How to Use RFORCE Load Collector

 

1. RFORCE bulk data

It Defines a static loading condition due to a centrifugal force field.

• SID refers to ID of Load collector.
• G defines node through which rotation vector acts.
• CID refers to global Cartesian coordinate system.
• A is rotational velocity in revolutions per unit time.
• R1, R2, R3 defines Rectangular components of rotation direction vector i.e. it defines rotation axis. The vector defined will pass through point G.
• RACC is Scale factor of the rotational acceleration in revolutions per unit time squared. The continuation line containing RACC is optional.
• IDFR is Set Identification Number of an element set (SET bulk data entry) to which this RFORCE entry applies. This field can be used to define different Rotational forces to different parts of the model.

2.Boundary Conditions

A circular disc is applied with angular velocity of 3000 rpm and centrifugal force is calculated as an output.

Parameters of circular disc:

• Outer radius= 15mm
• Inner radius= 1mm
• Thickness= 2mm

Material used: Steel

Cartesian coordinate system.

Translational DOFs are constrained.

3.Steps to follow

3.1 Create Cylindrical Coordinate System

1. Go to Analysis page > Systems > Create by node reference sub panel.
2. Select type as Cylindrical.
3. Select Origin node > Select node to define Z axis > Select node to define X axis.
4. Click on Create.

 Now this Newly created system must be assigned to all nodes of the model.

5. Select assign sub panel.
6. Select all nodes.
7. Select created cylindrical system.
8. Click on set displacement.

3.2 Create RFORCE Load Collector

1. Create new load collector for Rotational Force.
2. Select Card Image as RFORCE.
3. G defines node through which rotation vector acts. Select the node.
4. CID refers to global Cartesian coordinate system. Select the cylindrical system which you have created.
5. A is rotational velocity in revolutions per unit time. Enter value as 50.
6. R1, R2, R3 defines rotation axis, here Z axis is the shaft axis for Global as well as user defined system.

3.3 Create Load Step

1. Create new Load step and select Analysis type.
2. Select SPC load collector under SPC.
3. Select RFORCE load collector under LOAD.
4. Run the Analysis.

4. Results for Applied force (Centrifugal Force).

5. Validation of result

• For nodal mass (m) calculation,

                                                                =1.02e-04 kg

• Radial distance for node 285 from the center of disc (r) = 13e-3 m
• Angular velocity (w) = 314.16 rad/sec

Therefore,

Centrifugal force at node 285 = m*r*w²

                                             = 0.131 N