Material Properties: Stress Strain Curve Analysis

In summary, the conversation revolves around using a load deflection curve to determine material properties of an elastic material. The material in question is an elastic polymer and the conversation highlights the importance of obtaining complementary information such as Young's modulus and Poisson's ratio to accurately determine these properties. It is suggested to contact the manufacturer for more information and to ensure the accuracy of the load deflection curve.
  • #1
vm2007
3
0
Hi,

I need to use a load deflection curve to determine the material properties of a elastic material. The stress strain is far from being linear. Any suggestions??
 
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  • #2
I'd have to see the curve. Is it for something like copper?
 
  • #3
vm2007 said:
Hi,

I need to use a load deflection curve to determine the material properties of a elastic material. The stress strain is far from being linear. Any suggestions??
What material - metal, ceramic, polymer, . . . ?

Metals are exhibit linear elasticity up to the point where yielding occurs, however there is always some small amount of plasticity, or permanent deformation.

Besides the elastic modulus (Young's modulus), yield point (yield strength), and possibly Poisson's ratio, ultimate tensile strength, uniform and total elongation, what material property is one wishing to determine?
 
  • #4
its actually for a elastic polymer. I recived the load deflection curve (compression). and I need to obtain the material properties from it. ie. youngs modulus and poisson's ratio. any advice?
the curve is initially fairly linear, then rapidly increaces exponentially. I have the sectionally properties of the test piece.
 
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  • #5
... you can determine Young's modulus from the slope of the initial linear part, but other than that - especially the Poisson's ratio - you need some complementary information like for example about deformation in another principal-direction, or the shear modulus or so on (take a look at the "basic" equations of elasticity theory and the relations between these properties - so far it doesn't seem like you should be doing anything with the nonlinearities of the curve but they're there for "realistic feel" :biggrin:). Like Fred said, seeing the information you've available would help get deeper in getting to the roots of it all.
 
  • #6
thanks Vanechka... I think it might be wise for me to try to contact the manufacturer of the polymer to get a little more information.
 
  • #7
1. What is the exact material?
2. Can you attach the load deflection curve?
3. If you can, also include the testing specs.
4. What is the end use - include typical loading conditions.
 
  • #8
It may not be safe to get the first portion to calculate Youngs moduslus, there can be some distortion in the first part due to test machines internal dynamics. First be sure that graph is free from that.
 

1. What is a stress-strain curve?

A stress-strain curve is a graphical representation of the relationship between the stress applied to a material and the resulting strain. It shows how a material responds to applied forces and can provide insight into its mechanical properties.

2. How is a stress-strain curve created?

A stress-strain curve is created by subjecting a material to tensile or compressive forces and measuring the resulting stress and strain. This data is then plotted on a graph with stress on the y-axis and strain on the x-axis.

3. What information can be obtained from a stress-strain curve?

A stress-strain curve can provide information about a material's yield strength, ultimate tensile strength, and modulus of elasticity. It can also show the material's ductility, toughness, and ability to withstand deformation without breaking.

4. How does a material's microstructure affect its stress-strain curve?

A material's microstructure, such as grain size and composition, can greatly affect its stress-strain curve. For example, a material with smaller grain sizes may have a higher yield strength and greater ductility, resulting in a different curve shape compared to a material with larger grain sizes.

5. What factors can cause variations in stress-strain curves?

The properties of a stress-strain curve can vary depending on factors such as temperature, strain rate, and the presence of impurities or defects in the material. Different manufacturing processes or treatments can also result in variations in the curve shape.

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