5.8.2.4.4. Non-Linear Spring Damper

This example shows how the behavior of a spring can be altered to introduce a non-linear force-displacement relationship. The complete list of commands is shown below. A description of these commands follows.

Retrieve the spring object using its ID:
```
Spring=CS_Actuator.Find(_sid)
```
Create an array of real values and fill it with the pairs of values (elongation, force):
```
Spring_table=System.Array.CreateInstance(float,7,2)

#
# LENGTH transition values
spring_table[0,0]=0.
spring_table[1,0]=50.
spring_table[2,0]=60.
spring_table[3,0]=100.
spring_table[4,0]=140.
spring_table[5,0]=150.
spring_table[6,0]=200.
 
#
# Spring Stiffness
spring_table[0,1]=-100000.
spring_table[1,1]=-10000.
spring_table[2,1]=-1000.
spring_table[3,1]=0.
spring_table[4,1]=1000.
spring_table[5,1]=10000.
spring_table[6,1]=100000.
 
stiffness = CS_PointsTable(spring_table)
 
spring.SetTable(stiffness)
```
In this command, 7 represents the number of rows and 2 for the number of columns. The first column gives elongation and the second, the corresponding force value. This command generates a PointsTable assigned to the spring, as shown below.
Each spring object in the Mechanical GUI is actually a combination of a spring and a damper. The GetDamper method enables you to retrieve the damper object on a given spring, as shown below.
Introduce a table is to define a non-linear force velocity relation:
```
Damper=spring.GetDamper()
```