The Concept of Hysteresis in Materials: A Study on Bouncy Balls and Tires

Hysteresis, a phenomenon where a material's behavior is dependent on its previous state, can be observed in various forms of materials. In this study, we will explore hysteresis in two common materials: bouncy balls and tires.

The Bouncy Ball Analogy

------------------------

When we drop both bouncy balls and kick balls from the same height, we notice that the bouncy ball's bounce is significantly higher than the kick ball's. This means that the bouncy ball releases more energy after being compressed while hitting the ground than the kick ball. The reason for this lies in the concept of hysteresis. Hysteresis refers to the amount of energy lost by a material as it returns to its original state. In the case of the bouncy ball, it is able to release more energy due to its low hysteresis. On the other hand, the kick ball has a higher hysteresis, resulting in less energy being released.

A similar concept can be applied to tires. If you drop an old tire with a worn-out compound and compare it to a new tire with a fresh compound, you'll notice that the bouncy behavior of the new tire is significantly different from the old one. The new tire is able to deform without losing too much energy, whereas the old tire loses a lot of energy and mainly transforms into heat.

Tire Compounds: A Case Study

-----------------------------

The difference in hysteresis between old and new tires can be attributed to the type of compound used. A new tire typically has a high-quality compound that is designed to maintain its shape without losing too much energy, while an old tire with a worn-out compound loses more energy and transforms into heat.

For example, if you apply a very slow deformation to the new tire, it will deform whereas when you try to deform it at a higher speed, it will bounce back. This is due to the low hysteresis of the new compound. On the other hand, if you apply a high-speed deformation to the old tire, it will break and lose its shape.

The Importance of Frequency in Tire Behavior

------------------------------------------------

The frequency of deformation plays a crucial role in determining the behavior of tires. The majority of rolling resistance occurs as a result of the tire deforming as it comes into contact with the ground. However, this deformation is not instantaneous; it occurs at specific frequencies depending on how fast the tire is rotating.

A tire rotating at 100 km/h will deform about 15 times per second, which corresponds to an oscillation frequency of around 15 Hertz. This low-frequency range is where rolling resistance is most significant. On the other hand, the tread needs to react quickly to the unevenness of the road in order to maintain grip, and this occurs at a much higher frequency.

The Role of Silica in Tire Compounds

--------------------------------------

Before the introduction of silica into tire compounds, it was difficult to choose between a compound with high energy losses but high grip or one with low energy losses across all frequencies but less grip. However, the addition of silica has changed this paradigm. Silica compounds have low energy losses in the low-frequency range, meaning low rolling resistance, but high energy losses in the high-frequency range, resulting in more grip.

This allows us to separate the behavior of the compound depending on the speed and frequency of deformation. For example, if you set the speed of deformation to a low value, you'll see that the tire behaves similarly to one with high hysteresis, whereas at higher speeds, it exhibits characteristics similar to those with low hysteresis.

Conclusion

----------

In conclusion, the concept of hysteresis plays a crucial role in understanding the behavior of materials like bouncy balls and tires. By controlling the frequency of deformation and selecting the right type of compound, we can manipulate the hysteresis of these materials to achieve desired outcomes. The introduction of silica into tire compounds has revolutionized the industry by allowing us to separate the behavior of the compound depending on the speed and frequency of deformation.

The Eco-Marathon and Shell

---------------------------

As part of our study, we had the opportunity to visit the Shell Eco-marathon and participate in a manufacturing plant dedicated solely to producing ultra-low rolling resistance tires used by participating teams. It was an incredible experience that showcased the significant progress made in tire technology.

A special thank you goes out to Shell for sponsoring this video and bringing us to the Eco-marathon. Congratulations to this year's category winners!

