Buckling analysis of cyclone separator stand using SolidWorks
AIM
To perform buckling analysis on a cyclone separator stand with and without stiffener and find the change in factor of safety.
To run a design safety and find the optimum position for the stiffener.
SETUP
The cyclone separator is a device for separating solid particles from contaminated gas streams, and has long been used in industrial applications such as power generations, gas turbines, chemical processes and so forth
A reverse flow cyclone separator is an industrial assembly with no moving parts and a simple design.
The main cylindrical part of the cyclone separator is known as the body or barrel. The gradually narrowing conical section is known as the cone.
Un-treated gas enters tangentially through the inlet at the side of the separator. Entrained particles within the gas stream are separated from the gas stream and discharged through the reject port at the base of the separator. Cleaned gas exits through the accept port at the top of the separator.
THEORY
Bucking refers to sudden change in the shape of a component under the effect of applied load. For a structure under gradually increasing load, when the load reaches a critical value, the structure or a member(s) of the structure undergo change in shape and is said to have buckled.
Buckling may occur even though the stresses that develop in the structure are well below those needed to cause failure in the material of which the structure is composed. Further loading may cause significant and somewhat unpredictable deformations, possibly leading to complete loss of the member's load-carrying capacity. However, if the deformations that occur after buckling do not cause the complete collapse of that member, the member will continue to support the load that caused it to buckle. If the buckled member is part of a larger assemblage of components such as a building, any load applied to the buckled part of the structure beyond that which caused the member to buckle will be redistributed within the structure.
Buckling vs Bending
Bending is form of stress when a load is applied perpendicular to the long axis of a beam/column (transverse load). The load causes the beam/column to bend hence the name. Buckling is a form of failure when the beam or column is subjected to a load which exceeds its tensile strength parallel to its long axis (axial load).
Buckling indicates failure, irrespective of magnitude whereas bending is natural under transverse load and is not considered as failure as long as the deflection is within limits.
Factor of Safety (FOS)
It expresses how much stronger a system is than it needs to be for an intended load. Safety factors are often calculated using detailed analysis because comprehensive testing is impractical on many projects, such as bridges and buildings, but the structure's ability to carry a load must be determined to a reasonable accuracy.
There are several ways to determine the factor of safety however, most commonly it is expressed as the ratio of a structure's absolute strength to the actual applied load or as the ratio of yield stress to working stress. It implies that for a FoS =1, the structure will support only the design load and nothing more. Therefore, it is better to have aa higher factor of safety in order to minimise the risk of damage due to some unaccounted load conditions.
Buckling Factor of safety
It refers to the safety factor against buckling. It is the ratio of buckling load to the applied load. Since buckling can prove to be quite dangerous, hence it is always preferred to have large buckling factor of safety.
OBJECTIVE
The objective of this project is to perform buckling analysis on a cyclone separator stand with and without a stiffener on the legs and determine the buckling factor of safety.
Next we have to optimize the position of the stiffener on the legs in order to get maximum FOS.
Case 1: Without stiffener
Firstly, we isolate the stand from the cyclone separator assembly provided and save it as a part file.
Buckling analysis is performed on the stand. In order to do so, the bottom of each of the leg is fixed and a load of 150 kN is applied at the top.
The mesh is created and the study is run. The buckling factor of safety is determined.
Case 2: With stiffener
The stiffener is designed and placed at some initial position on the legs of the stand. The above process is repeated.
Once it is competed, a design study is done and the position of the stiffener is varied from 0.5m to 1.75m from the top. The buckling factor of safety is constrained and the goal is set to maximize it.
The design study is run and the optimum position for the stiffener is determined along with the corresponding buckling factor of safety.
OUTPUT
Without stiffener
With stiffener
OBSERVATION
From the study, we can clearly see that there is a significant increase in the factor of safety with the addition of stiffener. Thus, the stand becomes capable of withstanding greater loads with the addition of stiffener. The capacity further increases by determining the optimum position for the stiffener. It happens because the stiffener provides extra support nd rigidity to control the buckling of the stand.
RESULT
From the design study, we can deduce that the optimum position for the stiffener is 1000mm or 1m from the top where the factor of safety is maximum and is equal to 27.933.
CONCLUSION
Addition of a stiffener increases the safety of the structure. FoS increases from 9.39 without the stiffener to 27.93 with the stiffener at the ideal position.
The safety provided by the stiffener to the structure varies with the position of the stiffener. therefore, it is important to determine the ideal position to fix it. Buckling in general is considered to be a very harmful and dangerous phenomenon and thus, every measure is and must be taken to prevent it.