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首页> 外文会议>Annual Symposium on Quantitative Nondestructive Evaluation; 19980719-24; Snowbird,UT(US) >COMPOSITE-CONCRETE INTERFACE CHARACTERIZATION BY LAMB WAVES
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COMPOSITE-CONCRETE INTERFACE CHARACTERIZATION BY LAMB WAVES

机译：羔羊波对复合混凝土界面的表征

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In recent years, significant attention is being paid to the nation's dilapidated infrastructure. Examples of such structures include buildings that need to be retrofitted to resist seismic loads, bridges that must be strengthened to carry heavier traffic loads and concrete water and sewer pipes that have deteriorated due to corrosions. In most of these cases, the capacity of these structures can be increased by the introduction of additional tension-carrying materials. While steel has been traditionally used for such applications, fiber reinforced plastic (FRP) materials have been increasingly replacing steel in the last decade. The high tensile strength and corrosion resistance of FRPs make them an ideal substitute for steel. FRP plates can be epoxy bonded to the tension face of concrete beams, for example, to increase the flexural capacity of these members significantly. Masonry and concrete walls can be similarly strengthened and there are reported field applications of these techniques to buildings damaged in recent earthquakes. The success of such construction depends in large part on the bond between the FRP plates and the concrete substrate. Thus, there is great need for development of nondestructive testing methods that could easily identify defects in the bond line. Ultrasonic techniques have become one of the most popular nondestructive testing techniques because of their versatility and ease of operation. They can easily detect internal cracks and inclusion type defects in homogeneous or layered materials. However, they have their own shortcomings. They cannot penetrate very deep inside a highly attenuative material. Fibers in the FRP plate scatter away the ultrasonic energy and the epoxy resins used for the matrix material are very attenuative. Hence, these materials are difficult to inspect by ultrasonic signals if the transducers are used in the conventional frequency range (1 to 10 MHz). Only relatively low frequency ultrasonic waves can propagate through these materials. In this research relatively low frequency (below 1 Mhz) transducers are used to inspect the delamination between the concrete and the composite plate. Both longitudinal and Lamb waves are generated and used in this investigation. Although the use of longitudinal or P-waves for detecting internal defects in a material is not new, it is new for this particular application, i.e. for detecting delamination between concrete and FRP plate.
机译：近年来，人们对该国残旧的基础设施给予了极大的关注。这种结构的例子包括需要翻新以抵抗地震荷载的建筑物，必须加固以承受更大交通荷载的桥梁以及由于腐蚀而恶化的混凝土水和下水道。在大多数情况下，这些结构的能力可以通过引入附加的承力材料来增加。尽管传统上将钢用于此类应用，但在过去的十年中，纤维增强塑料（FRP）材料已越来越多地替代钢。 FRP的高拉伸强度和耐腐蚀性使其成为钢的理想替代品。可以将FRP板环氧树脂粘结到混凝土梁的张紧面上，例如，以显着增加这些构件的抗弯能力。可以类似地增强砖石和混凝土墙，并且据报道，这些技术在最近地震中受损的建筑物上的现场应用。这种结构的成功很大程度上取决于FRP板和混凝土基材之间的粘结。因此，非常需要开发可以容易地识别键合线中的缺陷的非破坏性测试方法。超声波技术因其多功能性和易操作性，已成为最受欢迎的无损检测技术之一。他们可以轻松地检测均匀或分层材料中的内部裂纹和夹杂物类型的缺陷。但是，它们有自己的缺点。它们不能穿透高度衰减材料内部的很深的区域。 FRP板中的纤维会散射掉超声波能量，并且用于基体材料的环氧树脂具有很强的衰减性。因此，如果换能器在常规频率范围（1至10 MHz）中使用，则这些材料很难通过超声波信号进行检查。只有相对较低频率的超声波才能传播通过这些材料。在这项研究中，使用相对较低频率（低于1 Mhz）的传感器来检查混凝土和复合板之间的分层。纵向波和兰姆波均会生成并用于此研究中。尽管使用纵波或P波检测材料中的内部缺陷并不是什么新鲜事，但对于这种特殊应用（例如，检测混凝土和FRP板之间的分层）而言，这是新的。

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