Research Summaries

Research Focus

The goal of our group is to advance computational design technologies (with a particular emphasis on topology optimization methods) to produce superior structural designs that are manufacturable and economical, while pushing the limits of structural efficiency. Our research spans:

  • multiple scales, from architected materials design to structural assemblies;
  • single and multi-material designs, including multiple isotropic or anisotropic (e.g., composite) materials
  • different manufacturing processes, including additive manufacturing, composites manufacturing, welding and casting; and
  • multiple application realms and physics.

The following are some areas of ongoing work.

Ongoing Research Work

Design of structural assemblies
Topology optimization has often been used for the design of single structural components. Prevalent methods represent the design using fields, thus rendering highly efficient, organic designs. These designs, however, do not conform to structures that are to be produced as the assembly of geometric primitives (e.g., stock material). Over the last years, our group has been advancing techniques (collectively known as the geometry projection method) to perform the topology optimization of structures that are made by  the combination of geometric primitives.
This picture shows an example of the optimal design of a cantilever beam with plates of constant thickness.
Topology optimization of architected truss lattices
One area where geometry projection techniques fit naturally is in the design of architected truss lattice materials to obtain desired properties. While truss lattices underperform thin-wall periodic materials in terms of stiffness-to-weight ratio, their open-cell configuration allows for their fabrication via additive manufacturing techniques. Over the last years, we have advanced topology optimization techniques to design truss lattice materials. Our techniques simultaneously determine the spatial layout of the struts within the unit cell and a) the best choice of material for each strut out of a set of available materials or b) the fraction of hole (for tubular struts) or fiber reinforcement (for struts made of a composite).
This figure shows to example of architected truss lattices
Design of structural assemblies made with composite materials
Another focus of our work is in advancing topology optimization techniques to design structural assemblies made of fiber-reinforced primitives (e.g., bars and plates). Our methods simultaneously determine the optimal layout of the primitives within a 3-dimensional design region and the fiber reinforcement of each primitive. The goal of these methods is to render designs that are amenable to conventional composite manufacturing processes for, e.g., structures made of laminates.
This figure shows an example of a frame design with fiber-reinforced bars obtained with topology optimization
Topology optimization of airframe structures
An application area that is driving some of our advances is the design of airframe structures made of primitives, such as the ribs-and-spars configurations of a wingbox. Our efforts include the incorporation of design-dependent aeroelastic loading, fail-safe design criteria, and failure criteria such as stress and buckling.
This figure shows an example of the topology optimization with fixed-thickness plates of the wingbox of a wing.
Design of synthetic bone scaffolds
Another significant area of interest is the computational design of synthetic bone scaffolds fabricated by additive manufacturing (direct ink writing) to repair bone defects. As with all of our research efforts, an important goal is to render designs that conform to the manufacturing process. We have advanced techniques to design scaffolds based on purely mechanical criteria (e.g., stiffness) and more recently on bone growth criteria, whereby bone growth into the scaffold is simulated using a time-dependent model in which the bone deposition rate is a function of a mechanical stimulus and the concentration of growth cells.
This picture shows an optimzed design of a synthetic bone scaffold fabricated via direct ink writing
Incorporation of local failure criteria in topology optimization
Our group has also made strides in incorporating into the optimization local failure criteria, such as stress and fatigue life constraints. We have formulated techniques to efficiently impose maximum stress and minimum (high-cycle) fatigue life for large-scale problems. In particular, the incorporation of fatigue life constraints considers non-proportional loading, which is common in many practical applications. 
This picture shows an example of a density-based topology optimization with fatigue life constraints.