Definition
The electronic universal testing machine is a general equipment that tests the static mechanical properties of materials or components through an electronic control system. It can perform mechanical tests in various modes such as tensile, compression, bending, and shear, and is widely used in quality control and R&D in materials science, construction engineering, automobile manufacturing, aerospace, packaging materials, and textiles. The core feature of this equipment is that it uses a servo motor to drive the ball screw to generate load, and measures the force value and deformation in real time through high-precision sensors, and the data is collected and analyzed by the computer system.
Principle
The working principle of the electronic universal testing machine is based on mechanical balance and electrical measurement technology. The system is mainly composed of a loading frame, a servo drive unit, a force sensor, a displacement encoder and control software. After the servo motor receives the control signal, it drives the ball screw to rotate through the reduction mechanism, driving the beam to move and applying a load to the specimen. A force sensor mounted on a beam or base converts the mechanical signal into an electrical signal, while a displacement encoder measures the distance the beam travels or directly the specimen deformation via an extensometer. These signals are transmitted to the computer by the data acquisition card, and the software calculates parameters such as stress, strain, and elastic modulus according to preset programs. Its fundamental mechanical relationship follows the expression of Hooke's law in the elastic range: σ = Eε, where σ is the stress, E is the elastic modulus, and ε is the strain.
Measurement method
The measurement method of the electronic universal testing machine is determined according to the test standard and the type of specimen. Common tests include tensile tests, compression tests, and three-point bend tests. Taking metal tensile testing as an example, usually according to ASTM E8 or ISO 6892 standards, the standard specimen is clamped in the upper and lower clamps, the movement speed of the beam is set, and the equipment continues to apply axial tension until the specimen breaks after starting. During the process, the load-displacement curve is synchronously recorded, and converted into the stress-strain curve through the original cross-sectional area and gauge of the specimen. For non-metallic materials such as plastics or rubber, it may be necessary to use an extensometer to measure the deformation within the gauge directly to improve strain measurement accuracy. The compression and bending test is carried out by replacing the clamp and support device, and adjusting the loading direction and mode.
Influencing factors
The accuracy of test results is influenced by multiple factors. Equipment factors include the calibration status of the force sensor, the response speed of the drive system, the neutrality of the fixture, and the frequency of data acquisition. Environmental factors such as laboratory temperature and humidity can affect material properties and sensor stability. Specimen factors include machining quality, dimensional tolerances, clamping methods, and strain rate control. Operational factors involve the understanding of test standards, software parameter settings, and data processing methods. For example, differences in the movement speed of the beam can lead to changes in strain rate, which may affect the yield strength and fracture behavior of the material. Therefore, following standardized operating procedures and performing regular equipment calibration are the basis for ensuring data reliability.
Applications
The application of electronic universal testing machine covers many industrial and scientific research fields. In the metal material industry, it is used to measure tensile strength, yield point, elongation after break, and other indicators. In the field of polymer materials, it is often used to analyze the toughness, creep properties and stress relaxation behavior of plastics. In building materials testing, the compressive and flexural strength of concrete, reinforcement and composite materials can be evaluated. The automotive industry uses it for component durability testing, such as mechanical verification of seat belts, springs, and plastic components. In addition, the equipment also plays a role in material property characterization and quality control in the research and development of packaging materials, textiles, wires and cables, and composite materials.
Selection considerations
When selecting, it is necessary to comprehensively evaluate the technical parameters and actual needs. Load capacity is the primary indicator, and the appropriate range should be selected according to the expected maximum force value of the specimen, usually with a certain margin. The size of the test space should be adapted to the size of the specimen and the installation of the fixture. The accuracy level refers to the resolution of the force value and the error of the value, and the accuracy of the general force value is not less than ±0.5% of the value. The displacement velocity range should cover the test rate specified by the relevant standard. Versatility considers whether the device supports multiple test modes and expansion capabilities, such as accessory interfaces such as high-temperature chambers and video extensometers. Software features need to meet data acquisition, analysis, and report generation requirements and meet applicable standards. In addition, equipment rigidity, ease of maintenance, and supplier technical support are also considerations for long-term use.