# Compression of closed thin inflatable cylindrical shell column filled with air: FEA tutorial

## Introduction

This is a tutorial of buckling analysis of closed thin cylindrical shell filled with air. The cylindrical shell is acting as column. It means a compressive load is acting on the top of vertically standing cylindrical shell which contains air inside.

The buckling and then post buckling analysis has been done using finite element package – abaqus.

The analysis has been broken down in two parts:

1. buckling analysis
2. post buckling analysis.

### Buckling analysis

Buckling analysis has been done using linear perturbation step. In this step only top compressive load is acting and the cylindrical shell is empty. This gives us buckling modes and critical loads. This gives us a idea that at what load it might buckle.

### Post buckling analysis

Post buckling analysis has been performed using dynamic explicit step. In this analysis, the cylindrical shell is filled with air and then a compressive load is applied on the top. Also, superposition of scaled modes has been used to introduce imperfection/perturbation in the cylindrical shell.

## Procedure/Demonstration

The steps for the above analysis has been demonstrated in following videos. These videos are self explanatory and contains the details of the model, load, material and other necessary properties/details to be used in the whole simulation.

Buckling of closed thin inflatable cylindrical shell: part 01

Buckling of closed thin inflatable cylindrical shell: part 02

Buckling of closed thin inflatable cylindrical shell: part 03

Buckling of closed thin inflatable cylindrical shell: part 04

Buckling of closed thin inflatable cylindrical shell: part 05

Buckling of closed thin inflatable cylindrical shell: part 06

## Simulation files

The instructions to use these files is given here.

It is very helpful because there may be things which may not be clear to you by just watching/following the video tutorials. So, you can download and play around with simulation files while watching/following tutorials.

## Take away

This tutorial is just for demonstration of the procedure. Buckling analysis certainly gives the lowest buckling load but post buckling analysis is very sensitive to the imperfection and the load applied. You may get another shape or displacement results just by changing the imperfection values. So many analysis with different imperfection is suggested to see the effect.  In this simulation the buckling analysis has been performed without air inside the shell. So the buckling load is expected to be lower. In post buckling analysis the air is filled, so the load at which the shell may buckle should be expected to be higher (not lower) than that without air. So a load applied in the post buckling analysis is higher than the first buckling load of the shell without air.

I sincerely thanks to Mr. Allif Firdaus Hassim to help me with this tutorial.

Thank you!

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## Author: learnsharewithdp

I am a mechanical engineer, digital content creator, ,blogger, educator and excited to learn everyday.