Difference between force-elongation and stress - strain diagram?

In summary, the conversation discusses the difference between force-elongation and stress-strain diagrams. Stress is derived from force, while strain is derived from elongation or displacement. The terms "force-elongation" and "load-displacement" are often used interchangeably, and modern testing machines have the ability to automatically calculate stress and strain. The conversation also mentions various resources for further information and diagrams on stress-strain and load-displacement curves.
  • #1
teng125
416
0
what is the difference between force-elongation and stress - strain diagram??

pls show some example such as diagrams for future reference

thanx
 
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  • #2
Well, stress is derived from force. Stress is the force divided by cross-sectional area.

By elongation, does one mean displacement? Strain is derived from elongation or displacement, and is the ratio of the change in elongation (displacement) to the intial elongation (displacement).

I believe that the term "force-elongation" is more commonly known as "load-displacement", and load and displacement are 'directly measured', and from these the corresponding stress and strain are calculated. Nowadays, tensile test machines have digital instrumentation and software to automatically calculate stress and strain from measured load and displacement.
 
  • #3
may i have some diagrams for the two cases above??

thanx
 
  • #4
http://www-ec.njit.edu/civil/som/define.html - find the entry for Stress - Strain Diagram. This page is useful for definitions.

Also see this discussion - http://www.ae.msstate.edu/vlsm/materials/stress_strain_diagrams/stress_strain_diagrams.htm

http://www.ni.com/pdf/academic/us/me105_lab3_2003.pdf (save target as) - useful discussion of engineering vs true stress-strain.

http://www.tpub.com/content/doe/h1017v1/css/h1017v1_69.htm

http://physics.uwstout.edu/Statstr/statics/Stress/strs32.htm

http://web.mit.edu/course/3/3.11/www/pset03/Definitions.pdf - (save target as)

Here is an image of a load-displacement curve, however the person placed stress and strain titles next to it and describes the image as a stress-strain curve. The title of the abscissa is "Deflection (in)", which indicates elongation or displacement.
http://invsee.asu.edu/srinivas/stress-strain/phase.html

This might be useful - http://scholar.lib.vt.edu/theses/available/etd-6197-6556/unrestricted/ch3.PDF (use save target as)

I am unable to find an example of a load-displacement curve and the derived stress-strain curve.
 
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  • #5
thanx...
 

1. What is the difference between force-elongation and stress-strain diagram?

Force-elongation and stress-strain diagrams are both graphical representations of the relationship between a material's deformation and the applied force. However, the main difference between the two is that force-elongation diagrams show the direct relationship between force and elongation, while stress-strain diagrams show the relationship between stress and strain, which takes into account the cross-sectional area of the material.

2. How are force-elongation and stress-strain diagrams related?

Force-elongation and stress-strain diagrams are related in that they both show the behavior of a material under applied force. The force-elongation diagram directly shows the applied force and the resulting elongation, while the stress-strain diagram shows the stress (force per unit area) and strain (change in length per unit length) of the material.

3. What information can be obtained from a force-elongation or stress-strain diagram?

From a force-elongation or stress-strain diagram, we can obtain important information about a material's properties such as its stiffness, strength, ductility, and toughness. These diagrams also allow us to analyze the behavior of a material under different loading conditions and to determine its ultimate strength and failure point.

4. What factors can affect the shape of a force-elongation or stress-strain diagram?

The shape of a force-elongation or stress-strain diagram can be affected by several factors, including the type of material, its composition and microstructure, the rate of loading, and the temperature. These factors can influence the material's response to applied force and its ability to withstand stress and strain.

5. How are force-elongation and stress-strain diagrams used in engineering applications?

Force-elongation and stress-strain diagrams are extensively used in engineering applications to design and analyze structures and components. They help engineers determine the appropriate material to use for a specific application, predict the behavior of a material under different loading conditions, and ensure the safety and reliability of structures and machines.

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