@article{oai:jaxa.repo.nii.ac.jp:00035095,
 author = {工藤, 英明 and KUDO, Hideaki},
 issue = {1},
 journal = {東京大学航空研究所集報},
 month = {Sep},
 note = {平面ひずみ鍛造および押出加工における加工所要圧力および変形を解析するために極限定理における上界を低下させる方法を採用し,少い手間で十分な精度のある結果を得る手法を考案した.この手法を用い,非硬化性材料の圧縮,盛上,作頭,押込,押出,穿孔押出鍛造,組合せ押出および圧印加工等を解析して新しい事実を見出すとともにそのうちすでに厳密解の知られているものについては比較を行いよい一致のあることがわかった., In the first part of the present work, a method was developed to analyse the plane strain forging and extrusion problems with minimum labor and sufficient accuracy. This was done by reducing the so called 'upper bound' for working pressure as low as possible without accounting for the lower bound. To begine with, a conception of 'unit rectangular deforming region' was introduced (Fig.1・1・1). The surrounding bodies of the region was considered to be rigid, and the relative slip resistance on each interface or boundary surface was assumed either zero ('smooth') or k ('rough'). A magnitude 'coefficient of internal energy dissipation' e was then calculated for each frictional boundary condition and height-width ratio a of the rectangular region by deviding the rate of internal energy dissipation E by 2k×(top surface area)×(pressing speed). After comparing several types of velocity field, the type which was composed of rigid triangles (Figs.1・1・4, 5, 6, 9, 10, 14 and 15) was found most suitable for the present purpose. The expressions for minimum e and the corresponding types of triangle velocity field were tabulated in Table 1・1・1, the values of e being graphed as functions of a as shown in Fig.1・1・16. In the next, the upper bounds for working pressure as well as the most suitable velocity fields in various working processes, such as 'compression' (Figs.1・2・1 (a) and 4 (a)), 'open-die extrusion' (Fig.1・2・6), 'heading' (Fig.1・2・11), 'indentation' (Figs.1・3・1, 3 (a), 7 and 8), 'extrusion' (Fig.1・4・1), 'piercing' (Fig.1・4・7), 'combined extrusion' (Figs.1・4・9 and 11), 'sideways extrusion' (Fig.1・4・12), 'extrusion-forging' (Fig.1・5・1), 'combined extrusion-forging' (Figs.1・5・9, 13 and 17) and 'closed-die coining' (Figs.1・6・1, 4 and 5), were analysed by deviding the work material into several 'unit rectangular deforming regions' and by using the above calculated values of e. Certain new informations on many working processes were thus obtained. On the other hand, some of the results were compared with the orthodox 'slip-line' solutions already reported by others, and general good agreements were found. (See Figs.1・2・2, 14, 1・3・4, 1・4・3, 1・5・5 and 6, in which the author's upper bounds and the exact solutions are indicated by solid and broken lines respectively. See also the velocity field comparisons, Figs.1・2・13, 1・3・2, 1・3・5, 1・4・5 and 1・5・7.), 資料番号: SA4134961000},
 pages = {37--96},
 title = {鍛造および押出加工に関する塑性力学的研究 : 第1報 平面ひずみ問題の解析},
 volume = {1},
 year = {1958}
}