Electro-hydraulic servo vs electromagnetic resonance, how to choose a fatigue testing machine?

When selecting a fatigue testing machine, the most common confusion that purchasers encounter is: What is the difference between electro-hydraulic servo and electromagnetic resonance (also called electromagnetic resonance)?Why is it called a "fatigue testing machine" but the price is several times different?Choosing the wrong driver will not only cost you more, but may also lead to inaccurate test data and high equipment failure rates.This article will systematically compare the differences between two mainstream fatigue testing machines from the four dimensions of working principle, performance parameters, applicable scenarios, and maintenance costs to help you make the correct selection decision.

1. Working principles of the two driving modes

1.1 Electro-hydraulic servo fatigue testing machine

The electro-hydraulic servo fatigue testing machine is driven by a hydraulic servo system. The flow and direction of the hydraulic oil are controlled through the servo valve, and the actuator is driven to apply dynamic loads to the specimen.Its core components include hydraulic power source, servo valve, actuator, force sensor and control system.The advantages of the electro-hydraulic servo system are its large load capacity and flexible waveform control, which can realize a variety of loading waveforms such as sine waves, triangle waves, square waves, and random waves.

1.2 Electromagnetic resonance fatigue testing machine

The electromagnetic resonance fatigue testing machine (also known as electromagnetic resonance type) uses the principle of electromagnetic excitation to generate alternating electromagnetic force through electromagnets, which excites the mechanical system of the testing machine to resonate, and applies cyclic load to the sample in the resonance state.Its core components include electromagnetic exciters, resonant springs, mass blocks, force sensors and control systems.The advantages of the electromagnetic resonance type are high frequency, low energy consumption, and no hydraulic oil pollution, making it suitable for large-volume high-cycle fatigue testing.

2. Comparison of core performance parameters

3. Analysis of applicable scenarios

3.1 Scenarios where electro-hydraulic servo is preferred

• Heavy load test: Fatigue testing of metal components and large parts with test force exceeding 100kN

• Low cycle fatigue (LCF) testing: Needs 0.01Hz-10Hz low frequency large strain cycle test

• complicatedwaveformLoad: Fatigue testing requiring random spectrum, program blocks, and custom waveforms

• Multi-axis composite loading: Tension-torsion composite, biaxial and other complex stress state tests

• environmentcouplingtest: Fatigue testing under special environments such as high and low temperatures, corrosion, and high pressure

• Fracture mechanics testing: Crack growth rate, fracture toughness and other tests that require precise control

3.2 Prioritize electromagnetic resonance scenarios

• High cycle fatigue (HCF) testing: S-N curve testing of large quantities of metal materials requiring 10⁶-10⁸ cycles

• Small and medium load test: Fatigue test of standard specimens with test force below 200kN

• Production quality inspection scene: Rapid fatigue acceptance of batch products such as auto parts, fasteners, springs, etc.

• Laboratory environment is restricted: A laboratory without an independent hydraulic station room and with strict requirements on noise and oil pollution

• Sensitive to long-term operating costs: Users who have high equipment usage and want to reduce electricity bills and maintenance costs

4. Selection decision-making process

It is recommended to follow the following four steps to make selection decisions:

1. Step 1: Determine the test force range.Select the appropriate range based on the maximum fatigue load of the material or component being tested.If the maximum load exceeds 200kN, electro-hydraulic servo is almost the only choice; if it is below 100kN, both can be considered.

2. Step 2: Determine the operating frequency.If the test requires low-frequency large strain below 10Hz, choose electro-hydraulic servo; if high-frequency fast test above 50Hz is required, choose electromagnetic resonance.10Hz-50Hz is the crossover range between the two, which needs to be judged in conjunction with other factors.

3. Step 3: Confirmwaveformand environmental needs.If complex waveforms or special environmental coupling are required, priority will be given to electro-hydraulic servo; if only standard sine wave high-cycle fatigue is required, electromagnetic resonance efficiency will be higher.

