Definition
Computerized tensile meter is a mechanical property testing instrument that integrates computer control and data acquisition system. It is mainly used to determine the mechanical properties of materials or components under static or quasi-static tensile, compression, peeling, tearing and other loads, such as maximum force value, elongation, elastic modulus, yield strength, etc. Through digitalization and automation technology, the instrument achieves high-precision control of the testing process and efficient analysis of results.
Principle
The core working principle of the computer tensile meter is based on the extension of Newton's second law and Hooke's law. The instrument usually consists of a mechanical loading unit, a force value sensor, a displacement sensor, and a computer control system. Mechanical loading units (such as servo motor-driven ball screws) provide controlled displacement or force; The force value sensor (usually strain gauge type) converts the force subjected to the specimen into an electrical signal; Displacement sensors, such as photoencoders, accurately measure the separation distance of the fixture or the deformation of the specimen. The computer system controls the loading process according to preset programs (such as constant speed stretching), collects and processes sensor signals in real time, and finally calculates the required mechanical parameters.
The relationship between stress (σ) and strain (ε) of a material in the elastic range is commonly described by the following linear models:
σ = E · ε
where E is the elastic modulus of the material.
Measurement method
Typical measurement methods for computerized tensile meters follow a standardized testing process. First, prepare a standard specimen according to relevant standards (such as ASTM, ISO, GB) and install it in the upper and lower fixtures to ensure alignment. Subsequently, the test parameters are set in the control software, including test speed, initial gauge distance, fracture judgment conditions, etc. After starting the test, the instrument applies a tensile load to the specimen at a constant rate while continuously recording force-displacement or stress-strain data. After the test, the software automatically analyzes the curve feature points, such as the proportional limit, yield point, maximum force point, and fracture point, and generates a test report containing key indicators. For tests such as peeling and tearing, the methods are similar, but the fixtures and results are interpreted differently.
Influencing factors
The accuracy and repeatability of measurement results are affected by a variety of factors. Specimen factors include material uniformity, preparation process, geometric size and shape compliance with standards. Instrument factors involve the calibration status of the force sensor, the coaxiality of the loading system, and whether the clamp is designed to prevent slippage or premature breakage. Environmental factors such as laboratory temperature and humidity can affect the performance of certain materials. Operating factors include specimen mounting neutrality, accurate marking of gauge gauge, and whether the test speed is set to meet standard requirements. Data processing factors, such as curve smoothing algorithms and feature point determination rules, also have an impact on the final result.
Applications
Computerized tensile meters have a wide range of applications. In the field of polymer materials, it is used to test the tensile strength and elongation at break of plastic films, rubber products, and composite materials. In the textile industry, it is used to determine the strength and elongation properties of fibers, yarns, and fabrics. In the packaging industry, it is used to evaluate the peel strength of adhesive tapes, the tensile strength of paper, and the compressive properties of packages. In the field of metal materials (e.g. filaments, foils), it can be used for the tensile performance test of foundations. In addition, in the electronic and electrical industry, it is also used for mechanical reliability testing of connectors and solder joints.
Selection considerations
When choosing a computerized tensile meter, a systematic evaluation is required. Start by defining the testing requirements, including the maximum force range of the material to be tested, the required accuracy, the test criteria, and the required accessories (e.g., different types of fixtures, environmental chambers). The force range of the instrument should cover the expected maximum force with an appropriate margin. The measurement accuracy must meet the requirements of relevant standards for laboratory instruments. The stability, ease of use and compliance with standard data processing capabilities of the control system and software are key. The mechanical properties of the instrument, such as rigidity and coaxiality, affect the accuracy of the test. In addition, consider the scalability of the equipment, such as the ability to integrate video extensometers or high-temperature furnaces, as well as the supplier's technical support and calibration service capabilities.