Bouncing Height of Cylindrical Tube: Equation & Properties

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SUMMARY

The discussion focuses on calculating the bouncing height of a cylindrical tube made of high-density polyethylene (HDPE) when dropped onto a concrete floor under Earth's gravity. Key parameters include the tube's density (960 kg/m³), tensile modulus (1500 MPa), and tensile strength at yield (31 MPa). The participants suggest using a spring-mass analysis to understand the energy transfer during impact, emphasizing the relationship between kinetic energy and elastic deformation. The equation Ep = Ek at impact = Ek at rebound + Elosses is highlighted as a fundamental concept for calculating impact forces and deformation.

PREREQUISITES
  • Understanding of kinetic energy and potential energy principles
  • Familiarity with material properties, specifically high-density polyethylene
  • Knowledge of basic mechanics, including spring-mass systems
  • Concept of elastic deformation and stress-strain relationships
NEXT STEPS
  • Research the impact force calculation using the equation F = (1/2 mv²/d)
  • Explore the principles of energy loss during elastic collisions
  • Study the effects of material properties on impact resistance and deformation
  • Learn about advanced modeling techniques for dynamic impact analysis
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Engineers, physicists, and materials scientists interested in impact mechanics, specifically those working with polymer materials and their behavior under dynamic loads.

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What is the equation to find the bouncing height of a cylindrical tube when the flat surface is falling on the floor under Earth's gravity? I know the mass, drop height and material properties of the cylindrical tube.
 
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And the floor properties too.
 
C
256bits said:
And the floor properties too.
Considering it as a concrete floor.

and Material of the tube is high-density polyethylene: Density 960 kg/m3, Tensile modulus 1500MPa Tensile strength at yield 31 MPa Charpy Imp strength 4.0 kJ/m2
 
Last edited:
Tech Guy said:
What is the equation to find the bouncing height of a cylindrical tube when the flat surface is falling on the floor under Earth's gravity? I know the mass, drop height and material properties of the cylindrical tube.
Do you know the rotation rate and impact angle?
 
Tube is falling normal to the ground without rotation.
 
Have you tried a simple spring -mass analysis to begin with, and then work your way up to the variable compression of the tube ( the part hitting the ground compresses the most )
Of course we don't know the energy loss.
It would be something like
Ep = Ek at impact = Ek at rebound + Elosses
 
256bits said:
Have you tried a simple spring -mass analysis to begin with, and then work your way up to the variable compression of the tube ( the part hitting the ground compresses the most )
Of course we don't know the energy loss.
It would be something like
Ep = Ek at impact = Ek at rebound + Elosses
I did not understand. It would be great if you can explain.

Actually I am trying to calculate the impact force due to freefall. As I know the KE due to fall, I need the impact distance to calculate the force (1/2 mv²/d).
If this is difficult to calculate theoretically, any equation to calculate impact time to use Newtons second law to calculate the Impact force?
 
Oh ok then.
You write an equation comparing the kinetic energy to the elastic deformation of the cylinder with the assumption that the concrete is rigid. ( which is not true but it gives you that worst case, I think ).
And solve for deformation of the cylinder.

Note:
1.You have a continuous force acting on the cylinder during deformation. This force is the weight of the cylinder. This adds work to the deformation.
2. The kinetic energy of the falling cylinder is absorbed by elastic energy within a reduced length less than the full length of the cylinder. This tends to increase the stress and deformation nearer the impact area.
 

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