The Experts below are selected from a list of 1356 Experts worldwide ranked by ideXlab platform
Inha Sung - One of the best experts on this subject based on the ideXlab platform.
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A study of the relationship between stick-slip and Micro-Scratches generation during chemical-mechanical polishing process
Journal of Mechanical Science and Technology, 2013Co-Authors: Soyoung Jung, Woo Yul Yang, Inha SungAbstract:An observation on the relationship between stick-slip phenomena and chatter scratch generation during chemical-mechanical polishing (CMP) was made using finite element analysis. The motivation for this work is based on the questions about the possibility of the stick-slip phenomena in the CMP process and the quantitative relation between the stick-slip behaviors and the formation characteristics of the scratch. The finite element simulation results showed that stick-slip friction could occur during CMP and it could be seen only in the case of the interactions with the particles trapped inside pad surface. Also, the stick-slip period increased with the density of interacting wafer surface material and the particle size had a significant effect on the stick-slip period and magnitude. It is expected that this work will aid the development of chatter scratch reduction technology.
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first observation on the feasibility of scratch formation by pad particle mixture in cmp process
Applied Surface Science, 2012Co-Authors: Inha SungAbstract:Abstract Micro-scratch formation on a post-chemical mechanical polishing (CMP) wafer surface is one of the critical problems that should be solved for miniaturization and reliability of a semiconductor device. In this study, the mechanism of micro-scratch formation during CMP was investigated through experiments and simulations. When a used pad was utilized in the experiments, it was found that Micro-Scratches could be generated by the polishing process that was done with DI water and additive only without abrasive particles. In order to analyze these Micro-Scratches under a used pad process, the change in surface properties of the polishing pad before and after the CMP was investigated using various surface sensitive techniques. In addition, 2-dimensional finite element analysis (FEA) of CMP process was performed to verify the experimental results. Especially, the FE model with a particle put inside a pad pore was considered to examine how it plays a role in micro-scratch generation. In summary, the scientific results from experiments and simulations in this study first revealed that the pad–particle mixture could be formed on the pad surface during CMP process, which would be one of the major factors leading to micro-scratch generation.
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First observation on the feasibility of scratch formation by pad–particle mixture in CMP process
Applied Surface Science, 2012Co-Authors: Inha SungAbstract:Abstract Micro-scratch formation on a post-chemical mechanical polishing (CMP) wafer surface is one of the critical problems that should be solved for miniaturization and reliability of a semiconductor device. In this study, the mechanism of micro-scratch formation during CMP was investigated through experiments and simulations. When a used pad was utilized in the experiments, it was found that Micro-Scratches could be generated by the polishing process that was done with DI water and additive only without abrasive particles. In order to analyze these Micro-Scratches under a used pad process, the change in surface properties of the polishing pad before and after the CMP was investigated using various surface sensitive techniques. In addition, 2-dimensional finite element analysis (FEA) of CMP process was performed to verify the experimental results. Especially, the FE model with a particle put inside a pad pore was considered to examine how it plays a role in micro-scratch generation. In summary, the scientific results from experiments and simulations in this study first revealed that the pad–particle mixture could be formed on the pad surface during CMP process, which would be one of the major factors leading to micro-scratch generation.
You Wang - One of the best experts on this subject based on the ideXlab platform.
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feasibility and safety of a cemented peek on pe knee replacement in a goat model a preliminary study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.
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Feasibility and Safety of a Cemented PEEK‐on‐PE Knee Replacement in a Goat Model: A Preliminary Study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:: Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.
Zhe Du - One of the best experts on this subject based on the ideXlab platform.
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feasibility and safety of a cemented peek on pe knee replacement in a goat model a preliminary study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.
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Feasibility and Safety of a Cemented PEEK‐on‐PE Knee Replacement in a Goat Model: A Preliminary Study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:: Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.
Sylvie Pommier - One of the best experts on this subject based on the ideXlab platform.
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On the link between long and short cracks: influence of the T-stress
2019Co-Authors: Besnik Sadriji, Bumedijen Raka, Yoann Guilhem, Didier Soria, Sylvie PommierAbstract:Some aircraft components, such as turbine disks, are subjected to very strict certification stages. Other than the fact that the material has a non-linear behaviour (Nickel base superalloy), the complex loading it experiences makes the definition of a fatigue cycle difficult. Moreover, during operation or maintenance those components are exposed to the creation of surface anomalies such as dents or scratches. Besides creating an initial residual stress state that is multiaxial, they create micro-cracks that lead into a significant effect of T-stress. This study aims to highlight the effect of T-stress during a mode I fatigue crack propagation and link it to the short crack effect. The crack propagation under a loading in terms of stress intensity factor depends on its initial length. In fact, the crack growth rate of a short crack is greater than the one for the long crack. Assuming that the difference between short and long cracks stems from T-stress, bi-axial tests have been performed in order to propagate a long crack as if it were a micro-crack. This can be done by changing the biaxiality state, i.e. creating a (KI,T) loading specific to a micro-crack. The results about T=0 MPa to negative T-stress tests show a major increase of the crack growth rate. Those results will be compared to the ones that arise from real short cracks. The challenge here is obtaining a mechanically short crack, meaning a large crack front but a small length. The strategy is then the following: from a drilled specimen, a fatigue loading is applied to propagate a crack to the threshold and to make it stop at a determined location. A sample containing the short crack, after EDM and polishing, is then extracted in order to apply a fatigue loading correlated to the one applied on long cracks. The comparison of the results obtained on short and long cracks will allow us to validate the assumption that the same fatigue crack growth is obtained if the loading (KI,T) is applied. If confirmed, it will be possible to measure short crack growth using tests on long cracks.
