This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Adaptive Control

Adhesion and Adhesives Edited by Dr. R. Houwink and Dr. G. Salomon. Vol. 1: Adhesives. Second, completely revised edition. Pp. xvi + 548. (Amsterdam, London and New York: Elsevier Publishing Company, 1965.) 135s.

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Adhesion and Adhesives

A review of finite element analysis of adhesively bonded joints

A comprehensive survey of the analytical, numerical and experimental methodologies for dynamics of multibody mechanical systems with clearance or imperfect joints

A general methodology for dynamic modeling and analysis of multibody systems with multiple clearance joints is presented and discussed in this paper. The joint components that constitute a real joint are modeled as colliding bodies, being their behavior influenced by geometric and physical properties of the contacting surfaces. A continuous contact force model, based on the elastic Hertz theory together with a dissipative term, is used to evaluate the intrajoint contact forces. Furthermore, the incorporation of the friction phenomenon, based on the classical Coulomb’s friction law, is also discussed. The suitable contact-impact force models are embedded into the dynamics of multibody systems methodologies. An elementary mechanical system is used to demonstrate the accuracy and efficiency of the presented approach, and to discuss the main assumptions and procedures adopted. Different test scenarios are considered with the purpose of performing a parametric study for quantifying the influence of the clearance size, input crank speed, and number of clearance joints on the dynamic response of multibody systems with multiple clearance joints. Additionally, the total computation time consumed in each simulation is evaluated in order to test the computational accuracy and efficiency of the presented approach. From the main results obtained in this study, it can be drawn that clearance size and the operating conditions play a crucial role in predicting accurately the dynamic responses of multibody systems.

https://repositorium.sdum.uminho.pt/bitstream/1822/23520/1/6.7.22%202010.pdf

A parametric study on the dynamic response of planar multibody systems with multiple clearance joints

Clearance is inevitable for assembly and mobility in the kinematic joints of mechanisms. Excessive value of this clearance leads to poor operational characteristics, and these result in losses in kinematic and dynamic performances of mechanism. In this study, effects of joint clearances on vibration and noise characteristics of mechanism are investigated. An experimental test rig has been set up, and a planar slider-crank mechanism having two joints with clearance has been used as a model mechanism. Joint clearance is modeled as a massless virtual link and continuous contact mode between journal and bearing in joint connection is considered in theoretical analyses. Three accelerometers and two microphones have been located at different points to measure the vibrations and noises on system during the mechanism motion. The results obtained for the cases with and without joint clearance are evaluated for vibration and noise characteristics of mechanism.

Experimental investigation of joint clearance effects on the dynamics of a slider-crank mechanism

Determining link parameters using genetic algorithm in mechanisms with joint clearance

As a result of design, manufacturing and assembly processes or a wear effect, clearances are inevitable at the joints of mechanisms. In this study, dynamic response of mechanism having revolute joints with clearance is investigated. A four-bar mechanism having two joints with clearance is considered as a model mechanism. A neural network was used to model several characteristics of joint clearance. Kinematic and dynamic analyses were achieved using continuous contact mode between journal and bearing. A genetic algorithm was also used to determine the appropriate values of design variables for reducing the additional vibration effect due primarily to the joint clearance. The results show that the optimal adjusting of suitable design variables gives a certain decrease in shaking forces and their moments on the mechanism frame.

Investigation on effect of joint clearance on dynamics of four-bar mechanism

In this paper, a dimensional synthesis method for a four-bar (4R) path generator mechanism having revolute joints with clearance is presented. Joint clearances are considered as virtual massless links. The proposed method uses a neural network (NN) to define the characteristics of joints with clearance with respect to the position of the input link, and a genetic algorithm (GA) to implement the optimization of link parameters using an appropriate objective function based on path and transmission angle errors. Training and testing data sets for network weights are obtained from mechanism simulation, and Grashof’s rule is used during the optimization process as constraint. The results show that the proposed method is very efficient for the purpose of modeling the joint variables and also adjusting the link dimensions to optimize planar mechanisms with clearances.

Selçuk Erkaya

Papers

Experimental investigation of joint clearance effects on the dynamics of a slider-crank mechanism

Determining link parameters using genetic algorithm in mechanisms with joint clearance

Investigation on effect of joint clearance on dynamics of four-bar mechanism

A neural-genetic (NN-GA) approach for optimising mechanisms having joints with clearance

Effects of joint clearance on the dynamics of a partly compliant mechanism: Numerical and experimental studies