/PROP/TYPE4 (SPRING)

Format

Definitions

Example (Seatbelt)

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/2
unit for prop
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/SPRING/2/2
Seatbelt 
#                  M                               sensor_ID    Isflag     Ileng
                5E-5                                       0         0         1
#                 K1                  C1                  A1                  B1                  D1
               0.001                   0                   0                   0                   0
# fct_ID11        H1  fct_ID21  fct_ID31  fct_ID41                     delta_min           delta_max
         1         2         0                   0                             0                   0
#                 F1                  E1             Ascale1             Hscale1
                   0                   0                   0                   0
/MOVE_FUNCT/1
Seatbelt 
#           Ascale_x            Fscale_y            Ashift_x            Fshift_y
                                   0.001
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1
Seatbelt loading force vs engineering strain 
#                  X                   Y
                  0.                  0.
               0.005                700.
                0.02               3100.
                0.03               5500.
                0.15              17000.
               1000.              17000.
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA

Comments

1. The spring has one translational degree of freedom in the local x direction which is defined between node N1 and N2 of the spring.
2. Spring is activated and/or deactivated by sensor defined in sens_ID and depends on I_sflag:
   • If I_sflag = 0, the spring element is activated by the sens_ID and cannot be deactivated. The initial length of the spring is based on the spring length at time=0.
   • If I_sflag = 1, the spring element is deactivated by the sens_ID and cannot be activated. The initial length of the spring is based on the spring length at time=0.
   • If I_sflag = 2, the spring is activated and/or deactivated by sens_ID and can switch activation state multiple times. If sensor is activated, the spring is active; if sensor is deactivated, spring is deactivated. The spring initial length, $l_0$ , is the distance between spring nodes at the time of sensor activation.
3. If I_leng = 1, the spring properties are based on the initial spring length. The input should be entered as:

   $M=\frac{m}{l_0}$	$K=k*l_0$
   $C=c*l_0$

   Each spring will then have the following properties in the model:

   $m=M\cdot l_0$	$k=\frac{K}{l_0}$
   $c=\frac{C}{l_0}$

   Where,

   $M$ , $K$ and $C$

   Spring values entered in the spring property fields

   $m$ , $k$ and $c$

   Spring’s actual physical mass, stiffness and damping

   $l_0$

   Initial spring length which is the distance between node N1 and N2 of the spring

   ${\delta }_{\min }^1\text{ and }{\delta }_{\max }^1$

   Failure values entered as engineering strain

4. Force computation. For additional information, refer to Stiffness Formulation in the User Guide.
   • If I_leng =0, the value of force $F$ in the spring is computed as:
     For H₁ = 1,2,4,5,6,7:(1)

     $$F=\mathrm{f}\left(\frac{\delta }{Ascal{e}_1}\right)\left[A_1+B_1\ln \left(\max \left(1,\left|\frac{\dot{\delta }}{D_1}\right|\right)\right)+E_1\mathrm{g}\left(\frac{\dot{\delta }}{F_1}\right)\right]+C_1\dot{\delta }+Hscal{e}_1\mathrm{h}\left(\frac{\dot{\delta }}{F_1}\right)$$

   Where, $\delta =l-l_0$ is the difference between the current length and the initial length of the spring element.

   with $-l_0<\delta <+\infty$

   If H₁ = 8:(2)

   $$F=\mathrm{f}\left(\frac{l}{Ascal{e}_1}\right)\left[A_1+B_1\ln \left(\max \left(1,\left|\frac{\dot{\delta }}{D_1}\right|\right)\right)+E_1\mathrm{g}\left(\frac{\dot{\delta }}{F_1}\right)\right]+C_1\dot{\delta }+Hscal{e}_1\mathrm{h}\left(\frac{\dot{\delta }}{F_1}\right)$$

   Where, $\text{0}<l<\infty$ and $-l_0<\delta <+\infty$

   If I_leng = 1, the value of force $F$ in the spring is computed as:(3)

   $$F=\mathrm{f}\left(\frac{\epsilon }{Ascal{e}_1}\right)\left[A_1+B_1\ln \left(\max \left(1,\left|\frac{\dot{\epsilon }}{D_1}\right|\right)\right)+E_1\mathrm{g}\left(\frac{\dot{\epsilon }}{F_1}\right)\right]+C_1\dot{\epsilon }+Hscal{e}_1\mathrm{h}\left(\frac{\dot{\epsilon }}{F_1}\right)$$
   Where,

   $\epsilon$

   Engineering strain

   $\epsilon =\frac{\delta }{l_0}$

   $\mathrm{f}\left(\epsilon \right)$

   Nonlinear stiffness is a function of engineering strain

   $\mathrm{g}\left(\dot{\epsilon }\right)\text{ and }h\left(\dot{\epsilon }\right)$

   Damping is a function of engineering strain rate

5. If H₁ > 0 and fct_ID₁₁ = s 0, $\mathrm{f}\left(\delta \right)=1\text{ or }\mathrm{f}\left(\epsilon \right)=1$ .