FRP Panelized Rearing Tank FEA

Current Status: Complete

Von Mises Skin Stresses

Von Mises Core Stresses

Global Displacement - Amplified

Global Displacement

Finalisation of the Mesh and about to Begin Boundary Conditions / Loading

Below is the addition of the mooring ring flanges on the global meshed model.

A preliminary report was prepared by myself on behalf of ABS Technology for the Middle Bay Sustainable Aquaculture Institute (MBSAI). This report precedes the final report and fabrication of the 30m rearing tank and the scenario investigated was in accordance with the Worley Parsons Westmar Report. Using Patran / Nastran Shell Elements, it was possible to generate a quality mesh.

The composite nature of laminates used as a primary structural material for the tank necessitated the use of 2D Shell elements. Therefore, the mid-surfaces were extracted from the solid CAD model provided and the pump ducts were removed from the geometry.

The use of the Shell Element is appropriate in this application as the various layers of the laminate can be characterized. It is also a good approximation as the thicknesses of the laminates are small relative to the general size of the individual components. Consequently, by selecting a Shell Element in Patran / Nastran, it was possible to model each layers of the laminates accurately.

For the purpose of this static analysis, an amalgam of loads was considered including South East winds of 31.5m/s, a current of 1.1m/s, wind load on handrails, wind on nets (Jump Net, Outer Walkway Nets, Bird Lid Net). Also taken into account were the effects of buoyancy from the multiple bodies constituting the tank assembly. Finally, mooring loads and a dummy load applied to the tank drain were also prescribed to the model.

Since water level inside the tank is quite close to the outside water level, the hydrostatic pressure induced on the various bodies is fairly small. Under steady state conditions, the buoyant equilibrium is reached when the water level inside the tank reaches approximately 7.6m. The head experienced by the walls and the bottom floor under this condition is solely the differential level between the inside and outside water level. Consequently, a 1’ head was assumed present at all times inside the tank.

Component	Location	Type of Load (Wind S-E and Current N-W)	Magnitude	Direction
Deck Platform 1-24	Upper Surface Corners	Moment ^ to S-E Direction	200N·m	^ to S-E
Deck Platform 1-24	Upper Surface Corners	Force	187,5N	S-E
Deck Platform 1-24	Inner Upper Surface Corners	Moment ^ to S-E Direction	2222 N·m	^ to S-E
Deck Platform 1-24	Inner Upper Surface Corners	Force	2083N	S-E
Deck Platform 8-20	Freeboard (Outter vertical Wall)	Distributed Force on all Surfaces	63740N	S-E
Sidewall 1-7, 21-24	Outer Wall	Distributed Force on all 12 Surfaces	150000N	N-W
Sidewall 1-24	Outer Wall	Buoyancy Force on outer Shell	442N	Up
Sidewall 1-24	Inner Wall	Hydrostatic Head	2.98 Pa	Normal
Bottom Floor 1-24	Bottom Surface	Buoyancy Force on all 24 surfaces	228N	N-W
Bottom Floor 1-24	Central Drain	Suction Pump	10000N	Down
Bottom Floor 1-24	Bottom Surface	Hydrostatic Head	2.98Pa	Normal