A computer model that describes the evolution of microstructures during the hot finishing rolling of SS400 steel has been proposed. It has been found that the microstructure strongly depends on processing of materials...A computer model that describes the evolution of microstructures during the hot finishing rolling of SS400 steel has been proposed. It has been found that the microstructure strongly depends on processing of materials and on their parameters, which affected the history of the thermomechanical variables, such as temperature, strain, and strain rate. To investigate the microstructural evolutions during the hot finishing rolling process, the rigid-thermoviscoplastic finite element method （FEM） has been combined with dynamic recrystallization, static recrystallization, and grain growth models. The simulation results show a good agreement with those from the prediction software online.展开更多
Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. Therefore, finish polishing is extremely important. The aim of this study was to investigate the difference...Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. Therefore, finish polishing is extremely important. The aim of this study was to investigate the difference in the surface roughness after finishing polishing of ethylene-vinyl-acetate (EVA) sheets and after application of the finishing liquid, and to evaluate its effectiveness. Total of 48 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;condition A = Robinson-brush;condition B = Lisko-Fine, and condition C = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speeds were 5000, 4000 and 6000 rpm for condition A, B, and C, respectively. Next, a finishing liquid was applied to each specimen. For application, a cotton swab was used, and it was applied by three reciprocations. A non-contact surface shape measuring machine was used for measuring surface roughness;the measurement range is 1.65 mm and the resolution is 0.01 nm. The arithmetic average height (Sa) was measured. The differences in the surface roughness before and 15 min after the application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control, condition C, B and A, and Sa was about 0.20, 1.98, 2.92, and 4.71 μm, respectively. The degree of reduction in roughness was about 1.0 μm or more than each polished state in conditions A and B. Condition C was not significantly different before and after application. No significant difference was observed between condition B and C after application. The results of this study showed that the surface roughness decreased due to the application of the finishing liquid when the surface roughness after finish polishing was about 2.0 μm or more.展开更多
Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. The aim of this study was to investigate the changes over time in surface roughness after finish polishing ...Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. The aim of this study was to investigate the changes over time in surface roughness after finish polishing of ethylene vinyl acetate (EVA) sheets and before and after finishing liquid application, and to evaluate its effectiveness. Total of 160 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;RB = Robinson-brush;LF = Lisko-Fine, and MW = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speed was 5000, 4000 and 6000 rpm for RB, LF, and MW, respectively. Next, a finishing liquid was applied to each specimen. Changes over time in surface roughness before and after application of the finishing liquid were compared by a non-contact surface shape measuring machine. The arithmetic average height (Sa) was measured. The measurement time points were before application, immediately after application, and at 5, 10, and 15 min after application. The changes over time of the surface roughness of the sheet before and after application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control;MW, LF and RB, and Sa were about 0.21 μm, 2.03 μm, 2.94 μm, and 4.72 μm, respectively. That showed the same order after finishing liquid application. Significant decrease in Sa for RB and LF were seen at 10 min after application and at 5 min after application, respectively. Sa of MW was not significantly different before and after application. The results of this study showed that a lubricity of about 1.0 μm increases within 5 - 10 min of application of finishing liquid, but in cases where polishing was performed to about 2.0 μm;the application of finishing liquid has no ef-fect.展开更多
This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions u...This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions using frequency response approach. Finite element modelling and frequency response analysis was conducted using finite element analysis software Package MSC.PATRAN/MSC.NASTRAN and fatigue life prediction was carded out using MSC.FATIGUE software. Based on the finite element results, different frequency response approach was applied to predict the cylinder block fatigue life. Results for different load histories and material combinations are also discussed. Results indicated great effects for all surface finish and treatment. It is concluded that polished and cast surface finish conditions give the highest and lowest cylinder block lives, respectively; and that Nitrided treatment leads to longest cylinder block life. The results were used to draw contour plots of fatigue life and damage in the worst or most damaging case.展开更多
文摘A computer model that describes the evolution of microstructures during the hot finishing rolling of SS400 steel has been proposed. It has been found that the microstructure strongly depends on processing of materials and on their parameters, which affected the history of the thermomechanical variables, such as temperature, strain, and strain rate. To investigate the microstructural evolutions during the hot finishing rolling process, the rigid-thermoviscoplastic finite element method （FEM） has been combined with dynamic recrystallization, static recrystallization, and grain growth models. The simulation results show a good agreement with those from the prediction software online.
文摘Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. Therefore, finish polishing is extremely important. The aim of this study was to investigate the difference in the surface roughness after finishing polishing of ethylene-vinyl-acetate (EVA) sheets and after application of the finishing liquid, and to evaluate its effectiveness. Total of 48 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;condition A = Robinson-brush;condition B = Lisko-Fine, and condition C = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speeds were 5000, 4000 and 6000 rpm for condition A, B, and C, respectively. Next, a finishing liquid was applied to each specimen. For application, a cotton swab was used, and it was applied by three reciprocations. A non-contact surface shape measuring machine was used for measuring surface roughness;the measurement range is 1.65 mm and the resolution is 0.01 nm. The arithmetic average height (Sa) was measured. The differences in the surface roughness before and 15 min after the application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control, condition C, B and A, and Sa was about 0.20, 1.98, 2.92, and 4.71 μm, respectively. The degree of reduction in roughness was about 1.0 μm or more than each polished state in conditions A and B. Condition C was not significantly different before and after application. No significant difference was observed between condition B and C after application. The results of this study showed that the surface roughness decreased due to the application of the finishing liquid when the surface roughness after finish polishing was about 2.0 μm or more.
文摘Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. The aim of this study was to investigate the changes over time in surface roughness after finish polishing of ethylene vinyl acetate (EVA) sheets and before and after finishing liquid application, and to evaluate its effectiveness. Total of 160 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;RB = Robinson-brush;LF = Lisko-Fine, and MW = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speed was 5000, 4000 and 6000 rpm for RB, LF, and MW, respectively. Next, a finishing liquid was applied to each specimen. Changes over time in surface roughness before and after application of the finishing liquid were compared by a non-contact surface shape measuring machine. The arithmetic average height (Sa) was measured. The measurement time points were before application, immediately after application, and at 5, 10, and 15 min after application. The changes over time of the surface roughness of the sheet before and after application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control;MW, LF and RB, and Sa were about 0.21 μm, 2.03 μm, 2.94 μm, and 4.72 μm, respectively. That showed the same order after finishing liquid application. Significant decrease in Sa for RB and LF were seen at 10 min after application and at 5 min after application, respectively. Sa of MW was not significantly different before and after application. The results of this study showed that a lubricity of about 1.0 μm increases within 5 - 10 min of application of finishing liquid, but in cases where polishing was performed to about 2.0 μm;the application of finishing liquid has no ef-fect.
基金Project (No. 03-02-02-0056 PR0025/04-03) supported by Ministry of Science, Technology and Innovation, Malaysia
文摘This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions using frequency response approach. Finite element modelling and frequency response analysis was conducted using finite element analysis software Package MSC.PATRAN/MSC.NASTRAN and fatigue life prediction was carded out using MSC.FATIGUE software. Based on the finite element results, different frequency response approach was applied to predict the cylinder block fatigue life. Results for different load histories and material combinations are also discussed. Results indicated great effects for all surface finish and treatment. It is concluded that polished and cast surface finish conditions give the highest and lowest cylinder block lives, respectively; and that Nitrided treatment leads to longest cylinder block life. The results were used to draw contour plots of fatigue life and damage in the worst or most damaging case.