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Short versus long crack fatigue crack growth: A new experimental approach
2018Co-Authors: Besnik Sadriji, Bumedijen Raka, Yoann Guilhem, Didier Soria, Sylvie PommierAbstract:Some aircraft components, such as turbine disks, are subjected to very strict certification stages. Other than the fact that the material has a non-linear behaviour (Nickel base superalloy), the complex loading it experiences makes the definition of a fatigue cycle difficult. Moreover, during operation or maintenance those components are exposed to the creation of surface anomalies such as dents or scratches. Besides creating an initial residual stress state that is multiaxial, they create micro-cracks that lead into a significant effect of T-stress. This study aims to highlight the effect of T-stress during a mode I fatigue crack propagation and link it to the short crack effect. The crack propagation under a loading in terms of stress intensity factor depends on its initial length. In fact, the crack growth rate of a short crack is greater than the one for the long crack. Assuming that the difference between short and long cracks stems from T-stress, bi-axial tests have been performed in order to propagate a long crack as if it were a micro-crack. This can be done by changing the biaxiality state, i.e. creating a (KI, T) loading specific to a micro-crack. The results about T=0 MPa to negative T-stress tests show a major potential increase. The effect of T-stress is along 40µm and lasts for 5k cycles. Those results will be compared to the one with real short cracks, the challenge here is obtaining a mechanically short crack, meaning a large crack front but a small length. The comparison of the results obtained on short and long cracks will allow us to validate the assumption that the same fatigue crack growth is obtained if the loading (KI,T) is applied. If confirmed, it will be possible to measure short crack growth using tests on long cracks.
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Short versus long cracks fatigue crack growth rate, a novel experimental approach
2018Co-Authors: Besnik Sadriji, Bumedijen Raka, Yoann Guilhem, Didier Soria, François Brugier, Sylvie PommierAbstract:Some aircraft components, such as turbine disks, are subjected to very strict certification stages. Other than the fact that the material has a non-linear behaviour (Nickel base superalloy), the complex loading it experiences makes the definition of a fatigue cycle difficult. Moreover, during operation or maintenance those components are exposed to the creation of surface anomalies such as dents or scratches. Besides creating an initial residual stress state that is multiaxial, they create micro-cracks that lead into a significant effect of T-stress. This study aims to highlight the effect of T-stress during a mode I fatigue crack propagation and to compare with the results on effective short cracks. The crack propagation under a loading in terms of stress intensity factor depends on its initial length. In fact, the crack growth rate of a short crack is greater than the one for the long crack [1,2]. Previous work done by Brugier on the propagation of short cracks showed that the effect of T-stresses cannot be neglected unlike long cracks where its effect is reasonably neglected. Thus, assuming that the difference between short and long cracks stems from T-stress (mode I), the goal is to see what is its effect on the fatigue propagation. Bi-axial tests have been performed, at the LMT on the multiaxial machine ASTREE, on cruciform specimens containing a 20mm notch, in order to propagate a long crack as if it were a micro-crack. This can be possible by changing the biaxiality state, i.e. creating a (KI, T) loading specific to a micro-crack, so that the crack tip “sees” the same loading as a micro-crack tip. Based on a 2D numerical model of the specimen, adequate loadings taking in account the crack length are calculated in order to get the right T-stress. Then, 40k cycles sequences divided into two 20k cycles blocks with different T-stress conditions have been applied during the tests. The results about T=0 MPa to T=-280 MPa tests show a major potential increase when the negative T-stress is applied. Thanks to the calibration law, this means that the crack length increases during a few thousands of cycles before getting back to a stabilized state. The effect of T-stress is along 90 mm and during about 5000 cycles. The discontinuity between the two blocks is due to phenomena out of interest. SEM observations are currently held in order to determine the crack growth mechanisms. Those results will be compared to the one with real short cracks, the challenge here is that it is difficult to get a mechanically short crack, meaning a large crack front but a small length. The comparison of the results obtained on short and long cracks will allow us to validate the assumption that the same fatigue crack growth is obtained if the loading (KI,T) is applied. If confirmed, it will be possible to measure short crack growth using tests on long cracks.
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Effect of T-stress on a Nickel base superalloy under mode I fatigue crack propagation
2016Co-Authors: Besnik Sadriji, Bumedijen Raka, Yoann Guilhem, François Brugier, Sylvie PommierAbstract:Some aircraft components, such as turbine disks, are subjected to very strict certification stages. In order to predict their fatigue lifetime, it is necessary to treat this type of cracks and include it in a damage tolerance approach. Thus, other than the fact that the material has a non linear behaviour (Nickel base superalloy), the complex loading it experiences makes the definition of a fatigue cycle difficult. Otherwise, elasto-plastic simulations on 3D structures over millions cycles makes this approach difficult. However, in order to overcome the first difficulty, an incremental model, relying on plastic blunting, is used. Concerning the second, a model reduction is applied to reduce simulation costs. Moreover, during maintenance stages those components are exposed to the creation of defects such as impacts or scratchs. They create micro-cracks and an initial residual stress state which is multiaxial and with gradients. Taking in account those defects implies considering T stresses and modeling the initial residual state in the vicinity of the defect. Bi-axial tests with T stress transitories are currently held in order to highlight their effect on the propagation, and a determination of the relevant quantities at the defect tip linked with a model reduction will be led to model the residual stress. A propagation criterion containing those ingredients will be set and incorporated in the incremental model
Zhanchun Li - One of the best experts on this subject based on the ideXlab platform.
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feasibility and safety of a cemented peek on pe knee replacement in a goat model a preliminary study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.
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Feasibility and Safety of a Cemented PEEK‐on‐PE Knee Replacement in a Goat Model: A Preliminary Study
Artificial Organs, 2018Co-Authors: Zhe Du, Zhanchun Li, You WangAbstract:: Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.