Overview#
A solved study gives you colored plots. Reading them correctly is a skill. The main tasks are to confirm that the setup was sensible, find the critical locations, quantify margin to failure, and decide what to change.
Always examine results in this order:
- Deformed shape (is it physically plausible?).
- Reaction forces (do they balance the loads?).
- Displacement magnitude (is it reasonable and in the expected direction?).
- Stress and safety factor (where, and how big?).
- Convergence (does it hold up under mesh refinement?).
Where to find it#
- After a solve completes, the results are listed in the Results node of the browser and the Results toolbar becomes available (panels include Result Tools, Compare and Deformation; the Inspect panel holds Reactions, probes and Min/Max).
- Static stress results in the browser: Safety Factor (default), Stress, Displacement, Reactions, Strain, Contact pressure and Contact force. Result types vary by study.
- Fusion has two results viewers. The online viewer (static stress, thermal, thermal stress, modal frequencies, structural buckling, injection molding, electronics cooling) uses Result Settings (settings icon next to the result name) and range sliders on the legend. The standard (legacy) viewer (shape optimization, nonlinear static stress, event simulation) uses a Result selection drop-down and Legend Options. Autodesk says studies are being migrated to the online viewer over time.
Step by step#
- Open the Results for the finished study. Select Displacement and choose Total (or X, Y, Z).
- Check the deformation scale (Results toolbar > Deformation panel). The default Adjusted scale exaggerates deformation (scale factor = 0.5 x bounding box diagonal / maximum displacement); options include Undeformed, Actual, Adjusted 0.5x, 2x and 5x. Nonlinear static and event simulation studies default to Actual.
- Play the animation or switch between Undeformed and the deformed view to verify support behavior.
- Check reactions. On the Results toolbar, click Inspect panel > Reactions, select the constrained vertices, edges or faces, and read the force and moment components and sum. The reactions in a direction should equal the total applied load in that direction with opposite sign.
- Switch to Stress and choose von Mises. Use Min/Max and the Surface Probe or Point Probe to read values at the extremes and at points of interest.
- Switch to Safety Factor. Below 1.0 some failure (permanent deformation or breakage) is predicted. Autodesk says designers frequently strive for a minimum between 1.5 and 6 depending on application, and that it cannot dictate your target. Default thresholds are Lower Target 2.0 and Upper Target 4.0 (red below, green between, blue above).
- Use the Max and Min range-of-interest sliders on the legend (online viewer) to hide values outside a range; data outside the range shows as wireframe. Set the range to the yield strength to see which regions exceed it. In the legacy viewer use Result Tools > Legend Min/Max.
- Use a cutting (slice) plane to inspect results inside the part; planes are stored under the Results node, and Mesh Lines style helps diagnose whether the mesh needs tightening.
- Compare with a refined mesh to confirm convergence.
- Use Compare (Results toolbar > Compare panel) to open up to four studies side by side and see how a design change shifted the result.
Options reference#
| Result | Meaning | Notes |
|---|---|---|
| Stress: von Mises | Effective total stress magnitude, always positive | Basis of the default Yield Strength safety factor |
| Stress: 1st Principal | The most positive principal stress (sigma 1) | Tensile critical; used by the Ultimate Tensile Strength safety factor |
| Stress: 3rd Principal | The most negative principal stress (sigma 3) | Compressive critical; 2nd Principal is the intermediate value |
| Stress: Normal XX/YY/ZZ, Shear XY/YZ/ZX | Stress tensor components | Positive normal stress is tension, negative is compression |
| Displacement: Total, X, Y, Z | How far each point moves from its original position | Includes rigid-body motion, which causes displacement without stress |
| Safety Factor | Strength divided by stress | Yield / von Mises (default) or ultimate / 1st principal |
| Strain: Equivalent, principal, components | Deformation relative to original dimensions | Equivalent is always positive |
| Reactions: Total, X, Y, Z (plus moments) | Force and moment at constrained locations | Individual nodal values depend on the mesh; totals should not |
| Contact pressure and Contact force | Pressure and force across contact interfaces | Computed for all contact types (Bonded, Separation, Rough, Sliding) |
| Min/Max | Labels the location and value of the extremes | Needs valid results |
| Point probe / Surface probe | Reads a value inside the model or on its surface | Point probes are fixed in global coordinates |
For structural buckling in the online viewer, displacement results are normalized and the legend shows no units.
Tips and pitfalls#
Warning: Stress at a singularity (sharp corner, point load, point support) is not a physical answer. Ignore the red dot if it does not converge, and instead evaluate nearby stress or fillet the geometry.
Tip: A contour that stops at the yield value looks fine but may hide that the real part has yielded. Set the upper bound of the legend to yield to see exactly which regions exceed it.
Warning: Safety factor in linear analysis assumes loads scale linearly. For buckling or large deflection, a safety factor of 3 from stress does not mean 3 times margin in load.
Tip: Compare against a hand calculation for at least one scenario (beam bending, axial load). It catches unit errors and sign mistakes.
Tip: Document each result: load, mesh size, element count, material, safety factor, date. You will want it later.
Warning: Stress results are only as good as material data. Printed plastics, castings and welded joints often have properties well below datasheet values.
Practice exercise#
Take the cantilever plate from the static stress practice. Show total displacement and compare with the hand formula. Then set the legend maximum equal to the yield strength of the chosen material and note whether any region exceeds it. Add a second study with double the load and use Compare. Expected result: displacement doubles, stress doubles, safety factor halves, confirming linear behavior.
