Spring Materials and Material Properties

Materials

Spring wire and bar materials available in the default material table supplied with ODOP:Spring include:

The corresponding "long names" not currently displayed in the ODOP:Spring user interface are:

By default, ODOP:Spring gets material property data from the materials table. Alternate material tables may be provided to contain material property values that match locally available materials or individual experience and preferences. Thus, the currently active materials table may not match the default table described above. For additional information, refer to:

• Restrictions
• NewDesignType

The way that ODOP:Spring handles material property data is dependent on the user specified settings of the Calculation Inputs: Material_Type and Prop_Calc_Method. Note that by default, when using a material selected from the materials table, allowable stresses are calculated as a function of wire diameter. In general, the user may ignore these details and use the defaults built into the program. Establish material property values simply by selecting a Material_Type. In the case that more control of material property data entering the calculations is desired, the details provided below and in Prop_Calc_Method may be useful.

Examples of these procedures are presented in tutorial section TUTOR5.

The Material_Type is used to indicate which entry in the material table should be used to determine material properties and allowable stress limits. Specifically, the term "material properties" includes the values for Density, Torsion_Modulus, and Tensile. The term "allowable stress limits" includes values for Stress_Lim_Stat and Stress_Lim_Endur which are normally calculated based on the material properties plus the current value of Wire_Dia combined with %_Tensile_Stat and %_Tensile_Endur.

To use a material that is not in the material table, or to use material property values that are different than those contained in the table, it is necessary to select an alternate setting for Prop_Calc_Method.

ODOP:Spring will treat material properties in one of three different ways depending on the value of the constant Prop_Calc_Method.

If Prop_Calc_Method has a value of 1 - Use values from material table (the normal default), then the material properties are selected and allowable stresses calculated as previously described. Specifically, if Prop_Calc_Method has a value of 1, ODOP:Spring will calculate the allowable stresses as a function of Wire_Dia. A log-linear interpolation scheme will use the values of Wire_Dia, plus the table supplied values of tensile at 0.010, tensile at 0.400, %_Tensile_Stat, and %_Tensile_Endur to calculate new values for Tensile, Stress_Lim_Stat and Stress_Lim_Endur at each step in the Search process. This insures that the allowable stresses used in the factor of safety calculations exactly match the trial values of Wire_Dia selected by Search.

If Prop_Calc_Method has a value of 2 - Use Tensile & %_Tensile_..., the user supplied values of Tensile, %_Tensile_Stat and %_Tensile_Endur are used to calculate the allowable stresses Stress_Lim_Stat and Stress_Lim_Endur.

If Prop_Calc_Method is set to a value of 3 - Use Stress_Lim_..., then ODOP:Spring will not modify the values of Stress_Lim_Stat and Stress_Lim_Endur in any way. These values will remain as established in the initial start point ("Startup") or as set by the user in the Advanced View Calculation Input section. The values of Material_Type, Tensile, %_Tensile_Stat and %_Tensile_Endur will be ignored.

In most cases, the user does not need to be concerned with these details. They are necessary only to use material properties or allowable stresses that are different from those determined by the materials table.

The following example illustrates how to establish a value of Torsion_Modulus that is different from the value in the material table. Stress_Lim_Stat and Stress_Lim_Endur will continue to be based on the current values of Tensile plus %_Tensile_Stat and %_Tensile_Endur whether established by the user or carried over from the values established in the materials table or startup. The order in which these changes are entered is significant.

CHANGE Prop_Calc_Method 2 - Use Tensile & %_Tensile_...
CHANGE Torsion_Modulus  xxxxxxxx

The same process applies to changing values for %_Tensile_Stat and %_Tensile_Endur.

The following example illustrates how to establish a value of %_Tensile_Stat that is different from the value in the material table. Stress_Lim_Stat and Stress_Lim_Endur will continue to be based on the new value of %_Tensile_Stat and existing value of %_Tensile_Endur. The order in which these changes are entered is significant.

CHANGE Prop_Calc_Method 2 - Use Tensile & %_Tensile_... 
CHANGE %_Tensile_STAT  xxxxxxxx 

The following example illustrates how to establish values of Torsion_Modulus, Stress_Lim_Stat and Stress_Lim_Endur. There will be no dependence on the Wire_Dia or any values from the materials table. The order in which these changes are entered is significant.

CHANGE  Prop_Calc_Method  3 - Use Stress_Lim_... 
CHANGE  Torsion_Modulus   xxxxxxxx 
CHANGE  Stress_Lim_Stat   yyyyyy 
CHANGE  Stress_Lim_Endur  zzzzzz 

The File : Save menu item will capture the complete status of the design including the material property information. After using the File : Open... menu item to read a previously saved design, the complete status of the design will be restored.

Additional information on controlling the way material property data is used in the calculations is presented in the section Design to Stress.

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