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nTop

Replacing spacecraft supermaterial with high-performance lattice

Key Software Capabilities

  • Lattice structures
  • Simulation

Summary

An engineering research team at NASA used nTop software to develop a unique lattice structure that allowed them to replace an expensive, long-lead time material in a benchtop laser measurement system with a safer, less expensive material—without compromising performance.

About: The NASA Goddard Space Flight Center is the nation’s largest organization of scientists, engineers, and technologists dedicated to building spacecraft, instruments, and new technology to study the universe.

  • Industry: Aerospace
  • Size: Large
  • Location: Greenbelt, Maryland
  • Application: Latticing


The project

Material selection for a laser benchtop system

Scalar field derived from thermal simulation used for optimization

The baseplate of the laser benchtop system tends to deform from the heat of the laser, affecting the accuracy of measurements. This issue is relevant to a wide range of laser, LiDAR and photonics systems used in aerospace. The original design was made from beryllium: a supermaterial used for its stiffness and thermal properties. But it is also expensive, its dust is hazardous, and only a few shops can machine it for aerospace applications.

The challenge

Change material, maintain performance

Thermal and structural properties of unit cells NASA evaluated to replace solid beryllium

The NASA team wanted to replace beryllium with a safer, less expensive material without compromising performance. The chosen material was A6061-RAM2, a general-purpose AM aluminum alloy. To accomplish this, the team wanted to create a lattice network that could achieve similar deformation performance with an equivalent elastic strain similar to beryllium, an equivalent stress less than beryllium, and mass targets within ±10% of beryllium.

You’re taking a cheaper and relatively weak material and asking how to make it outperform an extremely expensive advanced material that’s 33% lighter. You have five constraints and it’s a multi-physics problem. This is really difficult to solve.

Alex Souk

Senior Mechanical Design Engineer

NASA Goddard Space Flight Center

The solution

Systematic latticing with computational design

Computational design held the key, because it can be used to quickly generate and evaluate many different design possibilities and enhance specific characteristics, like strength and heat transfer. Using nTop to create and analyze 10 configurations of the design with varying lattice characteristics, the team was able to understand the effects each parameter had, and quickly identified an optimal configuration that satisfied the project objectives.

The results

  • ±10%

    Deformation difference between materials

  • 36x

    Lead time reduction

  • 10%

    Mass penalty

  • 20x

    Cost reduction

With this particular TPMS lattice, the difference between the two materials needs to be within 5 µm ±10%. We knew the aluminum would deform more than the beryllium. The question is, did we hit our requirement? In our case, the answer is yes.

Alex Souk

Senior Mechanical Design Engineer

NASA Goddard Space Flight Center

Why nTop?

Computational design was critical to this application. The NASA team was particularly interested in constructing a systematized lattice design methodology that could be shared and reused in many other applications across NASA. Because nTop remains at the forefront of computational design, it was a natural choice for this challenge.

Scalar ramping function

The ramping function in nTop was critical for lattice optimization. This lets engineers gradually change a value based on the scalar field. So NASA engineers could specify that in areas where deformation exceeds a certain threshold, a certain thickness is needed, then ramp it back down by the time it gets to low deformation. nTop varies the scale of design parameters based on actual simulation data.

Tested configurations of latticed plate using a ramped thickness parameter

Exploring design variants

The team believed the final component would feature Voronoi ribbing at the top layer to keep the skin strong, a gyroid-based lattice core, and an aluminum wrap. With nTop, the team was able to determine how the Voronoi ribbing impacted performance at a specific mass penalty. This helped them quickly iterate on a variety of configurations of ribbing structures and lattice networks.

Performance and mass characteristics of design variants evaluated for the project

Faster design iteration

Each iteration took about five minutes to develop, then was simulated in a separate ANSYS software platform, which is widely used in aerospace for validation. The NASA team appreciated the fact that nTop allowed them to build workflows knowing what variables they intended to change. They could copy the workflow and change the variables, knowing the model would update parametrically.

Overall design methodology from initial problem definition through to lattice selection and optimization

The configuration we chose prints really well. We were able to define the features of the lattice without any issues, with clear separation in strut thickness between the two boundary layers. The final part was fabricated at NASA’s Wallops Flight Facility in Virginia in nine days for $1,200.

Alex Souk

Senior Mechanical Design Engineer

NASA Goddard Space Flight Center

We’ve been using nTop for a little over a year and we’re already submitting to a scientific journal, we have pre-patent applications, and a part that is currently being qualified for flight on a spacecraft.

Alex Souk

Senior Mechanical Design Engineer

NASA Goddard Space Flight Center

Conclusion

Computational design capabilities in nTop empowered NASA researchers to replace an expensive, toxic material in a critical spacecraft component while meeting critical performance standards.

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