Pub Date : 1900-01-01DOI: 10.1299/jsmepes.2019.24.b123
Mitsuhiro Aoyagi, A. Uchibori, S. Kikuchi, T. Takata, S. Ohno, H. Ohshima
Sodium fire is one of key issues in sodium-cooled fast reactor (SFR) plants. JAEA has developed sodium fire analysis codes, a zone model code SPHINCS and a field model code AQUA-SF, to evaluate the consequence of sodium fire events. This paper describes a PIRT (Phenomena Identification and Ranking Table) process for sodium fire events. Ranking table for important phenomena and an assessment matrix are completed. Because a sodium fire event in an SFR plant involves complex phenomena, the ranking table has been established through both element- and sequence-based phenomena analyses in addition to the engineering judgement. The assessment matrix confirms sufficiency of experimental data for validation of models corresponding to the identified important phenomena in the sodium fire analysis codes. As a part of comprehensive validation based on the assessment matrix, an experimental analysis for a large-scale sodium spray fire experiment Run-E1 is conducted by using the SPHINCS and AQUA-SF codes. The analytical results of the both codes show good agreements with the experimental data of gas pressure transient. Difference from the experimental result of the maximum pressure are about 5% smaller in the SPHINCS code and about 10% larger in the AQUA-SF code. General validity for the codes would be confirmed through the comprehensive validation based on the assessment matrix.
{"title":"Evaluation of important phenomena through the PIRT process for a sodium fire event","authors":"Mitsuhiro Aoyagi, A. Uchibori, S. Kikuchi, T. Takata, S. Ohno, H. Ohshima","doi":"10.1299/jsmepes.2019.24.b123","DOIUrl":"https://doi.org/10.1299/jsmepes.2019.24.b123","url":null,"abstract":"Sodium fire is one of key issues in sodium-cooled fast reactor (SFR) plants. JAEA has developed sodium fire analysis codes, a zone model code SPHINCS and a field model code AQUA-SF, to evaluate the consequence of sodium fire events. This paper describes a PIRT (Phenomena Identification and Ranking Table) process for sodium fire events. Ranking table for important phenomena and an assessment matrix are completed. Because a sodium fire event in an SFR plant involves complex phenomena, the ranking table has been established through both element- and sequence-based phenomena analyses in addition to the engineering judgement. The assessment matrix confirms sufficiency of experimental data for validation of models corresponding to the identified important phenomena in the sodium fire analysis codes. As a part of comprehensive validation based on the assessment matrix, an experimental analysis for a large-scale sodium spray fire experiment Run-E1 is conducted by using the SPHINCS and AQUA-SF codes. The analytical results of the both codes show good agreements with the experimental data of gas pressure transient. Difference from the experimental result of the maximum pressure are about 5% smaller in the SPHINCS code and about 10% larger in the AQUA-SF code. General validity for the codes would be confirmed through the comprehensive validation based on the assessment matrix.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128088945","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.19-00388
Takumi Nakamura, Y. Arai, Tomohisa Kojima, T. Tsuji
If we use wood as a structural material, we can reduce carbon dioxide emission. In Japan, houses have been made by wood traditionally and wood is used as a structural material such as pillar and beam. In order to use wood as a structural material, a joint is necessary. The shapes of these traditional joints are determined empirically and used without any analytical evaluation such as stress analysis. Therefore, stress analysis is necessary in order to use such joints efficiently. In this study, we make stress analysis of gooseneck joint, which is one of the typical joint in japan. The strain distributions of the joint are measured, and the stress distributions are obtained by digital image correlation method (DIC). We also simulate gooseneck joint subjected to tensile load by using FEM. A male part and a female part are contacted in the joint region. Comparing FEM results to DIC results, the validities of both results are confirmed. Moreover, we propose the formulae to obtain the joint stress concentration factor by using the FEM results. The optimum shape, which gives the least maximum stress under uniaxial loading, is obtained by using the proposed formulae.
{"title":"Formulation of stress concentration factor and shape optimization of gooseneck joint under uniaxial tensile load","authors":"Takumi Nakamura, Y. Arai, Tomohisa Kojima, T. Tsuji","doi":"10.1299/transjsme.19-00388","DOIUrl":"https://doi.org/10.1299/transjsme.19-00388","url":null,"abstract":"If we use wood as a structural material, we can reduce carbon dioxide emission. In Japan, houses have been made by wood traditionally and wood is used as a structural material such as pillar and beam. In order to use wood as a structural material, a joint is necessary. The shapes of these traditional joints are determined empirically and used without any analytical evaluation such as stress analysis. Therefore, stress analysis is necessary in order to use such joints efficiently. In this study, we make stress analysis of gooseneck joint, which is one of the typical joint in japan. The strain distributions of the joint are measured, and the stress distributions are obtained by digital image correlation method (DIC). We also simulate gooseneck joint subjected to tensile load by using FEM. A male part and a female part are contacted in the joint region. Comparing FEM results to DIC results, the validities of both results are confirmed. Moreover, we propose the formulae to obtain the joint stress concentration factor by using the FEM results. The optimum shape, which gives the least maximum stress under uniaxial loading, is obtained by using the proposed formulae.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128148360","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.19-00318
Kyohei Kohsaka, K. Ushijima
In this study, the natural frequency of cylindrical sandwich tube with lattice core has been investigated using finite element method (FEM). In particular, effects of geometrical parameters such as the ratio of the diameter to length, unit-cell size and facesheet thickness on the natural frequency were discussed. It is revealed that the natural vibration frequency of the lattice sandwich tube can be predicted with a good accuracy in a wide range of tube length-to-diameter ratio L/D by substituting the equivalent material properties (initial stiffness Eeq and Poisson’s ratio νeq) and relative density ρeq into the analytical equations for a straight tube of a continuum medium.
{"title":"Study on vibration characteristics of cylindrical sandwich tube with lattice core","authors":"Kyohei Kohsaka, K. Ushijima","doi":"10.1299/transjsme.19-00318","DOIUrl":"https://doi.org/10.1299/transjsme.19-00318","url":null,"abstract":"In this study, the natural frequency of cylindrical sandwich tube with lattice core has been investigated using finite element method (FEM). In particular, effects of geometrical parameters such as the ratio of the diameter to length, unit-cell size and facesheet thickness on the natural frequency were discussed. It is revealed that the natural vibration frequency of the lattice sandwich tube can be predicted with a good accuracy in a wide range of tube length-to-diameter ratio L/D by substituting the equivalent material properties (initial stiffness Eeq and Poisson’s ratio νeq) and relative density ρeq into the analytical equations for a straight tube of a continuum medium.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125421460","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}
Pub Date : 1900-01-01DOI: 10.1299/TRANSJSME.18-00413
H. Hashimoto, K. Hashimoto, K. Mimura, I. Riku, T. Umeda
{"title":"Failure mode for SS400 notched specimen under repeated impact loading","authors":"H. Hashimoto, K. Hashimoto, K. Mimura, I. Riku, T. Umeda","doi":"10.1299/TRANSJSME.18-00413","DOIUrl":"https://doi.org/10.1299/TRANSJSME.18-00413","url":null,"abstract":"","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125732128","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.18-00297
Masao Yamamoto
During polymer melt extrusion from a circular nozzle, the extrudate at low flow rate shows a stable linear shape with smooth surface but the extrudate at higher flow rate shows unstable shapes with spiral, rosary, or zig-zag structures. This phenomenon is known as melt fracture and hampers high throughput production in polymer processing. For linear polymers, synchronized oscillation of flow volume, extrusion pressures, and shape distortion is frequently observed, and it is known as stick-slip melt fracture (SSMF). Since this phenomenon is an oscillation phenomenon, many studies have been performed to analyze the mechanisms based on the oscillation theory. However, most of previous studies have mainly used mathematical calculation, and therefore experimental evaluations of SSMF have rarely been performed. In this study, we conducted an experimental approach to elucidate the mechanism of SSMF by using high density polyethylene as a polymer with varied lengths of the extrusion nozzle. Experimental results were analyzed by the simple model based on the oscillation theory. In the model, we introduced a supply curve representing a relationship between flow rate and pressure at the supplying side and a flow curve representing a flow resistance at the nozzle side. As a result, it was clarified that SSMF is a phenomenon of self-exited oscillation and also relaxation oscillation caused by the compressive elasticity of polymer melt and the negative damping appearing in a flow curve. We verified that SSMF does not occur when the negative damping is lost by repressing slip at inner side of the nozzle. Furthermore, we identified conditions under which SSMF does not occur despite the existence of negative damping; occurrence of SSMF depends on the mode of polymer supplying, a constant flow mode or a constant pressure mode. The former causes SSMF but the latter does not.
