Indian Researchers Develop World’s Strongest 4D Printed Parts
Two Indian researchers have developed two 4D printed prototypes, which the researchers claim, are the world’s first & strongest prototypes built to date.
The prototypes are made from PLA material which is embedded with shape memory alloys (SMA) Ni-Ti and fabricated using FDM 3D printing technology. The Ni-Ti sheet adds strength to these 4D printed parts. A strength report of these parts shows that these 4D printed parts have a compressive strength of 150MPa which is closely equivalent to high strength concrete.
They have created prototypes of biocompatible and biodegradable materials and they actuate when put in hot water.
The first prototype is a simple “self-folding origami structure” with some design considerations, which successfully actuated to form the final part. The second one is a practically usable prototype “3 Jaw robotic gripper” which has been used to pick an object in hot water without using any bulky motors. The remarkable results obtained from this research can have a paradigm shift in the way we manufacture products.
What is 4D printing ??
Research
The research was undertaken to find the solutions to some of the underlying problems of the 3D printed parts. The components can change their shape when heat is provided to it which paves its application to environments where maintenance is very difficult like space and biomedical engineering where stents can be manufactured using this technology which can save millions of lives.
It has its application in piping, earthquake-resistant building and structures, soft robotics and what not. Future products will be self-assembling, self-healing, self-replicating and reconfigurable which will provide all materials the ability to cope up with the changing and challenging environment. In this research PLA based 3D printed parts with embedded Ni-Ti SMA sheet were fabricated using 4D printing technology.
Methodology
This research focuses on the basic capabilities of the emerging 4D Printing technology. Among various methods of getting 4D printed components, 3D printing with embedding smart materials has been utilized in this work. For embedding the SMA sheet into the PLA based 3D printed objects, the Ni-Ti SMA sheet has to be cut and micro-drilled. Therefore three different machining operations have been performed using Wire EDM, LASER, and ECM. Optimization of the three processes has been done based upon which confirmation test is conducted and the material is prepared. After that 3D printing process is used and the sheet is embedded within it during the printing hence giving 4D printed components.
From the above images, we can clearly see that the 4D printed prototype, when inserted in a tank of hot water quickly, changes its shape. The first row of the image shows the origami prototype which joined together to form a strong bond. The second row of the image shows a 4D printed prototype which when immersed in hot water changes its shape to form a strong robotic gripper which can lift heavy items.
A subsequent compression test was also carried out and the results can be seen as below.
Compression test
The image shows the sample part before and after compression test. It compressive strength of the parts is easily visible in the image by the deformation of the metallic strip. It is a visual indication of the strength of the 4D printed parts.
In the above image of the compression test report, you can clearly see that the compressive strength of the Indian 4D printed prototype is more than 150MPa which is quite high close to any high strength concrete. This suggests that the prototype can take high loads when used as a mechanical component in any mechanical systems.
Why is this research unique?
A lot of research on 4D printing is being carried out across various universities of the world but let us explain why this research is unique:
Firstly, an increasing number of researchers are carrying out research on 4D printing around the world but none of their prototypes exhibit a high strength product which can be used as a mechanical component.
Secondly, none of them have a practical application.
Thirdly, no research has ever used shape memory alloy with PLA material for 4D Printing.
And lastly, no other research has claimed their 4D Printed prototype as fully bio-degradable and bio-compatible. Both the prototypes in this new research are bio-degradable and bio-compatible so that can be used further in making user-friendly and user-safe prosthetics and stents.
Major challenges in 4D Printing
No simulation software and API: There is an absence of a simulation software which can clearly show how the 4D printed part will behave when it comes in contact with an external stimulus like heat, gravity, magnetics, etc. Such a unique software can help in overcoming a big hurdle. This will not only quicken the pace of research but also save a lot of costly resources. It will help in optimising the complete process.
There is no separate API (Application Programming Interfaces) which will enable the designers to define the characteristics of the materials they are made from.
High initial cost: 4D printing demands heavy initial monetary resources. As compared to the western countries where there is a dearth of funding for research. In the Asia Pacific region, and especially in India, research is mostly seen as an activity for large corporations and funding is always in short supply.
4D printing, no doubt, has high initial cost compared to 3D printing but given the fact that it also provides better functionalities, high productivity, reliability & high product life, it actually offers a better trade-off than 3D printing.
Moreover, products made using this technology unlike 3D Printed objects are not static and hence can have unprecedented applications in all fields of science and engineering.
Future Implications
This is just a beginning to understand the capabilities of 4D printing which will enable the design of a completely new system. This is an emerging technology having a lot of possible future applications like as follows:
Soft Robotics: Robotic grippers, like the ones created in this research, for use in industries can have a significant impact on the functionality.
Aerospace and Aviation
Space: In environments and conditions where access for manual repair is limited, conditions which are hostile like space it can be used for self-healing of materials. 4D printing with origami and kirigami will enable us to make anything in 2D shape easily carry it to space then add hot water or provide heat by electrical resistance to it and it will transform into a 3D object of your use.
Morphing Aircrafts: Since birds are the source of inspiration for airplane development, airplanes should, supposedly, look more like birds in order to become more energy efficient. However, airplanes today look quite different from birds in many aspects as through experiments and comparison between airplanes and birds, researchers have found that airplanes can achieve better efficiency if they can “behave” more like birds in flight, and morphing technology makes it possible.
It can be only possible by 4D printing technology as this provides a very good chance for us to make things that can change its shape and size according to a specific stimulus.
Healthcare
Stents: This technology can be used in healthcare for advanced nanoscale stents and drug delivery system. The 4D printed stent can be maneuvered to a spot and then made to change form by application for a stimulus. For example, 4D printed stent that is introduced into an artery and when ultrasound energy is applied it balloons up to its needed configuration
Better Prosthetics: Electroactive components for artificial limbs. An applied voltage changes the configuration of the 4D printed part so that it expands, contracts or bends. The motion is smoother and more lifelike than movement generated by mechanical devices.
Consumer Goods
Transformative Shoes or Garments:
Imagine a single shoe which can be used for multiple activities. If you start running, it adapts to being running shoes, if you play basketball, it adapts to support your ankles, if you walk on grass, it grows cleats, and if it is raining, it becomes waterproof.
Adaptable Tyre Compound: These tyres will be all water tyre which can change according to different road conditions.
Piping: Current pipe system is very rigid. To cater for higher flow capacity, we have to replace the whole pipeline. An adaptive 4D manufacturing capability to produce capacity adaptable pipes pipping with a variable diameter as per demand can significantly increase the flow efficiency.
This technology provides a lot of flexibility and customization to a product in a very short manufacturing lead time with the dynamic characteristics of changing its structure, functionality and adaptable to the environment that can be utilized to achieve maximum efficiency in any field of its usage.
