Optimise Wing Rib Spacing with FEA
Place ribs where the loads are—not where tradition says.
Last reviewed: March 2026Overview
In conventional aircraft wing design, internal ribs are typically spaced at equal intervals along the span. But the loads on a wing are anything but uniform—the root carries far more bending moment and shear than the tip. This raises a compelling question: what if you placed ribs closer together near the root, where loads are highest, and farther apart near the tip, where loads are lower? Could you achieve the same structural performance with fewer ribs, saving weight?
This project tackles that question using a simulation-driven approach. You will design a simplified wing box in SolidWorks, export it to ANSYS for structural analysis, and compare at least three rib layouts: a baseline with uniform spacing, a root-biased layout with ribs clustered toward the root, and a tip-biased layout (as a control). By examining von Mises stress distributions, tip deflection, and total structural mass, you will build an evidence-based argument for or against non-uniform rib spacing.
This type of structural optimisation thinking is exactly what aerospace companies do during preliminary design. Engineers at Airbus and Boeing routinely use FEA to question inherited design rules and find lighter solutions. Your investigation mirrors real trade studies performed on transport aircraft wing boxes—the only difference is scale and complexity. The workflow of hypothesise → model → simulate → compare → conclude is the core of engineering research, and this project gives you practice with every step.
What You'll Learn
- ✓ Design a simplified wing box structure with spars, ribs, and skin in SolidWorks.
- ✓ Set up a static structural FEA in ANSYS with realistic boundary conditions and aerodynamic load approximations.
- ✓ Compare multiple structural configurations systematically using quantitative metrics (stress, deflection, mass).
- ✓ Interpret von Mises stress contour plots and identify critical load paths in a wing structure.
- ✓ Present engineering trade-study results with clear data visualisation and defensible conclusions.
Step-by-Step Guide
Design the baseline wing box in SolidWorks
Create a rectangular wing box representing a simplified semi-span wing: 1 metre span, 250 mm chord, with a front spar and rear spar (both 2 mm aluminium sheet, full chord height of 30 mm). Add a top and bottom skin (1.5 mm aluminium sheet). For the baseline, insert 5 equally spaced ribs along the span at 200 mm intervals, each 1.5 mm thick. Use Al 6061-T6 for all components (yield strength 276 MPa, E = 68.9 GPa). Save the assembly and also save a copy—you will modify the rib positions in later variants.
Set up the ANSYS structural simulation
Import the SolidWorks assembly into ANSYS Mechanical (the free student version works well for this model size). Assign the aluminium material properties. Fix the root face of both spars and the root skin edges—this represents the wing attaching to the fuselage. Apply a distributed pressure load on the bottom skin to represent lift: for a 1,000 N total lift load on this semi-span, apply a spanwise-varying pressure that is highest at the root and tapers linearly to 50% at the tip. This approximates an elliptical lift distribution. Mesh with shell elements (SHELL181) at 5 mm element size and run a mesh convergence check by also trying 3 mm.
Run the baseline simulation and record results
Solve the static structural analysis. In the results, plot von Mises stress on the deformed shape and note the maximum stress location (it should be near the root, on the spar caps or skin). Record three key metrics: (1) maximum von Mises stress in MPa, (2) maximum tip deflection in mm, and (3) total structural mass from the SolidWorks mass properties. Also examine the stress in each rib individually—you should see that the root ribs carry significantly more stress than the tip ribs. Screenshot the stress contour and save the numerical results in a spreadsheet.
Design the root-biased rib layout
Go back to SolidWorks and create a new variant. Keep the same 5 ribs but redistribute them: place 3 ribs in the root half of the span (at approximately 80, 180, and 300 mm from the root) and 2 ribs in the outer half (at 500 and 750 mm). The idea is to reinforce the high-load region with closely spaced ribs while accepting wider spacing where loads are lower. Keep all rib thicknesses the same (1.5 mm) so the mass comparison is purely about positioning. Import this variant into ANSYS with identical loads, boundary conditions, and mesh settings, then solve.
Create additional variants and compare
Create at least one more variant: a tip-biased layout (3 ribs in the outer half, 2 near the root) as a negative control—you expect this to perform worse. Optionally, try a layout where you also vary rib thickness: thicker ribs (2 mm) near the root and thinner ribs (1 mm) near the tip, keeping total rib mass roughly constant. Run all variants through ANSYS with identical conditions. Build a comparison table with columns for variant name, rib positions, max stress, max deflection, total mass, and safety factor (yield / max stress). Create bar charts comparing these metrics across designs.
Analyse results and draw conclusions
Write up your findings as a short research report. Key questions to address: Did root-biased spacing reduce maximum stress compared to uniform spacing? By how much? Did tip deflection increase, decrease, or stay the same? Is there a weight saving if you can remove a rib from the tip region without exceeding stress limits? Discuss the trade-off: closer root spacing may reduce peak stress but increased tip spacing may increase local skin buckling risk. Acknowledge limitations of your simplified model (no buckling analysis, linear material, simplified loads) and suggest what a more advanced study would add. Include your stress contour screenshots and comparison charts.
Career Connection
See how this project connects to real aerospace careers.
Aerospace Engineer →
Structural sizing of wing internals is a core task for stress engineers at every airframe OEM; the trade-study methodology you practise here—comparing rib layouts against quantitative metrics—is exactly how preliminary design decisions are made on real aircraft programmes.
Aerospace Manufacturing →
Non-uniform rib spacing affects manufacturing complexity—jigs, tooling, and assembly sequences change when ribs are not evenly spaced. Manufacturing engineers must weigh structural benefits against production cost, and understanding the structural side of that trade-off is essential.
Aviation Maintenance →
Maintenance inspectors need to know where the highest-stressed structural members are located to prioritise inspections; understanding how rib spacing relates to load distribution directly informs inspection planning.
Drone & UAV Ops →
Small UAV designers face extreme weight pressure and often use non-uniform internal structure to save grams; the FEA-driven design approach in this project applies directly to lightweight UAV airframe optimisation.
Go Further
- Add buckling analysis — run a linear buckling (eigenvalue) analysis on each variant to check whether the wider rib spacing near the tip causes skin panels to buckle before yielding, and determine the critical panel width.
- Vary rib thickness with spacing — implement a design where both spacing and thickness vary along the span, keeping total structural mass constant, and check whether this combined approach outperforms spacing changes alone.
- Automate with Python scripting — use ANSYS PyMAPDL or ANSYS Workbench scripting to parametrically generate dozens of rib layouts and plot a response surface of stress vs. deflection vs. mass across the full design space.
- Compare to topology optimisation — run ANSYS topology optimisation on the wing box interior and see whether the algorithm naturally places more material near the root, validating your hypothesis from a different angle.