Nature is the best and the oldest engineer in the world – it has perfected the components of the human body for thousands of years to make them as light, powerful, and functional as possible. As a result, nowdays, engineers – through the science of bionics * – design and create concepts by following and investigating the examples of the nature. Many of us may think that it is unrealistic that the human bone could replace materials used in everyday design – such as iron, concrete, steel or copper.
Yet we might ask the question: is bone stronger than concrete? The answer is surprising: it depends.
The elasticity of bone is similar to that of the concrete, however, it is ten times stronger when it is compressed. As for its comparison with stainless steel, the bone has similar compressive strength but it is three times lighter. However, the properties of bones are not constant as they are made up of living tissues. They adapt to people’s lifestyles, become stronger or weaker due to age, environmental or health factors.
The genius of nature really shows itself when we try to replace what it has created: although built-in implants are necessary for many people, they can even be life-saving, their durability is not comparable to the life of real bone. For example, a knee joint deteriorates in 60 to 80 years, while an implant set during a knee replacement is good if it lasts for 20 years.
Engineers need to design these implants to withstand high strain – in everyday activities such as walking or jumping, the human skeletal structure gets loads that can be up to 20 times of its weight. Examples of such extreme loads are pressure, twisting, shearing or pulling.
How do bones withstand this enormous strain?
Bones can withstand these extreme loads due to their composite microstructure; they are made up of collagen fibers that the dense bone marrow and the minerals make even harder. They also contain water, protein, living cells and blood vessels. The ability of the bone to adapt to its environment, to the load, and its ability to change its properties are the real challenge for engineers. It is a complex and complicated task to create materials with similar properties. So that is why engineers carefully select both the raw materials and the design and modify them over and over again until the implant meets the expectations.
Searching for the best bone substitutes
Because the replication of all properties of the bone is not still possible, engineers always try to optimize medical devices for every specific case. For example, if a patient needs a bone graft **, engineers will work to harmonize the chemistry, components, and microstructure of the remaining bone. Calcium phosphate is well applicable because it stimulates bone growth and promotes the recovery. On the other hand, replacement of joints has additional challenges: engineers have to find materials with properties similar to those of the adjacent bone. Engineers must also ensure that the material selected is adequately resistant to corrosion and biocompatible.
Using a special material selection tool, engineers can match the right material to the patient and to their state of health. It becomes possible to design new materials that perform much better than the current ones.
Ansys Granta product family – the specialist of material science
All objects and products are made of material just as the various medical implants too. The creation of a new implant, a special replacement material made for the human body, is preceded by a lot of research work. Research leaders, design engineers, scientists, doctors, or biologists need detailed information about each material to make the right decisions. Various engineering simulations and simulation software can be great help for the digital development of implants and the creation of virtual prototypes. With their help and solution, the properties and behavior of each material can be well simulated without having to physically produce the implant. This shortens research time and reduces costs. The Ansys Granta product family provides outstanding assistance in the field of material science.
If you have any question about simulation solutions for therapeutical and medical devices, or engineering simulations and simulation software related to other fields, industries, feel free to contact us at firstname.lastname@example.org!
*Bionics, also known as biomimicry, is a comprehensive discipline that aims to translate solutions developed in nature into technical practice. Assuming that natural selection is the optimal solution to a problem.
**Bone graft implantation is a priority research area as for the bone defect replacement.