Worked example: a complete results review#
All numbers in this example are hypothetical, chosen to illustrate the reasoning; they are not Fusion output or Autodesk data. A steel hook (yield 250 MPa) carries 2000 N. Fusion reports: maximum displacement 0.8 mm, reaction force total 2000 N, peak von Mises 310 MPa at the inner curve, minimum safety factor 0.81.
- Reaction check: 2000 N equals the load. Setup is balanced.
- Displacement: 0.8 mm on a 120 mm hook is plausible (0.7 percent of size). The shape opens the hook, as expected.
- Stress: 310 MPa exceeds yield (250), with safety factor 0.81 on the yield criterion. Set the legend maximum to 250 MPa and note that the region above yield covers the inner curve over a length of about 12 mm and about 3 mm deep.
- Is it a singularity? The peak is on a smooth fillet, not a corner, so check convergence: refine to half size locally; if peak stress moves from 310 to 318 MPa (2.6 percent), it has converged.
- Decision: a linear safety factor below 1 means yielding. Either thicken the section by about 12 percent (stress falls roughly with the square for rectangular bending sections, so 1.12^2 = 1.25 reduces 310 to 248 MPa), or run a nonlinear study to see how much of the cross-section actually yields and whether the permanent set matters.
Choosing the right result for each failure mode#
| Failure mode | Result to read | Criterion |
|---|---|---|
| Ductile yielding | Von Mises stress, safety factor (yield) | SF above design minimum |
| Brittle fracture (cast iron, ceramic, glass) | 1st Principal stress, Ultimate Tensile Strength safety factor | Below ultimate / factor |
| Stiffness requirement | Displacement | Below your allowed deflection (a limit such as L / 360 is a general building-practice convention, not Autodesk guidance) |
| Bolt pull-out or gap opening | Contact pressure and reactions | Contact pressure stays positive where the joint should stay closed |
| Compression of thin walls | 3rd Principal stress and a structural buckling study | Buckling multiplier above 1 with margin |
| Thermal limit | Temperature | Below material limit with margin |
| Vibration | Modal frequencies | Natural frequencies away from the excitation frequency (the size of the margin is your own design decision) |
Hand-check formulas#
| Case | Stress or deflection |
|---|---|
| Axial load P, area A | sigma = P / A |
| Cantilever end load F, length L | sigma = 6 F L / (b h^2); delta = F L^3 / (3 E I) |
| Simply supported centre load F, span L | delta = F L^3 / (48 E I); M = F L / 4 |
| Pressure p in a thin cylinder, radius r, wall t | hoop stress = p r / t |
| Torsion of a solid round shaft, torque T, diameter d | tau = 16 T / (pi d^3) |
| Stress concentration (hole in wide plate) | Peak roughly 3 x nominal (classical value) |
For example, a 12 mm solid steel shaft with 20 N m of torque: tau = 16 x 20000 / (3.1416 x 1728) = 58.9 MPa; von Mises = sqrt(3) x 58.9 = 102 MPa.
Probes, sections and paths#
Use at least five probes: the maximum, a nominal-stress location far from features, a point on a fillet, a point at the load and a point at the constraint. Use a section view to see whether peak stress sits at the surface (bending) or through the thickness (shear, contact). If the contour is clipped at yield, reset the range to see actual maxima.
Hidden bodies and legend values#
By default the displayed results and legend range are based on the elements that are visible, so hiding a part changes the minimum and maximum values and the color contours. Use the Exclude Hidden Bodies setting (online viewer) or the Visible only option in the legend settings (legacy viewer) to control whether hidden bodies count. Autodesk also notes that the actual maximum and minimum values are always shown at the ends of the legend, even when you narrow the range of interest. The Number of Colors setting (up to 256) changes the smoothness of the legend, and the threshold slider flags values outside a band in red (above) and blue (below).
Documenting a result#
A one-line record is enough: "Hook v3, steel 250 MPa yield, 2000 N, 1.5 mm mesh at the fillet, 48k elements, peak von Mises 318 MPa, SF 0.79, reaction 2000 N, hand check OK, date." Save a screenshot of the legend with the range set.
Failure modes and fixes#
| Symptom | Cause | Fix |
|---|---|---|
| Most of the model shows as wireframe | Range of interest sliders are narrowed | Reset the Max and Min sliders |
| Deformation looks huge | Default Adjusted deformation scale exaggerates it | Choose Actual deformation in the Deformation panel |
| Stress looks fine but part failed in test | Fatigue, impact, residual stress or weak material | Re-evaluate assumptions; test the material |
| Min and max markers jump between runs | Singularities | Evaluate at fixed probes |
| Safety factor below 1 only in a tiny red patch | Singularity or a local peak that yields harmlessly | Check convergence; consider nonlinear |
| Compare shows no difference | Wrong studies picked, or results are out of date | Verify the studies and result types; re-solve outdated studies |
Practice exercise#
Do a full review of a simple part with predictions first.
- Take a 150 mm steel (E 200 GPa, yield 250 MPa) cantilever of 20 x 10 mm section carrying 80 N at the tip. Predict: sigma = 6 x 80 x 150 / (20 x 100) = 36 MPa; delta = 80 x 150^3 / (3 x 200000 x 1666.7) = 0.27 mm.
- Solve and record displacement, reaction, peak stress and safety factor (expected about 6.9 from 250 / 36).
- Set the legend maximum to 36 MPa and count which regions are above. Probe the root top and bottom faces for opposite signs.
- Repeat at 1/2 mesh and record the change.
- Double the load in a cloned study and use Compare; confirm displacement and stress double and safety factor halves.
Related#
- Static Stress Study
- Mesh Controls
- Loads and Constraints