Rapid freeze-thaw (FT) cycles were adopted to explore the damage deterioration mechanism and mechanical properties of sandstone specimens under the coupling effects of different chemical solutions and FT cycles. The variation regularities of the FT cycles and physical and mechanical properties of sandstone specimens immersed in different chemical solutions were analyzed by using sandstone sampled from a Chinese riverbank slope. The damage variable based on porosity variation was used in the quantitative analysis of the damage to the sandstone under the coupling effects of chemical corrosion and FT cycles. Experimental results showed that the sandstone specimens weakened substantially under those effects. Their fracture toughness K IC , splitting tensile strength, and compressive strength showed a similar deteriorating trend with various numbers of FT cycles. However, a difference exists in the deterioration degree of their mechanical parameters, i.e., the deterioration degree of their fracture toughness K IC is the greatest followed by that of splitting tensile strength, and that of compressive strength is relatively small. Strong acid solutions may aggravate the deterioration of FT damage in sandstones, but at the early stage of the experiment, strong alkaline solutions inhibited sandstone damage deterioration. However, the inhibiting effect disappeared when the number of FT cycles exceeded 25. The different chemical solutions had a different effect on the FT damage degree of the sandstone specimens; for example, SO 4 2-ions had a greater effect on FT damage than did HCO 3 -ions. Water-chemical solutions and FT cycles promote each other in deteriorating rocks and simultaneously affect the damage deterioration degree of sandstones.

No abstract

The propagation behaviour of Lamb waves in the functionally graded piezoelectric-piezomagnetic material plate with material parameters varying continuously along the thickness direction is investigated in this paper. The power series technique is employed to solve these variable coefficient ordinary differential equations. Dispersion equations are given for different boundary conditions. In numerical examples, the influence of the variation of each parameter on dispersion curves and cut-off frequency in electrically and magnetically open cases is discussed in detail. Results show that the elastic parameters and density varying along the thickness direction obviously influence the variation of phase velocity. Some variations in electric and magnetic parameters also affect the phase velocity but the influence is too small, while others almost cannot affect the dispersion curves. Cut-off frequency is closely related to two elastic parameters and to density, whereas other parameters almost cannot influence it. All the results can provide theoretical guidance not only for the analysis and design of a magnetoelectric transducer using functionally graded materials, but also for ultrasonic nondestructive evaluation.