Understanding and Applying Moment Loads in Abaqus | Abaqus torque load

1. What is the moment load? | torque loading

A moment of force, also commonly called torque, is a twisting force that can cause an object to rotate. It’s not the force itself, but rather the tendency of that force to cause rotation around a fixed point.

Here’s how it works:

Imagine a seesaw: The force you apply (your weight) and the distance you sit from the center (pivot point) determine how much the seesaw will rotate. A larger force or a greater distance from the center will create a larger moment, making the seesaw tilt more easily.

Mathematically: The moment of force is calculated by multiplying the force by the perpendicular distance from the pivot point to the line of action of the force.

The concept of moments is important in many areas of physics and engineering,  from understanding how levers work to analyzing the forces on a bolt being tightened with a wrench.

2. How to apply torque load in Abaqus?

As you may know, elements like continuum (solid) have no rotational degree of freedom. Therefore, you cannot apply moments nor rotations directly when using them. Then, the only way to apply torque is through a coupling constraint. You have to put a moment on a reference point and connect this point with the points on your structure.

Kinematic coupling constrains the motion of the coupling nodes to the rigid body motion of the reference node. The constraint can be applied to user-specified degrees of freedom at the coupling nodes with respect to the global or a local coordinate system.

Abaqus torque load

1. [In any module before Mesh] create a reference point (named as RP in Abaqus)

2. [In Interaction Module] define a coupling constraint:

Create Constraint > Type=Coupling > select RP as your constraint control point > select either Node Region or Surface (depending on your model) > Coupling Type=Kinematic

3. Apply your torque (moment) or rotational BC to defined RP

Also, there is a Tie constraint in the figure above; what is the difference between Tie and coupling? and wait, there is a Rigid body constraint as well. what is the difference between these three, huh? You can get your answers in the Lesson One of the Abaqus Free course.

Have you started simulation in Abaqus recently? I recommend you download these free tutorials here!  FREE ABAQUS TUTORIAL  

1. If you are using Abaqus/Explicit as solver (Steps like Dynamic, Explicit), you MUST assign Inertia to your RP avoid facing Error in job submission. In Properties module, in Menu Bar, select Special > Inertia > Create.

It would be helpful to see Abaqus Documentation to understand how it would be hard to start an Abaqus simulation without any Abaqus tutorial.

One note, when you are simulating in Abaqus, be careful with the units of values you insert in Abaqus. Yes! Abaqus don’t have units but the values you enter must have consistent units. You can learn more about the system of units in Abaqus.

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About Matt Veidth

Matt Veidth is a highly accomplished mechanical engineer with an impressive career spanning over 15 years. Renowned for his expertise in the field, Matt has become a driving force in the world of engineering education as a key member of a leading training website company. With a deep-rooted passion for finite element software, Matt has dedicated his career to mastering its intricacies and empowering others to do the same. Through his meticulously designed courses, he imparts his extensive knowledge and real-world experience to aspiring engineers, equipping them with the skills needed to excel in their professional journeys.

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