The wear and rolling contact fatigue (RCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroa...The wear and rolling contact fatigue (RCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroad analysis revealed that scaled laboratory-based wear testing is widely applied. However, it is necessary topredetermine the input parameters and observing parameters for scaled wear testing for three reasons: first, toemulate the real-world scenarios as closely as possible;second, to postprocess the results received from the scaledtesting and transfer them into real practice at full scale;third, to present the results in a legible/appropriate format.Therefore, most of the important parameters required for wear testing have been discussed with fundamental andsystematic explanations provided. Additionally, the transition of the parameters from the real-world into the testdomain is explained. This study also elaborates on the challenges of the RCF and wear testing processes andconcludes by providing major considerations toward successful testing.展开更多
The wear rate of dental restoration materials on fixed, removable, and implant prostheses is important in the maintenance of cuspate form, masticatory efficiency and occlusal stability. Many permanent restoration mate...The wear rate of dental restoration materials on fixed, removable, and implant prostheses is important in the maintenance of cuspate form, masticatory efficiency and occlusal stability. Many permanent restoration materials such as composite, amalgam, gold, or porcelain show enough resistance to wear, but the wear rates of newly developed materials are generally unknown. To evaluate the wear rate of these dental materials, in vivo (clinic) and in vitro methods can be used. Since in vivo investigations are expensive, time consuming, and difficult to standardize, various in vitro methods have been developed. The use of a chewing machine is considered the best method, because a variety of wear mechanisms, temperature changes, and chemical effects of food and drink can be simulated simultaneously. This paper describes a dual axis chewing simulator for in vitro wear test of dental restoration materials. It consists of 8 test chambers, two stepper motors and related mechanism, a hot and cool water circle system, and a control unit. In the chambers, samples and antagonists make chewing movements vertically and Albert Ludwigs University, School of dentistry, Freiburg, Germany (Lü XY, Kern M and Strub JR) horizontally driven by the stepper motors so that the gnashing and slippage of two teeth against each other is simulated. A weighted test object is programmed to collide with a sample under precise operator control. The antagonists strike against the samples at various speeds from a slow nudge to snapping. Sample holders are designed for installation of varying samples, from single teeth to complete dentures. Two baths, six valves, and a group of pipes are used for the thermocycling. The machine can simulate various chewing modes in the mouth, including fully programmable thermal water cycling between 5℃ and 60℃ The control unit consists of a computer system with a built in specific program. Important operations such as “Start”, “Zero point”, and “Stop” are carried out by pressing the function keys on the front board of the unit. During the programming process and the simulation, several test modes and relevant test parameters are shown on the monitor. The control unit is connected via a series of interfaces to different controlled parts of the machine, such as the stepper motors and the pumps of cool and warm water.展开更多
This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for sh...This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for shaping varies between 14% and 18% (latex/sand + latex ratio) for the carpet with the fabric of mosquito nets and between 16% and 18% for the one made with the fabric of cotton fiber. Thus, with a mixture of sand, fiber fabrics (cotton and mosquito nets) and rubber latex, carpets were developed. In addition, the wear test carried out on these samples indicates that it is possible to produce carpets with the new material made of rubber sand and latex: SABLATEX At room temperature. Following the characterization test, it resorts to only 16% latex with cotton fiber fabric, allowing to have carpets with good mechanical characteristics.展开更多
基金The authors would like to acknowledge the support of the Australasian Centre for Rail Innovation(ACRI)and their industry partners that have contributed to the HH27‘Wear Simulation Development-Stage 1’project.Dr Qing Wu is the recipient of an Australian Research Council Discovery Early Career Award(project number DE210100273)funded by the Australian Government.Tim McSweeney,Adjunct Research Fellow,Centre for Railway Engineering is thankfully acknowledged for his assistance with proofreading.
文摘The wear and rolling contact fatigue (RCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroad analysis revealed that scaled laboratory-based wear testing is widely applied. However, it is necessary topredetermine the input parameters and observing parameters for scaled wear testing for three reasons: first, toemulate the real-world scenarios as closely as possible;second, to postprocess the results received from the scaledtesting and transfer them into real practice at full scale;third, to present the results in a legible/appropriate format.Therefore, most of the important parameters required for wear testing have been discussed with fundamental andsystematic explanations provided. Additionally, the transition of the parameters from the real-world into the testdomain is explained. This study also elaborates on the challenges of the RCF and wear testing processes andconcludes by providing major considerations toward successful testing.
文摘The wear rate of dental restoration materials on fixed, removable, and implant prostheses is important in the maintenance of cuspate form, masticatory efficiency and occlusal stability. Many permanent restoration materials such as composite, amalgam, gold, or porcelain show enough resistance to wear, but the wear rates of newly developed materials are generally unknown. To evaluate the wear rate of these dental materials, in vivo (clinic) and in vitro methods can be used. Since in vivo investigations are expensive, time consuming, and difficult to standardize, various in vitro methods have been developed. The use of a chewing machine is considered the best method, because a variety of wear mechanisms, temperature changes, and chemical effects of food and drink can be simulated simultaneously. This paper describes a dual axis chewing simulator for in vitro wear test of dental restoration materials. It consists of 8 test chambers, two stepper motors and related mechanism, a hot and cool water circle system, and a control unit. In the chambers, samples and antagonists make chewing movements vertically and Albert Ludwigs University, School of dentistry, Freiburg, Germany (Lü XY, Kern M and Strub JR) horizontally driven by the stepper motors so that the gnashing and slippage of two teeth against each other is simulated. A weighted test object is programmed to collide with a sample under precise operator control. The antagonists strike against the samples at various speeds from a slow nudge to snapping. Sample holders are designed for installation of varying samples, from single teeth to complete dentures. Two baths, six valves, and a group of pipes are used for the thermocycling. The machine can simulate various chewing modes in the mouth, including fully programmable thermal water cycling between 5℃ and 60℃ The control unit consists of a computer system with a built in specific program. Important operations such as “Start”, “Zero point”, and “Stop” are carried out by pressing the function keys on the front board of the unit. During the programming process and the simulation, several test modes and relevant test parameters are shown on the monitor. The control unit is connected via a series of interfaces to different controlled parts of the machine, such as the stepper motors and the pumps of cool and warm water.
文摘This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for shaping varies between 14% and 18% (latex/sand + latex ratio) for the carpet with the fabric of mosquito nets and between 16% and 18% for the one made with the fabric of cotton fiber. Thus, with a mixture of sand, fiber fabrics (cotton and mosquito nets) and rubber latex, carpets were developed. In addition, the wear test carried out on these samples indicates that it is possible to produce carpets with the new material made of rubber sand and latex: SABLATEX At room temperature. Following the characterization test, it resorts to only 16% latex with cotton fiber fabric, allowing to have carpets with good mechanical characteristics.
