1, we first understand the basic concepts of testing
Measurement refers to all operations that determine the value of the attribute value of the measured object.
Tests are tests that have experimental properties, or can be understood as a combination of measurements and tests.
2, test technology content and tasks
1) Content of test technology
The main contents of the test technology research are: measured principle, measurement method, measurement system and data processing.
The measurement principle refers to the physical, chemical, biological, etc. phenomena on which the measurement is based and the overall laws. For example, piezoelectric crystals measure vibration acceleration based on piezoelectric effect; eddy current displacement sensors measure static and vibration displacements based on electromagnetic effects; thermocouples measure temperature based on thermoelectric effects and so on. Measurements of different natures are measured using different principles. Measurements of the same nature can also be measured using different principles.
After the measurement principle is determined, different measurement methods such as direct measurement or indirect measurement, electrical measurement or non-electric measurement, analog measurement or digital measurement are required according to the specific requirements of the measurement task and the actual situation on the site. Method, equal precision or unequal precision measurement method.
After determining the measurement principle and measurement method to be measured, it is necessary to design or select the device composition measurement system.
The actual test data must be processed to obtain correct and reliable results.
2) The task of testing technology
Test technology tasks
The tasks of test technology mainly include the following five aspects:
(1) In the equipment design, through the model test or on-site measurement of new and old products, provide objective evaluation for product quality and performance, and provide basic data for optimization of technical parameters and improvement of efficiency;
(2) In the retrofit of equipment, in order to tap the potential of the equipment in order to increase the output and quality, it is often necessary to measure the load, stress, process parameters and motor parameters of the equipment or parts, so as to provide a basis for equipment strength verification and bearing capacity improvement;
(3) In the purification and monitoring of working and living environments, it is often necessary to measure the intensity and frequency spectrum of vibration and noise. After analysis, the source of vibration is identified, and corresponding vibration reduction and noise prevention measures are taken to improve working conditions and working environment. Guarantor's physical and mental health;
(4) The discovery of scientific laws and the birth of new laws and formulas are inseparable from the testing techniques. From the experiment, we can find the law, verify the theoretical research results, and experiment and theory can promote each other and develop together.
(5) In industrial automation production, through the testing of the process parameters and data acquisition, the status monitoring, quality control and fault diagnosis of the equipment are realized.
3, the composition of the test system
The test system refers to the overall function of acquiring some kind of information, which is composed of related devices, instruments and test devices. In order to accurately obtain the information of the measured object, it is required that there must be a one-to-one correspondence between the output amount and the input quantity of each link in the test system. Moreover, the change in its output can accurately reflect the change in its input, that is, to achieve an undistorted test.
Incentive device
The information of a measured object is always represented by a certain physical quantity-signal. Some of the information can be revealed in the physical quantity of the measured object when it is in its natural state, and some information cannot be displayed or displayed. In the latter case, it is necessary to act on the measured object through an excitation device so as to generate a new signal in which the information we want to obtain is contained.
sensor
A sensor is a device that converts measured information into some sort of electrical signal. It includes the sensor and the converter in two parts. Sensors generally convert measured signals such as temperature, pressure, displacement, vibration, noise, and flow into some kind of easily detectable signal, while converters convert this signal into something that is easy to transmit, record, and process. signal.
Conditioning session
The conditioning of the signal is to convert the signal from the sensor into a form that is more suitable for further transmission and processing. The conversion of such signals is mostly the conversion between electrical signals. If the amplitude is amplified, the change of the impedance is converted into a voltage change or a frequency change, and so on.
Signal display and recording
The signal display and recording link is to display or store the test results from the signal processing link in the form that the observer can easily observe.
4, the development trend of test technology
The development of advanced technologies is changing with each passing day, and testing technology should adapt to this development. According to the requirements of the development of advanced manufacturing technology and the development laws of the test technology itself, new measurement principles and test methods, as well as test information processing technologies, are constantly being developed.
