Modelica spring-pendulum - modelica

Question

I want to model a simple "spring-pendulum" in modelica:
model Pendulum
parameter Boolean animation=true "= true, if animation shall be enabled";
inner Modelica.Mechanics.MultiBody.World world(axisLength=0.6)
Modelica.Mechanics.MultiBody.Parts.Body body1(
m=1,
animation=animation,
I_11=1,
I_22=1,
I_33=1,
r_CM={0,0,0},
cylinderDiameter=0.05,
sphereDiameter=0.2)
Modelica.Mechanics.MultiBody.Forces.Spring spring1(
coilWidth=0.01,
numberOfWindings=5,
c=20,
s_unstretched=0.2) ;
Modelica.Mechanics.MultiBody.Joints.Revolute revolute(phi(fixed=true), w(
fixed=true));
equation
connect(world.frame_b, revolute.frame_a)
connect(spring1.frame_a, revolute.frame_a)
connect(spring1.frame_b, body1.frame_a)
connect(revolute.frame_b, body1.frame_a
end Pendulum;
Trying to simulate the simulation fail - no error message.
Do i need a revolulte for a spring-pendulum? Thank you very much for your help!

Answer 1

Not exactly sure of what you're trying to model. If you make a drawing of your system you'll see that it won't represent what you're trying to model (I think).
Here's a pendulum with a spring:
model pendulum2
inner Modelica.Mechanics.MultiBody.World world annotation(Placement(visible = true, transformation(origin = {-80, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Modelica.Mechanics.MultiBody.Joints.Revolute revolute annotation(Placement(visible = true, transformation(origin = {-41.539, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Modelica.Mechanics.MultiBody.Joints.Prismatic prismatic(s.start = .5) annotation(Placement(visible = true, transformation(origin = {-10, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Modelica.Mechanics.MultiBody.Parts.Body body annotation(Placement(visible = true, transformation(origin = {25, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Modelica.Mechanics.MultiBody.Forces.Spring spring(c = 100, s_unstretched = .5) annotation(Placement(visible = true, transformation(origin = {-10, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
equation
connect(spring.frame_b, prismatic.frame_b) annotation(Line(visible = true, origin = {0, 10}, points = {{0, 10}, {0, -10}}));
connect(spring.frame_a, prismatic.frame_a) annotation(Line(visible = true, origin = {-20, 10}, points = {{0, 10}, {0, -10}}));
connect(prismatic.frame_b, body.frame_a) annotation(Line(visible = true, origin = {7.5, 0}, points = {{-7.5, -0}, {7.5, 0}}));
connect(revolute.frame_b, prismatic.frame_a) annotation(Line(visible = true, origin = {-25.77, 0}, points = {{-5.77, 0}, {5.77, 0}}));
connect(world.frame_b, revolute.frame_a) annotation(Line(visible = true, origin = {-60.77, 0}, points = {{-9.23, 0}, {9.23, 0}}));
annotation(Diagram(coordinateSystem(extent = {{-148.5, -105}, {148.5, 105}}, preserveAspectRatio = true, initialScale = 0.1, grid = {5, 5})));
end pendulum2;