In the article we published last week, we introduced the bioinspired materials and we talked about their application in one particular part of the car: the tyres. This time, we focus on two other features: the suspension system and the disc brakes.
The suspension system
The first system we’re going to analyze is the suspension system, which is composed mainly of springs that help to control the loads of the suspension and the shock absorbers, with the aim to absorb and filter kinetic energy transmitted by the tyres.
MR Spring damper climber plant-inspired
The department of Mechanical Engineering of Inha University, in Korea, has deisgned a smart spring damper inspired by the tendril structure of the climber plant using magneto-rheological (MR) fluid.
A tendril is a steam used by a climbing plant to support the climb and attach to other plants or structures; its strength is directly dependent on the concentration of the fluid inside the tendril.
We’re going to focus on the presence of some magnetic particles suspended randomly in a carried oil which align themselves to the line of the magnetic field when the latter is applied. Based on this aspect, the MR spring has been designed as a hollow helical structure filled with MR fluid and winded with copper wire.
Prototype of an hydraulic bioinspired damper
Regarding bioispired dampers, the University of California has designed and tested a prototype of it inspired by the energy dissipation mechanism present in the abalone shell, bones and titin (muscle tissue protein) that constitute a passive damper system. This mechanism is provided by the sacrificial bonds and hidden length. Speaking in technical terms, what are these things mentioned above? The sacrificial bonds are bonds that break before the main structural link is broken, while the hidden length is the part of the molecule that was contrained by the sacrificial bond.
The design of this damper was based on the energy dissipation mechanism found in bones that presents a force-displacement curve. on the other side, the prototype performance was tested on an automotive suspension system under sinusoidal road disturbances during numerical simulation. After this step, the performance of the prototype was compared with the simplified suspension system model, the quarter car model.
Disc brake
The last part of the car we’re going to analyze together with Micaela is the disc brake. We usually see it in racing cars and we often hear a lot about it but, in technical terms, what’s a disc brake? It’s defined as “an element that rotates with the wheel. When pads are pushed by calipers against the disc brake to reduce the rotation, the kinetic energy is converted into heat by friction.”
Disc brake inspired by owl wing and locust surface
After a short introduction, we focus on the bioinspired disc brake: in this case, we talk about disc brake inspired by owl wing and locust surface. Reserachers at Fuzhou University, in China, have designed a bioinspired disc brake in order to reduce vibration and noise, improving wear resistance and braking efficiency.
In order to achieve the first goal, owl wings were taken as biological inspiration, while for the second task, the surfaces of locusts’ bodies were the bionic prototype. Let’s start with the owl wings, known for having different properties that distinguish them from other birds. Amongst them, we have the silent flight, which is mainly due to the design of the wings. Their size is much bigger than other types of birds, allowing owls to fly without flapping too much their wings and producing less noise.
Secondly, turbulences are broken down into micro-turbulences thanks to the primary feathers that are serrated like a comb. In addition to this, the leading edge attenuates the sound and shifts the air flow angle.
Talking about locusts, one of their main features is the ability to change the surface structure to reduce wear resistance. Starting from these properties and from what we’ve said about owl wings previously, a 3D model of the bioinspired disc brake was designed. the structure of the owl wing was used to create grooves of helical distribution on a circular structure, while the locust surface was the inspiration for the spiral steel pray surface in the disc brake.
As a result, the structure of the bioinspired disc brake has reduced the contact area between the disc and the pads, and increased the contact between the disc brake and the air improving the heat conduction and heat convection ability.
After these two articles, we can say that the link between nature and engineering is more frequent than we might expect; in addition to this, the application of bioinspired materials can prove to be crucial in the automotive industry.
We would like to thank Micaela, who kindly shared her thesis with us.
Comments