作者关于用abaqus进行buckling analysis得到buckling mode, 以及将buckling mode乘以magnitude作为缺陷imperfection，并且对column进行nonlinear analysis分享了整个建模的过程，分成两部分，希望能有帮助 （youtube视频）：
ABAQUS: eigenvalue buckling analysis of Cee section column under compression (1)ABAQUS: nonlinear analysis of Cee section column under compression (2)ABAQUS特征值分析/video/1072600395498606592ABAQUS非线性屈曲分析/video/1072600872722173952
笔者对基于屈曲特征值分析，得到屈曲模态，将其作为基础引入缺陷，然后进行非线性屈曲分析的基本步骤以及注意点进行了小结，以便查阅：
Step1: Eigenvalue buckling analysis
Input the following before *End STEP
*NODE FILE, GLOBAL=YES, LAST MODE=1 ##come combine several buckling modes as the initial imperfection
U
Save U of the first buckling mode in the form of .fil
Step2: Introduce imperfection
Input before *Step #edit input file ** After STEP: Step-1 before *Step, name=Step-1, nlgeom=YES
*IMPERFECTION , FILE=Results, STEP=1
1, 1e-1
1e-1 is 1/10 of the shell thickness
Step3: Perform the postbuckling analysis.
Input the following before *End STEP
*NODE FILE, GLOBAL=YES, LAST MODE=1 ##come combine several buckling modes as the initial imperfection
U
Save U of the first buckling mode in the form of .fil
关于视频，针对特征值分析以及非线性分析的 take away notes:
Buckling eigenvalue analysis
1. material orientation definition: tools-create datum-csys-cylinderical edit material orientation using csys for different regions.
2. Define shell-composite section definition
3. Produce .fil with the buckling mode by "edit keywords" add following before *end step to: *NODE FILE U
Nonlinear analysis
1. Material failure criterion: Hashin damage criterion (this is not verified, but can give an example about how it works)
2. Step-field output- Toggle failure indicators of four Hashin damage criterion to visualize failure status.
3. Displacement control (edit displacement in the boundary condition manager)
4. Define imperfection by adding the following before **STEP (note: several buckling modes can be combined with different magnitude) *IMPERFECTION, FILE=filename, STEP=1 1, imperfection_magnitude
5. How to exact data from results and draw load-displacement curve in excel.
文档资料：ABAQUS Analysis User’s Guide
视频资料：/watch?v=uGVfu3hK43Y
