Creating Helical Springs

You can create a helical spring between bodies to simulate their elastic behavior when submitted to loads.

Before you begin:
  • Create at least two bodies.
  • Create a mechanism.
See Also
About Springs
  1. From the Machine Elements section of the action bar, click Spring .
    In the tree, the spring element appears under the Machine Elements node of the active mechanism.
  2. Select Helical .
  3. From the Location section, specify how to locate or position the spring in the mechanism (the spring ends are attached to the specified locations on the respective bodies):
    1. Specify the Spring end 1, which is the first attachment location on the connecting body.
    2. Specify the Spring end 2, which is the second attachment location on the connecting body.
  4. From the Motion Behavior options, select one of the following to specify the general motion characteristics of the spring:
    OptionDescription


    Extension    		 Provides elasticity (resistance to the relative motion) only in the elongation direction.

    The stiffness of the spring is considered as zero if the actual distance between the attachment locations (spring ends) is less than the spring free length.

    The spring always acts point-to-point. The spring axis is defined by the line joining the spring attachment location points.


    Compression    		 Provides elasticity only in the compression direction.

    The stiffness of the spring is considered as zero if the actual distance between the attachment locations is greater than the spring free length.


    Bidirectional    		 Provides elasticity (resistance to the relative motion) in both the elongation and compression directions.
  5. If you selected Compression or Bidirectional from the Motion Behavior options, select one of the following from the Level of detail options:
    OptionDescription
    Point to point The spring always acts along the line joining the spring attachment points.

    Therefore, the spring forces are applied only along the spring.
    Shear and bending The spring considers the effects of shearing (translation motion between the spring ends in a plane perpendicular to the spring axis) and bending (rotation of the Spring end 2 about axes perpendicular to the spring axis).

    Torsion stiffness about the spring axis is neglected. You can select whether the Spring axis is X, Y, or Z. The Spring end 1 orientation is taken as the reference for the axis directions.
  6. Optional: If the spring elastic properties must be derived from the dimensions, click Specify values in the Spring Dimensions section.
    1. Enter a value for the Mean diameter, which is the spring diameter measured at the center of the wire cross-section.

      You can also compute this value as the average of the inner and outer diameter of the spring.

    2. Enter a value for the Wire diameter, which is the wire diameter of the spring.
    3. Enter a value for the Number of coils, which is the active number of coils of the spring.
    4. From the Material selection options, select Steel ASTM A228 (shear modulus of 79289.7295 N/mm^2) or Steel ASTM A313 (shear modulus of 68947.59087 N/mm^2).
  7. From the Spring Length options, select one of the following
    OptionDescription
    Unloaded Nominal condition of the spring free of external loads.
    Preloaded Assembled configuration with a known applied preload.

    The spring angle is measured between the spring ends about the spring axis.

  8. If you selected Unloaded from the Spring Length options, enter the value for the Free length.

    The Free length is the spring length in unloaded configuration.

  9. If you selected Preloaded from the Spring Length options, do the following:
    1. Enter the value for the Assembled length, which is the spring length in assembled configuration.
    2. Enter the value for the corresponding Design preload acting on the helical spring at this length, which is the applied force to maintain the spring in the assembled configuration.

      The app calculates the actual free length of the spring automatically based the preloaded configuration.

  10. From the Elastic Properties options, select one of the following:
    OptionDescription
    Direct input Defines the stiffness properties of the spring based on user-specified values.
    Derived from dimensions Defines the elastic properties the spring automatically based on the user-specified Spring Dimensions.

    The spring rate specifies the stiffness in the axial direction (along the spring axis).

  11. If you selected Direct input, from the Elastic Properties options, do the following:
    1. From the Spring rate options, select if the stiffness is given using a Value input or a Function .
    2. If the Level of detail is set to Shear and bending, specify the Shear stiffness [The stiffness in the shear direction (plane perpendicular to the spring axis)] and the Bending stiffness [The stiffness in the bending direction (axes perpendicular to the spring axis)].
  12. Optional: From the Damping Properties options, enter a value for the Damping constant, which is the linear material damping of the spring.

    This option provides the slight damping inherent in any physical coil spring; it is not meant to define a detailed damper. Entering a value of 0 or a value that is too low can cause undamped or weekly damped oscillations of the spring even for small forces or torques.

  13. Click OK.