Application of dynamic fatigue testing machines in automobile manufacturing: test standards, specimen requirements and selection guide

1. Dynamic fatigue testing machine - the core equipment for automobile manufacturing quality control

In the automobile manufacturing industry, the fatigue life of components is directly related to the safety and reliability of the vehicle.Dynamic fatigue testing machineAs the core equipment for evaluating the durability performance of materials under cyclic loads, it has become a standard equipment in the laboratories of automobile OEMs and parts suppliers.Produced by Shandong Huayan Intelligent Equipment Group Co., Ltd.Electronic servo tension and compression fatigue testing machine(20KN, frequency 0.1-20Hz adjustable) andElectro-hydraulic servo dynamic fatigue testing machineseries, widely used in fatigue performance verification of automobile body structural parts, chassis parts, fasteners and other products.

This article will systematically sort outDynamic fatigue testing machineThe test standards, sample requirements, test methods and selection precautions in the automobile manufacturing scenario are important for automobile manufacturing enterprises.Fatigue testing machine selectionProvide professional references.

2. Commonly used test standards in automobile manufacturing scenarios

2.1 Basic standards for fatigue testing of metallic materials

2.2 Specific standards for the automotive industry

• QC/T 1037-2016"Metal Materials for Automotive Fatigue Test Methods": The core specification of the automotive industry requires the use of road spectrum loads to conduct working condition simulation fatigue tests to more realistically simulate the load changes when the car is driving.
• T/CSTM 00790.2-2022"Thin Steel Plate for Automobiles Part 2: Axial Force Controlled Fatigue Test Method": A dedicated fatigue test method for thin steel plates (thickness 0.5-2.5mm) used in automobile bodies.
• GB/T 47315-2026"Road Simulation Bench Test Method for Vehicle Structural Durability": A newly released standard in 2026 that stipulates the axle coupling and wheel coupling test methods for vehicle structure durability.
• ISO 16750 series: International standard for environmental reliability testing of road vehicles.

3. Sample requirements

3.1 Axial fatigue specimen (GB/T 3075)

• Shape size: The diameter of the gauge section is 6~10mm, and the length is ≥3 times the diameter; the clamping part should be coaxial with the axis of the specimen.
• surface quality: The surface roughness of the gauge section is Ra≤0.8μm, and there are no surface defects such as scratches and burrs.
• Batch consistency: The same batch of specimens should have the same shape, size and surface condition.
• Quantity requirements: Prepare at least 3 to 5 samples for each set of tests (one for each different stress level, used to draw the S-N curve).

3.2 Automobile thin steel plate specimen (T/CSTM 00790.2)

For automotive thin steel plates with a thickness of 1.0~2.5mm, the recommended uniform gauge section specimen size is:

• Test section width w = (1~3)t (t is plate thickness)
• Parallel segment length Lp = (1~3)w
• Fillet radius r = (3~10)t
• For thin plates with a thickness less than 1mm, attention should be paid to the time-displacement curve jitter problem during testing.

3.3 Weldment specimens

• The weldment sample must include the weld and heat-affected zone to simulate the actual welded joint.
• Can be referencedISO 18592:2009Perform multi-point welding and multi-axial specimen fatigue testing (thickness range 0.5-5mm).

3.4 Automobile structural parts/component samples

• Chassis swing arms, control arms and other parts can be referred toSAE J1099Perform standardized fatigue life testing.
• Before testing, non-destructive testing (magnetic particle testing or ultrasonic testing) should be performed on the sample to ensure that there are no initial defects.

4. Test method

4.1 Stress control method (high cycle fatigue)

• Control method: Constant amplitude stress cycle to determine fatigue life.
• stress ratio: Commonly used are R=0.1 (pull-pull) and R=-1 (completely reverse).
• frequency selection: Select according to material and sample size, generally 10-100Hz to avoid sample heating.
• Termination condition: The sample breaks or reaches a predetermined number of cycles (usually 10^7 times).

4.2 Strain control method (low cycle fatigue)

• Control method: Constant amplitude strain cycle, suitable for scenarios with a large total strain range.
• Applicable standards: GB/T 15248, ASTM E606.
• Specimen type: Equal cross-section specimen (strain ≤ 2%) or funnel-shaped specimen (strain > 2%).

4.3 Road spectrum load simulation method

• The road load data (road spectrum) collected by the actual vehicle is used to replace the constant amplitude load.
• Real working conditions such as bumpy road impacts and cornering lateral loads are simulated through program block loading.
• It is closer to the actual use scenario of the car and is the test method recommended by QC/T 1037.

4.4 S-N curve measurement

Using a combination of group method and lifting method:

• Group method: Test 3-5 specimens each under 3-5 stress levels to obtain the median fatigue life.
• Lifting method: Determine the fatigue limit, adjust the stress level step by step, and obtain the fatigue limit under the specified life through statistical analysis.

5. Precautions for model selection

5.1 Load range matching

• Automobile body sheet parts: usually within 10KN, optionalElectronic servo fatigue testing machine.
• Chassis structural parts, subframe: 50-200KN, optionalElectro-hydraulic servo fatigue testing machine.
• Large components of axles and frames: more than 200KN, requiring large tonnageElectro-hydraulic servo dynamic fatigue testing machineOr a multi-channel coordinated loading system.

5.2 Frequency range confirmation

• High cycle fatigue test (10^7 cycles): High frequency model (≥50Hz) is required to shorten the test cycle.
• Low cycle fatigue test: low frequency is enough (0.1-10Hz), focusing on strain control accuracy.
• Shandong HuayanElectronic servo tension and compression fatigue testing machineThe frequency range is 0.1-20Hz, suitable for medium and low frequency fatigue testing with small and medium loads.

5.3 Waveforms and control modes

• Must support sine wave, triangle wave, square wave and other waveforms.
• Both stress control and strain control modes need to be supported.
• High-end requirements should support program block spectrum loading (road spectrum simulation).

5.4 Fixture and tooling customization capabilities

• Auto parts have different shapes, requiring manufacturers to have the ability to customize fixtures.
• Shandong Huayan can according to customer needsCustomized products, providing supporting tooling design for one customer, one solution.

5.5 Data collection and reporting

• The equipment should have real-time load, displacement, and strain data collection functions.
• Supports automatic S-N curve drawing and fatigue limit calculation.
• The test report must comply with GB/T 2611 and the corresponding national standard requirements for material testing.

6. Shandong Huayan dynamic fatigue testing machine product recommendations

Shandong Huayan Intelligent Equipment Group Co., Ltd. is a national high-tech enterprise focusing onFatigue testing machineR&D and production for many years.For the automobile manufacturing industry, the following products are recommended:

• 20KN electronic servo tension and compression fatigue testing machine: Test space 0-300mm, displacement resolution 0.01mm, amplitude range adjustable 0-100mm, frequency 0.1-20Hz, supports sine wave, triangle wave and other waveforms, suitable for fatigue testing of automobile thin plates and small parts.
• HYYL-4000 multi-oil circuit dynamic hydraulic loading system: Large-tonnage electro-hydraulic servo fatigue testing machine, suitable for fatigue testing of large structural parts such as axles and frames.
• Six-channel axle fatigue test bench: Multi-channel coordinated loading to simulate the actual stress conditions of the axle.

Fatigue testing machines are supplied directly from the manufacturer and can be customized on demand.

Consultation hotline: 13465928815

Company official website: www.huayantest.cn