Additive manufacturing has proved to be one of the most disruptive innovations to modern industry. Whether used for prototyping or manufacturing, additive methods — especially 3D printing — have completely revolutionized the way manufacturers design, develop, and produce products and parts. The 3D printing process is used across a range of industrial sectors, including aerospace, automotive, medical, and even food and beverage.
In recent years, though, researchers have developed ways to make this innovative technology even more sophisticated — by tapping into the fourth dimension. While the fourth dimension remains a mysterious, almost mystical concept that physicists, engineers, and mathematicians have theorized about for years, when dealing with additive manufacturing, it simply refers to the inclusion of the elements of time and motion in addition to the standard measurements of length, width, and depth.
What does this mean exactly? Put simply, a 4D-printed object will transform itself over time. Once printed, an object can self-assemble or reshape itself entirely.
How 4D Printing Works
Like 3D printing, 4D printing uses a layer-by-layer stereolithographic method to transform digital designs into fully realized, physical objects. The main difference between the two processes is the use of specialized materials in the 4D printing process that can be “programmed” to behave in a certain way. These materials are formulated to react to specified stimuli, such as water submersion, heat, or electricity. Then, once exposed to the specified stimuli, the object contorts and folds into its final shape.
For example, let’s say you want the final product to be a cube, but need to ship it in a flat container. Using a specialized design, a 4D printer creates a set of two-dimensional, flat squares. The flat squares are arranged in a specific pattern and, via the design and materials, are “programmed” to transform once exposed to a specific catalyst. Let’s say the catalyst is water. The squares remain flat and inactive until they are submerged fully in water. The squares then fold themselves until they form the desired cube shape.
4D Printing Methods and Materials
4D printing is made possible through the use of specific materials. When developing programmable designs for a dynamic object, many 4D-printing labs focus primarily on formulating advanced “smart” materials, which are designed to respond to external stimuli. Typically, these materials are hydrogels, shape-memory polymers (SMPs), or cellulose composites.
Smart materials are not new to the industrial world; for example, common components such as motors, power sources, actuators, and sensors utilize some type of piezoelectric material. When triggered by the presence of mechanical stress, these materials produce an electric voltage.
Current and Future Applications for 4D Printing
The concept of 4D printing began gaining traction in 2013, when computer scientist and MIT assistant professor Skylar Tibbits coined the phrase during a presentation he gave at a TED conference. Tibbits, known as a pioneer of 4D printing, discussed the concept of self-assembly, in which “disordered parts build an ordered structure through only local interaction.”
Since then, Tibbits and his team have been experimenting with self-assembly and programmable materials in his MIT-based research lab, where they have utilized 4D-printing principles and other self-assembly techniques to develop cutting-edge concepts such as smart textiles, transformable architecture, and even self-assembling mobile phones.
While many of these projects and ideas are still in the research and experimentation phase, Tibbits and other proponents of 4D printing see a future in which this technology can be used in a range of applications — from architectural facades that adapt to the weather to shoes that respond to foot activity in order to offer the proper comfort and support.
Additive manufacturing, especially 3D printing, has made its mark on the worlds of manufacturing and engineering, changing the way industry operates and the way designers approach the development and production process.
As the use of smart materials becomes increasingly prevalent, 4D printing may eventually become a standard manufacturing technique. Although the technology is in its infancy, industry leaders already have a lot of exciting ideas for potential applications. As the method continues to gain traction, professionals across all types of industries will be keeping an eye on its progress and development.
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