/PROP/TYPE45 (KJOINT2)

Block Format Keyword Describes the joint type spring between two rigid bodies.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/PROP/TYPE45/prop_ID/unit_ID or /PROP/KJOINT2/prop_ID/unit_ID
prop_title
Type Kn ScF Cr sens_ID Skew_ID1 Skew_ID2
To be defined for each non-blocked translational DOF (depending on joint type)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Kti fct_Kti SDi- SDi+ Icomb_ti    
Ct fct_Cti              
Kfxi FFi fct_FFi          
To be defined for each non-blocked rotational DOF (depending on joint type)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Kri fct_Kri SAi- SAi+ Icomb_ri    
Cri fct_Cri              
Kfri FMi fct_FMi          

Definitions

Field Contents SI Unit Example
prop_ID Property identifier

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
prop_title Property title

(Character, maximum 100 characters)

 
Type Joint type (Joint Types List)
= 1
Spherical joint
= 2
Revolute joint
= 3
Cylindrical joint
= 4
Planar joint
= 5
Universal joint
= 6
Translational joint
= 7
Oldham joint (planar without rotation DOF)
= 8
Fixed (rigid) joint
= 9
Free joint

(Integer)

 
Kn Stiffness for blocked DOF. 3
= 0
Stiffness is automatically calculated.
> 0
Valued entered is the stiffness.

Default = 0.0 (Real)

[ N m ]
ScF Scale factor for Kn. 3

If Kn = 0: Scale factor on both translational and rotational stiffness.

Default = 1.0 (Real)

If Kn > 0: Scale factor on only the rotational stiffness.

Default = 10.0 (Real)

 
Cr Critical damping factor. 4

Default = 0.05 (Real)

 
sens_ID Sensor identifier. 2

(Integer)

 
Skew_ID1 First skew system identifier . 7

(Integer)

 
Skew_ID2 Second skew system identifier. 7

(Integer)

 
Kti Translational stiffness of non-blocked DOF. 3

If fct_Kti = 0: Constant translational stiffness value.

If fct_Kti > 0: Translational stiffness scale factor.

Default =1.0 (Real)

[ N m ] or None
fct_Kti Translational force versus displacement function identifier of non-blocked DOF.

(Integer)

 
SDi-, SDi+ Negative and Positive stopping displacement. 6

Default = 0.0 (Real)

[ m ]
Cti Translational viscosity coefficient of non-blocked DOF. 4

If fct_Cti = 0: Constant translational viscosity.

If fct_Cti > 0: Translational viscosity scale factor.

Default = 1.0 (Real)

[ Ns m ] or None
fct_Cti Translational viscous force versus displacement rate function identifier.

(Integer)

 
Kfti Elastic stiffness for friction and stop displacement 5

Default = 0.0 (Real)

[ N m ]
FFi Frictional force value. 5

Default = 0.0 (Real)

[ N ] or None
fct_FFi Frictional force versus displacement function identifier.

(Integer)

 
Icomb_ti Combining stop displacements flag. 9
=0 (Default)
Stop displacements independent.
=1
Stop displacements are combined together.

(Integer)

 
Kri Rotational stiffness coefficient of non-blocked DOF. 3

If fct_Kri = 0: Constant rotational stiffness value.

If fct_Kri > 0: Rotational stiffness scale factor.

Default = 1.0 (Real)

[ Nm rad ] or None
fct_Kri Rotational moment versus rotational angle function identifier.

(Integer)

 
SAi-, SAi+ Positive and Negative stopping angles in radians. 6

Default = 0.0 (Real)

[ rad ]
Cri Rotational viscosity coefficient of non-blocked DOF.

If fct_Cri = 0: Constant rotational viscosity value.

If fct_Cri > 0: Rotational viscosity scale factor.

Default = 1.0 (Real)

[ Nms rad ] or None
fct_Cri Rotational viscosity moment versus rotational angle rate function identifier.

(Integer)

 
Kfri Elastic stiffness per radian unit for friction and stop angle. 5

Default = 0.0 (Real)

[ Nm rad ]
FMi Frictional moment value of non-blocked DOF. 5

If fct_FMi = 0: Constant frictional moment value.

If fct_FMi > 0: Frictional moment scale factor.

Default = 0.0 (Real)

[ Nm ] or None
fct_FMi Frictional moment versus rotational angle function identifier.

(Integer)

 
Icomb_ri Combining stop angles. 9
=0 (Default)
Stop angles are independent.
=1
Stop angles are combined together.