"WEBVTTKind: captionsLanguage: enhello everyone and welcome I am at the Shell eco-marathon America's here in Detroit Michigan and we're going to be talking about rolling resistance as it relates to the efficiency of your car the shell eco-marathon is a competition where students around the globe compete to design build and test vehicles with a goal of creating a vehicle that goes the furthest distance using as little energy as possible when it comes to designing for efficiency there are five major forces which a vehicle needs to overcome there's the resistive force caused by aerodynamics as a result of drag and possibly wind there's the internal friction of the vehicle such as the engine transmission suspension brakes and so on there's the force of gravity when the vehicle is moving uphill there's the force of inertia for which the vehicle must accelerate a mass and overcome the energy required to do so and finally which we'll be discussing in detail with Michelin in this video a sponsor of the shell eco-marathon there's the force of rolling resistance as a result of the tires contact with the road rolling resistance is the energy consumed by a tire as it travels over a specific distance energy is lost as heat when the tire deforms on the road creating the contact patch and then returns to its original state as the tyre continues to rotate how much energy is lost as a result of the tires hysteresis hysteresis is the difference between the amount of energy that is absorbed when a rubber object is stretched or compressed versus how much energy is released when the rubber object returns to its original state in short it's the amount of energy lost after a cycle of being stretched to illustrate the idea of hysteresis I have a bouncy ball and a kick ball when I drop both of these objects from the same height you'll notice that the bouncy ball bounce is significantly higher than the kick ball this means that it is releasing more energy after being compressed while hitting the ground than the kick ball and thus has a low hysteresis the kick ball however has a higher hysteresis and doesn't bounce as high because more of the energy that goes into compressing the ball is transformed into heat the same concept can be applied to tires if you see this is an old compound I would say and this is a new compound if I like to drop you'll see one is bouncing and not the other Amina this one lose a lot of energy and mainly thermal energy if I have a micro camera thermal camera or a problem very accurate drop you will see that this one is hotter than this one okay that's exactly the same that we have on a tire a new tire so a new tire is able to deform without losing too much energy that's why the way we used to of course reduce their running residence this analogy doesn't take into consideration however that a tires main purpose is grip designing a tire is of course a compromise between the two and a low hysteresis tyre for example a tire similar to the bouncy ball will tend to be efficient with less grip while a high hysteresis tire is inefficient but has significantly more grip now all of this makes it seem like there's no way to both reduce rolling resistance while increasing or maintaining grip but fortunately that's not the case the introduction of silica and tire compounds has completely changed the tire industry to understand how this is possible we need to understand the frequency for which the tire is vibrating and the scenarios for which this is beneficial the majority of rolling resistance occurs as a result of the tire deforming as it comes into contact with the ground the frequency at which this occurs depends on how fast the tire is rotating oscillating a specific point on the tire one time per revolution a tire rotating at 100 km/h will deform about 15 times per second a load frequency of 15 Hertz relatively speaking this is a low frequency range this low frequency range is the range that is important for rolling resistance grip however comes from how the tire behaves as it distorts to the unevenness of the road the tread needs to react quickly to the changing surface in order to maintain grip and this is a much higher frequency Distortion before the introduction of silica into tire compounds you could typically only choose between a compound with high energy losses and high grip across all frequencies or low energy losses across all frequencies resulting in less grip this is where silica plays by different rules silica compounds have low energy losses in the low frequency range meaning low rolling resistance but high energy losses in the high frequency range meaning they have high grit thanks to silica we are able to separate the behavior of the compound depending of the speed I will set the speed of deformation of frequency let's have a look on this for example you see it's very interesting compound because you can explain many things without it if I I try to deform it very slowly you see I can deform it at the Infinity but I deform it very slowly yeah okay now if I try to do exactly the same at I speed it breaks and you see the behavior completely different and it's exactly the opposite we are on the tyre because for the tyre from the Greek word where we have a high speed or the deformation of the road graph roughness okay we are able to deform and to lose energy for the grip whereas for running resistance where it's low frequency because it's linked okay to the rolling of the wheel of course we lose much less energy and just to finish with this very interesting compound you'll see that as I'd explained when I apply a very slow deformation it deforms whereas when I want to use every high speed deformation for example try to make it bones well it bouncing that's why thanks to cutting-edge technologies were able to manage both grip and rolling resistance michelin is one of many partners that plays an important role at the shell eco-marathon dedicating a manufacturing plant for two days per year just for making the ultra low rolling resistance tires used by the teams to give you an idea of just how low the rolling resistance is on these unique tires it's about 1/4 of that measured in kilograms per tonne versus a train with steel wheels on a steel rail of course a huge thank you to shell for sponsoring this video and bringing me out to the Eco marathon and congratulations to this year's category winners if you have any questions or comments feel free to leave them below thanks