Fatigue testing is the laboratory method used to predict how a metal, spring, fastener, rubber or composite part behaves under repeated loading — the data engineers need to verify design life, set inspection intervals, and qualify suppliers before parts go into service. This page covers what fatigue tests measure, which test type fits which application, and the failure modes the machine has to expose. For a side-by-side of machine types, specifications and selection criteria, see our Fatigue Testing Machines: Types & How to Choose guide.

What fatigue testing actually measures

Every fatigue test on a CHENJI machine records load cycles (N), peak/valley stress or force (σ / F), and strain or displacement until a defined end-point is reached. The end-point is what separates one test method from another:

• High-cycle fatigue (HCF) — typically 10⁵–10⁷ cycles at 1–100 Hz; failure is initiated at a surface or sub-surface defect. Standards include ASTM E466 (force-controlled) and ISO 1099 (strain-controlled axial).
• Low-cycle fatigue (LCF) — <10⁵ cycles with measurable plastic strain; governed by ASTM E606 / ISO 12106.
• Thermo-mechanical fatigue (TMF) — superimposed thermal and mechanical cycles up to 1200 °C; for hot-section components.
• Rotating-beam fatigue — constant bending stress on a spinning specimen (e.g. CHENJI NZW-20 Nm); classic for spring-wire and fastener-wire qualification.
• Resonance fatigue — operates at the specimen’s natural frequency (typically 75–100 Hz on our machines) with very low energy input; the workhorse for high-cycle spring testing.

The ASTM E4 / ISO 7500-1 calibration classes in our fatigue machine guide define the load-cell accuracy you can trust across those cycles — typically Class 1 (±0.5% of indicated load) for the electro-hydraulic and electronic frames we ship.

Choosing a fatigue machine by application

Match the drive principle to the cycle count you need and the stiffness of the specimen:

Source: application ranges and force envelopes come from the existing Fatigue Testing Machines guide and the product cards in the Products in This Series block below. Where a number above is not directly shown on our own product page, it is marked [to-confirm].

Common failure modes the test should expose

A fatigue machine is only useful if the failure mode it produces matches what the part sees in service. The four modes our customers look for, and the cycle range where each one dominates:

• Fatigue crack initiation at inclusions, surface scratches or decarburised layers (HCF, >10⁵ cycles) — resolved by fracture-mechanics-based life prediction.
• Crack propagation under constant-amplitude or overload blocks — captured with Paris-law da/dN vs ΔK curves on servo-hydraulic frames.
• Creep-fatigue interaction at temperatures above ~0.4 T_m — the reason the high-temperature furnace option exists for our 10–100 kN frames.
• Loosening / settlement under vibration for fasteners and threaded joints — tested on the TPJ-W10 shock-absorber / pre-loaded spring setup.

Specifications that matter for procurement

• Load frame capacity — 1 kN to 3000 kN across the CHENJI EDT, electro-hydraulic and resonance series (see Products in This Series below).
• Frequency range — 1–100 Hz on most frames; the resonance machines hold 75–100 Hz with ±0.001 mm displacement amplitude stability.
• Stroke — typically 70–100 mm on electronic frames, 100 mm on the TPJ spring testers.
• Grips, fixtures, furnaces — quoted per application; high-temperature furnaces reach 1200 °C continuous, 1600 °C short-time.
• Calibration class — ISO 7500-1 / ASTM E4 Class 1 on every load cell we ship.

For full numbers, drawings and lead times, request a quotation via the form below or email annie@chenjitester.com.

Frequently asked questions

The following questions cover what engineering teams most often ask before issuing an RFQ. Standards referenced below are the same ones used in the product datasheets linked from this page.

• What standards cover fatigue testing? — ASTM E466 / ISO 1099 for force- and strain-controlled axial HCF; ASTM E606 / ISO 12106 for LCF; ISO 7800 for rotating-beam wire tests; ISO 7500-1 / ASTM E4 for load-cell calibration.
• What test frequency do your fatigue machines run at? — 1–100 Hz on electronic and servo-hydraulic frames; the resonance testers hold 75–100 Hz at low drive power.
• How do I choose between a static and a fatigue testing machine? — Use a static (universal) tester for tensile / compression proof loads and one-cycle stress-strain data; use a fatigue tester when the design life has to be qualified against >10⁴–10⁷ cycles.
• Can the machines test springs, bolts and automotive parts? — Yes — the TPJ / TNS series is dedicated to springs (mechanical, 10–30 kN), the electro-hydraulic frames cover M10–M36 bolts and automotive components.
• Do you supply load-calibration and traceability? — Every CHENJI frame ships with an ISO 7500-1 / ASTM E4 calibration certificate traceable to national standards.
• Can fatigue testing be done at high temperature? — Yes — furnace options cover ambient to 1200 °C continuous and 1600 °C short-time, mounted on the 10–100 kN servo-hydraulic frames.
• What is the MOQ and lead time? — 1 unit MOQ; standard lead time 30–45 working days ex-works China for catalogue models, longer for custom furnaces and fixtures.
• Where do you export, and what certifications do you hold? — CHENJI exports under ISO 9001; destinations on record include Southeast Asia, the EU and South America — [to-confirm] latest export-country list from VO.

Request a quotation

Send your specimen geometry, expected force / cycle envelope, and any standards you need to comply with. We will reply with a frame recommendation, fixture list and lead time within one working day.

Request a quotation: fill the contact form or email annie@chenjitester.com.