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mechanic667

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- Thread starter mechanic667
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In summary, the metal tube can deflect downwards freely before it yields, plastic has a lower Young's modulus than 304 stainless steel, and the stress in the plastic will be difficult to ignore when determining the deflection of the metal tube.

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mechanic667

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berkeman

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How is the fixed end supported? Is the full circumference of the metal tube welded to a vertical metal wall? How is the load supported at the far end of the tube? Is there a plate welded to the end and the plate supports the weight of the load?

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mechanic667

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Essentially I have a metal tube sticking out of a hole of a plastic part. The metal tube is glued inside of the plastic part prior to exiting the hole. This hole has a relatively small clearance between the plastic part and metal tube, therefore I am treating this problem as a cantilever beam problem where the end that is fixed is the point at which the tube exits the metal part.berkeman said:

How is the fixed end supported? Is the full circumference of the metal tube welded to a vertical metal wall? How is the load supported at the far end of the tube? Is there a plate welded to the end and the plate supports the weight of the load?

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What yield criterion are you using?

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berkeman

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Wouldn't the plastic yield plastically before the metal tube?mechanic667 said:Essentially I have a metal tube sticking out of a hole of a plastic part. The metal tube is glued inside of the plastic part prior to exiting the hole.

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mechanic667

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Van mises for this caseChestermiller said:What yield criterion are you using?

I don't believe so. Essentially what the problem looks like is a a metal tube coming out of a hole in a plastic part, however, once outside the hole there is no plastic material below the metal tube, meaning it can deflect downwards freely if that makes sense. Sorry if that was a little confusing.berkeman said:Wouldn't the plastic yield plastically before the metal tube?

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berkeman

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What are the Young's modulus plots for this plastic (which plastic material is it?) compared to the Young's modulus plot of 304 stainless?mechanic667 said:Essentially what the problem looks like is a a metal tube coming out of a hole in a plastic part, however, once outside the hole there is no plastic material below the metal tube, meaning it can deflect downwards freely if that makes sense.

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Joe591

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-shear

-bending

-deformation/rotation of beam in plastic.

The stress in the plastic will be difficult to ignore because it might reach yield before the steel rod does. For the steel you can surely use standard bending and shear deflection equations. The rotation in the plastic is not a simple matter. I am not aware of standard equation for such a case.

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FEAnalyst

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You could use this simplified standard approach: $$\sigma_{y}=\frac{M_{y}}{S}=\frac{M_{y}}{\frac{\pi(D^4-d^4)}{32D}}$$ In this case: $$205=\frac{M_{y}}{\frac{\pi(2^4-0.5^4)}{32 \cdot 2}}$$ Thus: ##M_{y}=160.38 \ Nmm##. Now let's find the deflection: $$y=\frac{FL^{3}}{3EI}=\frac{FL^{3}}{3E \frac{\pi(D^4-d^4)}{64}}$$ In this case: $$y=\frac{38.646 \cdot 4.15^{3}}{3 \cdot 190000 \cdot \frac{\pi (2^4-0.5^4)}{64}}=0.00619418 \ mm$$

But this beam has very unusual dimensions so the accuracy of calculations using beam theory might be lower than expected.

But this beam has very unusual dimensions so the accuracy of calculations using beam theory might be lower than expected.

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Elasticity refers to the ability of a material to deform under applied force and return to its original shape once the force is removed. In the case of a tubular cantilever beam, elasticity is important because it determines the beam's ability to withstand bending and twisting without permanent deformation.

The elasticity of a tubular cantilever beam is typically measured using a stress-strain curve. This involves applying different levels of force to the beam and measuring the corresponding amount of deformation. The slope of the curve at any given point represents the beam's elasticity or stiffness.

The elasticity of a tubular cantilever beam is affected by several factors, including the material properties of the beam (such as Young's modulus and Poisson's ratio), the geometry of the beam (such as its length and diameter), and the type of loading applied to the beam (such as bending or torsion).

The elasticity of a tubular cantilever beam is directly related to its ability to withstand external forces without breaking or permanently deforming. A beam with higher elasticity will be able to support larger loads and experience less deformation under the same amount of force. This is important for ensuring the structural integrity and safety of the beam.

Yes, the elasticity of a tubular cantilever beam can be improved by using materials with higher Young's modulus, optimizing the beam's geometry for the specific loading conditions, and using reinforcement techniques such as adding additional layers or changing the cross-sectional shape. However, it is important to note that increasing the elasticity of a beam may also increase its weight and cost.

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