(Integer)

 

Joint Types List

Type No. Joint Type dx dy dz θ X θ Y θ Z
1 Spherical x x x 0 0 0
2 Revolute x x x 0 x x
3 Cylindrical 0 x x 0 x x
4 Planar x 0 0 0 x x
5 Universal x x x x 0 0
6 Translational 0 x x x x x
7 Oldham x 0 0 x x x
8 Rigid x x x x x x
9 Free 0 0 0 0 0 0
Where:
x
Denotes a blocked DOF
0
Denotes a free (user-defined) DOF

Example (Rotational)

#RADIOSS STARTER
/UNIT/2
unit for prop
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE45/2/2
Revolute 
### - Define angle limit < 0.52rad 
### - And define friction moment 100GPa to block angle (if it reached the limit)
#     Type                  KN                 SCF                  CR  SENSORID
         2                   0                   0                   0         0
#                KR1Func_ID_Kr                SA1-                SA1+  Icomb_r1
                   0         0                   0                 .52         0
#                CR1Func_ID_Cr
                   0         0
#               KFR1                 FM1   FCT_FM1
                   0                 100         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA

Example (Translational)

#RADIOSS STARTER
/UNIT/2
unit for prop
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE45/12/2
Translational 
### - define displacement limit: -100mm ~ 100 mm
#     Type                  KN                 SCF                  CR  SENSORID
         6                   0                   0                  .2         0
#                KX1Func_ID_Kx                SD1-                SD1+  Icomb_t1
                   0         0                -100                 100         0
#                CX1Func_ID_Cx
                   0         0
#               KFX1                 FF1   FCT_FF1
                1000                   0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA

Comments

  1. Spring element:
    • The identifier must be unique in each element family, but it is advised to have a unique element identifier in the global model for each element type.
    • More than one spring block can be used to define a part.
  2. Spring DOF:
    • Joint properties are defined in a local coordinate system of the joint element.
    • The total number of joint DOF computed in the local coordinate system frame is six:

      δ X , δ Y , δ Z , θ X , θ Y , θ Z

    • Blocked and free DOF are distinguished for each joint type.
    • The blocked DOF are characterized by a constant stiffness. By default, if no stiffness value is entered, the value of the stiffness is automatically computed to preserve the time step.
    • The translational and rotational DOF are defined as:(1)
      δ = d x 2 d x 1
      Where, d x 1 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGKbGaam iEamaaBaaaleaacaaIXaaabeaaaaa@392C@ and d x 2 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGKbGaam iEamaaBaaaleaacaaIXaaabeaaaaa@392C@ are total displacements of two joint nodes in the local coordinate system.(2)
      θ = θ 2 θ 1

      Where, θ 1 and θ 2 are total relative rotations of two connected body axes, with respect to the local coordinate system of the joint.

    • If sens_ID is defined, then the joint becomes fully blocked (all degrees of freedom) when the sensor is activated.
  3. Forces and moments calculation:
    • The force in direction δ is computed as:
      Linear spring:(3)
      F = K t i δ + C t i δ ˙

      K t i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHlbWaaS baaSqaaiaadshacaWGPbaabeaaaaa@3946@ : translational stiffness ( K t x , K t y , K t z )

      C t i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHdbWaaS baaSqaaiaadshacaWGPbaabeaaaaa@393E@ : translational viscosity ( C t x , C t y , C t z )

      Nonlinear spring:(4)
      F = K t i f ( δ ) + C t i g ( δ ˙ ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHgbGaey ypa0JaaC4samaaBaaaleaacaWG0bGaamyAaaqabaGcciGGMbWaaeWa aeaacaWH0oaacaGLOaGaayzkaaGaey4kaSIaaC4qamaaBaaaleaaca WG0bGaamyAaaqabaGcciGGNbWaaeWaaeaaceWH0oGbaiaaaiaawIca caGLPaaaaaa@4664@
    • The moment in θ direction is computed as:
      Linear spring:(5)
      M = K ri θ + C ri θ ˙

      K r i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHlbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@3944@ : rotational stiffness ( ( K r x , K r y , K r z ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaqadaqaai aadUeadaWgaaWcbaGaamOCaiaadIhaaeqaaOGaaiilaiaadUeadaWg aaWcbaGaamOCaiaadMhaaeqaaOGaaiilaiaadUeadaWgaaWcbaGaam OCaiaadQhaaeqaaaGccaGLOaGaayzkaaaaaa@4239@ )

      C r i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHlbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@3944@ : rotational viscosity ( ( C r x , C r y , C r z ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaqadaqaai aadoeadaWgaaWcbaGaamOCaiaadIhaaeqaaOGaaiilaiaadoeadaWg aaWcbaGaamOCaiaadMhaaeqaaOGaaiilaiaadoeadaWgaaWcbaGaam OCaiaadQhaaeqaaaGccaGLOaGaayzkaaaaaa@4221@ )

      Nonlinear spring:(6)
      M = K ri f ( θ ) + C ri g ( θ ˙ )
    • The joint length may be, but is not necessarily equal to 0. It is recommended to use a 0 length spring to define a spherical joint or a universal joint.
    • To satisfy the global balance of moments in a general case, correction terms in the rotational DOF are calculated as:(7)
      M θ x = M θ x + L y × F z L z × F y
      (8)
      M θ y = M θ y + L z × F x L x × F z
      (9)
      M θ z = M θ z + L x × F y L y × F x

      Joints do not have user-defined mass or inertia, so the nodal time step is always used.

