Wear Resistance & Contact Damage Calculator — Wear Risk, Plastic Contact Risk and Material Compatibility
Evaluate wear risk index using contact stress, material hardness, lubrication regime and surface quality.
Enter the known values and review the calculated result
Input parameters
Use consistent values and select the intended engineering units.
Material properties
Contact conditions
Results
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Method, application and limitations
Review the calculation method, intended application and engineering assumptions before using the result in a design decision.
Formula and calculation method
Wear risk index formula:
σy = H / 3
Ucontact = σ / σy
Rplastic = min(Ucontact, 2)
Rwear = Ucontact · kcontact · klubrication · ksurface · kadhesion · kabrasive
Rhardness = H / H2
S = |1 – Rhardness|
Material compatibility score:
- S < 0.1 → compatibility score = 0.25 and kadhesion = 1.5
- 0.1 ≤ S < 0.3 → compatibility score = 0.6 and kadhesion = 1.2
- S ≥ 0.3 → compatibility score = 1.0 and kadhesion = 1.0
Contact factor:
- Sliding contact → kcontact = 1.5
- Mixed contact → kcontact = 1.2
- Rolling contact → kcontact = 0.7
Lubrication factor:
- Dry contact → klubrication = 1.6
- Boundary lubrication → klubrication = 1.25
- Lubricated contact → klubrication = 0.65
Surface factor:
- Rough surface → ksurface = 1.5
- Machined surface → ksurface = 1.1
- Polished surface → ksurface = 0.75
Abrasive factor:
- H / H2 > 2 → kabrasive = 1.3
- H / H2 ≤ 2 → kabrasive = 1.0
where:
- Rwear — wear risk index (-)
- Rplastic — plastic contact risk (-)
- σy — estimated yield strength (Pa)
- H — material hardness (Pa)
- H2 — counter material hardness (Pa)
- E — Young’s modulus (Pa)
- σ — contact stress (Pa)
- Ucontact — contact utilization (-)
- Rhardness — hardness ratio (-)
- S — hardness similarity measure (-)
When to use this calculator
When to use this calculator:
- Assess contact damage risk for a sliding material pair under a defined contact stress.
- Compare dry, boundary and lubricated contact conditions for the same material hardness.
- Check whether contact stress exceeds the elastic contact threshold based on estimated yield strength.
- Evaluate whether similar material hardness may increase adhesive wear tendency.
- Compare polished, machined and rough surface conditions using the wear risk index.
How to interpret the result
Wear risk index is defined as contact utilization corrected by contact type, lubrication regime, surface quality, adhesion tendency and abrasive hardness ratio.
Plastic contact risk is defined as contact utilization limited to a maximum value of 2. Material compatibility score is defined from hardness similarity: very similar hardness gives 0.25, moderately similar hardness gives 0.6 and larger hardness difference gives 1.0.
Increasing contact stress increases plastic contact risk and wear risk index. Increasing material hardness decreases contact utilization because estimated yield strength increases. Dry contact, sliding contact and rough surface increase wear risk index through higher correction factors.
- Safe — plastic contact risk is below 1.0 and wear risk index is not greater than 1.2.
- Warning — plastic contact risk is below 1.0 but wear risk index is greater than 1.2.
- Limit — plastic contact risk is greater than or equal to 1.0 and lower than 1.2.
- Unsafe — plastic contact risk is greater than or equal to 1.2.
- Invalid — one or more required inputs are outside the allowed numeric or selection range.
The result is used to compare contact damage tendency between material pair, contact type, lubrication regime and surface quality combinations.
Calculation example
Example:
A user wants to estimate contact damage risk for a hardened component sliding against a softer counter material in dry contact with a machined surface.
- Material hardness: H = 1,200,000,000 Pa
- Young’s modulus: E = 210,000,000,000 Pa
- Counter material hardness: H2 = 900,000,000 Pa
- Contact stress: σ = 250,000,000 Pa
- Contact type: sliding
- Lubrication regime: dry
- Surface quality: machined
Estimated yield strength is σy = 400,000,000 Pa, contact utilization is 0.625, plastic contact risk is 0.625, hardness ratio is 1.333 and wear risk index is 1.238.
Assumptions and limitations
- Estimated yield strength is calculated as material hardness divided by 3.
- Plastic contact risk is equal to contact utilization and is capped at 2.
- The elastic contact threshold is fixed at contact utilization equal to 0.6.
- Contact type is limited to sliding, rolling and mixed.
- Lubrication regime is limited to dry, boundary and lubricated.
- Surface quality is limited to polished, machined and rough.
- Adhesion factor and material compatibility score are based only on hardness similarity.
- Abrasive factor increases only when material hardness is more than twice counter material hardness.