A PhD student in the Department of Computer Science at the University of Colorado Boulder has developed a new design system software package that could reshape the way in which engineers design multi-material objects – and has released it open source.
Charles Wade’s open-source tool, which he dubbed OpenVCAD, maps not just shapes but also where different materials belong in a 3D object, potentially transforming 3D printing by enabling engineers to design multi-material objects more efficiently.
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The project was developed in the Matter Assembly Computation Lab led by assistant professor Robert MacCurdy of the Paul M Rady Department of Mechanical Engineering. ‘There’s certainly a history of multi-material design study and practice that existed well before OpenVCAD,’ said MacCurdy. ‘But we believe the overhead of writing specific code for specific projects every single time prevents engineers from doing as much design as they could. With OpenVCAD, we’re doing all of that work once – and doing it really well – so that people have built-in infrastructure to represent these spatially varying multi-material designs.’
Designing objects with multiple materials has long pushed the limits of conventional CAD software. According to Wade and MacCurdy, traditional design tools tend to represent objects as boundary surfaces only. This means they operate with an implicit assumption that everything inside of a boundary surface is all made up of the same material.
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One of the major areas of interest in mechanics is something called gradient design, in which two materials are gradually blended together from one to another – like a shoe sole that shifts from firm at the bottom to soft at the top. But without a powerful design tool, translating rough steps into smooth transitions can be overwhelmingly difficult.
That’s why Wade developed OpenVCAD. The software package acts almost as a set of convenience tools that allow people not only to easily compose complex functions, but also to assign them as materials to objects in a 3D printer.
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‘This is the first multi-material, code-based design tool that is widely available,’ Wade said. ‘It allows for good complexity when printing objects, it’s accessible and it’s intuitive to write and design. Unlike traditional CAD software, where you’re forced to sketch everything out for each change and you cannot represent graded materials, our tool allows users to change one small variable and watch the whole design update in an easy way.’
The team’s new paper explores OpenVCAD’s capability across a variety of 3D printers, including one available to MacCurdy’s lab group that allows for object printing with up to five materials at a time. However, it’s the project’s potential impact for the entire engineering community that excites them.
According to MacCurdy and his team, the OpenVCAD software can be used to help researchers design objects relevant to just about any industry and field. Surgeons in need of realistic planning models to practice on can take advantage of the tool’s gradient mixing properties. Soft robotics experts can use it to create flexible actuators that bend in one direction but remain straight and stiff in another. Engineers who need to simulate complex multi-material objects can design in OpenVCAD and easily export a simulation-ready file.
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OpenVCAD can even apply specific mechanical properties to specific parts of lattice structures, which are often used for impact-absorbing capabilities to achieve more complicated designs.
‘We’re able to rely on OpenVCAD’s core capabilities to represent multi-material objects in a bunch of different domains,’ said MacCurdy. ‘But there is a lot more coming in certain areas that we are excited about and we’re really hoping this approach to multi-material design takes off.’
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OpenVCAD is a completely open-source tool, meaning it’s widely available for engineers around the world to use. It even comes equipped with a Python implementation so that any user can easily import the team’s repository and get to work with just a single line of code.
‘We want this to be widely available to people,’ Wade said. ‘We have a growing base of external researchers from other institutions who are using this tool and we hope to enable that community to do their best work.’
The research has been published in Additive Manufacturing.