SUMMARYA large superconducting coil wound with a Cable-inConduit (CIC) conductor caused an additional AC loss, which cannot be estimated from the short conductor sample test results. It was confirmed that the additional AC loss was generated by long current loops in the CIC conductor. Magnetic field decays of the loops with various long-time constants were observed through Hall probes. We propose a mechanism for the formation of the long loops. The CIC conductor is composed of several staged subcables. If one strand on the surface of a subcable contacts the other strand on the surface of the adjacent subcable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches and thereby form a pair of long loops. We numerically traced each strand in the CIC according to a method in which the subcables at all substages rotate around the center of inertia. The calculated long-time constants of the long loops were slightly shorter than the observed ones. We labeled all strands by order in a real CIC conductor, disassembling the cable carefully after peeling the conduit. It was found that the strands in a triplex were widely displaced from their original positions, so that their contacting lengths became longer than the calculated ones. This fact makes the time constant of the loop longer and hence can explain the observed long-time constants. The proposed mechanism is effective for estimating the long loops causing additional AC losses in the coil.

A large superconducting coil wound with a Cable‐in‐Conduit (CIC) conductor caused an additional AC loss, which cannot be estimated from the short conductor sample test results. It was confirmed that the additional AC loss was generated by long current loops in the CIC conductor. Magnetic field decays of the loops with various long‐time constants were observed through Hall probes. We propose a mechanism for the formation of the long loops. The CIC conductor is composed of several staged subcables. If one strand on the surface of a subcable contacts the other strand on the surface of the adjacent subcable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches and thereby form a pair of long loops. We numerically traced each strand in the CIC according to a method in which the subcables at all substages rotate around the center of inertia. The calculated long‐time constants of the long loops were slightly shorter than the observed ones. We labeled all strands by order in a real CIC conductor, disassembling the cable carefully after peeling the conduit. It was found that the strands in a triplex were widely displaced from their original positions, so that their contacting lengths became longer than the calculated ones. This fact makes the time constant of the loop longer and hence can explain the observed long‐time constants. The proposed mechanism is effective for estimating the long loops causing additional AC losses in the coil. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 50–57, 2003; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/eej.10064

The drawbead technique is very important for sheet metal forming in order to control defects such as springback, cracking, wrinkling. Therefore, approximation calculation models of drawbead force have been proposed in the past. However, such calculation models were applied to mild steel or aluminum alloy. In this paper, we propose an approximation calculation model of high-strength steel using the energy method and taking into account the Bauschinger effect. The calculation results were compared with the experiment results obtained under several drawbead shape conditions, and it was confirmed that the prediction value of drawbead force has good accuracy. Also, the through-thickness strain after passing through a drawbead was in good agreement with what obtained using stress reduction parameter due to Bauschinger effect. Moreover, it was found that the strain decreases effectively when the drawbead width is larger than the drawbead height. As a conclusion, the approximate calculation model discussed here is a practical and effective means of designing what tools.Key words: sheet metal forming，drawbaed force，high-strength steel，Bauschinger effect，energy method． * ㈱先端力学シミュレーション研究所 〒351-0198 和光市広沢 2-1

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