OptiStruct enhances the design process by:

The design process can be viewed as an optimization process to find structures, mechanical systems, and structural parts that fulfill certain expectations towards their economy, functionality, and appearance. Generally, the design process is an iterative procedure consisting of the following components:

Today’s testing ground is usually the computer. Finite element analysis (FEA) and Multi-body dynamics analysis (MBD) are the most used tools for computational design testing. The results of computational analyses are used to determine design improvements.

Changes to the design are introduced in all phases of the process. At a certain stage of this process, changes to the concept become prohibitive. The concept phase plays a fundamental role concerning overall efficiency of the design and the cost of the overall development process.

In the concept phase of a design process, the freedom of the designer is limited only by the specifications of the design (Figure 1). Today, the decision on how a new design should look is based largely upon a benchmark design or on previous designs. The decision making is based on the experience of those involved in the design process. Conceptual design tools such as topology and topography optimization can be introduced to enhance the process. The concept can be based on results of a computational optimization rather than on estimations. Using topology and topography optimization, the initial design step is already based on input generated using computational analysis. Topology and topography optimization redefine the role of computational analysis and simulation in the design process. Finite element analysis has matured from a testing tool to a design tool.

Figure 1: Decision making in the design process.

Figure 2 compares the design process using topology optimization with the conventional method of leaving the concept entirely to experience and intuition. The overall cost of design development can be reduced substantially by avoiding concept changes introduced in the testing phase of the design. This is the major benefit of modifying the design process by introducing topology and topography optimization.

In the real world, the design process is not as straightforward as described above. The design is not just driven by one performance measure -- it has to be viewed as a multidisciplinary task. Today, the different disciplines work more or less independently. Analysis and optimization is performed for single phenomena such as linear static behavior or noise, vibration and harshness. Still, the idea persists that if one performance measure improves, the whole performance improves. A simple example shows that this is not quite true. Take the design of a car -- a high stiffness is necessary for good driving and handling, and high deformability is important for the crashworthiness of the design. This shows that improving one measure may result in degrading another. Therefore, compromises must go into the formulation of the optimization problem. The definition of the design problem and of the design target is most important. The solution can be left to computational means. Multidisciplinary considerations, especially in the conceptual design, are, in many ways, still active research topics and are being covered by future developments of topology optimization. However, the inclusion of manufacturing constraints into topology and topography optimization is already implemented in OptiStruct.

Figure 2: The design process without and with the use of topology optimization.

OptiStruct also provides size and shape optimization to completely support the design process with finite element based structural optimization. Using the advanced interfacing with HyperMesh, the generation of input data for structural optimization becomes an easy task. This allows structural optimization to be integrated into the design process seamlessly.

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