What is Hertz contact theory?
What is Hertz contact theory?
Hertzian contact stress refers to the localized stresses that develop as two curved surfaces come in contact and deform slightly under the imposed loads. It gives the contact stress as a function of the normal contact force, the radii of curvature of both bodies and the modulus of elasticity of both bodies.
What is the Hertz model?
The Hertz contact model consists of a nonlinear formulation based on an approximation of the theory of Mindlin and Deresiewicz [Mindlin1953]. This model can be installed at both ball-ball and ball-facet contacts, and is referred to in commands and FISH by the name hertz.
What is Hertz law?
[′hərt·səs ‚lȯ] (mechanics) A law which gives the radius of contact between a sphere of elastic material and a surface in terms of the sphere’s radius, the normal force exerted on the sphere, and Young’s modulus for the material of the sphere.
What shape is the pressure profile of an elastic cylindrical contact?
Pressure profile is parabolic (which assumes that the shape of the bodies in contact can also be approximated well with parabolic shapes, e.g., sphere, ellipse or a cylinder) All the assumptions of the classical theory of elasticity apply (small strain, homogeneous material).
What do Hertz mean?
cycles per second
The number of hertz (abbreviated Hz) equals the number of cycles per second. The frequency of any phenomenon with regular periodic variations can be expressed in hertz, but the term is used most frequently in connection with alternating electric currents, electromagnetic waves (light, radar, etc.), and sound.
What is referred to as Hertz pressure?
The Hertz contact stress usually refers to the stress close to the area of contact between two spheres of different radii. After Hertz’s work, people do a lot of study on the stresses arising from the contact between two elastic bodies. An improvement over the Hertzian theory was provided by Johnson et al.
What is the formula of contact pressure?
Contact pressure = Applied Load/ Area of contact.
What is a hertz frequency?
Frequency is the rate at which current changes direction per second. It is measured in hertz (Hz), an international unit of measure where 1 hertz is equal to 1 cycle per second. Hertz (Hz) = One hertz is equal to one cycle per second. Cycle = One complete wave of alternating current or voltage.
What does 2 hertz mean?
An example: Frequency describes the number of waves that pass a fixed place in a given amount of time. So for the time it takes for a wave to pass is half a second. Then the frequency is 2 per second or 2 Hertz. If two hundred and forty (240) waves pass in an hour, the frequency is 4 Hertz.
What is the contact pressure between two bodies?
Suppose that two elastic bodies are in contact at a single point. If the bodies are pressed with a force, say F, the contact, because of deformation, will not be in a single point but will be over a small area of the surface of each body. This surface is called the pressure surface.
What is a pressure contact?
The contact pressure is the ratio of the normal load to the true contact area, which is the sum of the front and rear areas. It may be called the scratch hardness only in the case of plastic contact. Contact pressure as a function of the contact strain.
Is 20 Hz high or low?
Sound at 20-200 Hz is called low-frequency sound, while for sound below 20 Hz the term infrasound is used. The hearing becomes gradually less sensitive for decreasing frequency, but despite the general understanding that infrasound is inaudible, humans can perceive infrasound, if the level is sufficiently high.
How is the Hertzian contact theory useful for engineers?
Hertz contact theory is a classical theory of contact mechanics and is a very useful tool for engineers and researchers. Even though the derivation of the theory is relatively difficult, the final solution is a set of simple analytical equations relating the properties of the system to the developed stress.
What did Hertz say about non adhesive contact?
Hertzian theory of non-adhesive elastic contact. In Hertz’s classical theory of contact, he focused primarily on nonadhesive contact where no – tension force is allowed to occur within the contact area.
How is the Hertzian contact described for two spheres?
For the case of two spheres in contact as shown in Fig.4. In this case the Hertzian contact is an ellipse and is described by major () and minor axes of the contact ellipse: where . The functions in the previous equations are approximated as follows:
What are the expressions of the Hertz contact theory?
List of all expressions of the Hertz contact theory is given here (this list includes solution for spherical, elliptical (point) contacts and cylindrical (line) contact). A Matlab code of Hertz solution is given here .