projects / 14

Balsa Wood Truss Bridge — Mechanics of Deformable Solids

course MTE 219 (MODS) institution University of Waterloo simulation SolidWorks FEA analysis Method of Joints & Sections

Culminating structural design and optimization project for MTE 219: Mechanics of Deformable Solids at the University of Waterloo. Engineered an ultra-lightweight balsa wood truss bridge designed to maximize payload-to-weight structural efficiency under center-point loading. Combined analytical method-of-joints force calculations with SolidWorks FEA simulations using orthotropic balsa material properties to resolve axial tensions, compressions, and Euler buckling limits across each link.

Analytical Truss Equilibrium: Resolved exact member force distributions (tension vs. compression) across 3D pin-connected nodes using the Method of Joints and Sections.
SolidWorks FEA Simulation: Configured static displacement and stress finite element analyses under 32.5 N load with deformation scaling up to 112× to validate flexural stiffness.
Buckling & Link Sizing: Tailored individual member cross-sections, reinforcing compressive top chords against out-of-plane buckling while optimizing tension diagonals.
Destructive Physical Testing: Evaluated the assembled bridge on a laboratory load fixture with suspended deadweights, confirming high payload-to-mass performance.

Lab Testing · Destructive Center Load Fixture

Balsa Truss Bridge Under Ultimate Payload Center Load Test

SolidWorks CAD · Parametric 3D Truss Assembly

SolidWorks 3D Parametric Balsa Truss Bridge Assembly Model

Physical Load Testing & 3D Assembly CAD — Experimental load testing on custom center-point fixture alongside the 40 cm parametric SolidWorks bridge assembly.

01Mechanical Design & Parametric Truss Geometry

Modeled a 40.0 cm span, 10.0 cm tall Warren/Pratt hybrid truss in SolidWorks with lateral cross-bracing and transverse deck beams.
Parametric individual link architecture: engineered eye ends with Ø0.30 cm pin holes and Ø1.52 cm outer margins to prevent joint tear-out shear.
Calculated Method of Joints and Method of Sections force equilibriums to dictate cross-sectional thickness (0.33 cm) and member widths.

Full Bridge CAD · Dimensioned Isometric

SolidWorks dimensioned bridge assembly showing span, height, and width

Parametric Member CAD · Pin Joint Link

Parametric link member drawing with pin hole diameter and width callouts

3D Truss Topology & Member Detailing — Complete assembly envelope dimensions (40 cm × 8.5 cm × 10 cm) and single-link parametric geometry.

02SolidWorks FEA Simulation & Structural Optimization

Configured static displacement and stress finite element studies in SolidWorks Simulation applying 32.5 N test loads across central node fixtures.
Evaluated resultant displacement heatmaps (URES contour) across design iterations with deformation scales up to 112× to identify flexure hot spots.
Optimized compression top chords against Euler buckling while slimming pure tension diagonals to maximize strength-to-weight ratio.

FEA Study · Truss Bridge v3 Static Displacement

SolidWorks Simulation static displacement plot of Truss Bridge v3

Full Assembly Static FEA Simulation — Resultant displacement plot under 32.5 N center point load (deformation scale 51.87×, peak deflection 0.79 mm).

Comparative Study · Ladder Truss

FEA static displacement analysis of ladder truss design

Comparative Study · Thin Truss v3

FEA static displacement analysis of thin truss iteration

Structural Topology Iterations — Comparative finite element analyses evaluating Ladder Truss vs. Thin Truss Design 3 under simulated loads.

03Fabrication & Destructive Load Testing

Precision fabricated structural balsa members with drilled pin joints to eliminate eccentricity and ensure uniform load sharing.
Conducted destructive load test on laboratory fixture, supporting suspended deadweight stack to determine maximum payload.
Correlated physical deflection against FEA simulation predictions, demonstrating high structural efficiency in MTE 219.

Laboratory Load Test · Center-Point Deadweight

Balsa bridge supporting suspended weights on lab testing rig

Physical Failure & Deflection Testing — Physical bridge loaded on rigid upright supports with suspended deadweight stack to determine ultimate load capacity.