Definition
The high-low temperature, humid-heat alternating vibration three-integrated testing machine is a kind of test equipment used to simulate the performance of products under complex environmental conditions. It integrates three stresses: temperature, humidity and vibration, and conducts synchronous or sequential composite environmental tests on samples under controllable conditions to evaluate their reliability and adaptability under multi-factor coupling.
How it works:
The device is based on the principle of combining environmental simulation with mechanical excitation. The temperature control module realizes high temperature, low temperature and rapid temperature change through the refrigeration system and heating system. The humidity control module regulates the relative humidity in the chamber through the steam generation and condensation mechanism. The vibration module generates a specific frequency and amplitude of mechanical excitation by means of an electric or hydraulic shaker. The control system coordinates the modules to operate precisely according to the preset program, and its synergistic relationship can be expressed as:
Etotal = f(T, H, V, t)
where EtotalFor the comprehensive environmental effect, T is the temperature, H is the humidity, V is the vibration parameter, and t is the time variable.
Measurement method
A number of parameters need to be monitored during the test. Temperature measurement usually uses platinum resistance or thermocouple sensors, and is calibrated according to relevant standards. The humidity measurement mostly uses capacitive polymer thin film sensors, which are verified by the dry and wet bulb control method. The vibration parameters were collected by accelerometer and charge amplifier, and the frequency response and power spectral density were analyzed. The data acquisition system records the temporal changes of each parameter with a sampling rate of not less than 1Hz, and verifies the compliance of the test conditions through the environmental stress screening profile.
Influencing factors
The accuracy of test results is influenced by a variety of factors. In terms of equipment, performance parameters such as cavity uniformity, temperature change rate, and lateral motion ratio of vibrating table directly affect the accuracy of stress application. In terms of samples, the mass distribution, heat capacity and surface characteristics of the specimens will lead to local microenvironment differences. In terms of operation, sensor placement, sample mounting stiffness, and test profile design can have a significant impact on the results. The coupling effect of temperature gradient and vibration transfer function requires special attention.
Applications:
This equipment is widely used in the reliability verification of industrial products. In the field of electronic and electrical appliances, it is used to evaluate the connection reliability of circuit boards under the combined conditions of temperature and humidity cycling and vibration. In the auto parts industry, verify the durability of on-board equipment under simulated climate and road vibration; In the aerospace field, the performance stability of airborne equipment under the combined action of rapid temperature change and mechanical vibration is tested. In the field of materials science, the degradation mechanism of composites under the synergistic effect of damp-heat aging and mechanical fatigue is studied.
Key points of selection
When selecting a model, technical parameters and usage requirements should be comprehensively considered. The temperature range should cover the product storage and operating limits, with a typical range of -70°C to +150°C; Humidity ranges from 20%RH to 98%RH normally; The vibration system needs to meet the requirements of maximum load, frequency range and acceleration index. The volume of the cavity should be reserved for no less than three times the volume of the sample to ensure airflow circulation. The control system should have multi-stress synchronous programming capabilities and safety interlock functions. In terms of energy efficiency, the matching degree between cooling power and heat load should be evaluated, and the ease of maintenance should pay attention to the operability of seal replacement and vibration system calibration.