{"title":"Elucidation of mechanisms for stick slip melt fracture of polymer melt (Experimental analysis of unstable flow of high density polyethylene melt)","authors":"Masao Yamamoto","doi":"10.1299/transjsme.18-00297","DOIUrl":"https://doi.org/10.1299/transjsme.18-00297","url":null,"abstract":"During polymer melt extrusion from a circular nozzle, the extrudate at low flow rate shows a stable linear shape with smooth surface but the extrudate at higher flow rate shows unstable shapes with spiral, rosary, or zig-zag structures. This phenomenon is known as melt fracture and hampers high throughput production in polymer processing. For linear polymers, synchronized oscillation of flow volume, extrusion pressures, and shape distortion is frequently observed, and it is known as stick-slip melt fracture (SSMF). Since this phenomenon is an oscillation phenomenon, many studies have been performed to analyze the mechanisms based on the oscillation theory. However, most of previous studies have mainly used mathematical calculation, and therefore experimental evaluations of SSMF have rarely been performed. In this study, we conducted an experimental approach to elucidate the mechanism of SSMF by using high density polyethylene as a polymer with varied lengths of the extrusion nozzle. Experimental results were analyzed by the simple model based on the oscillation theory. In the model, we introduced a supply curve representing a relationship between flow rate and pressure at the supplying side and a flow curve representing a flow resistance at the nozzle side. As a result, it was clarified that SSMF is a phenomenon of self-exited oscillation and also relaxation oscillation caused by the compressive elasticity of polymer melt and the negative damping appearing in a flow curve. We verified that SSMF does not occur when the negative damping is lost by repressing slip at inner side of the nozzle. Furthermore, we identified conditions under which SSMF does not occur despite the existence of negative damping; occurrence of SSMF depends on the mode of polymer supplying, a constant flow mode or a constant pressure mode. The former causes SSMF but the latter does not.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125760459","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.20-00105
Takashi Tanaka, Y. Oura, S. Maeda, Zhiqiang Wu
This research presents the evaluation method of contact-type failure level based on nonlinear wave modulation. It is difficult to detect contact-type failures using a linear ultrasonic inspection. The detection method based on nonlinear wave modulation has been proposed to detect the contact-type failure. Nonlinear wave modulation is the phenomenon, which is explained by contact acoustic nonlinearity (CAN) of ultrasonic caused by low-frequency vibration. The SDOF model for nonlinear wave modulation consists of modal mass, modal damping and modal stiffness which coefficient fluctuates caused by CAN of ultrasonic vibration. This model is described by time-varying linear model when the frequency ratio of the frequency of low-frequency vibration to frequency of ultrasonic vibration is sufficiently small. When the fluctuation frequency of coefficient of modal stiffness caused by low-frequency vibration is sufficiently smaller than the frequency of ultrasonic vibration, the instantaneous natural frequency of ultrasonic vibration fluctuates in synchronization with fluctuation of time-varying coefficient of modal stiffness. Therefore, the fluctuation of natural frequency can be used as a novel index for evaluation of failure level independent of viscous damping. In this paper, the estimation method of fluctuation of the natural frequency is proposed and verified using time response analysis. Firstly, the linear time-varying model of nonlinear wave modulation is introduced. The mechanism of fluctuation of natural frequency is explained by introduced model. Secondly, the estimation method of fluctuation of natural frequency based on the linear time-varying model is proposed. The phase fluctuation occurs as the result of the fluctuation of natural frequency. Finally, it is confirmed that the fluctuation of natural frequency can be estimated from time-invariant transfer function and phase modulation. The fluctuation range of natural frequency is the failure index.
