Stress-Strain / Tensile Test Simulator
Pull a virtual specimen of steel, aluminum, copper or a brittle polymer and watch the live stress-strain curve trace through elastic, yielding, necking and fracture.
Pick a material and a specimen cross-section, then pull the specimen with the load slider (or press Auto pull). Watch it stretch and thin at the neck, and see the stress-strain curve trace out live until it fractures.
About the Stress-Strain / Tensile Test Simulator
Free stress-strain / tensile test simulator. Pull a virtual specimen of steel, aluminum, copper or a brittle polymer and watch the live stress-strain curve trace through elastic, yielding, necking and fracture. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for engineering, the stress-strain / tensile test simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Pull a virtual specimen of steel, aluminum, copper or a brittle polymer and watch the live stress-strain curve trace through elastic, yielding, necking and fracture. Use it to explore engineering ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Stress-Strain / Tensile Test Simulator
- Use the controls to change Material, Reference material (faint curve), Cross-section area, Gauge length L₀, Pull (strain). The simulation reacts instantly.
- Pick an option such as Steel, Aluminum, Copper, Acrylic (polymer) to switch modes or load an example.
- Press "Compare a second material", "Auto pull", "Reset / new test" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Pull the acrylic polymer specimen and compare how little it stretches before fracture against steel or copper.
- Use Auto pull on copper and watch how far it necks before it finally breaks — copper is one of the most ductile common engineering metals.
- Increase the cross-section area and note that the stress-strain curve (a material property) does not change, even though the force needed to reach the same stress goes up.
- Reset and pull steel slowly with the manual slider, stopping right at the yield point marker, then continue past it toward the UTS marker.
Key ideas you can learn
- Engineering stress (σ = F / A₀) and engineering strain (ε = ΔL / L₀) are both measured against the specimen's original dimensions, which is why stress appears to drop during necking even though the material is actually getting stronger locally.
- The straight-line elastic region obeys Hooke's law (σ = E·ε); its slope is the elastic modulus E, a measure of stiffness that is completely separate from strength.
- The yield point marks where permanent (plastic) deformation begins — beyond it, the specimen will not return to its original length when unloaded.
- Ductile metals keep gaining strength after yielding (strain hardening) up to the ultimate tensile strength (UTS), then start to neck — thin locally — before fracturing at a lower engineering stress than the UTS.
- Brittle materials show almost no yielding: the curve stays nearly straight right up to a sudden fracture near the UTS, with very little permanent stretch beforehand.
Engineering stress: σ = F / A₀ (load divided by the original cross-section area)
Engineering strain: ε = ΔL / L₀ (elongation divided by the original gauge length)
Elastic region: σ = E·ε (Hooke's law), slope of the straight part of the curve is the elastic modulus E
Yielding & strain hardening: once past the yield point, ductile metals keep taking more stress up to the ultimate tensile strength (UTS) while stretching permanently
Necking: past UTS the cross-section starts to shrink locally; engineering stress (based on the original area) then falls until fracture
Resilience & toughness: both are the area under the stress-strain curve (energy absorbed per unit volume). Resilience is the area up to the yield point (energy recovered if unloaded elastically); toughness is the total area up to fracture (energy absorbed before breaking, including permanent deformation) — shown here in MJ/m³.
Compare materials: turn on the reference curve to overlay a second material's full theoretical stress-strain curve (faint, dashed) on the same axes as the one you're pulling — a quick way to see which is stiffer (steeper slope), stronger (higher peak) or more ductile (stretches further before fracture).
Where this is used in the real world
Tensile testing is the standard way engineers qualify materials for bridges, pressure vessels, aircraft structures, fasteners and medical implants, and it is exactly how the material property tables used in beam, shaft and truss design (elsewhere on this site) are actually measured in a lab.
Who is this simulation for?
Engineering and technology students, makers, robotics clubs and teachers of design and technology. It gives a hands-on feel for how machines behave before you build a real one.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why does the stress-strain curve go down after the peak (UTS) for ductile materials?
After the ultimate tensile strength, deformation localizes into a "neck" — a narrow region that thins faster than the rest of the specimen. The true stress at that neck keeps rising, but engineering stress is calculated using the original cross-section area A₀, which no longer matches the actual (smaller) area carrying the load, so the calculated engineering stress falls even as the material is still working harder locally.
What is the real difference between a ductile and a brittle material on this graph?
A ductile material (like steel, aluminum or copper) yields and stretches a lot — often 10-45% strain — absorbing energy before fracture. A brittle material (like the acrylic polymer here) has very little plastic region: it deforms almost elastically right up until it suddenly fractures, typically at only a few percent strain, giving little warning before failure.
Why do steel and aluminum have such different elastic moduli even though both are metals?
Elastic modulus comes from the strength of atomic bonding and crystal structure, not from alloying for strength. Steel's iron-based structure has stronger, stiffer atomic bonds than aluminum's, giving it roughly triple the elastic modulus (about 200 GPa vs 69 GPa), even though some aluminum alloys can have a similar or higher yield strength than mild steel.
Is the Stress-Strain / Tensile Test Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Stress-Strain / Tensile Test Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.