料属性、边界条件和载荷。 - 时间步设置：根据问题的特性选择合适的时间步
长，以确保分析的准确性和效率。 - 求解设置：选择求解方法（如直接求解或
迭代求解），并设置求解参数。 - 结果分析：评估结构的动态响应，如位移、速
度、加速度和应力等。
1.2.3 示例
假设我们有一个简单的梁结构，需要进行瞬态动力学分析，以评估其在冲
击载荷下的响应。以下是一个使用 MSC Nastran 进行瞬态动力学分析的示例：
1.2.3.1 模型定义
在 MSC Nastran 中，我们首先定义梁的几何和材料属性。这里我们使用一
个简单的梁单元（CBEAM）和线性弹性材料模型。
BEGIN BULK
$ Define the material properties
MAT1,1,30000.,0.3,0.283
$ Define the beam section properties
SECTID,1,1,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01
$ Define the beam element
CBEAM,1,1,2,1,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.
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