  4. Stiffness of spring
    • Coefficients K t i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHlbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@3944@ and K r i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHlbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@3944@ are used as constant stiffness, if there are no user-defined functions. If a function is defined, the corresponding stiffness coefficient becomes a scale factor for the function.
    • If Kn = 0, the blocking stiffness area is automatically computed at the beginning of the computation for both translational and rotational blocked DOF, in order to preserve the time step. These values are also selected according to the physics and must be higher than the stiffness of the neighboring elements.
    • If Kn = 0, then Scf is a scaling factor applied to both translational and rotational blocking stiffness. If Kn > 0, then Scf is applied only on blocking rotational stiffness. This parameter can be used to manually adjust the blocking stiffness in rotation.
  5. Viscous of spring
    • Coefficients C t i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHdbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@393C@ and C r i MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHdbWaaS baaSqaaiaadkhacaWGPbaabeaaaaa@393C@ are used as linear viscosity coefficients, if there are no user-defined functions. If a function is defined, the corresponding coefficient becomes a scale factor for the function.
    • There are two ways to introduce viscous damping:
      • Defining a critical damping (for blocked DOF only):

        Viscous damping is defined in terms of the critical damping factor. The critical damping coefficient is calculated using the blocking stiffness value of the element. The mass and inertia are equal to half of the values for each rigid body connected to the joint. The approximation is then satisfactory, if only one joint is connected to each rigid body. Otherwise, the critical damping is over-estimated; in which case, the damping factor in the Radioss input should be decreased. The same damping is applied to all blocked DOF.

      • User-defined constant or nonlinear damping:

        It is possible to define independent damping parameters for each free DOF.

  6. Friction
    • Friction is not activated, if Kfti or Kfri are not defined.
    • FFi and FMi are used as constant friction force and moment, if there are no user defined functions. If the friction function number is not 0, FMi and FFi become a scale factor for the functions (default = 1.0).
  7. Spring limit
    • If a non-zero value is specified for SDi- or SDi+, then an additional penalty force is applied to prevent the displacement to exceed SDi+ for positive displacement and SDi- for negative displacement. This penalty force is computed using Kfti.
    • If a non-zero value is specified for SAi- or SAi+, then an additional penalty moment is applied to prevent the angle to exceed SAi+ for positive rotation or SAi- for negative rotation. This penalty moment is computed using Kfri
  8. Skew of spring
    • If Skew_ID1 is defined, the initial local coordinate system is defined by Skew_ID1. If Skew_ID1 = 0, the local coordinate system is computed according to the additional nodes of the spring. Refer to /SPRING for more information.
    • If Skew_ID2 is defined, rotation angles of the joint are initialized according the rotation between Skew_ID1 and Skew_ID2. Values of the initial angles can be check in the Starter output file. For revolute (TYPE2), cylindrical (TYPE3) and planar (TYPE4) joints only θ X MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH4oqCda WgaaWcbaGaamiwaaqabaaaaa@391E@ can be initialized. The first axis of Skew_ID1 and Skew_ID2 must be parallel.


      Figure 1. Computation of Initial Rotation Angle for Revolute Joint (TYPE2)
    • If Skew_ID2 is non-zero and Skew_ID1 =0, then Skew_ID1 is the global coordinate system.
    • The local coordinate system orientation is updated according node_ID1 (/SPRING) rotation.
  9. Combined stop displacements/angles:
    • If Icomb_ti = 0: the stop displacements are independent (default) as shown in Figure 2. Stop displacement will be checked separately in each direction.
    • If Icomb_ti = 1: the stop displacements of all the free translational DOF are combined. The stopping criteria is no longer applied on the displacement but on the norm of the combined displacements see Figure 3.
    • 2 or 3 stop displacements can be combined
    • If stop displacements are combined, the same value of SDi- and SDi+ must be used for each DOF.
    • The above descriptions for stop displacements also apply for stop angles defined using Icomb_ri.


Figure 2. Planar Joint with Independent Stop Displacements, Icomb_ti=0


Figure 3. Planar Joint with 2 Combined Stopping Displacements, Icomb_ti=1