VALICALC / MECHANICAL ENGINEERING SUITE / DS20
Calculate basic fatigue life from an explicitly entered equivalent load, or from documented per-case radial/axial coefficients. Variable load and speed are weighted by actual revolutions. Arrangement, static capacity, speed and manufacturer-model qualification remain separate checks.
Verified mathematical models with explicit assumptions. Component capacity and applicability are shown as separate checks.
Labeled example inputs • SI calculations • Project revision 0 • No account or cloud upload
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Revolution-weighted equivalent dynamic load
2,987.60316 NMean speed including standstill
1,125 rpmDuty-cycle revolutions
135,000Maximum applicable static load
4,000 NRequired C for entered basic life
26,207.41394 N| Condition | Dynamic P (N) | Static P0 (N) | RPM | Duration (s) | Revolutions |
|---|---|---|---|---|---|
| 1 | 2,000 | 2,000 | 1,500 | 3,600 | 90,000 |
| 2 | 4,000 | 4,000 | 750 | 3,600 | 45,000 |
C and applicable equivalent loads must be documented. Zero revolution/load cases do not establish infinite real bearing life.
Basic static load is checked independently of rotating fatigue; static coefficient applicability remains a user-source requirement.
Use an applicable manufacturer limit under the actual lubrication/temperature conditions; not a universal RPM coefficient.
Nominal diameters only; required fit, clearance, shoulder and mounting remain unverified.
Entered P/P0 must already include the actual applicable radial/axial load model.
Locating/floating or opposed pair is recorded, but axial reaction centers, preload and bearing compliance need a qualified arrangement model.
No verified model catalog or complete lubrication/contamination/reliability dataset. No component is automatically recommended.
p = 3 for balls or 10/3 for rollers; L10 = (C/P)^p million revolutions.
For a repeating spectrum, N_i = n_i t_i/60; P_eq = (ΣP_i^p N_i / ΣN_i)^(1/p). Standstill does not add rotating fatigue damage.
Life in repeating-duty hours includes entered standstill duration. Required C is solved by summing basic revolution damage for the specified life, not by averaging loads/time directly.
Static P0, speed and nominal bore compatibility are independent criteria. No life or load result implies an approved bearing arrangement.
Basic L10 is statistical 90% reliability fatigue life, not actual service life. Lubrication, contamination, minimum load, temperature, fits, seals, preload and misalignment are not established by L10.
Per-case X/Y/X0/Y0 and their switching conditions must come from the exact bearing type/model. The worksheet does not manufacture e-thresholds, axial reaction distribution or pair preload.
No bearing catalog is embedded. Required C is a mathematical criterion, not a model recommendation. Basic radial static P0 = max(Fr, X0Fr+Y0Fa) only applies when that model and coefficients are appropriate.
Two equal-duration cases at 2000 N / 1500 RPM and 4000 N / 750 RPM give a revolution-weighted ball-bearing equivalent load of 2987.603 N. An illustrative documented C = 20 kN would produce 4444.44 basic L10 hours over the repeating spectrum; standstill time contributes no fatigue revolutions.
Basic 90% reliability fatigue model; p = 3 ball, 10/3 roller. Variable conditions are weighted by revolutions, not arithmetic load averages. No modified life or actual service-life warranty.
Only explicitly supplied applicable coefficients; exact model and switching thresholds must be reviewed independently. No axial arrangement/preload inferred.
SKF bearing life and load ratings / product-specific equivalent-load guidance.
Textbook references identify the method context. Historical numerical catalog, material and service-factor tables have not been copied or treated as current product ratings.
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No. The worksheet separates mathematical results from criterion-specific checks. Actual motor, belt, gear, shaft, bearing and joint capacity need applicable current source data and engineering review.
The worksheet recalculates the outputs and geometry from the entered actual dimensions or discrete tooth/link count. Dependent checks are reevaluated; previously saved results are not restored as approvals.