Name: tire deformation and rolling resistance
Uploaded: 2023-09-22T11:49:30.000Z
Duration: 1 min 21 s
Channel: JoVE

K12 Standards

Arizona Science Standards

High School

Physical Science

HS.P3

HS.P3U2.7

Rolling Resistance

Sabit bir hızda yuvarlanan bir lastik düşünün. Üzerine etki eden kuvvetler ağırlığı ve normal kuvvettir.
Temas yüzeyleri deforme olur ve sınırlı bir temas alanı oluşturur. Bu, her temas noktasında normal kuvvetlerin dağılımına neden olur.
Bu alanın ön kısmı, yuvarlanma hareketini geciktiren deformasyona uğrar.
Buna karşılık, arka kısım, lastiği ileri iten nispeten daha küçük bir restorasyona tabi tutulur.
A'ya etki eden bileşke normal kuvvet, bu kuvvetlerin toplamıdır.
Lastiğin sabit bir hızda yuvarlanmasını sağlamak ve ağırlığın A civarındaki momentini dengelemek için, lastiğin merkezine yatay bir itici kuvvet uygulanmalıdır. Burada tüm kuvvetler aynı anda olmalıdır.
A noktasındaki moment denge koşulu, yuvarlanma direnci katsayısı cinsinden itici kuvveti verir.
Yarıçap üzerindeki yuvarlanma direnci katsayısı ile çarpılan ağırlık, genellikle kinetik sürtünme katsayısı ile ağırlığın çarpımından daha küçüktür.
Bu nedenle, yuvarlanma sürtünme kuvveti, kayma kuvvetinden daha küçüktür.

<ol>
	<li>Hibbeler, R.C. (2016). Mühendislik Mekaniği \u2012 Statik ve Dinamik. Hoboken, New Jersey: Pearson Prentice Salonu. sayfa 452 \u2012 439.</li>
	<li>Meriam, J.L.; Kraige, L.G. ve Bolton, J.N. (2020). Mühendislik Mekaniği \u2012 Statik. Hoboken, New Jersey: John Wiley. sayfa 372.</li>
	<li>Bira, F.P.; Johnston, E.R.; Mazurek, D.F; Cromwell, P.J. ve Öz, B.P. (2019). Mühendisler için Vektör Mekaniği \u2012 Statik ve Dinamik. New York: McGraw-Tepesi. sayfa 469.</li>
</ol>

döner tekerlek sürtünmesi

Bir katı silindir, durağan bir sert yüzeyde istikrarlı bir şekilde dönüyorsa, yüzeyin silindire uyguladığı normal kuvvet, temas noktasındaki teğetle dik açı yapar. Bununla birlikte, hiçbir malzeme tamamen rijit olmadığı için yüzeyin silindire tepkisi bir dizi normal basınca neden olur.

Örneğin, beton sert yüzeyde dönen bir sert silindir hayal edin. Silindirin ağırlığı onun altındaki yüzeyi sıkıştırır. Silindir hareket ettikçe, önünde bulunan malzeme şekil değiştirmeye bağlı olarak yavaşlar, ancak arkasındaki malzeme deforma olmuş durumdan kurtularak silindiri ileri iterek ilerler. Silindire bu şekilde etki eden normal basınçlar, sonuçta oluşturdukları kuvvetlerle (Nd ve Nr) tasvir edilir. Deformasyon kuvveti (Nd) ve yatay bileşeni restorasyon kuvvetinden (Nr) daha büyüktür, bu da silindirin hareketini sürdürebilmek için silindire yatay bir sürüş kuvvetinin uygulanmasını gerektirir.

Rulman sürtünmesi öncelikle bu etki nedeniyle meydana gelir, ancak yüzey yapışması ve temas yüzeyleri arasındaki görece mikro kayma da daha az ölçüde etkiler.

Bu kavramı daha da açıklamak için, bir lastiğin sabit bir hızda dönmesini düşünün. Üzerine etki eden ana kuvvetler, aşağıya doğru dikey olarak etkileyen ağırlığı ve yere dik olarak etkileyen normal kuvvetidir. Lastik döndükçe, temas alanının ön kısmı deformasyona uğrar ve lastiğin dönme hareketini yavaşlatır. Buna karşılık, arka kısım görece daha küçük bir restorasyon deneyimleyerek lastiği ileriye doğru iter. Sonuç olarak, temel noktasında etkileyen sonuçta normal kuvvetin, bu karşılıklı kuvvetlerin toplamı olduğunu söyleyebiliriz.

