Design for AM: CAD Tools, Simulation, Voxels & the Future of AM Design

July 23, 2025 | Reading time: 6 min

 

In a special live recording from the Rapid + TCT Show in Detroit, the Additive Snack Podcast featured the insightful Dr. Andreas Vlahinos, a true mastermind of design in additive manufacturing (AM). With a long and decorated career, Dr. Vlahinos shared his perspective on the evolution of design for additive manufacturing (DfAM), the exciting projects he's tackled, and the passion that continues to fuel his innovative work.

 

The Evolution of Design for Additive Manufacturing: From Catch-Up to Simulation-Driven Innovation

Dr. Vlahinos recalled a time when parametric CAD systems allowed engineers to create designs with internal complexities that traditional manufacturing couldn't produce. Then, advancements in AM powders, machines, and scanning techniques outpaced design capabilities, meaning we were able to build parts we couldn't design. This spurred an evolution in CAD, with new companies and tools emerging to enable the design of complex geometries like lattice structures, including gyroids — structures he was introduced to in the 80s but couldn't fully utilize until recently.

The real game-changer in the last three years, according to Dr. Vlahinos, has been the "enormous progress in simulation-driven design." Now, it's possible to run Finite Element Analysis (FEA) on a solid part, store the results, and then use that data to, for example, vary the thickness of a gyroid based on residual or von Mises stress.

A critical hurdle was the interoperability between traditional Boundary Representation CAD geometry and voxel-based geometries generated by advanced DfAM tools. The recent shift in simulation technology, embracing voxel-based approaches, has enabled real-time simulation within the design environment. Designers can now see simulation results as they design, allowing immediate modifications based on stress points.

 

Bridging the Knowledge Gap: Tools and Training

Despite these advancements, the workforce has often fallen behind. Dr. Vlahinos attributed this to several factors: the rapid pace of technological improvement with every software release; academia not keeping up with these new tools; and the bureaucratic process of accrediting new courses. The result is that engineers are graduating without knowledge of these critical DfAM capabilities.

To combat this, the industry is increasingly turning to in-house, just-in-time training. Dr. Vlahinos himself trained 480 engineers at Lockheed Martin last year, many of whom were unaware of the advanced DfAM tools already available within their existing software.

He personally utilizes tools like PTC Creo, with its integrated voxel-based design and Creo Simulation Live, and nTopology (now nTop) for its powerful implicit modeling capabilities, which allow for the creation of vast lattice structures and unique operations like blending gyroids with solid CAD or shelling gyroids for double-walled structures. While powerful, he notes that nTop's usability and interoperability, though improving, still present challenges.

Impacting Human Life: The Femur Implant Project

When asked about his most exciting recent projects, Dr. Vlahinos highlighted a profoundly impactful medical case from about two years prior. A young lady with cancer in her femur needed an implant within a week to avoid amputation.

This involved quickly learning to process DICOM data from a CT scan to generate an STL, convert it to a solid model, virtually resect the cancerous bone, design the implant with integrated brackets, and incorporate radially based lattice structures for osseointegration, all while ensuring a channel for a surgical nail.

The implant was printed and successfully implanted, and the patient was walking without a limp within two weeks. While this "labor of love" was more rewarding than any paid project, Dr. Vlahinos noted the conservative nature of the medical field, hoping for more openness to DfAM-enabled innovations like hinged implants.

Creo 8-Gyroid Lattices

The Heat Exchanger Design Process: A Deep Dive

Dr. Vlahinos then detailed his meticulous process for designing additively manufactured heat exchangers: 

  1. Feasibility ("Could I, Should I"): Can it be printed within the envelope? Is the material available? Do we have printer access? Then, critically, does it make economic sense compared to traditional methods (e.g., tube-and-shell or brazed plate)? This involves a total cost-of-ownership analysis, considering factors like fatigue life and maintenance.
  2. Performance targets and digital library: What performance is needed? Dr. Vlahinos aims to at least double the existing solution’s performance. The goal is to create a digital twin — an as-designed model and an as-printed model (including orientation, supports, machining allowances) stored in a PLM system for on-demand printing.
  3. Initial design and CFD: Identify inlets and outlets, define a chunky bounding volume, and run CFD analysis on this volume with basic inlet/outlet temperatures and pressures. TPMS structures, often used, inherently have a low pressure drop.
  4. Flow-guided shaping: The resulting flow lines from CFD guide material placement, carving out recirculation regions and defining the basic heat exchanger volume.
  5. Conjugate heat transfer and efficiency: Once the solid volume is defined, run conjugate heat transfer analysis to determine temperatures and pressures throughout and calculate the heat exchanger's efficiency.
  6. Design exploration and optimization: If efficiency is low, parameters like unit cell size and lattice type are explored. A Design of Experiments (DOE) approach is used, running multiple configurations. Results are visualized (e.g., parallel plots, Pareto fronts) to identify optimal designs.
  7. Manufacturability and collaboration: Once the optimized design is presented to manufacturing, constraints like support structure removal, machining allowances, and datums for post-processing are addressed. Manufacturing considerations, like minimum printable wall thickness, are fed back into the DOE ranges.
  8. Manufacturing process simulation: Analyzing the area-versus-height plot can reveal abrupt cross-sectional changes that might cause issues, prompting design modifications like corrugated plates or ramped features.

 

Inspiring the Next Generation (and the Current One)

For designers new to AM or struggling with it, Dr. Vlahinos advises that education should be about inspiration, not just information.

He begins his DfAM courses by showcasing nature's brilliant designs — how trees use topology optimization or how butterfly wings achieve long spans with thin structures.

He then provides "seeds" for innovation, like embedding heat pipes within the chassis of electronic boards by designing internal cavities, adding a few drops of water, and sealing them. The hardest part, he believes, is overcoming the mindset ingrained by 150 years of design for subtractive manufacturing.

Dr. Andreas Vlahinos's insights paint a vibrant picture of a rapidly evolving field, where sophisticated tools, rigorous processes, and, above all, a collaborative mindset unlock the full potential of AM.

 

Connect and Learn More

For more from Dr. Andreas Vlahinos: