Analyze pressure loading with Poisson response in seconds. Enter modulus, ratio, and starting dimensions easily. See strains, changes, and exports for clear engineering reports.
Under uniaxial loading, the axial strain depends on stress and modulus:
εa = σ / E
Poisson effect links transverse strain to axial strain:
εl = −ν εa
For small strains, volumetric strain is approximated as: εv ≈ εa + 2εl.
| σ (MPa) | E (GPa) | ν | εa (με) | εl (με) | ΔL for L0=1000 mm | ΔT for T0=20 mm |
|---|---|---|---|---|---|---|
| 50 | 200.0 | 0.30 | 250 | -75 | 0.2500 mm | -0.0015 mm |
| 80 | 70.0 | 0.33 | 1,143 | -377 | 1.1429 mm | -0.0075 mm |
| 120 | 110.0 | 0.28 | 1,091 | -305 | 1.0909 mm | -0.0061 mm |
| 30 | 3.2 | 0.38 | 9,375 | -3,563 | 9.3750 mm | -0.0713 mm |
| 10 | 1.5 | 0.45 | 6,667 | -3,000 | 6.6667 mm | -0.0600 mm |
Table uses microstrain for readability and small-strain assumptions.
When a solid is pushed or pulled, it rarely deforms in only one direction. The Poisson effect captures the coupled lateral change that accompanies axial strain. Under pressure-driven loading, engineers use it to estimate diameter reduction, thickness growth, and volume change. This calculator connects applied stress, Young’s modulus, and Poisson ratio into practical strain outputs. It reports axial strain, lateral strain, and an approximate volumetric strain for quick screening.
Poisson ratio ν describes how strongly a material contracts sideways when stretched. Metals often fall near 0.25–0.35, while polymers can approach 0.45. A higher ν increases lateral strain magnitude, which is critical for seals, press-fit joints, and thin-walled members.
Pressure and uniaxial stress share identical units, so the tool accepts Pa, kPa, MPa, GPa, and psi. If you work from test hardware, the force-area mode converts force and cross-section into stress using σ = F/A. This helps unify lab data with design calculations.
Young’s modulus sets stiffness and governs axial strain via εa = σ/E. Typical values are about 200 GPa for steels, 70 GPa for aluminum alloys, 110 GPa for many titanium alloys, and roughly 1–5 GPa for common plastics. Selecting the correct modulus prevents overestimating deformation under the same pressure.
Strain is dimensionless and often reported as microstrain (με) for readability. For example, 50 MPa applied to steel (E ≈ 200 GPa) gives εa ≈ 250 με. That corresponds to only 0.25 mm change over a 1 m gauge length.
Lateral strain is computed as εl = −ν εa. If ν = 0.30 and εa = 250 με, then εl ≈ −75 με. On a 20 mm diameter rod, that predicts a diameter change near −0.0015 mm, which can still matter for precision fits.
The volumetric strain approximation εv ≈ εa + 2εl is useful for quick checks. It assumes strains are small and linear elastic behavior holds. For larger strains, anisotropy, plasticity, or nonlinear elasticity can dominate, so treat εv as an initial estimate rather than a final compliance value.
A consistent workflow is: choose the input mode, confirm units, compute strains, then add dimensions to get ΔL and ΔT. Use the CSV download for spreadsheets and QA logs. Use the PDF export for design reviews, lab notebooks, and compliance documentation.
Q1: Is “pressure” the same as “stress” in this calculator?
Yes. Both use force per area. Enter pressure when loading acts uniformly, or stress when it represents uniaxial loading. Units and math remain identical here.
Q2: What Poisson ratio should I use for metals?
Many steels and aluminum alloys sit around 0.25–0.35. If you have a datasheet value, use it. Otherwise, 0.30 is a reasonable starting point for quick checks.
Q3: Why is lateral strain negative during tension?
Under tension, most materials contract laterally, so εl is negative while εa is positive. The minus sign in εl = −ν εa enforces that physical behavior.
Q4: Can I use this for compression?
Yes. Enter a negative stress for compression. Axial strain becomes negative, and lateral strain becomes positive, indicating lateral expansion during compressive loading.
Q5: When is the volumetric strain estimate unreliable?
It is less reliable for large strains, plastic deformation, foams, and strongly nonlinear materials. It also assumes isotropic linear elasticity and small deformations.
Q6: Do I need to enter dimensions?
No. Strains are computed without dimensions. Add L0 and T0 only if you want ΔL and ΔT in a chosen length unit.
Q7: What is a typical strain level for elastic design?
Many designs aim to keep elastic strains in the hundreds to a few thousand microstrain, depending on material limits and safety factors. Always validate with your applicable code or test data.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.