The Study On Acoustic Emission Characteristic Parameters And Damage Model During Metal Material Damage Process

In the metal structures or components nondestructive testing, the use of acoustic emission technology can achieve real-time monitoring, so as to discover more early cracks initiation, position and its extension, and can exactly find injured parts and damage degree. But because the acoustic emission is more sensitive to external factors, so it’s critical to do studies on acoustic emission characteristics of metal structures or components at real engineering stress states for effective qualitative analysis and quantitative analysis. This paper, based on acoustic emission testing technology, has studied on acoustic emission characteristics of metal specimens in two stress states, tensile and bending, and established the metal material damage model based on research results of acoustic emission characteristics. The followings are the primary contents:(1) Author studied acoustic emission properties of standard plate specimen tensile failure, with taking into account two material types, cast iron and Q235steel, respectively. In order to obtain acoustic emission characteristics under different external factors (different material types and different stress states), acoustic emission characteristic parameter, association chart and spectrum are analysed for three specimens of Q235steel (no precast gap,8mm and12.5mm length precast gap).(2) Typical tensile specimens of Q235steel are tested for the damage location. The results show that, not only does it meets with positioning precision, but also can,to some extent, respond some characteristics of the acoustic emission sources.(3) Acoustic emission characteristics of beam specimens of Q235steel for three point bending have researched, considering three specimens (no precast gap,15mm and25mm length precast gap) of acoustic emission characteristic parameter analysis, association chart analysis and spectrum analysis under different external factors.(4) On the basis of study on the acoustic emission characteristics, the metal meterial damage model is established by choosing acoustic emission accumulated rings as the referenced parameters and a verifying test is given. The experimental result indicates that the damage model established for metal material damage quantitative is accurate.