Specific embodiment >>
In terms of mechanical engineering, test technology needs to be developed in the following areas:
1) Diversification of measurement methods
2) Visual Test Technology
3) The size continues to develop at two extremes
The development trend of test technology is embodied
(1) The development of sensors in the new, micro, and intelligent directions;
(2) The development of test instruments to high precision, multi-function, miniaturization, on-line monitoring, performance standardization and low price;
(3) Parametric measurement and data processing are computer-centric, which enables the automation, integration and network development of measurement, analysis, processing, printing, drawing, status display and fault prediction.
Diversification of measurement methods
1 Application of multi-sensor fusion technology in manufacturing sites Multi-sensor fusion is a method to solve measurement information acquisition in the measurement process, which can improve the accuracy of measurement information. Since multi-sensors acquire information in different ways or from different perspectives, information fusion between them can be used to eliminate false memories and improve measurement accuracy.
2 Building block type, combined measurement method Increase the flexibility of the test system to achieve the purpose of testing different targets at different levels.
3 portable measuring instruments such as portable optical interferometers, portable large-scale three-dimensional measurement systems, etc., used to solve large-scale measurement problems in the field.
4 Virtual Instrument Virtual instrument is the application of virtual reality technology in the field of precision testing. One is to virtualize a variety of digital test instruments into a digital intelligent test instrument supported by a computer; the other is to study virtual manufacturing. The virtual measurement in virtual measuring blocks, virtual coordinate measuring machines, etc.
5 Smart Structure It belongs to structure detection and fault diagnosis. It is an interdisciplinary discipline that integrates intelligent technology, sensing technology, information technology, bionic technology, and materials science, making the concept of monitoring transition to online, dynamic, active real-time monitoring and control.
Visual test technology
Visual testing technology is an emerging testing technology based on computer vision research. Different from visual pattern recognition, visual comprehension and other aspects of computer vision research, visual test technology focuses on the geometric dimensions of objects and the position measurement of objects, such as rapid measurement of three-dimensional surface shapes, coaxial measurement of large workpieces, coplanarity measurement, etc. . It can be widely applied to active and real-time measurement processes such as on-line measurement and reverse engineering.
Two extreme developments
The two extremes refer to the large size and small size relative to the current measurement size. The measurement of the usual size has been widely noted, and a variety of test methods have also been developed. In recent years, due to the rapid development of the national economy and the urgent need, the requirements for testing in production and engineering have exceeded the range we can test in many aspects, such as the measurement of aircraft profiles, the measurement of key components of large-scale machinery, and the guide rails of high-rise buildings. Collimation measurement and on-site calibration of tank trucks require large-scale measurements; the rapid development of microelectronics and biotechnology, the exploration of the needs of the microscopic world of materials, and the continuous improvement of measurement accuracy require micrometer and nanometer tests. Nanometers are also available in a wide variety of optical interferometers, quantum interferometers, capacitance micrometers, X-ray interferometers, frequency-following Fabry gauges, scanning electron microscopy (SEM), scanning tunneling microscopy (STM5, test technology). (Applications), Atomic Force Microscopy (AFM), Molecular Measurement Machine M3 (molecular measuring machine), etc.
Video on demand area:
Real-time automatic detection
Integrated monitoring system
Vibration and noise monitoring
Application in chemical industry
Application on lifting
Shaker
6, the test course learning requirements
Test technology is a comprehensive technology. Modern test systems are often a combination of electromechanical, hardware and software, and intelligent, automated systems. It involves many technologies such as sensing technology, microelectronic technology, control technology, computer technology, signal processing technology, and precision mechanical design technology. Therefore, test workers are required to have deep multidisciplinary knowledge, such as mechanics, electricity, signal processing, automatic control, mechanical vibration, computer, mathematics, and so on.
Test technology is also a branch of experimental science. Learning must be closely combined with theoretical study in order to obtain basic experimental skills training.
Through the study of this course, students are required to:
(1) Grasp the basic theory of test technology, including the time domain and frequency domain description methods of the signal, the principle and method of spectrum analysis and correlation analysis, signal conditioning and signal processing basic concepts and methods;
(2) Master the basic principles and applicable scope of various typical sensors and recording instruments;
(3) The overall design capability of the test system in terms of machines, electricity, and computers;
(4) With experimental data processing and error analysis capabilities.