Definition
Servo tensile testing machine is a kind of equipment that uses servo motors as the power source to apply controllable static or dynamic loads such as tension, compression, bending, shearing and other static or dynamic loads to materials or components through a precision control system, and synchronously and accurately measure their mechanical property parameters. It belongs to the category of material testing machine, which is widely used in industrial quality inspection, scientific research and development, teaching experiments and other fields, and is a key instrument for evaluating the mechanical behavior of materials.
Principle
The core working principle of the servo tensile testing machine is based on closed-loop servo control and high-precision sensing technology. The system is driven by a servo motor to drive a precision ball screw or similar drive mechanism to drive the movement of the moving beam, thereby exerting force on the specimen mounted between the fixtures. During the test, the force sensor detects the applied force value in real time, while the encoder or displacement sensor simultaneously measures the displacement of the beam or the deformation of the specimen. These signals are transmitted to the controller, which is compared to user-set target values such as stress rate, strain rate, or displacement rate, and closed-loop control is formed by adjusting the output of the servo motor, ensuring that the test process strictly follows the preset procedures.
Its control modes mainly include displacement control, force control and strain control. The fundamental mechanical relationship follows classical theories such as Hooke's law, for example, in the elastic range, the relationship between stress (σ) and strain (ε) can be expressed as:σ = E × ε, where E is the elastic modulus of the material.
Measurement methods and processes
A typical measurement process begins with the preparation of the specimen, which is processed into the specified shape and size according to relevant standards (e.g. ASTM, ISO, GB, etc.). Mount the specimen in the upper and lower fixtures and ensure alignment. The test parameters are then set in the control software, including test type, control mode, rate and termination conditions. After starting the test, the device is loaded according to the program and collects force, displacement, and deformation (if using an extensometer) data synchronously. The software plots curves in real time, such as stress-strain curves. After the test, the system automatically calculates and reports key performance parameters such as maximum force, tensile strength, yield strength, elongation at break, and modulus of elasticity.
Influencing factors
The accuracy and repeatability of the measurement results are affected by multiple factors. In terms of specimens, the preparation process, geometry, surface state and uniformity of the material itself form the basis. Equipment factors include the calibration status and range selection of the force sensor, the clearance and coaxiality of the transmission system, and the response speed and stability of the control system. Environmental conditions such as ambient temperature and humidity may affect the performance of certain materials and the operation of equipment. The operating process is also critical, such as the appropriate selection of the fixture, the neutral installation of the specimen, the correct installation and calibration of the extensometer, and the compliance of the test rate settings.
Main application areas:
The application of servo tensile testing machine covers many industrial and scientific research fields. In the metal material industry, it is used to test the strength and plasticity of wires, rods, and plates. In the polymer and plastics industry, it is used to evaluate the tensile and tear properties of films, tubes, and composites. In the field of textile fibers and ropes, it is used to determine the breaking strength of monofilaments, yarns, and fabrics. In the rubber and elastomer industry, it is used to test tensile strength and permanent deformation. In the field of building materials, it is used to evaluate the mechanical properties of steel bars, concrete components, and geosynthetics. In addition, in electronic products, it is also used for strength testing of connectors, solder joints, and adhesive joints.
Key points to consider in selection
Choosing the right servo tensile testing machine is a systematic work. The primary consideration is the force range and accuracy, which covers the maximum force value of the material to be measured and leaves a margin, while paying attention to the accuracy level of the sensor. The second is the test space, that is, the effective stroke and width between the fixtures, which need to adapt to the size of the specimen and possible future needs. The stiffness and coaxiality of the frame of the device can affect the accuracy of the test, especially for high-strength or high-modulus materials. The control mode should meet the requirements of the relevant test standards for rate control. Fixtures are important accessories that need to be selected or customized according to the shape and material properties of the specimen. Software features should support required test standards, provide comprehensive data analysis and report generation, and be highly scalable. In addition, it is necessary to consider the long-term stability of the equipment, the convenience of maintenance, and the technical support and service capabilities of the supplier.