Altair India

HYPERWORKS FOR STUDENTS

Projects using OptiStruct

Shape Optimization of Engine Block





Areas covered:

Geometry Abstraction for FE modeling.

Automatic Mesh Generation.

Free-shape optimization with Stress 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: An assembly model for the engine of a model aircraft has been proposed. Any design changes must only be incremental - structural changes are ruled out by the project-deadlines. Instead, the designers have asked that attention be paid to the outer profile of the engine block. The radii chosen at the CAD stage were not based on any calculations. The goal now is to start with the given shape and check if changes to the shape can reduce stresses. Engine design is multi-disciplinary, since heat transfer and fluid flow (for combustion) are at least as important as structural design. There are also forces that the engine experiences because of the movement of the piston. It may seem that a topology optimization on the engine block to suggest material layout is a good idea, but there are thermal considerations that are important, and these have not been provided to us. Remember that thermal heat capacity of the engine, its heat-dissipation characteristics, etc. are more important than weight-reduction. There is no functional basis for the outer-profile of the engine block. We can only work with the exterior, and with areas away from the mounting and assembly points. Ideally we should carry out an analysis of the entire assembly. Unfortunately that is not within the scope of the design. In actual usage, a range of allowable values for subsystems (stresses, natural frequencies, etc.) should be provided to the component designer by the system-integrator. In the absence of these, we will concentrate on the behavior under static loading.

Battery Tray Design





Areas covered:

Geometry Abstraction for FE modeling.

Automatic Mesh Generation.

Constrained optimization with FRF excitation.

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: A design for the tray to hold the battery of an automobile has been proposed. The basis for the model is a study of earlier designs. The designer wants to know how the tray will perform under the range of excitations it is likely to experience when mounted on the vehicle. Also, the CAD designers have asked whether ribs can be added to minimize the deformation. The goal is to start with the given shape and check if the FRF displacement can indeed be reduced, and to suggest to the designer the likely increase in weight. The starting point of the problem is the IGES file of the CAD assembly. A frequency-domain load is applied to simulate a frequency-sweep: from 0 to 1000 Hz. The proposed design is made from 2 mm thick sheet metal, and is designed to assemble with pre-designed components. It has to carry 2 batteries that together weight 15 kg. Design for static loads is quite easy, but the problem here is that when the engine is running, the tray is expected to receive excitations at a wide range of frequencies. How can we design it for these dynamic loads?

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