根据网上金属轧制视频教程演化来的三层板轧件辊压轧制，报错总是solver pivot warning和One or more bodies may be underconstrained and experiencing rigid body motion. 求解器输出里也经常出现辊子外表面pilot node 的ROTX的问题“There are 1 small equation solver pivot terms (e.g., at the ROTX degree of freedom of node 20918) which had to be constrained to produce a solution.  This typically indicates a numerically unstable model. Please check your results carefully.  ”请问大神这个模型如果欠约束的话应该如何施加约束比较好？如果约束没问题的话到底是哪里出了问题？下面是设置

1. 轧辊刚体，轧件柔性体三层板镁合金/橡胶/镁合金，轧件层间添加debonding，

2. 轧辊与轧件外表面摩擦接触，添加增强拉格朗日算法和自动刚度更新，调整为adjust to touch

3. 轧辊外表面添加了body-ground的旋转副，轧件后端添加一个位移约束释放x方向的自由度
   

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