4. Step 4: Evaluate the fulllife cycle cost.The purchase cost of electro-hydraulic servo is high and the maintenance cost is high; the purchase cost of electromagnetic resonance is moderate and the use cost is low.If the annual usage of the equipment exceeds 2,000 hours, the long-term cost advantage of electromagnetic resonance is obvious.

5. About Shandong Huayan Intelligent Equipment Group

Shandong Huayan Intelligent Equipment Group Co., Ltd. is located in Jinan, the main R&D base for testing machines in China. It is an enterprise integrating R&D, production and sales.The company's core team has 20 years of experience in the testing machine industry, specializing in the development and production of a full range of testing equipment such as electro-hydraulic servo fatigue testing machines, electronic universal testing machines, hydraulic universal testing machines, impact testing machines, pressure testing machines, torsion testing machines, etc., and can customize non-standard fatigue testing systems according to customer needs.

Huayan Intelligent Equipment's fatigue testing machine product line covers two technical routes: electro-hydraulic servo type and electromagnetic resonance type. It can provide professional selection suggestions and customized solutions based on customers' test materials, load range, frequency requirements and budget.The company has passed ISO9001 quality management system certification, participated in the formulation of more than ten industry group standards, and has 17 national patents. The group has Tianhua Metrology and Testing (Shandong) Co., Ltd., which can provide customers with full-chain services from equipment sales, installation and commissioning to measurement and calibration.

If you are purchasing a fatigue testing machine, please contact Shandong Huayan Intelligent Equipment. Our professional engineers will recommend the most suitable driving method and equipment configuration for you based on your actual testing needs.

6. FAQ

Q1: Electro-hydraulic servo fatigueTesting machineand electromagneticResonanceWhich fatigue testing machine is more accurate?

A: Within their respective optimal working ranges, the force value control accuracy of electro-hydraulic servo is usually higher (up to ±0.5%), and the accuracy of electromagnetic resonance near the resonance point can also reach ±1%.However, electro-hydraulic servo control accuracy has obvious advantages in low frequency bands and complex waveforms, and electromagnetic resonance testing is more efficient under high-frequency sine waves.

Q2: FatigueTesting machineIs the higher the frequency the better?

A: No.Frequency selection needs to match test requirements.High-cycle fatigue testing (more than 10⁶ cycles) is suitable for using high-frequency equipment to improve efficiency; low-cycle fatigue testing (10²-10⁴ cycles) requires low frequency and large strain, which high-frequency equipment cannot meet.Excessive frequency may also cause heating of the sample and data deviation. The appropriate frequency should be selected according to relevant test standards.

Q3: ElectromagneticResonancefatigueTesting machineCan we do high and low temperature environmental testing?

A: Yes, but there are certain restrictions.The electromagnetic resonance type can be used with high and low temperature environmental chambers, but since the resonance principle is sensitive to system mass and stiffness, the introduction of environmental devices may affect the resonance frequency and stability.For environmental coupling fatigue testing that requires precise temperature control and a large temperature range, the electro-hydraulic servo type has better compatibility.

Q4: Domestic fatigueTesting machineIs there a big gap with imported brands?

A: In recent years, domestic fatigue testing machine technology has made significant progress. In the field of electro-hydraulic servo type, domestic brands have been able to meet most industrial quality inspection and scientific research needs, and the price is only 1/3 to 1/2 of imported brands.In special fields such as ultra-high-end, ultra-high frequency, and multi-axis composite, imported brands (such as MTS, Instron, and ZwickRoell) still have technical advantages.Domestic high-quality brands can fully meet the routine fatigue testing needs of most enterprises.

Q5: FatigueTesting machineHow often do I need to calibrate?

A: According to the national metrological verification regulations JJG 556, fatigue testing machines are generally calibrated once a year, mainly calibrating force value, displacement and frequency parameters.If the frequency of use is high and the data accuracy is strict, it is recommended to calibrate it every six months.Calibration should be completed by a qualified measurement and testing institution. Tianhua Measurement and Testing Company, a subsidiary of Shandong Huayan Intelligent Equipment Group, can provide customers with convenient calibration services.