The relationship between dynamic stiffness and vibratin amplitude

In summary, the conversation discusses the relationship between dynamic stiffness and vibration amplitude. It is mentioned that many references and experimental results show that the stiffness decreases as amplitude increases, but the reason for this remains unclear. The possibility of a constant force input is also considered, with the explanation that if force remains constant while displacement increases, stiffness must decrease. However, the reason for this phenomenon is still unknown and it is suggested that further theoretical explanations are needed.
  • #1
joannall
2
0
many references tell that the dynamic stiffness will reduce when vibration amplitude increases. And the experimental result is just so. But why there is such rule?who can explain it theoretically?
 
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  • #2
Are you assuming a constant force input? Think of F=kX over a broad range of frequencies, with k being your dynamic stiffness. if X increases with a constant F, the k has to decrease. Or maybe you are thinking of something different?
 
  • #3
i think we should know which is the reason and which is the result. K is the property of materials or components, we can get it by testing force and displacement. of course, the force can't be constant in the experiment. that's to say, the force will increase with the increase of displacement, but their increasing rate are different. so K is different.but i can't explain why K get smaller at higher amplitude in dynamic test.

who can explain such phenomenon theoretically?
 

FAQ: The relationship between dynamic stiffness and vibratin amplitude

1. How is dynamic stiffness defined?

Dynamic stiffness is a measure of the relationship between the applied force and the resulting displacement of a structure or material under dynamic loading conditions. It is typically expressed in units of force per unit displacement, such as N/m or lb/in.

2. What factors affect dynamic stiffness?

The dynamic stiffness of a material or structure is affected by several factors, including the material properties (such as elasticity and density), the geometry and dimensions of the structure, and the frequency and amplitude of the applied vibrations.

3. How does dynamic stiffness relate to vibration amplitude?

The relationship between dynamic stiffness and vibration amplitude is inverse: as the dynamic stiffness of a material or structure increases, the vibration amplitude decreases. This means that stiffer materials or structures will experience smaller vibrations under the same loading conditions compared to more flexible materials or structures.

4. Can dynamic stiffness be measured?

Yes, dynamic stiffness can be measured through various experimental methods, such as dynamic mechanical analysis (DMA) or modal analysis. These techniques involve subjecting a material or structure to a range of dynamic loading conditions and measuring the resulting displacement or response.

5. How is dynamic stiffness used in engineering and design?

Dynamic stiffness is an important factor in the design and analysis of structures and materials that are subject to dynamic loading, such as buildings, bridges, and machinery. It is used to ensure the structural integrity and stability of these systems and to optimize their performance under varying loading conditions.

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