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Showing posts from December, 2020

Tire Longitudinal Slip : tire road contact patch behavior and effective rolling radius - vehicle dynamics

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 Contents Effective Rolling Radius and Longitudinal wheel Speed Quiz : what happens in the effective radius in braking and acceleration If any change in radius, it it longer or shorter in braking Tyre longitudinal slip in acceleration Tyre longitudinal slip in braking Conclusion Effective Rolling Radius and Wheel Speed When a car stops, tire is loaded vertically by its weight. At that time, vertical wheel radius to the road surface is R L and unloaded circumferential radius is R u . When a car starts on straight and level road, the longitudinal speed of wheel center Vx is neither ωR L nor ωR U . Real longitudinal speed of tire center will be somewhere between ωR L and ωRu. You can get the effective rolling radius if you count the number of wheel turns and measure the distance at a given constant speed. The effective rolling radius can be described as the ratio of  the vehicle speed to the angular velocity of wheel as shown in the equation above. Effective Radius Re can be e...

vehicle mass center effects on braking & acceleration - why do the braking and acceleration bring about the yawing motion of the vehicle?

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CG effect on braking & acceleration Summary  Quiz : Which brake should keep its function for the entire braking process if you choose only one brake among 4? Why does a car tend to rotate at braking and accelation? What are the effects of CG location on braking and acceleration Effects of vertical location Effects of horizontal location Where is the best CG location of perfect car Figuring out the answer to this quiz, you will have a chance to think about the important effects of CG related to its height and horizontal location on braking and acceleration. And we will have a discussion on why a car tend to rotate at braking and acceleration. Then, I will explain what are the effects of CG location on braking and acceleration. Effects of vertical location, effects of horizontal location. Finally, I will explain what is the best CG location of perfect car. Review I picked up this picture from my previous article. As I explained, front tire braking force and vertical reaction forc...

Vehicle Weight Transfer in braking and acceleration - Why should the mass center get lower ?

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What are your main concerns when you buy your car? Style? Color? Fuel efficiency? Engine power? The purpose of articles in this blog is to provide valuable tips helping you choose a perfect car and use those knowledge as your driving skill. The information in the website give you various knowledge mostly about working principles of car components and systems, vehicle dynamics, electric vehicles, and etc., but, which are not the knowledge to choose a good car for you. However, what I’m trying to show in my articles is about valuable tips to choose a good car. Definition of perfect car Good car is the car which has maximum performance with minimum weight and keep that performance for its lifetime. The outstanding ability of perfect car can be boiled down as minimizing the forces and moments during its all driving conditions and keep its remarkable performance for good compared to the non-perfect cars. You will know why it shows this features if you continue to visit my website. Types of ...