关键词: 管道, 断裂, 应力, 强度, 实验室试验

Abstract: In view of the speciality of displacement and strain fields around crack tip,the test procedure of sticking film moire interferometry has been introduced into the measuring of fracture parameters for pressurized piping.With the theory of wavefront interference,equations representing the displacement and strain in piping surface has been obtained.Measuring theory of fracture parameters has also been examined.It is found that the measuring results obtained by sticking film moire interferometry become sensitive to rigid boby movements due to the existence of piping curvature.Furthermore,when the curvature and the area to be measured are big enough,the effects of rigid boby movements to the measuring results may not be eliminated even the symmetric incident light path is adopted.To increase the measuring accuracy,some improvements on experimental techniques of sticking film moire interferometry have been made,some supplementary devices relating to the cutting,fixing,and sticking of the film are devised.Moreover,a software of measured data processing is developed.With the improved sticking film moire interferometry,the displacement field,strain field,strees intensity factor,crack opening displacement and J-intergral around the axial through crack tips of three pipings are measured.It is showed that the measured stress intensity factor and crack opening displacement are approximate to the theoretical solutions based on "D-M" model,value of J-integral in plastic region around crack tip varies as the integral path,and as the integral path come near the elastic region,J-integral value decreases to the theoretical solution.

Key words: piping, fracture, stress, strength, laboratory testing