This paper introduces integral resonant control, IRC, a simple, robust and well-performing technique for vibration control in smart structures with collocated sensors and actuators. By adding a direct feed-through to a collocated system, the transfer function can be modified from containing resonant poles followed by interlaced zeros, to zeros followed by interlaced poles. It is shown that this modification permits the direct application of integral feedback and results in good performance and stability margins. By slightly increasing the controller complexity from first to second order, low-frequency gain can be curtailed, alleviating problems due to unnecessarily high controller gain below the first mode. Experimental application to a piezoelectric laminate cantilever beam demonstrates up to 24 dB modal amplitude reduction over the first eight modes.

http://iopscience.iop.org/article/10.1088/0964-1726/16/2/023/pdf

Integral resonant control of collocated smart structures

Many composite materials and structures are susceptible to defects, which can significantly reduce the strength of structures and may grow to failure. To avoid the catastrophic failure of structures, development of a reliable method of structural health monitoring is one of the most important keys in maintaining the integrity and safety of structures. Dynamic response-based damage detection offers a simple procedure as an alternative to the conventional nondestructive evaluation techniques. However, this technique depends on the quality of measured data for its identification accuracy. In this article, experimental aspects of dynamic response-based damage detection technique on carbon/ epoxy composites are addressed. Smart piezoelectric materials are used as sensors or actuators to acquire the curvature modes of structures. These materials are surface-bonded to the beams. An impulse hammer is used as an actuating source as well. Four types of damage detection algorithms are evaluated for several possible ...

Experimental Damage Identification of Carbon/Epoxy Composite Beams Using Curvature Mode Shapes:

Structural dynamics of microsystems—current state of research and future directions

Vibration of beams with arbitrary discontinuities and boundary conditions

A combined analytical and experimental study is conducted to develop efficient and effective damage detection techniques for beam-type structures. Unlike many other vibration-based damage detection...

Improved Damage Detection for Beam-type Structures using a Uniform Load Surface

This paper presents a theoretical analysis of the application of piezoceramic transducers to cantilever beam modal testing. Four pairs of sensors and actuators, including accelerometer - point force, accelerometer - PZT, PVDF - point force and PVDF - PZT, are considered. The frequency response functions (FRFs) for the four pairs of sensors and actuators are first derived and written in the conventional modal format. The characteristics of modal parameters can thus be interpreted through the FRFs. A column of the FRF matrix can then be obtained based on the theoretical formulation. A curve-fitting algorithm is then applied to extract the modal parameters, such as natural frequencies, mode shapes and damping ratios. Results show that any sensor - actuator pair can successfully determine natural frequencies and damping ratios. Point types of transducer result in the displacement mode shapes, while piezoceramic transducers that are strip types and distributed in sense give the mode shapes of the slope difference between the edges of piezoceramic transducers. The paper provides the theoretical basis of applying piezoceramic transducers to experimental modal analysis and numerically supports the feasibility of cantilever beam modal testing using piezoceramic transducers.

https://iopscience.iop.org/article/10.1088/0964-1726/6/1/013/pdf

Feasibility analysis of using piezoceramic transducers for cantilever beam modal testing

Analysis of three-roller continuous and synchronous calibration process of straightness and ovality for large thin-walled pipes considering the weld

Straightening is an important process in the production and application of shafts, tubes, and various profiles. According to the springback theory of small curvature plane bending, the pure bending process and springback of in-plane curved beam with symmetrical section were analyzed, and the over-bend straightening theory was established. Based on this, the straightening mechanism of the existing over-bend straightening process was revealed; that is, a zigzag straightening moment was applied in the three-point multi-step straightening process to approximate the smooth curve of theoretical moment, while the multi-point one-time straightening technology was to discretize the theoretical curve using the broken line, so both of them needed a load correction coefficient to compensate the error between the actual load and theoretical calculation. In order to realize the complete loading of theoretical curve, a new technology of three-roll continuous straightening was further proposed and the experimental equipment for shafts and tubes was built. In order to match the characteristics of a pipe section, an accurate moment calculation equation was established. Three-roll continuous straightening experiments of the tube showed that the straightness of the straightened workpiece could be controlled within 1.5‰, which meets the standard requirements. Therefore, it is suggested that the over-bend straightening theory can predict the load required for straightening in-plane curved parts with any symmetrical cross-section, and the three-roller continuous straightening process is an efficient and highly accurate straightening technique.

/pdf/pure-bend-and-over-bend-straightening-theory-for-in-plane-674r7k0i.pdf

Chung-Chei Wang

Papers

Feasibility analysis of using piezoceramic transducers for cantilever beam modal testing

Analysis of three-roller continuous and synchronous calibration process of straightness and ovality for large thin-walled pipes considering the weld

Pure-Bend and Over-Bend Straightening Theory for In-Plane Curved Beams with Symmetrical Section and Straightening Mechanism Analysis