WOLFRAM SYSTEM MODELER
SpoolWithAPreLoadModel of a preloaded spool using ElastoGap components. |
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SystemModel["EducationExamples.MechanicalEngineering.SpoolWithAPreLoad"]
To avoid chattering when using a spool in a hydraulic valve, it is often necessary to hold the spool in a locked position until the external force exceeds a certain threshold value. In this example of a spool with a preload, we will explore the interaction between such a force and the spool's position.
In order to get the full experience of this example, you need the following:
These pages show an overview of the example. For the full example, open the accompanying notebook SpoolWithAPreLoad.nb.
The system is a standard example in the Modelica.Mechanics.Translation library showing an example of usage of the ElastoGap component (the outer and inner contacts in the model). The ElastoGap component is essentially a spring-damper component with a gap, meaning that the spring damper will only be used if the gap is closed. This behavior simulates the desired preload to the spool.
A force is generated from a source and applied to the spool. When the spool has moved a threshold distance, which has the effect of loading a force in a spring, the gap is closed in the Contact components and the spool will begin to move.
Above is a diagram view of the model.
In the accompanying notebook, the behavior of this system is animated and can be interacted with.
forceAmplitude |
Value: 150 Type: Force (N) Description: Amplitude of input force. |
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forceFrequency |
Value: 0.01 Type: Frequency (Hz) Description: Input force frequency. |
length |
Value: 0.0115 Type: Length (m) Description: Spool length. |
mass |
Value: 0.15 Type: Mass (kg) Description: Spool mass. |
housingLength |
Value: 0.0305 Type: Length (m) Description: Length of spool housing. |
housingDamping |
Value: 2500.0 Type: TranslationalDampingConstant (N·s/m) Description: Damping from friction for the spool sliding in the housing |
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innerContactA |
Type: ElastoGap |
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innerContactB |
Type: ElastoGap |
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spool |
Type: Mass |
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fixedLe |
Type: Fixed |
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springPlateA |
Type: Mass |
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springPlateB |
Type: Mass |
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spring |
Type: Spring |
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outerContactA |
Type: ElastoGap |
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outerContactB |
Type: ElastoGap |
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rod1 |
Type: Rod |
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friction |
Type: Damper |
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force |
Type: Force |
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housing |
Type: Rod |
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rod3 |
Type: Rod |
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rod4 |
Type: Rod |
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rod2 |
Type: Rod |
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sineForce |
Type: Sine |