Designing suspension parts in SolidWorks requires a solid understanding of both the software's capabilities and real-world suspension geometry. Whether you're designing a control arm, a coil spring, or a sway bar link, the process involves precise 3D modeling, motion simulation, and stress analysis. This guide walks through the essential techniques and best practices for creating functional, manufacturable suspension components in SolidWorks.
Understanding Suspension Geometry in SolidWorks
Before opening SolidWorks, it's critical to define the suspension geometry. This includes mounting points, travel limits, and linkage lengths. A clear sketch or CAD layout of the overall suspension system helps ensure parts will work together. In SolidWorks, use top-down assembly modeling to reference key points: create a skeleton sketch of the chassis and wheel locations, then build individual parts relative to that skeleton.
Key Design Features for Control Arms, Springs, and Links
- Control Arms: Typically A-arms or trailing arms. Model them as welded tube or stamped steel structures. Use weldments (structural members) for tubular arms, or sheet metal features for stamped designs. Include bushings or ball joint pockets as separate bodies.
- Coil Springs: Use helical sweep features. Define spring parameters such as wire diameter, coil diameter, free length, and number of active coils. For realistic simulation, create a simplified coil model using a sweep along a helix.
- Sway Bars: Modeled as bent tubes. Use 3D sketches and sweep features. Include end links as separate components for easier assembly.
- Bushings: Represent as cylindrical bodies with appropriate material properties for later simulation.
Step-by-Step Modeling of a Control Arm
- Create a new part and define a datum plane representing the chassis mount points.
- Sketch the arm profile in a top or side view. Include the ball joint center and bushing centers.
- Use the Sweep or Weldment feature to create the arm body. For tubular arms, use 'Structural Member' with a circular tube profile.
- Add mounting holes using hole wizard. Ensure hole patterns match standard fasteners (e.g., M12 or 1/2" bolts).
- Add bushings as separate parts, then assemble them using concentric mates. Alternatively, model bushing pockets as cut features on the arm.
- Apply fillets to reduce stress concentrations. Consider using SolidWorks Simulation later to optimize fillet radii.
- Save and build an assembly with wheel hub, chassis frame, and the control arm. Use mates to define actual pivot axes.
Simulating Suspension Movements with SolidWorks Motion
SolidWorks Motion (available in Premium or via add-in) allows you to simulate suspension travel. Start by defining joints: revolute joints for ball joints and bushings, translational joints for shock absorbers. Apply a vertical force at the wheel center to simulate bump travel. Use Motion to generate plots of displacement, velocity, and acceleration, which help validate geometry and detect interference.
- Bump and Rebound: Define a sine wave input at the wheel to see full travel.
- Roll Center Analysis: Not directly available but can be inferred by tracking instant centers of the suspension links.
- Interference Detection: Run motion and let SolidWorks flag contact between components.
Using SolidWorks Simulation for Stress Analysis
Once the geometry is set, perform finite element analysis (FEA) to ensure the part can handle loads. Important steps:
- Apply fixtures: Simulate bushings as fixed or with appropriate stiffness (use spring connectors).
- Apply loads: Typical loads include vehicle weight (static load factor) and impact loads (2-3x static). Include lateral loads for cornering.
- Mesh: Use a mix of solid and shell mesh depending on part complexity. Refine mesh around small features like fillets.
- Analyze results: Check von Mises stress against material yield strength. Look for safety factors of 1.5 minimum for fatigue.
- Optimize: Modify thickness, tube diameter, or gusset placement to reduce weight while maintaining strength.
For welded assemblies, use weld bead simulations or treat as bonded contacts. SolidWorks Simulation cannot easily model weld fatigue, but it provides a good starting point.
Best Practices for Suspension Part Design
- Use Configurations: Create different versions (e.g., left vs. right control arms) using mirror configurations or design table.
- Standardize Hardware: Use Toolbox bolts and nuts to speed up assembly and ensure correct thread data.
- Reference Geometry: Use global variables and equations for key suspension dimensions. This makes it easy to adjust track width or ride height.
- Check for Interference: Perform full travel motion analysis before finalizing.
- Consider Manufacturing: Avoid sharp inside corners; use constant wall thickness for stamped parts; design for weld accessibility.
- Document: Add GD&T (Geometric Dimensioning and Tolerancing) in drawings using DimXpert.
Final Recommendation
For engineers making suspension parts in SolidWorks, focus on a top-down assembly approach with a skeleton sketch to define hardpoints. Use weldments for tubular arms and sheet metal for stamped parts. Leverage SolidWorks Motion to validate travel and detect interference early, and SolidWorks Simulation to verify strength. Keep designs modular: separate bushings, ball joints, and springs as distinct parts for easier swaps and updates. Avoid over-complicating models; a well-planned simple design often outperforms one with excessive detail. Invest time in creating parametric relations so that future revisions are quick. If you are new to suspension design, start with a simple double-wishbone mockup and gradually add complexity. SolidWorks is a powerful tool when combined with sound engineering judgment.