The Research Of Computer Measuring And Controlling System For Hydraulic Universal Testing Machine

The researches on computer control hydraulic universal testing machine are today's main hot spot in domestic and foreign testing machine fields. In this paper, based on mastering a lot of dynamic information of testing machine, researching the computer control technology applied to testing machine, a computer measuring and controlling system for hydraulic universal testing machine has been developed. The system has been successfully applied to a 300kN testing machine improvement in the Central Laboratory of Mechanical Engineering, Zhejiang University of Technology. What's more, with ShangHai ShenLian testing machine factory, microcomputer control hydraulic universal testing machine is developed. They can meet the control requirements of stress rate and strain rate in the international standard ISO 6892:1998(E) and the national standard GB228-2002. In practical application, they acquire good results.The follows are the main works of the paper.1. The sensors applied in the measuring and controlling system are studied. Design of structure and size of large range extensometer and improvement on its type of fastening are thoroughly discussed.2. The application of the PID control is researched. On the basis of classic PID control and fuzzy control, fuzzy adaptive PID control is designed, which is applied in testing machine for stress, strain and displacement control.3. Developing a software for the testing machine measuring and controlling system. The software can automatically switch control mode according to standard in the process of tensile testing and automatically judge constitutive mode of material. At the same time, it can automatically measure elastic modulus E, yield strength o s, proof strength, non-proportional extention o 0.2, percentage extention 8 , tensile strength o b, etc. It can applied in industry practice.