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Analysis of Thermal Residual Stress/Strain in REBCO Coated Conductor Tapes
Dizon, John Ryan C.,Nisay, Arman Ray N.,Dedicatoria, Marlon James A.,Munoz, Rodrigo C.,Hyung-Seop Shin,Sang-Soo Oh Institute of Electrical and Electronics Engineers 2014 IEEE transactions on applied superconductivity Vol.24 No.3
<P>2G HTS coated conductor (CC) tapes are now used for electric device applications. The residual stress/strain induced in HTS coating films in CC tapes during cool down influences the critical current, Ic, and should be investigated. In this study, the thermal residual stress/strain induced in the REBCO coating film was calculated from deposition temperature (1073 K) to 77 K by thermo-mechanical analysis and numerical simulation. Additionally, the improvement in irreversible strain limit, εirr., with copper electroplating has been investigated.</P>
Dizon, John Ryan C.,Bonifacio, Rolly,Park, Sung-Taek,Shin, Hyung-Seop The Korean Society of Superconductivity and Cryoge 2007 한국초전도저온공학회논문지 Vol.9 No.4
In practical applications of HTS tapes for electric devices such as coils and power cables, the jointing of HTS tapes is inevitable even though long length tapes have recently been achieved. The critical current, $I_c$, degradation behaviors with tensile and bending deformations were investigated in commercially available YBCO coated conductor tapes. When the V-I relationship was measured at the jointed section of the lap-jointed YBCO CC tapes, the resistance at the joint decreased with increasing joint length. The critical load for 95% $I_c$ retention were determined for the IBAD and RABiTS YBCO tapes and they were 175 and 355N, respectively. Fracture occurred at the unjointed part which represents strong copper lamination and solder jointing. The electro-mechanical properties of lap-jointed CC tapes depended on the properties of single tapes. The V-I behavior under bending strain was similar with the tensile case.
Estimation of Residual Stress in ReBCO Coated Conductor Tapes Using Various Methods
Dizon, John Ryan C.,Shin, Hyung-Seop,Ko, Rock-Kil,Ha, Dong-Woo,Oh, Sang-Soo The Korean Society of Superconductivity and Cryoge 2008 한국초전도저온공학회논문지 Vol.10 No.4
The residual stress induced in the superconducting layer was estimated using analytical approach coupled with electro-mechanical test results and XRD measurements. The residual stress measured based on the $I_{c}/I_{c0}$-strain degradation behavior showed similar value with the measured residual stress using XRD. The calculated residual stress based on the thermal analysis showed the lowest value. This could be explained by the additional intrinsic residual stresses induced in the superconducting film during deposition.
Shin, Hyung-Seop,Dizon, John Ryan C.,Bonifacio, Rolly,Park, Jeong-Soo The Korean Society of Superconductivity and Cryoge 2007 한국초전도저온공학회논문지 Vol.9 No.2
The critical current, $I_c$, degradation behaviors with bending strain were investigated in a commercially available YBCO coated conductor tape. In particular, the strain reversibility of $I_c$ and the influence of repeated bending on $I_c$ have been studied. Also, repeated bending at 77 K was done in order to understand the Ie behavior under cyclic bending strains. A reversible behavior of $I_c$ has been found up to a high bending strain of 1.60% for the RABiTS/MOD processed CC sample with copper reinforcement. Under repeated bending, the Ie showed a 95% $I_c$ retention up to 100 cycles for bending strains of 1.0% or less. The n-value behavior showed a good agreement with the $I_c$ degradation behavior, representing that any cracking did not occur on the YBCO film resulting from the reinforcement provided by the copper stabilizers.
외부보강된 밀봉 상태가 다른 Bi-2223테이프의 가압 LN<sub>2</sub>하에서 임계전류의 굽힘변형률 의존성
신형섭,박정수,Shin, Hyung-Seop,Dizon, John Ryan C,Park, Jeong-Soo,Rolley, Bonifacio 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6
The critical current degradation behaviors of multifilamentary Bi-2223 superconducting tapes under pressurized liquid nitrogen were investigated using a r-shaped sample holder which gives a series of bending strains to tape. Three kinds of externally-reinforced Bi-2223 tapes with different hermeticity were used as samples. The tape with the thicker reinforcement layer had a better bending strain tolerance of $I_c$, but when the bending strain was calculated at the outermost filament, the $I_c$ degradation behavior became identical. For all samples, $I_{c0}$ decreased with the increase of applied pressure, but the $I_c$ degradation behavior with bending strain at each pressure level was similar. Furthermore, after depressurization from 1 MPa to atmospheric pressure, $I_c$ was completely recovered to its initial values. When the samples were warmed up to room temperature after pressurization tests, the ballooning damage occurred at lower bending strain regions. The region where ballooning was observed was identical to the one where the significant $I_c$ degradation occurred.