{"title":"Evaluation of contact-type failure development using fluctuation of natural frequency caused by nonlinear wave modulation (Verification of estimation method of natural frequency fluctuation by time response analysis)","authors":"Takashi Tanaka, Y. Oura, S. Maeda, Zhiqiang Wu","doi":"10.1299/transjsme.20-00105","DOIUrl":"https://doi.org/10.1299/transjsme.20-00105","url":null,"abstract":"This research presents the evaluation method of contact-type failure level based on nonlinear wave modulation. It is difficult to detect contact-type failures using a linear ultrasonic inspection. The detection method based on nonlinear wave modulation has been proposed to detect the contact-type failure. Nonlinear wave modulation is the phenomenon, which is explained by contact acoustic nonlinearity (CAN) of ultrasonic caused by low-frequency vibration. The SDOF model for nonlinear wave modulation consists of modal mass, modal damping and modal stiffness which coefficient fluctuates caused by CAN of ultrasonic vibration. This model is described by time-varying linear model when the frequency ratio of the frequency of low-frequency vibration to frequency of ultrasonic vibration is sufficiently small. When the fluctuation frequency of coefficient of modal stiffness caused by low-frequency vibration is sufficiently smaller than the frequency of ultrasonic vibration, the instantaneous natural frequency of ultrasonic vibration fluctuates in synchronization with fluctuation of time-varying coefficient of modal stiffness. Therefore, the fluctuation of natural frequency can be used as a novel index for evaluation of failure level independent of viscous damping. In this paper, the estimation method of fluctuation of the natural frequency is proposed and verified using time response analysis. Firstly, the linear time-varying model of nonlinear wave modulation is introduced. The mechanism of fluctuation of natural frequency is explained by introduced model. Secondly, the estimation method of fluctuation of natural frequency based on the linear time-varying model is proposed. The phase fluctuation occurs as the result of the fluctuation of natural frequency. Finally, it is confirmed that the fluctuation of natural frequency can be estimated from time-invariant transfer function and phase modulation. The fluctuation range of natural frequency is the failure index.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125974785","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.19-00189
Yu Yamane, F. Fujii, Naoya Ishibashi
Low back disorder is a commonly observed worker injury in Japan. Statistical figures revealed that there were 600 to 900 workers who were absent from work more than four days every year because of the low back pain caused by handling heavy objects in the manufacturing industries. Use of mechanical lifters can be a solution but there are still many illshaped heavy objects which should be handled manually in the workplace. Wearable power assist devices can provide physical support to workers who are handling heavy loads in their daily work. The present paper proposes a two-class weight discriminator for lifting-up motion of a human worker, looking to use the output of the proposed discriminator in the control of the wearable power assist device in the future. The proposed discriminator mainly uses the magnitude of two dimensional acceleration spikes measured during a lift-up task using an accelerometer mounted on his/her shoulder, when he/she is trying to do a lift-up motion. We formulated and trained both the linear and the nonlinear support vector machines (SVMs) for the classification of the feature vectors, and evaluated the trained SVMs with independent evaluation dataset. Satisfactory discrimination accuracy has been observed both with the linear and the nonlinear SVMs which use the reaction acceleration feature values. We also evaluated the use of additional three dimensional accumulated body motion accelerations as supplemental feature vector elements. Higher dimensional SVMs were formulated and trained accordingly and the result of discrimination accuracy clarified both positive and negative aspects of high dimensional feature vector for the discrimination of two load weight classes in lift-up motions.
