Aug.22, 2012

Imagine the complex objects you printed on a 3d printer and it broke into pieces during transportation. The problem is, 3D printer can't check if the 3D object is structurally stable after it is printed.

"Even when a model looks perfectly fine on your computer, its physical representation after 3D printing might not be structurally sound and it can simply break down," says Ondrej Stava at Adobe in San Jose, California.

How to prevent that from happening?

Ondrej Stava and his team have developed a system that addresses the printability issues by providing automatic detection and correction of the problematic cases.

This is an very exciting project: the system can check potential problems caused by gravity and gripping forces and evaluate by combining a lightweight structure analysis solver with 3D medial axis approximations.

They focus on structural problems resulting from forces that can occur when the object is standing or when it is held at probable locations, such as pedestals or appro-priately sized handles.

Then they fix these areas using methods such as hollowing, thickening, and strut insertion.

(click to enlarge)

Local thickening increases the strength of the object's thin parts, and it preserves the form and the surface detail of the object.

 

Struts can be inserted to prevent nonrigid deformations of the object, and they are automatically placed at locations that are least visible to the user.

 

Hollowing eliminates material inside the object, reducing the weight of certain parts to alleviate the stress at other locations. Hollowing may also lower the cost by reducing the amount of used material.

"Care is taken not to modify the model in a way that would cause a significant visual alteration." The process repeats until all problematic cases are corrected. Then the toughened-up model is ready to be sent to a 3D printer.

(click to enlarge)

(A model of a dragon was first hollowed to reduce stress caused by its weight if held by the head (a). The stress decreased, but the neck had to be still thickened (b,c). The object was still too front heavy causing a twist deformation on the legs (c), that was eliminated by fixing the model to the pedestal by a strut (red) (d). These steps were done automatically by our system.)

(The handle of the soccer cup can break under pressure
of the grip (a). Our method automatically connects all parts of the handle together by means of five different struts (b).)

(The thin neck of a Spore creature can snap easily if the printed model is held by its head and tail. The local thickening correction strengthens the neck without a significant effect on the visual appearance of the model. all images credit: purdue university)

This is the first system ever that combines both physically based analysis with automatic geometric corrections for better 3D printing quality. This technology can benefit the whole 3D printing community and all future consumers by saving their time and money.

The team tested their technique successfully on game characters and technical models. And their next plan is to improve the system to use for multiple materials and models with moving parts.

 

Source: Purdue University via new scientist

 

Posted in 3D Software

 

 

 

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