Altair India

HYPERWORKS FOR STUDENTS

Projects using OptiStruct

Redesign of Aluminum Housing





Areas covered:

Geometry Abstraction for FE modeling.

Automatic Mesh Generation.

Constrained optimization with Stress constraints.

Design interpretations of FE results.

Transfer of an FE model to a CAD modeler for post-optimization detailed-design.

Description of the Problem: A military tank carries projectiles in tubes. To protect the projectiles, a flap closes the exit of the tube. When ready to fire the flap opens, leaving the exit clear for the projectile. Each flap is controlled by an actuator, which is an electromechanical device consisting of a motor, a cam, a gear train, and a few other components. All components are mounted inside a housing, which is then sealed. The housing itself is bolted to the tank body. In the current design the housing is machined from an Aluminum casting. The housing-manufacturer has been informed that the units have developed cracks near the mounts. No data on conditions causing the failure, pattern of failure, etc are available. No changes can be made to the mounting points on the tank. The internal components (i.e. the actuator) also cannot be modified or relocated. The design problem is: How would you redesign the housing? The supplier wants to change the housing material from Aluminum to Steel. One option is to maintain the same dimensions and switch the material to Steel. The student should be asked to consider that since the forces that cause stresses are due to the deadweight, increasing the stiffness will not help if the mass also increases. Steel is stiffer than Aluminum, but is also heavier.

Frequency Optimization of Vehicle Floor





Areas covered:

Geometry Abstraction for FE modeling.

Automatic Mesh Generation.

Constrained optimization with frequency constraints.

Use of manufacturing-constraints.

Design interpretations of FE results .

Transfer of an FE model to a CAD modeler for post-optimization detailed-design.

Description of the Problem: Typically made of sheet metal, the floor separates the seating / cargo area from the underbody. As with most other components in a vehicle, avoidance of resonance is important. Vehicle designers provide ranges of frequencies to component designers, who must ensure that these are complied with. Plane sheet panels exhibit poor stiffness and NVH performance due to their flexibility. A common and cost-effective approach in the automotive industry to improve the stiffness and NVH performance of sheet panels is the addition of beads. The design challenge is to make changes to the proposed shape, without altering mounting points or other assembly aspects, to ensure that the base frequency is above 40 Hz. The design problem involves the specifications, the methods of addressing these, and the potential for success. The last point is the most important: in design, a negative result is also extremely useful. It is very possible that the floor, with the given thickness, will not be able to attain the required characteristics.

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