<img alt="Figure 1" src="/files/ftp_upload/14328/14328_Figure_1v2.svg" style="text-align: center; height: 350px;" />

Lastiği sabit bir hızda döndürmek ve ağırlığın A noktası etrafındaki momentini dengelemek için, lastiğin merkezine yatay bir sürüş kuvveti (F) uygulanmalıdır. Denge için, lastik üzerinde etki eden tüm kuvvetler birbirini kesmelidir. A noktasındaki moment denge koşulunu kullanarak, sabit hızı korumak için gerekli olan sürüş kuvvetini sürtünme katsayısı (a) üzerinden belirleyebiliriz.

<img alt="Equation 1" src="/files/ftp_upload/14328/14328_Equation_1v2.svg" style="text-align: center; height: 28px;" />

Bu sürüş kuvveti genellikle kinetik sürtünme katsayısıyla lastiğin ağırlığının çarpımından daha küçüktür.

<img alt="Equation 2" src="/files/ftp_upload/14328/14328_Equation_2v2.svg" style="text-align: center; height: 28px;" />

Bu ilişki, dönen sürtünme kuvvetinin genellikle bir lastiğin bir yüzey üzerinde kayması durumunda deneyimlenen kayma kuvvetinden daha küçük olduğunu ima eder. Sonuç olarak, dönen sürtünme bir aracın performansı için kayan sürtünmeden daha az zararlıdır.

Döner Tekerlek Sürtünmesi

Katı bir silindir rijit bir yüzey üzerinde sabit bir şekilde yuvarlandığında, yüzeyin silindire uyguladığı normal kuvvet, silindirdeki teğete diktir.

Education

JoVE Core

Mechanical Engineering

Makine Mühendisliği

Unit 1

Ünite 1

Friction

Sürtünme

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

tire deformation and rolling resistance

Tire deformation and rolling resistance explain why a rolling wheel still needs a driving force. When a solid cylinder or tire rolls on a rigid surface, the normal force is perpendicular to the surface at the contact point. But real materials are not perfectly rigid, so the surface pushes back with a spread of normal pressures instead of one single force.

A hard cylinder on a softer surface compresses the material under it. As the cylinder moves forward, the material in front of the contact area slows because it is being deformed. The material behind the cylinder begins to recover, and that recovery pushes the cylinder forward.

These effects are often shown as two resultants, N d for the deformation force and N r for the restoration force. The deformation force and its horizontal component are larger than the restoration force. Because of that imbalance, a horizontal driving force must be applied to keep the cylinder moving.

The same idea applies to a tire rolling at constant speed. Its weight acts downward, and the ground provides an upward normal force. The front of the contact patch deforms and slows the tire, while the rear part restores more weakly and pushes it forward. The resultant normal force at point A is the sum of these opposing effects.

To keep the tire in equilibrium and maintain constant speed, a horizontal driving force F must act at the center of the tire. Using moment equilibrium about point A, the needed driving force can be written in terms of the rolling resistance coefficient a. This force is usually smaller than the force from kinetic friction, so rolling resistance is less harmful than sliding when a tire skids.

Rolling resistance is mainly caused by surface deformation, but adhesion and small-scale sliding between surfaces can also play a smaller role. These effects help explain why rolling wheels still lose some energy even when they do not appear to slip.

Tire Deformation and Rolling Resistance

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Tire deformation and rolling resistance explain why a rolling wheel still needs a driving force. When a solid cylinder or tire rolls on a rigid surface, the normal force is perpendicular to the surface at the contact point. But real materials are not perfectly rigid, so the surface pushes back with a spread of normal pressures instead of one single force. A hard cylinder on a softer surface compresses the material under it. As the cylinder moves forward, the material in front of the contact...

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key terms and concepts

Learn how tire deformation creates rolling resistance, why a driving force is needed, and how it compares with sliding friction in moving wheels.

Tire Deformation and Rolling Resistance | JoVE K12

JoVE Core Makine Mühendisliği, denge, kuvvetler, kafes kiriş analizi ve yapısal mekanik gibi temel konuları kapsayan kısa, anlaşılması kolay animasyonlu videolar sunar. Gerçek dünyadaki uygulamalarını keşfedin ve bilim insanlarının önderlik ettiği deneylerle bu kavramların uygulanmasına tanık olun.

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Tire Deformation and Rolling Resistance

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