Design Of Temperature & Humidity Control System Of Temperature-Stress Test Machine

During a high-speed period of basic facility construction in China, large engineering quantity of concrete makes it much important to reduce and avoid concrete crazing. Measuring and evaluating concrete crazing sensitivity is first operative step to keep away from its cracks. The emergence of cracks is direct relation to temperature-stress, and the temperature change has the important influence to the structure-stress condition.In order to work out the temperature & humidity control system, aiming at the Temperature-Stress Testing machine temperature & humidity control system, summarize the domestic and foreign present researches, analyze the influence to the concrete anti-crazing caused by the changes of the temperature and the humidity, and adopt the research method which combined the theory and practice.Firstly introduce the basic control principle of the temperature & humidity and the development condition of the temperature-stress testing machine, narrate the research method and the present situation, the virtual instrument technology and the characteristics of the database software SQL Sever 2000. Then, according to the examination characteristic and method of the concrete temperature & humidity, put forward the whole plan of the temperature & humidity control system, including hardware plan and software plan.The hardware design is divided into two aspects: data acquisition and temperature & humidity control. Data acquisition is mainly made use of the signal-conditioning board and the data acquisition control card to realize multi-channel signal-conditioning and signal acquisition, temperature & humidity control aspect utilizes the temperature control template and the environment simulation box to realize the accommodation of temperature & humidity through executive implement drove by the control card, according to the experimental request.The software design is the key part of the system design, which based on LabVIEW development platform, includes data acquisition module, data processing and display module, control module, as well as some hardware drive procedure. Data acquisition module, which is made up of the initialization procedure, the parameter setting procedure and signal acquisition procedure, mainly accomplishes the acquisition of the temperature & humidity signal. Data processing and display module achieves the signal transform through weighted-average method, transfers database to realize data storage and inquiry, exactly displays the signal at the different time and the trend via the united way of the numeric display and the graph. Control module adopts PID arithmetic to realize the temperature & humidity adjustment.