How is normal stress measured in biological tissues?

In summary, the conversation discusses a homework problem assigned by an engineering professor to design a tool for measuring normal stress in biological tissue. The problem requires the tool to measure a range of 1000 dyn/cm^2 to 1,000,000 dyn/cm^2, but the group is unsure of how normal stress is measured. The suggestion is made to measure the force and area and divide the two, and the professor wants the group to focus on the design rather than the specifics. The conversation also mentions the use of a scale and the definition of stress as the modulus of elasticity multiplied by the deformation, or force divided by area. Overall, the conversation centers on determining how to measure normal stress in the body.
  • #1
chusifer
7
0
ok...my engineering professor just gave us this crazy homework problem. he wants use to design a tool to measure the normal stress in a biological tissue. now it doesn't have to be extremely detailed in any way, but...we don't even know how normal stress is measured. the problem asks for it to measure 1000 dyn/cm^2 up to 1,000,000 dyn/cm^2. now...this is obviously impossible, and he said that. he just wants us to think about the design.

so my question is...how does a tool measure normal stress?
 
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  • #2
isn't that the question you're supposed to answer?
 
  • #3
Measure the force. Measure the area. Divide the two.
 
  • #4
well I am suppose to...design some type of tool specific to a certain condition dealing with the body. I am not really asking the specifics, I am more just asking how does any device...like a scale, measure the normal stress?
 
  • #5
like how enigma said.
skin on a body is stretched. every seen before and after pictures of a very fat person before and after lipo? skin is stretched over the body. because it is stretched it subject to a restoring force. this is proportional to the amount your skin is stretched(clearly). how would you find out how much the skin is stretched on your body when it is still on your body?
 
  • #6
Well Stress is defined as

[tex] \sigma = E \delta D [/tex]

where E is the modulus of elasticity of the body, and D is the deformation.

Also
[tex] \sigma = \frac{F}{A} [/tex]

Do like enigma said.
 

1. How is normal stress defined?

Normal stress, also known as tensile stress, is defined as the force per unit area that is acting on a material in a direction perpendicular to the material's surface.

2. What is the formula for calculating normal stress?

The formula for calculating normal stress is σ = F/A, where σ is the normal stress, F is the force acting on the material, and A is the cross-sectional area of the material.

3. What are the units of measurement for normal stress?

The units of measurement for normal stress are typically newtons per square meter (N/m²) in the SI system, or pounds per square inch (psi) in the imperial/US customary system.

4. How is normal stress measured in practical applications?

In practical applications, normal stress can be measured using instruments such as stress gauges or load cells. These devices measure the force acting on a material and can calculate the normal stress based on the material's cross-sectional area.

5. How does normal stress affect the behavior of materials?

Normal stress can cause materials to deform, or change shape, depending on their physical properties. When the stress exceeds the material's strength, it can lead to failure or breakage. However, within the material's elastic limit, normal stress can cause temporary deformation that will return to its original shape once the stress is removed.

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