Pendulum benchmark - implicit dynamics

@Disla , I believe, ccx explicit has a floating or uninitialized variable. This data set runs sometimes and sometimes not. It seems to be random whether it like to run as explict or not :slight_smile:

**
**   ---   Coordinates for 15 dgr starting angle
***Node
**1, 0.0, 0.0, 0.0 
**2, 61.7638090, -183.185165, 0.0
**3, 41.7638090, -183.185165, 0.0
**4, 41.7638090, -203.185165, 0.0
**5, 61.7638090, -203.185165, 0.0
**6, 61.7638090, -183.185165, 1.0
**7, 41.7638090, -183.185165, 1.0
**8, 41.7638090, -203.185165, 1.0
**9, 61.7638090, -203.185165, 1.0
**10, 51.7638090, -193.185165, 0.0
**11, 51.7638090, -193.185165, 1.0
**12, 0.0, 0.0, 0.0 
**   ---   Coordinates for 45 dgr starting angle
***Node
**1, 0.0, 0.0, 0.0 
**2, 151.421356, -131.421356, 0.0
**3, 131.421356, -131.421356, 0.0
**4, 131.421356, -151.421356, 0.0
**5, 151.421356, -151.421356, 0.0
**6, 151.421356, -131.421356, 1.0
**7, 131.421356, -131.421356, 1.0
**8, 131.421356, -151.421356, 1.0
**9, 151.421356, -151.421356, 1.0
**10, 141.421356, -141.421356, 0.0
**11, 141.421356, -141.421356, 1.0
**12, 0.0, 0.0, 0.0 
**   ---   Coordinates for 135 dgr starting angle
*Node
1, 0.0, 0.0, 0.0
2, 151.421356, 151.421356, 0.0
3, 131.421356, 151.421356, 0.0
4, 131.421356, 131.421356, 0.0
5, 151.421356, 131.421356, 0.0
6, 151.421356, 151.421356, 1.0
7, 131.421356, 151.421356, 1.0
8, 131.421356, 131.421356, 1.0
9, 151.421356, 131.421356, 1.0
10, 141.421356, 141.421356, 0.0
11, 141.421356, 141.421356, 1.0
12, 0.0, 0.0, 0.0 
**
*Element, Type=C3D6, Elset=body
34, 2, 3, 10, 6, 7, 11
35, 5, 2, 10, 9, 6, 11
36, 3, 4, 10, 7, 8, 11
37, 4, 5, 10, 8, 9, 11
**
*Nset, Nset=BodyCenter
10
*Nset, Nset=Origon
12
**
*Material, Name=Steel
*Density
7.8E-09
*Elastic
210000, 0.3
**
*Solid section, Elset=body, Material=Steel
**   ---  Using a stiff spring as connecting rod
*Element, Type=springa, Elset=Espring
200, 10, 12
**
*Spring, Elset=Espring
 
1000000.
**   ---   Locking the mass moment of initia
*Equation
2
2,2,1.,3,2,-1.
2
2,3,1.,3,3,-1.
**node,dir,fact,node,dir,fact ......... = 0
**
*Step, Nlgeom, Inc=4000
*Dynamic, Explicit
0.001, 0.75, 1E-05, 0.001
**
*Boundary, op=New
Origon, 1, 3, 0
**
*Dload, op=New
Body, Grav, 9820, 0, -1, 0
**
*Node print, Nset=BodyCenter, Totals=Yes
V
**
*Node file
RF, U, V
*El file
S, E
*End step

Hi,

@Calc_em . Finally solve it with Explicit but energy Balance says I need to decrease even more the time step as maximum velocity is still too low. Still don’t understand the Explicit advantage.

@fgr Nice model to work with. I have had to decrease considerable the Spring K to get a good result.
I have noticed Wave Speed for the spring is not computed although it can mess the convergence.

Wave Speed for mat. 2 -1.0000000000000000
Good match with theoretical expected result.

Thank you both! :grinning:

goodkick II