In this video, learn about the implications of the loading and boundary conditions available in SOLIDWORKS Simulation.
- [Instructor] We'll now review the loads and boundary conditions that are going to be applied to the model. There are two sets of loading actions to be applied to the model, one for the compressive case and one for the axial case. In both cases, the loads are applied at the little end. Let's select the little end view. Compressive case is going to be spread over the 120 degrees arc using the two surfaces highlighted here. We use the endpoints of the fillet runout rather than exactly 120 degrees.
This is a reasonable approximation. The applied force will be correct, but the area will be slightly less than the conventional method. The pressure will be a fraction higher. The pressure will be a constant pressure distribution acting normal to these surfaces. The tensile load will be applied to the opposite pair of faces, selected here. The surface distribution is now over 120 degrees, but it will vary as a sinusoidal distribution about the horizontal axis.
This is a standard engineering assumption when applying a tensile load to a lug-type feature. Now SolidWorks has a specific form of loading which can handle this type of distribution. It's called a bearing load, and we'll see that later. Let's go back to our standard view. For both load cases, we're going to constrain the model at the big end. Now, to be realistic, we should have a different constraint system for each load case. The tensile case will react against the right-hand face of the big end.
The compressive case will react against the left-hand side of the big end. We're going to use a fixed constraint over the complete 360 degrees inside of the inner face on these surfaces here. This is effectively super-gluing the big end down to a rigid crank. It is not a realistic load path. This means that we will have to ignore stresses local to the big end, and our analysis is really only valid for the little end and for the shaft to the conrod.
On a full project analysis, I would calculate and apply the reaction forces at the big end as equivalent pressure distributions. That puts the model in the load balance for the two load cases, but then we would still have to apply constraints, to stop the model flying around in space. There are two ways to do that. We can apply a minimum constraint set of exactly 60 degrees of freedom, and that's called the three-two-one method. Alternatively, we can apply inertia relief. These methods are outside the scope of this course.
We will stick to fixing the big end constraint fully. So in conclusion, we've seen how we're going to apply the loads and boundary condition strategy. The limitation of the method we've chosen means that the stresses around the big end are not going to be realistic. However, we will be able to predict stresses at the little end and at the conrod shaft.
- Setting up Simulation properties and defined views
- Preparing the geometry
- Setting up a local coordinate system
- Splitting surfaces
- Defining the constraint and the loads
- Running analysis
- Contour control
- XY plots