中文摘要：

研究了复合圆管的管间界面特性对周向超声导波二次谐波发生效应所产生的影响.在二阶微扰近似条件下,将周向超声导波传播过程中的非线性效应视为其线性波动响应的一个二阶微扰.采用界面弹簧模型对复合圆管的管间界面特性进行描述.根据导波的模式展开分析方法,伴随基频周向超声导波传播所发生的二次谐波可视为由一系列二倍频周向导波模式叠加而成.管间界面特性的变化可从多个方面对二倍频周向导波模式的展开系数及声场产生影响,尤其是界面特性的变化所引起的周向超声导波相速度的改变,将显著地影响到二次谐波随传播周向角的积累增长程度.理论及数值分析结果表明,周向超声导波的二次谐波发生效应随管间界面特性的改变而发生非常敏感的变化,可将其用于准确定征复合圆管的管间界面性质.

英文摘要：

The influences of the interfacial properties on second-harmonic generation by primary circumferential ultrasonic guided wave（CUGW） propagation in a composite tube are investigated in this paper. Within a second-order perturbation approximation, the nonlinear effect of primary CUGW propagation may be treated as a second-order perturbation to its linear response. Due to the interfacial spring model, the properties of interface between the inner and outer circular tubes constituting the composite tube are characterized by the normal and tangential interfacial stiffness values. According to the technique of modal expansion analysis for waveguide excitation, the second-harmonic field of primary CUGW propagation can be decomposed into a series of double frequency CUGW modes. It is found that changes of the interfacial properties of composite tube will obviously influence the efficiency of second-harmonic generation by primary CUGW propagation. Specifically, for a given composite tube with a perfect interface, an appropriate fundamental and double frequency CUGW mode pair that satisfies the phase velocity matching condition can be chosen to enable the double frequency CUGW mode generated by the primary CUGW propagation to accumulate along the circumferential direction, and an obvious second-harmonic signal of primary CUGW propagation to be observed. When the changes of the interfacial properties of composite tube（versus the perfect interface with infinite interfacial stiffnesses） take place, the effect of second-harmonic generation by primary CUGW propagation will be influenced in the following aspects. Firstly,the changes of the interfacial properties in the case of perfect interface may provide different acoustic fields for the primary CUGW. This will influence the magnitude of the modal expansion coefficient of double frequency CUGW mode generated, because both the second-order bulk forcing source（due to the double frequency bulk driving force） and the second- order surface/interface forcing source（due