How to Choose the Right Method for Structural Optimization

Manufacturers are constantly looking for ways to design lightweight, cost-efficient, and high-performing products. In this article, we examine a few simulation-driven design technologies and importantly how and when to apply them in a product development process.

Topography Optimization

Topography optimization helps manufacturers to design and optimize any thin-walled part. Like a drum skin, these thin sheet structures can be easily excited, causing undesirable noise, vibration and even damage under certain conditions.

To improve the vibration characteristics, local shape modifications such as beads are added for stiffness. Most of the time, the location, shape, and orientation of these beads is based on the natural geometry of the part and the designer’s experience. Topography optimization enables designers to define spaces where beads can and cannot be added, the width of the beads, as well as the draw direction, angle, and height. This means only practical designs are generated, with optimal patterns.

A software-optimized bead pattern will often dramatically outperform a traditional layout, maximizing stiffness, frequency response or other performance objectives – without adding mass or manufacturing complexity.

Topology Optimization

Imagine a simple beam that needs to carry a single load. Engineers can typically draw upon experience to propose a workable solution. But when faced with a complex part, packaged into a tight space, that needs to carry multiple loads, they could use a helping hand.

Rather than validating an existing design, topology optimization uses physics to enhance human creativity by proposing forms that can be easily evolved into a finished product. It enables rapid design exploration and improved development productivity, all the while flagging opportunities for part consolidation.

Engineers can apply manufacturing constraints at the beginning stages of design, including material, extrusion, symmetry, draw direction, cavity avoidance, and overhand angle. They can define where structure can and cannot be, and apply the expected loads that the part will see in use. Topology optimization takes it from there, generating optimal, manufacturable structures that meet performance objectives with minimum mass or maximum stiffness.

Size, Shape, and Free-Shape Optimization

Topology and topography optimization deliver great concepts, but even the most promising new designs need to be fine-tuned. This is where size, shape, and free-shape optimization come in.

Size optimization is widely used to find optimal solutions for key product characteristics, such as cross-sectional thicknesses, material choice, and other part parameters.

When designers see high-stress concentrations during their initial concept analysis, they’ll turn to shape and free-shape optimization to reduce the potential for product failure. Shape optimization enhances an existing geometry by adjusting the height, length, or radii of the design – morphing the part to distribute stress more evenly.

Free-shape optimization provides even greater flexibility by allowing designers to mark the area targeted for stress reduction. The software then creates a new, improved geometry for that area of the part. But this greater simulation freedom comes with a trade-off; free-shape optimization will not preserve small design features such as fillets. So, it’s important to understand the detailed geometry constraints of your design in order to confidently select which tool to use for fine-tuning.

Free-Size Optimization

Free-size optimization is the most specialized of these methods and is often applied to optimize machined structures and parts stamped from tailor-welded blanks. It is perhaps most widely used, however, in the design of complex laminate composite components.

Free-size optimization helps engineers find the optimal thickness, optimal ply shapes, and optimal stacking sequence for laminate composites. Engineers can set manufacturing constraints – such as the number of fiber orientations, the maximum thickness of each orientation, and the total laminate thickness – and then quickly generate an ideal concept design.

Free-size optimization uses the concept of super-plies to define a continuous distribution of thickness for each fiber orientation that meets the part performance requirements. Then, engineers can fine-tune the designs using ply-bundle sizing optimization. Each bundle represents multiple plies of the same orientation and shape while considering detailed behavior constraints, including ply failure. Finally, a ply stacking sequence optimization arranges every laminate to satisfy all manufacturing constraints while delivering optimal performance.

To learn about applying simulation-driven design for structural analysis and optimization, visit https://www.altair.com/structures-applications/.