When setting up a model in static simulations, I often run through the bolt/pin process to create connections that will transfer loads to joining bodies, defining the connection by selecting the appropriate geometry on the holes we are using for the pin/bolt and running the simulation. But what happens when we want to analyze the actual connection itself to verify if the bolt/pin is going to withstand the stress generated by the model conditions? How can we determine whether or not the designed geometry of the bolt, its material, grade and preload will pass or fail? SolidWorks has a very useful tool for defining a pin/bolt check plot to look at just this.
By looking at the axial, bending and shear forces acting on each bolt/pin within the assembly defined through the simulation study, SolidWorks compares this with other parameters (strength and area) to calculate axial, bending and shear load ratios to equate a combined ratio.
The inverse of this sum is then used against the defined factor of safety in the bolt/pin definition to give a pass/fail output.
To take a look at how this tool can be used to determine model geometry and the required bolt, material and grade to use, I have set up a simple assembly with two configurations; 8 mm and 10 mm diameter bolt studies to analyze.
In this particular model, I have multiple bodies being bolted together in series; this must be defined in the advanced option in the bolt property manager. Select the advanced option located in the lower portion of the property manager and select the cylindrical wall of the body/bodies that are in series of the connection (figure 2).
I want to take a look at the check/fail plot for a low carbon SAE Grade 2 8mm bolt series. To do this, I define the bolt connections within the static simulation design tree. Remember, to properly define bolts in a simulation, you must have no penetration set as the contact set between the parts you are connecting. SolidWorks will set your model as globally bonded; this must be redefined in order to properly delineate bolt connections (Figure 3).
Now its time to run the study and take a look at the check plot results for the bolt connectors. Just as you would define a stress plot, right click on the results folder and select ‘Define Pin/Bolt check plot,’ and click the green check mark (Figure 4).
For this particular study, we see that with our defined load and bolt selection, all four connections fail with respect to our predefined FOS of 2 for the 8 mm bolt configuration, giving us a calculated factor of safety of .816 (Figure 5).
After determining that the 8mm bolt configuration is not suitable for our desired factor of safety, I apply the same loads to the 10mm bolt configuration to a duplicate study. Again, we see that the selected material for our bolts will not be sufficient for our FOS.
From here I create a third duplicated study in which I apply a SAE grade 5 cold-drawn 1045 steel bolt to the assembly and run the study. Again, creating a check plot for bolts/pins shows that this is sufficient for my design and highlights the bolts in green to show they are okay for this applied load (Figure 5).
This is just one of the many simple to use tools that Solidworks Simulation has to offer. The pin/bolt check plot is a fast and effective way to verify assembly design before final physical testing, greatly reducing the cost of manufacturing multiple prototypes for physical testing.