Zixin Wang

Bio: Zixin Wang is an academic researcher from Tongji University. The author has contributed to research in topics: Damper & Tuned mass damper. The author has an hindex of 5, co-authored 6 publications receiving 254 citations. Previous affiliations of Zixin Wang include Purdue University.

Particle impact dampers: Past, present, and future

Abstract: Particle damping, an effective passive vibration control technology, is developing dramatically at the present stage, especially in the aerospace and machinery fields. The aim of this paper is to provide an overview of particle damping technology, beginning with its basic concept, developmental history, and research status all over the world. Furthermore, various interpretations of the underlying damping mechanism are introduced and discussed in detail. The theoretical analysis and numerical simulation, together with their pros and cons are systematically expounded, in which a discrete element method of simulating a multi-degree-of-freedom structure with a particle damper system is illustrated. Moreover, on the basis of previous studies, a simplified method to analyze the complicated nonlinear particle damping is proposed, in which all particles are modeled as a single mass, thereby simplifying its use by practicing engineers. In order to broaden the applicability of particle dampers, it is necessary to implement the coupled algorithm of finite element method and discrete element method. In addition, the characteristics of experimental studies on particle damping are also summarized. Finally, the application of particle damping technology in the aerospace field, machinery field, lifeline engineering, and civil engineering is reviewed at length. As a new trend in structural vibration control, the application of particle damping in civil engineering is just at the beginning. The advantages and potential applications are demonstrated, whereas the difficulties and deficiencies in the present studies are also discussed. The paper concludes by suggesting future developments involving semi-active approaches that can enhance the effectiveness of particle dampers when used in conjunction with structures subjected to nonstationary excitation, such as earthquakes and similar nonstationary random excitations.

Studies on Seismic Performance of Precast Concrete Columns with Grouted Splice Sleeve

Abstract: In order to validate the seismic performance of precast concrete members with steel sleeve connections, pseudo-static tests on four prefabricated columns with vertical grouted splice sleeve connections and on a control group of two cast-in-situ columns have been conducted The test results indicated that the failure modes of the prefabricated columns and of the cast-in-situ columns are basically identical but differences exist in their crack distribution The cast-in-situ columns mainly crack horizontally at the bottom of the column, whereas the prefabricated columns have horizontal cracks above the sleeves, and then form diagonal cracks downwards and develop many wider cracks within the range of height of 300 mm at the bottom of the column The hysteresis curves of the prefabricated columns are plump, which demonstrates that prefabricated columns have satisfactory energy-dissipating capacity Moreover, the stiffness degradation of the prefabricated specimens is slower than that of the cast-in-situ specimens The ultimate displacement angle of the prefabricated columns is up to 1/104–1/54, which satisfies the requirements of the inter-story drift ratio during major earthquakes Finally, some recommendations on practical seismic design pertinent to the precast concrete members with grouted splice sleeves are proposed

Experimental Comparison of Dynamic Behavior of Structures with a Particle Damper and a Tuned Mass Damper

Abstract: This paper investigates the dynamic behavior of structures with a particle damper (PD) and a tuned mass damper (TMD) by shaking table tests and aeroelastic wind tunnel tests The influence

贝叶斯滤波与平滑 (Bayesian filtering and smoothing)

Abstract: Filtering and smoothing methods are used to produce an accurate estimate of the state of a time-varying system based on multiple observational inputs (data). Interest in these methods has exploded in recent years, with numerous applications emerging in fields such as navigation, aerospace engineering, telecommunications, and medicine. This compact, informal introduction for graduate students and advanced undergraduates presents the current state-of-the-art filtering and smoothing methods in a unified Bayesian framework. Readers learn what non-linear Kalman filters and particle filters are, how they are related, and their relative advantages and disadvantages. They also discover how state-of-the-art Bayesian parameter estimation methods can be combined with state-of-the-art filtering and smoothing algorithms. The book’s practical and algorithmic approach assumes only modest mathematical prerequisites. Examples include MATLAB computations, and the numerous end-of-chapter exercises include computational assignments. MATLAB/GNU Octave source code is available for download at www.cambridge.org/sarkka, promoting hands-on work with the methods.

Designs, analysis, and applications of nonlinear energy sinks

Abstract: Nonlinear energy sink (NES) is an appropriately designed nonlinear oscillator without positive linear stiffness. NES can suppress vibrations over a wide frequency range due to its targeted energy transfer characteristics. Thus, investigations on NES have attracted a lot of attention since a NES was proposed. Designs, analysis, and applications of NESs are still active since different configurations are needed in various practical circumstances. The present work provides a comprehensive review of state-of-the-art researches on NESs. The work begins with a survey of the generation of a NES and its important vibration control characteristics. The work highlights possible complex dynamics resulting in a NES coupled to a structure. The work also summarizes some significant design on the implements of optimal damping effects and the offsets of NES shortcomings. Then, the work details the applications of NESs in all engineering fields. The concluding remarks suggest further promising directions, such as NESs for multidirectional vibration reduction, NESs with nonlinearities beyond the cubic, potential deterioration caused by a NES, low-cost NESs, NESs for extremely low frequency range, and NESs integrated into active vibration controls. There are 383 references in the review, including some publications of the authors.

A state-of-the-art review on the vibration mitigation of wind turbines

Abstract: Wind energy as one of the renewable energies is serving as an indispensable role in generating new electric power. The worldwide installation of wind farms has considerably increased recently. To extract more wind resources, multi-megawatt wind turbines are usually designed and constructed with large rotors and slender tower. These flexible structures are susceptible to external dynamic excitations such as wind, wave and seismic loads. The excessive vibrations can compromise the wind energy conversion, lead to the structural fatigue damage and even result in the catastrophic failure of wind turbines in harsh environmental conditions. Various control devices have been proposed and used to mitigate the unwanted vibrations of wind turbines to enhance their safety and serviceability. This paper aims to provide a state-of-the-art review of the current vibration control techniques and their applications to wind turbines. Firstly, the widely used control strategies in engineering structures are briefly introduced. Their applications to suppress the adverse vibrations of the structural components of wind turbines, mainly the tower and blades, are then reviewed and discussed in detail. It can be concluded that the vibration mitigation of wind turbines is very challenging due to the fact that the dynamic behaviours of wind turbines are very complicated, which are associated with the aerodynamics, rotation of the blades, interaction between the tower and rotating blades, and soil-structure interaction, etc. Moreover, it is a challenge to straightforwardly use many of the conventional control devices because of the limited spaces in the tower and blades.