Jixie qiangdu (Jan 2021)
RESEARCH ON SHUTDOWN STRESS AND FATIGUE LIFE OF AIR CONDITIONING PIPING
Abstract
It is very important to determine the reasonable shutdown stress of air-conditioning piping,and it is related to the piping reliability and development cost. Firstly,the piping shutdown stress was studied through a large number of stress tests and statistical analysis methods. Then the piping shutdown fatigue life was calculated based on the force number and S-N fatigue life curve. Finally,the fatigue acceleration tests of pipe fitting under single part and complete machine assembly are carried out respectively. The results show that: The piping will be subjected to 2 ～ 3 stress shocks at the shutdown moment,the average number of shocks is 2. 6 times; The first impact stress is the largest,and the subsequent impact stress attenuates slightly;Vibration table and counterweight block can be used to generate stable stress impact,which can reach millions of times in a short time,and the component fatigue can be verified quickly; Piping bending will reduce the piping fatigue life,the operating pressure and temperature have little influence on pipe fatigue life,welding has little influence on piping,since there is a distance between the welded part and the bent part; In order to ensure the piping reliability under the limit state,the piping shutdown stress should be below 62 MPa.