for watchinghello everyone and welcome I am at the Shell eco-marathon America's here in Detroit Michigan and we're going to be talking about rolling resistance as it relates to the efficiency of your car the shell eco-marathon is a competition where students around the globe compete to design build and test vehicles with a goal of creating a vehicle that goes the furthest distance using as little energy as possible when it comes to designing for efficiency there are five major forces which a vehicle needs to overcome there's the resistive force caused by aerodynamics as a result of drag and possibly wind there's the internal friction of the vehicle such as the engine transmission suspension brakes and so on there's the force of gravity when the vehicle is moving uphill there's the force of inertia for which the vehicle must accelerate a mass and overcome the energy required to do so and finally which we'll be discussing in detail with Michelin in this video a sponsor of the shell eco-marathon there's the force of rolling resistance as a result of the tires contact with the road rolling resistance is the energy consumed by a tire as it travels over a specific distance energy is lost as heat when the tire deforms on the road creating the contact patch and then returns to its original state as the tyre continues to rotate how much energy is lost as a result of the tires hysteresis hysteresis is the difference between the amount of energy that is absorbed when a rubber object is stretched or compressed versus how much energy is released when the rubber object returns to its original state in short it's the amount of energy lost after a cycle of being stretched to illustrate the idea of hysteresis I have a bouncy ball and a kick ball when I drop both of these objects from the same height you'll notice that the bouncy ball bounce is significantly higher than the kick ball this means that it is releasing more energy after being compressed while hitting the ground than the kick ball and thus has a low hysteresis the kick ball however has a higher hysteresis and doesn't bounce as high because more of the energy that goes into compressing the ball is transformed into heat the same concept can be applied to tires if you see this is an old compound I would say and this is a new compound if I like to drop you'll see one is bouncing and not the other Amina this one lose a lot of energy and mainly thermal energy if I have a micro camera thermal camera or a problem very accurate drop you will see that this one is hotter than this one okay that's exactly the same that we have on a tire a new tire so a new tire is able to deform without losing too much energy that's why the way we used to of course reduce their running residence this analogy doesn't take into consideration however that a tires main purpose is grip designing a tire is of course a compromise between the two and a low hysteresis tyre for example a tire similar to the bouncy ball will tend to be efficient with less grip while a high hysteresis tire is inefficient but has significantly more grip now all of this makes it seem like there's no way to both reduce rolling resistance while increasing or maintaining grip but fortunately that's not the case the introduction of silica and tire compounds has completely changed the tire industry to understand how this is possible we need to understand the frequency for which the tire is vibrating and the scenarios for which this is beneficial the majority of rolling resistance occurs as a result of the tire deforming as it comes into contact with the ground the frequency at which this occurs depends on how fast the tire is rotating oscillating a specific point on the tire one time per revolution a tire rotating at 100 km/h will deform about 15 times per second a load frequency of 15 Hertz relatively speaking this is a low frequency range this low frequency range is the range that is important for rolling resistance grip however comes from how the tire behaves as it distorts to the unevenness of the road the tread needs to react quickly to the changing surface in order to maintain grip and this is a much higher frequency Distortion before the introduction of silica into tire compounds you could typically only choose between a compound with high energy losses and high grip across all frequencies or low energy losses across all frequencies resulting in less grip this is where silica plays by different rules silica compounds have low energy losses in the low frequency range meaning low rolling resistance but high energy losses in the high frequency range meaning they have high grit thanks to silica we are able to separate the behavior of the compound depending of the speed I will set the speed of deformation of frequency let's have a look on this for example you see it's very interesting compound because you can explain many things without it if I I try to deform it very slowly you see I can deform it at the Infinity but I deform it very slowly yeah okay now if I try to do exactly the same at I speed it breaks and you see the behavior completely different and it's exactly the opposite we are on the tyre because for the tyre from the Greek word where we have a high speed or the deformation of the road graph roughness okay we are able to deform and to lose energy for the grip whereas for running resistance where it's low frequency because it's linked okay to the rolling of the wheel of course we lose much less energy and just to finish with this very interesting compound you'll see that as I'd explained when I apply a very slow deformation it deforms whereas when I want to use every high speed deformation for example try to make it bones well it bouncing that's why thanks to cutting-edge technologies were able to manage both grip and rolling resistance michelin is one of many partners that plays an important role at the shell eco-marathon dedicating a manufacturing plant for two days per year just for making the ultra low rolling resistance tires used by the teams to give you an idea of just how low the rolling resistance is on these unique tires it's about 1/4 of that measured in kilograms per tonne versus a train with steel wheels on a steel rail of course a huge thank you to shell for sponsoring this video and bringing me out to the Eco marathon and congratulations to this year's category winners if you have any questions or comments feel free to leave them below thanks for watching\n"