Study on the integrity detection and evaluation method of damaged pipeline
To detect the integrity of damaged pipeline and accurately evaluate its damaged condition, a CCD image data guided digital automatic ultrasonic testing system was designed to realize the dynamic measurement of a pipeline damaged surface, and extract the characteristic parameter of damaged pipeline. Based on the three-dimensional discrete point set which gathered to describe the integrity of damaged pipeline, we establish a damaged pipeline entity model which is closer to the actual condition, analyze and simulate mechanical properties under the actual load by using the numerical simulation software (ABAQUS), to get the most dangerous region and the trend of stress and displacement. This method provides more reliable reference for integral safety analysis and evaluation of damaged pipeline.
Finite element analysis and experimental research on the buried pipelines in case of uneven settlement of the building foundation
This paper is dedicated to the study of the stress of buried pipelines to find the regularity of the pipeline-soil interaction under the foundation of uneven settlement through finite element analysis In DOIng our research, we have adopted electrical measurement method to monitor the mechanical behavior of the buried pipelines in case of uneven settlement of the building foundation.As is known, buried pipelines are the material basis of urban survival and development.A considerable number of buried pipelines are laid down over the soft soil underground basis of a non-linear and uneven settlement, making the mechanical analysis complicated.Actually, high-stress areas of pipelines were found in the intersection connecting the pipelines on the surface as well as the buried pipelines.Therefore, it would take four months to complete a circle of successful monitoring work of the pipelines.The test results have shown that the stress of the buried pipelines tends to become greater and greater with the uneven settlement of foundation, which indicates that the pipeline-laying stress seems to be greatly influenced by the uneven settlement of the foundation. However, when the mechanical behavior of the buried pipelines in the case of the foundation uneven settlement was analyzed by using numerical simulation and emulation software ABAQUS, it proves possible to gain the uneven settling amount of the foundation needed in the finite element analysis from the test.Furthermore, the initial conditions of the finite element analysis turn out to be in accordance with the experiment.The results of finite element analysis also prove to be in conformity with the experimental results except for the place of pipeline with portiforium and fluid impact.In addition, we have also analyzed the influential factors of the buried pipelines stress.The results show that the main factor of the fluctuation of pipes stress comes from the vibration of the internal pressure.But the vibration of internal pressure was not the main factor of the pipeline-soil interaction. Deformation modulus and position ratio, which serve as the main factors of the pipeline-soil interaction, have actually little influence on the piping stress.Thus, the paper has developed a stress analysis and numerical simulation method of the stress of buried pipelines in case of uneven settlement on the basis of our research work in hoping to provide an excellent technical support for the mechanical analysis and safety evaluation of buried pipeline stress.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.