Assembling and Analyzing the Complete Model in SolidWorks

Welcome back to the Multibody Dynamics using SolidWorks blog series! In this tutorial, we will assemble the previously modeled components and conduct a motion analysis of the entire system. Starting with SolidWorks, we will perform an assembly using the crank, piston, connecting rod, end caps, and Gudgeon pin, ensuring that the components are properly aligned and constrained.

Step 1: Starting the Assembly

Open SolidWorks and click on “File > New > Assembly.” Begin by importing the crank component. Since the first component in SolidWorks is always fixed, right-click on the crank and set it to “Float” for flexibility in assembly.

Step 2: Constraining the Components

Activate the temporary axis to align components correctly. Start by selecting the crank axis and the right plane to set a coincident mate. Similarly, apply coincident mates between the top plane, axis, and other components. Once the crank is positioned, import the piston, connecting rod, and end caps. Use the control key to select multiple components and import them at once.

Step 3: Connecting Rod and Crank Pin Alignment

Ensure that the connecting rod is aligned properly by selecting the axis of the crank pin and the rod’s axis. Use the “Coincident” mate. Afterward, apply a distance mate between the rod and crank, typing in a value of 1 mm to maintain a small space between them.

Step 4: Fixing Design Details

During assembly, you might notice that some parts need adjustments. In this case, we needed to refine the fillet of the connecting rod. By right-clicking the part and selecting “Open Part,” you can quickly apply fillet operations. Set a fillet radius of 2.7 mm on the connecting rod’s edges and apply it to the necessary locations.

Step 5: Inserting the Gudgeon Pin and Piston

Now insert the Gudgeon pin into the piston. Use the coincident mate for their axes to ensure proper alignment. If the piston moves incorrectly, select the front plane of both components and use another coincident mate to lock them together.

Step 6: Setting Additional Constraints

To avoid unwanted motion, we’ll add constraints to the Piston and Gudgeon pin. Select their respective planes and apply coincident mates to ensure the piston moves only along its axis. Similarly, add mates between the connecting rod and the piston.

Step 7: Preparing for Motion Analysis

Once the assembly is complete, we can proceed with the motion analysis. Make sure the SolidWorks Motion Add-in is activated. Next, add a motor to the crank axis and set it to rotate at 1,200 RPM. For accuracy, adjust the frame rate to 7,200 frames per second, ensuring precise calculation.

Step 8: Establishing Contacts and Gravity

For the simulation to be accurate, establish contacts between components such as the crank, end caps, connecting rod, Gudgeon pin, and piston. Set the material type to “Steel Dry” for each contact. Finally, enable gravity and set it to act along the Y-axis.

Step 9: Running the Motion Analysis

With the assembly and contacts ready, run the simulation. Since we’re calculating a high number of frames per second, the analysis will take some time. Afterward, you’ll observe smooth motion of the crank, connecting rod, and piston.

Step 10: Analyzing Results

Once the motion analysis completes, plot the linear displacement of the piston. This plot should display a smooth curve, indicating proper motion. Additionally, check the angular velocity of the crank to verify it’s rotating at the intended 7,200 degrees per second. Lastly, export the results into a spreadsheet for further analysis.

Conclusion

By following these steps, you can successfully assemble, simulate, and analyze a complex mechanical system in SolidWorks. This process is essential in understanding the dynamics of systems like a crankshaft and piston assembly, and it provides invaluable insight into multibody dynamics using SolidWorks.

Explore more about multibody dynamics courses, SolidWorks tutorials, and SolidWorks certification programs at Skill-Lync to enhance your proficiency in mechanical engineering simulations.

This blog is part of our ongoing series on Multibody Dynamics.

If you missed the previous posts, check them out here.

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