How Additive Manufacturing Helps Achieve Topology Optimization And Why You Might Care

by Arvind Krishnan

End-use parts are now being produced with 3D printing technologies that are often lighter and stronger than their counterparts produced with traditional manufacturing processes. Because you can create designs with greatly reduced mass using additive manufacturing, SOLIDWORKS Simulation and Stratasys 3D printers become a natural match, enabling you to create designs that will keep you ahead of the competition.

Brief History of Rapid Prototyping

Historically, adhering to manufacturing processes guided how a part was designed.  In the past thirty years, 3D printers have played an increasingly prominent role in rapidly creating prototypes of these designs to get an accurate form and feel of the design before production.

Optimization with respect to mass was rarely the central theme of a design because the final shape would be too complex to manufacture using traditional (subtractive manufacturing) methods.

But these shapes can now be created with an additive manufacturing approach. In today’s world, because of 3D printing, there are a variety of different methods to optimize your designs to ensure it is safe and built as efficiently as possible.

Optimizing your Design

One method to perform optimization is by changing dimensions such as thickness in the design. FEA software like SOLIDWORKS Simulation allows users to change specific dimensions to reduce mass. The user can specify constraints on important parameters such as maximum deformation and stress limits to ensure the design is safe. This method gives the user maximum control and does not drastically change the shape of the design other than specified dimensions within a range.

The next method is called topology optimization. This method will remove material from different regions of the design as long as specified constraints are adhered to. Most software that does this will let the user specify loads, fixtures, and faces that must be retained. Once this is setup, material will be removed from different regions of the design while ensuring that the user specified limitation of strength, stress, or displacement is not violated. In most cases when using this method, the final design is drastically different than the initial shape.

The final method of optimization is by adding lattice formations to a design, where the user has the option of specifying a density of a lattice structure on the inside. This way, material density changes from a discrete ‘yes’ or ‘no’ variable to a continuous one of varying mass; each region can have a varying amount of material, which helps produce new and effective designs. Lattice structure designs have been used specifically in compressive, load-bearing applications like a car bumper.

Challenges and Constraints to Additively Manufactured End-Use Parts

The biggest challenge to incorporating these optimization methods is the fact that the part design may not be intuitive or will look radically different. Since traditional manufacturing constraints do not apply, the designer has a lot of freedom to create organic shapes. As Michael Idelchik1 of GE research said, “You need almost an artistic approach to design, the ability to model and analyze structures, and also the knowledge to pick the right material.”

If the part is hollow on the inside, or has lattice structures, then removing support material needs to be taken into consideration. A hollow part cannot be enclosed from all directions as the support structures formed inside cannot be dissolved.

Similarly, the dimensions of the part have to be within the maximum and minimum specified dimensions of the 3D printer. When building multiple parts or multiple struts close to each other, clearances in the build chamber need to be taken into account. Lastly, the resolution of the print dictates thickness dimensions.

The mechanical design of parts hasn’t changed much in the last century until the development of additive manufacturing. It seems reasonable to expect that 3D printing will begin a new era of innovative design ideas, enabling the creation of more efficient designs that can be more organically shaped.

 

 

1. http://www.gereports.com/post/77131235083/jet-engine-bracket-from-indonesia-wins-3d-printing

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