A vibration amplifier is first proposed for adding to a test vehicle to enhance its capability to detect frequencies of the bridge under scanning. The test vehicle adopted is of single-axle and modeled as a single degree-of-freedom (DOF) system, which was proved to be successful in previous studies. The amplifier is also modeled as a single-DOF system, and the bridge as a simple beam of the Bernoulli–Euler type. To unveil the mechanism involved, closed-form solutions were first derived for the dynamic responses of each component, together with the transmissibility from the vehicle to amplifier. Also presented is a conceptual design for the amplifier. The approximations adopted in the theory were verified to be acceptable by the finite element simulation without such approximations. Since road roughness can never be avoided in practice and the test vehicle has to be towed by a tractor in the field test, both road roughness and the tractor are included in the numerical studies. For the general case, when the amplifier is not tuned to the vehicle frequency, the bridge frequencies can better be identified from the amplifier than vehicle response, and the tractor is helpful in enhancing the overall performance of the amplifier. Besides, the amplifier can be adaptively adjusted to target and detect the bridge frequency of concern. For the special case when the amplifier is tuned to the vehicle frequency, the amplifier can improve the vehicle performance by serving as a tuned mass damper, as conventionally known. This case is of limited use since it does not allow us to target the bridge frequencies. Both bridge damping and vehicle speed are also assessed with their effects addressed.

中文翻译：

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用于在桥梁上行驶的测试车辆的自适应放大器：理论研究

首先提出了一种振动放大器，用于添加到测试车辆中，以增强其检测扫描中桥梁频率的能力。所采用的测试车辆是单轴的，并被建模为单自由度（DOF）系统，这在之前的研究中被证明是成功的。放大器也被建模为单自由度系统，电桥被建模为伯努利-欧拉类型的简单梁。为了揭示所涉及的机制，首先针对每个组件的动态响应以及从车辆到放大器的传递性推导出了封闭形式的解决方案。还介绍了放大器的概念设计。在没有这种近似的情况下，通过有限元模拟验证了理论中采用的近似是可以接受的。由于道路不平整在实践中是无法避免的，并且在现场测试中测试车辆必须由拖拉机牵引，因此道路不平整和拖拉机都包含在数值研究中。为了一般情况，当放大器是未调整相对于车辆频率而言，从放大器中识别桥频比车辆响应更好，拖拉机有助于提高放大器的整体性能。此外，放大器可以适应性地调整为目标并检测关注的电桥频率。为了特殊情况当放大器是调谐对于车辆频率，放大器可以通过用作调谐质量阻尼器来提高车辆性能，如传统所知。这种情况的用途有限，因为它不允许我们以桥接频率为目标。还评估了桥梁阻尼和车辆速度，并解决了它们的影响。