當病人脊椎側彎的情況下，需對胸椎曲線做矯正，其胸椎曲線為有反曲點如S形，故需由兩段曲率組成。本文對Ti-6Al-4V及316L不銹鋼進行反覆的彎曲試驗，發現第一道次的應變對第二道次並無影響，在實作上可將第一道次之殘留應變乎略，其誤差依然在可接受的範圍。因此做二道次成形之S形金屬桿的彎曲，可使用單曲率推導所得的回彈公式直接做回彈補償。
在實驗中，針對兩種現行醫療用材料，316L不銹鋼及Ti-6Al-4V之金屬棒進行彎曲試驗，所獲得的結果與利用力學的理論推導所得最大下壓量，其差異可在1mm以下。在二道次雙曲率曲線製作上，Ti-6Al-4V及316L不銹鋼之最大誤差也都在1mm以下，驗證了理論解析解預測回彈量的正確性。
在數值模擬方面，DEFORM有限元素法模擬在單道次彎曲回彈預測上，與實驗結果相吻合，而在做多道次回彈分析時，因brick網格在多次反覆變形後產生嚴重扭曲變形，將會在預測回彈時產生較大的誤差。
最後藉由一病例，配合本文程式及新型彎桿器，實際將矯正用金屬桿曲線彎製出，並量測其最大彎曲量，與設計值誤差均小於1mm.

The former design of new rod-bender can only manufacture one curvature rod and the springback prediction is for one pass as well. But the patients of Scoliosis need S-shaped corrective spinal rod. Because of the inflection point of the curve, the rod needs to be bended through twopasses to form S-shaped curve. The bending and reverse bending experiments are performed with two kinds of material, Ti-6Al-4V and 316L stainless steel. The experimental results show that the first pass has almost no influence on the second pass. Accurate curve can be obtained although the residual stress ignored. The springback formulation can still predict springback of the S-shaped bending processes.
The maximum displacement of single curvature bending experiments is close to the analytical prediction for Ti-6Al-4V and 316L stainless with the error smaller than 1mm. The bending experiments of bi-curvature rod also show the same result. Hence the accuracy of springback compensation has been verified.
On numerical simulation, the results of DEFORM FEM simulation have good agreement with the single curvature bending experiments. However, the prediction of DEFORM FEM simulation will be no longer accurate because the shape of the brick element is twisted severely by sequence reverse bending.
Finally, by taking a clinical case for example, the corrective spinal rod is reconstructed by the program and bended by the new rod-bender. Compared with the design value, the error of the maximum displacement is less than 1mm.

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