There is much research conducted on the vehicle technologies required for operation of autonomous vehicles(AV) on public roads, as well as analysis of the interaction between AV and the road environment. However, limi...There is much research conducted on the vehicle technologies required for operation of autonomous vehicles(AV) on public roads, as well as analysis of the interaction between AV and the road environment. However, limited research exists on the impact of AV on road pavement structures. The research includes issues such as the effect of more channelized traffic loading, shorter inter-vehicle following distances and potential higher traffic volumes of more uniform vehicle types and loads. This paper discusses the application of existing and generation of new, relevant accelerated pavement testing(APT) data in understanding the effects of AV on pavement infrastructure. The paper presents development of provisional guidelines for the use and application of APT data to ensure that road pavement structures cope with anticipated increase in AV use. It is concludes that the use of AV fleets on existing road pavement infrastructure may lead to different behaviors and responses than what became the norm under non-autonomous vehicle fleets;appropriate analysis of existing APT data will contribute to the improved understanding of these expected changes in behaviors and responses; appropriate planning of AV operations-focused APT is possible with existing technology to contribute to the provision of economic and durable road pavement infrastructure in future.展开更多
In order to predict the lifetime of products appropriately with long lifetime and high reliability,the accelerated degradation testing(ADT)has been proposed.Composite wind turbine blade is one of the most important co...In order to predict the lifetime of products appropriately with long lifetime and high reliability,the accelerated degradation testing(ADT)has been proposed.Composite wind turbine blade is one of the most important components in wind turbine system.Its fatigue cycle is very long in practice.A full-scale fatigue testing is usually used to verify the design of a new blade.In general,the full-scale fatigue testing of blade is accelerated on the basis of the damage equivalent principle.During the full-scale fatigue test ing,blade is subjected to higher testing load than normal operat ing conditions;consequently,the performance degradation of the blade is hastened over time.The full-scale fatigue testing of blade is regarded as a special ADT.According to the fatigue failure criterion,we choose blade stiffness as the characteristic quantity of the blade performance,and propose an accelerated model(AM)for blade on the basis of the theories of ADT.Then,degradation path of the blade stiffness is modeled by using Gamma process.Finally,the lifet ime prediction of full-scale megawatt(MW)blade is conducted by combining the proposed AM and blade stiffness degradation model.The prediction results prove the reasonability and validity of this study.This can supply a new approach to predict the lifetime of the full-scale MW blade.展开更多
In order to assess the difference in performance of pavements under conventional loading and accelerated loading,in this paper,based on the characteristics of pavement strain recovery in accelerated pavement tests(APT...In order to assess the difference in performance of pavements under conventional loading and accelerated loading,in this paper,based on the characteristics of pavement strain recovery in accelerated pavement tests(APTs),we define accelerated loading and conventional loading in pavement permanent deformation research.The finite element method is then used to establish a flexible contact model between tire and asphalt pavement.By using simulation,the difference in dynamic stress and rutting of a pavement under the two different loadings is studied.It is discovered that if the APT forms an accelerated loading effect,the pavement will produce deeper rutting under the same axle loading cycle.展开更多
基金supported by the National Research Foundation of South Africa
文摘There is much research conducted on the vehicle technologies required for operation of autonomous vehicles(AV) on public roads, as well as analysis of the interaction between AV and the road environment. However, limited research exists on the impact of AV on road pavement structures. The research includes issues such as the effect of more channelized traffic loading, shorter inter-vehicle following distances and potential higher traffic volumes of more uniform vehicle types and loads. This paper discusses the application of existing and generation of new, relevant accelerated pavement testing(APT) data in understanding the effects of AV on pavement infrastructure. The paper presents development of provisional guidelines for the use and application of APT data to ensure that road pavement structures cope with anticipated increase in AV use. It is concludes that the use of AV fleets on existing road pavement infrastructure may lead to different behaviors and responses than what became the norm under non-autonomous vehicle fleets;appropriate analysis of existing APT data will contribute to the improved understanding of these expected changes in behaviors and responses; appropriate planning of AV operations-focused APT is possible with existing technology to contribute to the provision of economic and durable road pavement infrastructure in future.
基金the National Natural Science Founda-tion of China(No.51665029)。
文摘In order to predict the lifetime of products appropriately with long lifetime and high reliability,the accelerated degradation testing(ADT)has been proposed.Composite wind turbine blade is one of the most important components in wind turbine system.Its fatigue cycle is very long in practice.A full-scale fatigue testing is usually used to verify the design of a new blade.In general,the full-scale fatigue testing of blade is accelerated on the basis of the damage equivalent principle.During the full-scale fatigue test ing,blade is subjected to higher testing load than normal operat ing conditions;consequently,the performance degradation of the blade is hastened over time.The full-scale fatigue testing of blade is regarded as a special ADT.According to the fatigue failure criterion,we choose blade stiffness as the characteristic quantity of the blade performance,and propose an accelerated model(AM)for blade on the basis of the theories of ADT.Then,degradation path of the blade stiffness is modeled by using Gamma process.Finally,the lifet ime prediction of full-scale megawatt(MW)blade is conducted by combining the proposed AM and blade stiffness degradation model.The prediction results prove the reasonability and validity of this study.This can supply a new approach to predict the lifetime of the full-scale MW blade.
基金the National Key Research and Development Program of China(Nos.2017YFF0205600 and 2017YFF0205602)the Fundamental Research Funds for the Central Universities(No.FRF-TP-18-048A1),China。
文摘In order to assess the difference in performance of pavements under conventional loading and accelerated loading,in this paper,based on the characteristics of pavement strain recovery in accelerated pavement tests(APTs),we define accelerated loading and conventional loading in pavement permanent deformation research.The finite element method is then used to establish a flexible contact model between tire and asphalt pavement.By using simulation,the difference in dynamic stress and rutting of a pavement under the two different loadings is studied.It is discovered that if the APT forms an accelerated loading effect,the pavement will produce deeper rutting under the same axle loading cycle.
