer(outermost layer:a composite film consisting of B2O3,sepiolite,graphite,and metal oxide films;intermediate layer:metal oxide films)plays a pivotal role in improving friction stability.Finally,there are significant optimizations in the GA algorithm,especially GA-GB model has the best prediction effect on the maximum friction temperature.
文摘Research into converting waste into viable eco-friendly products has gained global concern.Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscriminately occupying the land.This study reviews the literature in the broad area of green composites in search of materials that can be used in automotive brake pads.Materials made by biocomposite,rather than fossil fuels,will be favoured.A database containing the tribo-mechanical performance of numerous potential components for the future green composite was established using the technical details of bio-polymers and natural reinforcements.The development of materials with diverse compositions and varying proportions is now conceivable,and these materials can be permanently connected in fully regulated processes.This explanation demonstrates that all of these variables affect friction coefficient,resistance to wear from friction and high temperatures,and the operating life of brake pads to varying degrees.In this study,renewable materials for the matrix and reinforcement are screened to determine which have sufficient strength,coefficient of friction,wear resistance properties,and reasonable costs,making them a feasible option for a green composite.The most significant,intriguing,and unusual materials used in manufacturing brake pads are gathered in this review,which also analyzes how they affect the tribological characteristics of the pads.
基金Financial support from the National Natural Science Foundation of China(No.51572026)is gratefully acknowledged.
文摘To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produced and tested using a scale dynamometer under various initial braking speeds(IBS).The results showed that at IBS lower than 250 km/h,both TiC and Al_(2)O_(3) particles acted as hard points and exhibited similar friction-increasing behavior,where the increase in friction was not only enhanced as IBS increased,but also enhanced by increasing the volume fraction of the abrasives.However,at higher IBS,the friction increase was limited by the bonding behavior between the matrix and abrasives.Under these conditions,the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al_(2)O_(3) because of its superior particle-matrix bonding and coefficient of thermal expansion(CTE)compatibility.Because of the poor interface bonding between the matrix and Al_(2)O_(3),a transition phenomenon exists in the Al_(2)O_(3)-reinforced composite,in which the friction-increasing effect diminished when IBS exceeded a certain value.
基金financed with the means of Liaoning Provincial Science and Technology Department natural Science Regional Joint Fund project,No.2022-YKLH-03.
文摘In order to predict the remaining service life of brake pads accurately and efficiently,and to achieve intelligent warning,this paper proposes a CNN-LSTM brake pad remaining life prediction model based on an attention mechanism.The model constructs a non-linear relationship between brake pad features such as brake temperature,brake oil pressure and brake speed and brake pad wear data through convolutional neural network(CNN)and long and short term memory network(LSTM),as well as capturing the time dependence that exists in the brake pad wear sequence.The attention mechanism is also introduced to assign different weight values to the features output from multiple historical moments,highlighting the features with high saliency and avoiding the influence of invalid features,so as to improve the prediction effect of the remaining brake pad life.The results show that the proposed CNN-LSTM-Attention model can effectively predict the remaining life of brake pads,with the mean absolute error MAE value of 0.0048,root mean square error RMSE value of 0.0059 and coefficient of determination R2 value of 0.9636;and compared with the BP model,CNN model,LSTM model and CNN-LSTM model,the coefficient of determination R2 values are closest to 1,with an improvement of 8.26%,5.25%,3.99%and 1.85%respectively,enabling more effective monitoring and intelligent warning of the remaining brake pad life.
基金Funded by the Beijing Talent and Innovation Project (No. 2006)
文摘In order to improve the performance of non-asbestos composite auto brake pads that are composed of matrix resin, reinforced material and fillers, a novel method with new technology of self-heal microcapsules was proposed. Nano reinforced fillers＇ effects were also considered in the experiment project. Five recipe designs for new composite auto brake pads were carried out and cor-responding samples were prepared as well. The friction coefficient and wearing properties at certain temperature, impact intensity and hardness were comparatively studied. Investigations indicate that properties of such composite auto brake pads meet the requirements of the national standards while microcapsule＇s weight content varies from 5.5wt%-1.09wt% of matrix resin and microcapsule＇s loca-tion varies in the pads. Nano reinforced fillers have the effects of increasing composites＇ impact in-tensity and hardness. Application of self-healing microcapsules in auto brake pads is feasible.
文摘Abrasives,such as oxides of alumina(Al),silica(Si),zirconia(Zr),chromium(Cr)etc.,are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during braking and will contribute to maintain the desired friction level.However,these inorganic particles have less adhesion with the resin/binder and hence are easily dug out during wearing process contributing to higher wear.If efforts are made to enhance the filler‐matrix adhesion,not only the wear of friction material(FM)should reduce,the particles may stay for a longer time on the tribo‐surface of the pads to contribute fully towards controlling the coefficient of friction(μ).In the present study,alumina particles were selected for siloxane treatment to improve the filler‐matrix adhesion.Two types of eco‐friendly(free from asbestos and Cu)brake‐pads were developed using alumina as a theme ingredient(treated and untreated)keeping all the parent formulation identical.An additional type of brake‐pads without alumina particles was also developed to observe the effect of abrasive particles on the tribo‐performance.The performance properties(physical,mechanical,and tribological)of brake‐pads were compared when evaluated in identical conditions.The tribotesting was done on full‐scale brake inertia dynamometer following the procedure in Japanese automobile standard(JASO C 406).It was observed that siloxane treatment affected both friction and wear of brake‐pads in a beneficial way.Wear resistance got increased 35%for siloxane treated pads.Worn surfaces were analysed using scanning electron microscopy(SEM)and energy dispersive X‐ray(EDAX)technique.
文摘In this study,we evaluated the wear properties of four brands of brake pad available in the Nigerian market.In particular,we assessed the tribo performance and service life of the brake pads.We purchased four commercial brands of brake pads used in light duty cars and coded them as AU,SN,TY and SM,respectively.A small piece of the brake pad lining materials was carefully chiseled from the back plates to obtain samples for the experiments.We conducted Brinell hardness tests using a tensometer and a pin-on-disc test rig to determine the coefficient of friction and the wear characteristics of the materials.We then correlated the wear on each set of brake pads with the running time and used Weibull’s equation to determine average service life.Sample TY exhibited the highest hardness value(29.09)and sample SN the lowest(10.05).The determined coefficients of friction ranged between 0.3-0.36,with sample AU exhibiting the lowest value and sample SM the highest.Sample SN showed the lowest wear rate of 3.53×10^(9) g/min,while the wear rates of samples TY,AU,and SM were 5.64×10^(8),8.19×10^(9),and 2.10×10^(8) g/min,respectively.The relative service life of samples SN,TY,and AU were similar,with average values of 2778.09,2725.41,and 2717.34 min,respectively,and SM had a relatively low service life(2017.82 min).We conclude that the overall performances of Nigerian brake pads do not meet all the specifications for friction materials used in road vehicle brake linings and pads.
