What is mechanical contact stress?

Mechanical contact stress The contact of the body with a hard surface or edge that results in the compression of tissue. Can also result when using a part of the body as a hammer or striking instrument.

What is the meaning of mechanical stress?

Stress, Mechanical

a measure of internal forces that arise in a body being deformed as a result of external forces. … The interaction of contiguous parts of the body along the section is replaced by forces.

What does contact stress mean?

Contact stress happens when force is concentrated on a small area of the body, pinching or crushing tissue and causing discomfort and often pain. You experience contact stress, for example, when the edge of a work surface digs into your forearm or wrist.

Which of the following is an example of contact stress?

Examples of contact stress include resting wrists on the sharp edge of a desk or workstation while performing tasks, pressing of tool handles into the palms, especially when they cannot be put down, tasks that require hand hammering, and sitting without adequate space for the knees.

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What is contact stress in ergonomics?

Contact Stress

Internal stress occurs when a tendon, nerve, or blood vessel is stretched or bent around a bone or tendon. External contact stress occurs when part of your body rubs against a component of the workstation, such as the chair seat pan or edge of the desk.

What are the 5 mechanical stresses?

There are five fundamental types of loading: compression, tension, shear, torsion, and bending. Stress is the force applied to a material, divided by the material’s cross-sectional area.

What is normal stress formula?

A normal stress is a stress that occurs when a member is loaded by an axial force. The value of the normal force for any prismatic section is simply the force divided by the cross sectional area.

How do you reduce contact stress?

  1. Pad object or add carrying handles.
  2. Wear gloves with padded palms when lifting or holding the object.
  3. Use team lifts to spread the weight.
  4. Use pallet jacks or other mechanical material handling tools.
  5. Break heavy or bulky loads into smaller, more manageable loads.

What is Hertz contact theory?

Hertz theory assumes that surfaces are continuous and nonconforming, strains are small, each solid can be considered as an elastic half-space, and surfaces are frictionless. Under these assumptions, only normal pressure acts between two bodies due to Hertz contact producing normal displacements of the surfaces.

How do you calculate contact pressure?

In a rectangular section ring, the mean specific contact pressure P (MPa) is calculated; P = E (m1 – s1)/d1/(7.07(d1/a1 – 1)3), where E (MPa) is the Young’s Modulus and the dimension of every part is given in mm.

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What are ergonomic principles?

Ergonomic reduces the unwanted tension, awkward position of the body. Ergonomic is focused in making the work your easier and comfortable, this thereby reduces any kind of stress, risk and enhances the satisfaction and productivity.

What is ergonomic posture?

Posture is the position or carriage of the body in a sitting or standing position. It is very easy to have a bad posture when sitting at a computer workstation. Even good posture when held for a long time can lead to fatigue or discomfort.

What is awkward posture?

Awkward postures means working with various parts of the body in bent, extended or flexed positions rather than in a straight or neutral position. Working in awkward postures increases the exertion and muscle force that employees must apply to complete a task and compresses tendons, nerves and blood vessels.

How often should you get up and stretch when typing?

It is recommended that a person break for 5-10 minutes for every hour spent at a workstation. If possible, it is ideal to stand up and walk for this time (e.g., work tasks that involve standing, walking, or at minimum, a change of body position). Some of these stretches can be done at the same time.

What are ergonomic risk factors?

The three primary ergonomic risk factors that cause MSDs are awkward posture, high force, and high or long frequency. Combination of postures, forces and frequencies increase the chance of developing an MSD.

Which two of the following can be caused by reduced blood flow while holding a static posture?

Static postures (or “static loading”) refer to physical exertion in which the same posture or position is held throughout the exertion. These types of exertions put increased loads or forces on the muscles and tendons, which contributes to fatigue. … Reduced blood flow also slows down delivery of oxygen to the muscles.