U.S.-Australia Cooperative Science: Development of Force-Frequency Shifting for Low Frequency Structural Vibrations Testing

该奖项支持宾夕法尼亚州立大学的Martin Trethewey教授和澳大利亚维多利亚州莫纳什大学的Leonhard Koss教授之间为期三年的合作研究项目。本项目将开展用于低频结构振动测试的力频移(FFS)技术的研究。民用和建筑结构的实验振动测试已被证明有助于健康评估和为有问题的设施开发减振器。这些目标系统的特点是：1)低固有频率，2)大质量，3)高阻尼。这些条件为试验性的模态测试或主动控制应用创造了一套严格的振动激励规范。振动激励问题源于在低固有频率下产生高幅值力的固有困难。本研究的目的是开发和评估一种新的低频振动激励技术，最终适用于民用、建筑和重型机械结构的振动激励。通过机械调制过程，将高效产生的高频激励力的分量移位到低频。正是这种移位的低频激励信号才是本文研究的重点。该项目汇集了两个拥有互补专业知识和研究能力的实验室的努力。大型系统振动测试的价值已经形成了提供与许多不同问题有关的有价值信息的可靠记录。这方面的研究将有助于评估桥梁结构健康、建筑物人员可接受性、风激励运动、隔震性能和敏感设施(如医用核磁共振设备)的楼板振动。该项目通过研究生和本科生的参与促进国际人力资源的发展。通过思想和技术的交流，这个项目将扩大我们的基础知识基础，促进国际理解与合作。研究结果将发表在国际科学期刊上，并将在美国和国外的科学会议上公布。

0115593TretheweyThis award supports a three year collaborative research project between Professor Martin Trethewey of the Pennsylvania State University and Professor Leonhard Koss of Monash University in Victoria, Australia. This project will undertake a study of the development of Force Frequency Shifting (FFS) for low frequency structural vibrations testing. Experimental vibration testing of civil and architectural structures has proven helpful in health assessment and in developing vibration absorbers for troublesome facilities. These target systems are characterized by having 1) low natural frequencies, 2) large mass, and 3) high damping. These conditions create a demanding set of vibration excitation specifications for experimental modal testing or active control applications. The vibration excitation problem stems from the inherently difficulty in creating high amplitude forces at low natural frequencies. The goal of the research is to develop and evaluate a novel low frequency vibration excitation technique ultimately suitable for vibration excitation of civil, architectural, and heavy machinery structures. Through a mechanical modulation process, a component of an efficiently generated high frequency excitation force is shifted to a low frequency. It is this shifted low frequency excitation signal that is the focus of this research. The project brings together the efforts of two laboratories that have complementary expertise and research capabilities. The value of vibration testing of large-scale systems has developed a proven track record of delivering valuable information in relation to a number of varied issues. Research in this are could assist in the assessment of bridge structural health, building occupant acceptability, wind excited motion, earthquake isolation performance and floor vibration for sensitive installations such as medical MRI equipment. The project advances international human resources through the participation of graduate and undergraduate students. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. Results of the research will be published in international scientific journals and will also be presented at scientific meetings in the U.S. and abroad.