{"title":"Two-class load weight discriminator in a lifting-up task using acceleration metrics of human body","authors":"Yu Yamane, F. Fujii, Naoya Ishibashi","doi":"10.1299/transjsme.19-00189","DOIUrl":"https://doi.org/10.1299/transjsme.19-00189","url":null,"abstract":"Low back disorder is a commonly observed worker injury in Japan. Statistical figures revealed that there were 600 to 900 workers who were absent from work more than four days every year because of the low back pain caused by handling heavy objects in the manufacturing industries. Use of mechanical lifters can be a solution but there are still many illshaped heavy objects which should be handled manually in the workplace. Wearable power assist devices can provide physical support to workers who are handling heavy loads in their daily work. The present paper proposes a two-class weight discriminator for lifting-up motion of a human worker, looking to use the output of the proposed discriminator in the control of the wearable power assist device in the future. The proposed discriminator mainly uses the magnitude of two dimensional acceleration spikes measured during a lift-up task using an accelerometer mounted on his/her shoulder, when he/she is trying to do a lift-up motion. We formulated and trained both the linear and the nonlinear support vector machines (SVMs) for the classification of the feature vectors, and evaluated the trained SVMs with independent evaluation dataset. Satisfactory discrimination accuracy has been observed both with the linear and the nonlinear SVMs which use the reaction acceleration feature values. We also evaluated the use of additional three dimensional accumulated body motion accelerations as supplemental feature vector elements. Higher dimensional SVMs were formulated and trained accordingly and the result of discrimination accuracy clarified both positive and negative aspects of high dimensional feature vector for the discrimination of two load weight classes in lift-up motions.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"436 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127910653","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.22-00060
Daisuke Suzuki, Ken Takahashi, Yoshiaki Okamura, Takafumi Nagatomo
{"title":"Load state of tapered roller bearings used for pinion gear of gear units in electric railway vehicle","authors":"Daisuke Suzuki, Ken Takahashi, Yoshiaki Okamura, Takafumi Nagatomo","doi":"10.1299/transjsme.22-00060","DOIUrl":"https://doi.org/10.1299/transjsme.22-00060","url":null,"abstract":"","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128198047","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.19-00037
K. Harima
The purpose of this paper is to show a new gravity compensator which allows for the passive vertical weightless motion. The conventional zero gravity simulators could not simulate the vertical balance and weightless motion passively at the same time. For example, the simulator using the counter weight of the same mass can only simulate half the acceleration of the weightless motion because an external force acts on both the object and the counter weight. On the other hand, the simulator using the low stiffness spring is difficult to balance. Firstly in this paper for such a trade-off, a new concept which is named degree of zero gravity (DOZ for short) is introduced. By using DOZ we can estimate how similarly the system simulates the acceleration in zero gravity. Secondly, a new gravity compensator which uses a heavy counter weight and a pantograph mechanism is introduced and evaluated by means of DOZ. When an external force acts on the object of the gravity compensator, most of the energy acts on the relatively lightweight object by using the heavy counter weight. It follows the passive vertical weightless motion of the object. Finally, numerical results show the effectiveness for the passive vertical weightless motion. The main results obtained are 0.86 times the acceleration in zero gravity when an external force is applied and the disturbance acceleration of 2.3 × 10−4g or less when an external force is not applied.