신형섭,John Ryan C. Dizon,Rolly Bonifacio,박정수 한국초전도.저온공학회 2007 한국초전도저온공학회논문지 Vol.9 No.2
The critical current, Ic, degradation behaviorswith bending strain were investigated in a commercially available YBCO coated conductor tape. In particular, the strain reversibility of Ic and the influence of repeated bending on Ic have been studied. Also, repeated bending at 77 K was done in order to understand the Ic behavior under cyclic bending strains. A reversible behavior of Ic has been found up to a high bending strain of 1.60% for the RABiTS/MOD processed CC sample with copper reinforcement. Under repeated bending, the Ic showed a 95% I c retention up to 100 cycles for bending strains of 1.0% or less. The n-value behavior showed a good agreement with the Ic degradation behavior, representing that any cracking did not occur on the YBCO film resulting from the reinforcement provided by the copper stabilizers.
Influences of Bending Temperature on the I$_{c}$ Degradation Behavior of Bi-2223 tapes under Bending
Shin Hyung Seop,Dizon John Ryan C.,Katagiri Kazumune,Kuroda Tsuneo The Korea Institute of Applied Superconductivity a 2005 한국초전도저온공학회논문지 Vol.7 No.2
The I$_{c}$ degradation behavior of Bi-2223 tapes bent at RT and 77K were investigated using the bending device invented by Goldacker. Test results on fixing the tape at RT and 17K showed no difference. At 17K and RT bending, the critical strain was 0.67 and 0.50$\%$, respectively, for the VAM-l tape. For the AMSC tape, it was 0.94 and 0.88$\%$, respectively. These results show that there is additional residual stress in the superconducting filaments to be bent at 17K which shifts the formation of cracks into smaller bending radii. This was proved by computational analysis based on the mixture rule of composites. For the VAM-l tape, the Ie degradation behavior using the Goldacker type device shifted to higher strain levels at about 0.5$\%$, as compared with the FRP sample holders which have a critical bending strain of about 0.24$\%$. Also, for the externally reinforced AMSC tape, Ie degradation using the Goldacker type device begins at a higher strain level, at 0.88$\%$ as compared with using FRP sample holders, at 0.74$\%$. The difference between both cases can be explained by the tensile' and thermal stresses that the tapes were subjected to during fixing (soldering) when the FRP sample holders were used.
Influences of Bending Temperature on the Ic Degradation Behavior of Bi-2223 tapes under Bending
신형섭,John Ryan C. Dizon,Kazumune Katagiri,Tsuneo Kuroda 한국초전도.저온공학회 2005 한국초전도저온공학회논문지 Vol.7 No.2
The Ic degradation behavior of Bi-2223 tapes bent at RT and 77K were investigated using the bending device invented by Goldacker. Test results on fixing the tape at RT and 77K showed no difference. At 77K and RT bending, the critical strain was 0.67 and 0.50%, respectively, for the VAM-1 tape. For the AMSC tape, it was 0.94 and 0.88%, respectively. These results show that there is additional residual stress in the superconducting filaments to be bent at 77K which shifts the formation of cracks into smaller bending radii. This was proved by computational analysis based on the mixture rule of composites. For the VAM-1 tape, the Ic degradation behavior using the Goldacker type device shifted to higher strain levels at about 0.5%, as compared with the FRP sample holders which have a critical bending strain of about 0.24%. Also, for the externally reinforced AMSC tape, Ic degradation using the Goldacker type device begins at a higher strain level, at 0.88% as compared with using FRP sample holders, at 0.74%. The difference between both cases can be explained by the tensile and thermal stresses that the tapes were subjected to during fixing (soldering) when the FRP sample holders were used.