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In order to determine whether asphaltenes dissolved in certain solvents, the Hansen solubility parameters (HSPs) of asphaltenes and maltenes extracted from SZ36-1 vacuum residual were measured, and a new parameter Δδ tn was obtained by extending the HSP based on the results of asphaltene dissolution experiments. Δδ tn was calculated by the relative differences of the components of HSP between asphaltene and the solvent. The rationality of the Δδ tn was verified from three aspects: the selection of solvent that can dissolve asphaltene, dispersion of asphaltene in various solvents, and compatibility of asphaltenes and maltenes, which further proved that asphaltenes might be dissolved in maltenes. The Δδ tn can be well used to judge whether asphaltene can dissolve in a certain solvent.

No abstract

Quantification of damage sizes in cylindrical structures such as pipes and rods is of paramount importance in various industries. This work proposes an efficient damage quantification method by using a dry-point-contact (DPC) transducer based on the non-dispersive torsional waves in the low-frequency range. Theoretical analyses are first carried out to investigate the torsional wave interaction with different sizes of defects in cylindrical structures. A damage quantification algorithm is designed based on the wave reflections from the defect and end. Capitalizing on multiple excitations at different frequencies, the proposed algorithm constructs a damage image that identifies the geometric parameters of the defects. Numerical simulations are conducted to validate the characteristics of the theoretically-predicted wave-damage interaction analyses as well as the feasibility of the designed damage quantification method. Using the DPC transducer, experiments are efficiently carried out with a simple physical system. The captured responses are first assessed to confirm the capability of the DPC transducer for generating and sensing torsional waves. The sizes of the defects in two representative steel rods are then quantified with the proposed method. Both numerical and experimental results demonstrate the efficacy of the proposed damage quantification method. The understandings of the wave-damage interaction and the concept of the damage quantification algorithm lay out the foundation for engineering applications.