{"title":"Analytical study of a new gravity compensator to allow for the accurate weightless motion in the vertical direction","authors":"K. Harima","doi":"10.1299/transjsme.19-00037","DOIUrl":"https://doi.org/10.1299/transjsme.19-00037","url":null,"abstract":"The purpose of this paper is to show a new gravity compensator which allows for the passive vertical weightless motion. The conventional zero gravity simulators could not simulate the vertical balance and weightless motion passively at the same time. For example, the simulator using the counter weight of the same mass can only simulate half the acceleration of the weightless motion because an external force acts on both the object and the counter weight. On the other hand, the simulator using the low stiffness spring is difficult to balance. Firstly in this paper for such a trade-off, a new concept which is named degree of zero gravity (DOZ for short) is introduced. By using DOZ we can estimate how similarly the system simulates the acceleration in zero gravity. Secondly, a new gravity compensator which uses a heavy counter weight and a pantograph mechanism is introduced and evaluated by means of DOZ. When an external force acts on the object of the gravity compensator, most of the energy acts on the relatively lightweight object by using the heavy counter weight. It follows the passive vertical weightless motion of the object. Finally, numerical results show the effectiveness for the passive vertical weightless motion. The main results obtained are 0.86 times the acceleration in zero gravity when an external force is applied and the disturbance acceleration of 2.3 × 10−4g or less when an external force is not applied.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121726496","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}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.20-00284
Gen Uchida, T. Yamada, Kohichi Miura, Hwa-Soo Lee
In the grinding process, the difference of the grinding wheel surface condition affects a grinding performance and a ground surface roughness. It is well known that the grinding wheel surface topography is changed by the difference of dressing condition and the self-sharpening. Therefore, to estimate the optimal dressing conditions and/or manage the grinding wheel life, it is required that the relationship between the grinding wheel surface topography and the grinding characteristic is clarified. From such a viewpoint, by the proposed measuring method called a measured focus position recalculation method, the grinding wheel surface shape is measured before and after dressing and groove grinding. This study aims to quantitatively evaluate the relationship between the grinding wheel surface topography, grinding force and ground surface roughness. From experimental results, by extracting only the changed part of the grinding wheel surface shape before and after dressing and groove grinding, it was found that changes in the grinding wheel surface could be evaluated. Moreover, the abrasive grain cutting edge density, the abrasive grain contact area ratio and the successive cutting-point spacing were calculated by measured results of the grinding wheel with dressing lead changed. By these calculated results, it was clarified that the effect of the grinding wheel surface topography of the difference of dressing lead could be evaluated quantitatively. Finally, it was experimentally clarified that the normal grinding force had the same tendency as the contact area per abrasive grain cutting edge, the ground surface roughness had the same tendency as the successive cutting-point spacing.
{"title":"Quantitative evaluation of grinding wheel surface condition and effect of dressing condition on characteristics of grinding","authors":"Gen Uchida, T. Yamada, Kohichi Miura, Hwa-Soo Lee","doi":"10.1299/transjsme.20-00284","DOIUrl":"https://doi.org/10.1299/transjsme.20-00284","url":null,"abstract":"In the grinding process, the difference of the grinding wheel surface condition affects a grinding performance and a ground surface roughness. It is well known that the grinding wheel surface topography is changed by the difference of dressing condition and the self-sharpening. Therefore, to estimate the optimal dressing conditions and/or manage the grinding wheel life, it is required that the relationship between the grinding wheel surface topography and the grinding characteristic is clarified. From such a viewpoint, by the proposed measuring method called a measured focus position recalculation method, the grinding wheel surface shape is measured before and after dressing and groove grinding. This study aims to quantitatively evaluate the relationship between the grinding wheel surface topography, grinding force and ground surface roughness. From experimental results, by extracting only the changed part of the grinding wheel surface shape before and after dressing and groove grinding, it was found that changes in the grinding wheel surface could be evaluated. Moreover, the abrasive grain cutting edge density, the abrasive grain contact area ratio and the successive cutting-point spacing were calculated by measured results of the grinding wheel with dressing lead changed. By these calculated results, it was clarified that the effect of the grinding wheel surface topography of the difference of dressing lead could be evaluated quantitatively. Finally, it was experimentally clarified that the normal grinding force had the same tendency as the contact area per abrasive grain cutting edge, the ground surface roughness had the same tendency as the successive cutting-point spacing.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115814400","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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