The tensile testing machine, or universal material testing machine, is a key equipment used to determine the mechanical properties of materials under tensile, compression, bending, shear, and other states. Its core principle is to apply a controllable force to the specimen and measure the deformation of the specimen simultaneously, so as to obtain key parameters such as stress-strain curve, tensile strength, yield strength, elastic modulus, etc. According to the different power sources and force measurement methods, modern tensile testing machines are mainly divided into two categories: electronic and hydraulic. The two technology paths differ significantly in structure, performance, and application.
Electronic tensile testing machine
Electronic testing machines usually use servo motors to drive ball screws or timing belt drives to generate testing force. The force value measurement relies on high-precision strain gauge load sensors. The control system precisely controls the movement of the motor through closed-loop feedback, allowing for precise control of loading speed and force. The formula for calculating the force value is usually based on the relationship between the sensor output signal and the calibration factor:F = k × V, among themFforce value,kFor the calibration coefficient,VOutput voltage signal to the sensor. The electronic testing machine has the advantages of compact structure, low noise, no hydraulic oil pollution, high control accuracy, and easy to achieve complex program control (such as holding and circulating).
Hydraulic tensile testing machine
The hydraulic testing machine uses hydraulic oil as the power transmission medium to apply the test force by driving the cylinder piston movement through the hydraulic pumping station. Force measurement can be achieved by means of a pressure sensor (oil pressure measurement) or a load sensor. The force value provided is usually large and the system stiffness is high. Under constant loading rate, the stability of the force value is better. Its basic principle is based on Pascal's law, the force generated by the cylinderF = P × A, among themPfor oil pressure,Ais the effective area of the piston. The main feature of the hydraulic testing machine is that it can generate a very large test force relatively conveniently, and has an application basis in large load and long stroke tests.
Performance comparison and selection considerations
Choosing between electronic or hydraulic is a combination of testing needs, budget, and laboratory conditions. The following table compares the typical characteristics of the two from multiple dimensions.
| Contrast dimensions | Electronic tensile testing machine |
| Force value range | Usually in the range of low to medium force values (e.g. Newtons to hundreds of kiloNewtons) |
| Loading rate control | High control accuracy, wide rate range, good low-speed performance |
| Measurement accuracy | Load and deformation measurement resolution is usually high |
| Equipment structure | The structure is relatively compact and has a small footprint |
| Operation and maintenance | Daily maintenance is simple, no need for hydraulic oil replacement |
| Applicable test types | It is suitable for complex tests such as precision tensile, compression, peeling, cyclic loading, etc |
| operating environment | Clean, no risk of oil stains, and low noise levels |
| Acquisition cost | There may be some advantages within the conventional force value range |
| Contrast dimensions | Hydraulic tensile testing machine |
| Force value range | Easy to achieve large loads (up to a few trillions of Newtons or more) |
| Loading rate control | It is stable under constant load, but it is relatively complex to implement complex speed change procedures |
| Measurement accuracy | Accuracy depends on system configuration, and high-precision system costs increase |
| Equipment structure | Hydraulic pumping stations are required, and the overall footprint is usually large |
| Operation and maintenance | Hydraulic fluid and seals need to be checked and replaced regularly |
| Applicable test types | Suitable for static tensile, compression, and bending tests with large loads and long strokes |
| operating environment | There is a potential risk of oil leakage, and there is some noise in the operation of the pumping station |
| Acquisition cost | In the large tonnage sector, it may be cost-effective |
Suggestions for selection and decision-making paths
Decision-making should begin with a clear analysis of the testing needs: first determine the maximum force value, specimen size and required stroke for the routine test; Secondly, the requirements of the test standard for loading rate control accuracy and data acquisition frequency are clarified. Furthermore, consider whether complex modes such as fatigue testing and stress relaxation are required. For laboratories with force requirements below 300kN and requirements for control accuracy, cleanliness and versatility, such as testing metal wires, polymer materials, textiles, small parts, etc., electronic type is a common choice. For areas that need to test large load samples such as concrete components, large metal structural parts, and cables, the hydraulic type can better meet their force value and space requirements. At the same time, the power configuration, space layout, maintenance capacity and long-term operating costs of the laboratory should also be taken into account.
Summary
Electronic and hydraulic tensile testing machines are technical solutions for different application scenarios, and there is no absolute difference between advantages and disadvantages. The electronic version stands out for precision, control flexibility and environmental friendliness, while the hydraulic type has traditional advantages in terms of high-load output. The core of selection is to match the technical characteristics of the equipment with the standard requirements of the material to be tested and the actual conditions of the laboratory. It is recommended to consult relevant material testing standards (such as ASTM, ISO, GB, etc.) in detail before making a decision, and obtain samples for actual testing and verification as much as possible to ensure the effectiveness of the investment.
References
1. ASTM E4, Standard Specification for Verification of Test Force Values.
2. ISO 7500-1, "Verification of Static Uniaxial Testing Machine for Metal Materials Part 1: Verification and Calibration of Force Measurement System for Tensile/Pressure Tester Force".
3. "Mechanical Properties Test of Materials", textbooks and technical manuals for related industries in China.