Buckling analysis on a cyclonic separator stand

OBJECTIVE:

1. To perform a buckling analysis on a cyclonic separator stand to understand its buckling characteristics.
2. To perform a buckling analysis on the same model with a metallic stiffener added and evaluate the change in the buckling factor of safety.
3. To perform a parametric design study on the model to find the optimum position of stiffener and the thickness of the stiffer, to maximise the buckling factor of safety.

GEOMETRIC MODEL:

The geometric 3D model of the cyclonic separator stand was provided along with the tutorial. The unnecessary parts in the model were suppressed and saved into a part file format (.sldprt). The new saved model was opened using Solidworks.

BOUNDARY CONDITIONS:

The same boundary conditions were applied to all the three models;

• Buckling analysis under the new study was selected.
• Material applied - Alloy steel
• Fixtures - The four legs of the cyclonic separator stand was fixed.
• Load - A load of 150kN was applied on the top face of the stand.
• Mesh- Mesh size of 18mm with tolerance size of 0.9mm were used.

CASE 1 - BUCKLING ANALYSIS WITHOUT STIFFENER:

• The boundary conditions were applied to the model.
• The study was run to solve the simulation.

RESULTS:

INFERENCE:

The buckling factor of safety of 9.3547 was obtained under the given conditions. The structure is stable under the loading conditions and is not expected to fail.

CASE 2 - BUCKLING ANALYSIS WITH STIFFENER:

• A stiffener was added to the structure at a bottom offset of 1000mm from the top face of the stand. Stiffener thickness of 75mm was defined.
• The boundary conditions were applied.
• The study was run to solve the simulation.

RESULTS:

INFERENCE:

The buckling factor of safety of 27.577 was obtained under the given conditions. Thus, the structure has become better compared to the earlier design without stiffener. The design has become 3 times better compared to previous. The structure is stable under the loading conditions and is not expected to fail.

CASE 3- PARAMETRIC STUDY TO DETERMINE THE OPTIMUM POSITION AND THICKNESS OF STIFFENER

A parametric design study was started. The following things were defined.

Variables:

• Offset distance of stiffener moved from 250mm to 1500mm with a step value of 250mm.
• The thickness of stiffener changed from 20mm to 120mm with a step value of 20mm.

Constraints:

• The minimum buckling factor of safety was set to 25

Goal:

• Maximise the buckling factor of safety.
• Minimise the thickness of the stiffener.
• Total no. of scenarios 36.

RESULTS:

Component name	Units	Current	Initial	Optimal	Scenario1	Scenario2
Stiffener thickness	mm	75	75	75	20	40
Offset distance	mm	1000	1000	1000	250	250
Buckling Factor of Safety1		27.576529	27.576529	27.576529	10.008496	10.991599
Buckling Factor of Safety2		27.576529	27.576529	27.576529	10.008496	10.991599
Dimension1	mm	75	75	75	20	40

Component name	Units	Scenario3	Scenario4	Scenario5	Scenario6	Scenario7
Stiffener thickness	mm	60	80	100	120	20
Offset distance	mm	250	250	250	250	500
Buckling Factor of Safety1		11.767163	12.177147	12.396346	12.523006	10.438522
Buckling Factor of Safety2		11.767163	12.177147	12.396346	12.523006	10.438522
Dimension1	mm	60	80	100	120	20

Component name	Units	Scenario8	Scenario9	Scenario10	Scenario11	Scenario12
Stiffener thickness	mm	40	60	80	100	120
Offset distance	mm	500	500	500	500	500
Buckling Factor of Safety1		13.141742	14.976645	15.858685	16.322100	16.586916
Buckling Factor of Safety2		13.141742	14.976645	15.858685	16.322100	16.586916
Dimension1	mm	40	60	80	100	120

Component name	Units	Scenario13	Scenario14	Scenario15	Scenario16	Scenario17
Stiffener thickness	mm	20	40	60	80	100
Offset distance	mm	750	750	750	750	750
Buckling Factor of Safety1		10.846201	15.836319	19.676456	21.549610	22.518213
Buckling Factor of Safety2		10.846201	15.836319	19.676456	21.549610	22.518213
Dimension1	mm	20	40	60	80	100

Component name	Units	Scenario18	Scenario19	Scenario20	Scenario21	Scenario22
Stiffener thickness	mm	120	20	40	60	80
Offset distance	mm	750	1000	1000	1000	1000
Buckling Factor of Safety1		23.050318	10.944871	17.348551	23.990150	28.554022
Buckling Factor of Safety2		23.050318	10.944871	17.348551	23.990150	28.554022
Dimension1	mm	120	20	40	60	80

Component name	Units	Scenario23	Scenario24	Scenario25	Scenario26	Scenario27
Stiffener thickness	mm	100	120	20	40	60
Offset distance	mm	1000	1000	1250	1250	1250
Buckling Factor of Safety1		31.553377	33.405010	10.648359	15.506347	19.686344
Buckling Factor of Safety2		31.553377	33.405010	10.648359	15.506347	19.686344
Dimension1	mm	100	120	20	40	60

Component name	Units	Scenario28	Scenario29	Scenario30	Scenario31	Scenario32
Stiffener thickness	mm	80	100	120	20	40
Offset distance	mm	1250	1250	1250	1500	1500
Buckling Factor of Safety1		22.174479	23.832024	25.112261	10.121953	12.783618
Buckling Factor of Safety2		22.174479	23.832024	25.112261	10.121953	12.783618
Dimension1	mm	80	100	120	20	40

Component name	Units	Scenario33	Scenario34	Scenario35	Scenario36
Stiffener thickness	mm	60	80	100	120
Offset distance	mm	1500	1500	1500	1500
Buckling Factor of Safety1		14.924836	16.215261	17.115261	17.837139
Buckling Factor of Safety2		14.924836	16.215261	17.115261	17.837139
Dimension1	mm	60	80	100	120

INFERENCE:

Based on the parametric study, the optimum offset distance of the stiffener and the thickness of the stiffener was found to be 1000mm and 75mm respectively. When you go through the results table, you may find the conditions which give more buckling FOS with more thickness. However, the optimised result will be the one with 1000mm offset and 75mm thickness.

CONCLUSION:

All three objectives were studied. Under the loading condition without stiffener, the Buckling FOS was 9.3547. It was made better to 27.577 with the addition of a stiffener of thickness 75mm at an offset of 1000mm from the top surface. Under the parametric study, the same design yielded the optimum solution.