Buckling analysis on a cyclonic separator stand and Design Study for optimization of Stiffener position.

Aim: Buckling analysis on a cyclonic separator stand and Design Study for optimization of Stiffener position.

Theory:

Buckling Analysis:

In many design projects, engineers must calculate the factor of safety (FOS) to ensure the design will withstand the expected loadings. Calculations require correctly recognizing the mechanisms of failure, and this is a difficult task. All too often we associate structural failure only with yielding and are satisfied when design analysis shows a sufficient FOS related to yield.

The linear-buckling analysis calculates buckling load magnitudes that cause buckling and associated buckling modes. FEA programs provide calculations of a large number of buckling modes and the associated buckling-load factors (BLF). The BLF is expressed by a number which the applied load must be multiplied by (or divided — depending on the particular FEA package) to obtain the buckling-load magnitude.

Nonlinear-buckling analysis requires that a load be applied gradually in multiple steps rather than in one step as in a linear analysis. Each load increment changes the structure’s shape, and this, in turn, changes the structure’s stiffness. Therefore, the structure stiffness must be updated at each increment. In this approach, which is called the load control method, load steps are defined either by the user or automatically so the difference in displacement between the two consecutive steps is not too large.

Buckling load factor (BLF): It is an indicator of the factor of safety against buckling or the ratio of buckling load to the applied load.

PROCEDURE:

• Start a new case study
• As we are asked to run the buckling simulation only on the cyclonic separator stand, exclude the parts of the cyclonic separator and apply the material for the stand
• Now define boundary conditions such as the fixtures and the force (150kN).
• Create mesh and run the study and make a note of Buckling Factor Of Safety (FOS) and the amplitude.
• Now model the stiffener for the cyclonic separator stand, start a new case study.
• Apply the material and boundary conditions, mesh and run the simulation.
• Make a note of the buckling factor of safety
• Now start a new design study for optimizing the position of the stiffener based on the buckling factor of safety.
• Make a note of position with the maximum buckling factor of safety.

Design and Modelling:

Results:

Buckling analysis of stand without stiffener:

The factor of Safety:

Design optimization study:

Design Variables Name Type Value Units offset Range with Step Min:250 Max:1750 Step:250 mm Constraints Sensor name Condition Bounds Units Study name Buckling Factor of Safety is greater than Min:25.000000 Buckling with stiffener Goals Name Goal Properties Weight Study name Buckling Factor of Safety Maximize Buckling Factor of Safety 10 Buckling with stiffener

Study Results:

Buckling analysis of stand stiffener at optimal Position:

The factor of Safety:

Conclusion:

From the above study, we can conclude that the buckling can be reduced if we add a stiffener in between the legs of the cyclonic separator stand, which increases the buckling factor of safety. And also we have found out the optimal position of the stiffener, which resists the buckling most.